Winston H. Hickox

Secretary for 

Environmental 

Protection

Gray Davis

Governor 

FIELD EVALUATION OF 

UNDERGROUND STORAGE TANK SYSTEM 

LEAK DETECTION SENSORS

August 2002 

State Water Resources Control Board 

Underground Storage Tank Program 

P.O. Box 944212 

Sacramento, CA 94244 

www.swrcb.ca.gov/cwphome/ust/

This document was prepared by the following 

State Water Resources Control Board staff: 

Shahla Dargahi Farahnak, P.E., Senior Water Resources Control Engineer 

Scott Bacon, Sanitary Engineering Technician 

Raed Mahdi, Water Resources Control Engineer 

The following State Water Resources Control Board staff 

assisted in the collection and tabulation of field data:

Eric Luong, Engineering Student Assistant 

Jennifer Redmond, Student Assistant 

Raul Barba, Engineering Student Assistant 

Special thanks to all the regulatory agency inspectors who responded 

to our survey and worked with our staff in the field. 

Thanks to the following individuals for their contributions in reviewing this document: 

Mark Barolo, United States Environmental Protection Agency 

Curt Johnson, Alabama Department of Environmental Management 

Mike Kadri, Michigan Department of Environmental Quality 

John Kneece, South Carolina Department of Health and Environmental Control 

Marcel Moreau, Marcel Moreau Associates 

Norwood Scott, United States Environmental Protection Agency 

Tim Smith, United States Environmental Protection Agency, Region 9 

Laura Chaddock, State Water Resources Control Board 

Liz Haven, State Water Resources Control Board 

Erin Ragazzi, State Water Resources Control Board 

Michael Sahlin, State Water Resources Control Board 

Barbara Wightman, State Water Resources Control Board

Thanks to the following service companies for working with our staff in the field: 

Afford-a-Test Scott Co. 

AllStar Service Station Systems 

Champion Precision Tank Testing Tait Environmental 

Contract Environmental Services Tank-Tek 

Ehlert Petro Maintenance Tanknology 

Gettler-Ryan, Inc. Tri-State Environmental 

Orange County Tank Testing, Inc Triangle Environmental 

R.L. Stevens Vesco 

Sales West Maintenance & Construction 

Funding for this field evaluation was provided in part by the 

United States Environmental Protection Agency

TABLE OF CONTENTS

EXECUTIVE SUMMARY ...........................................................................................................................................1 

INTRODUCTION.........................................................................................................................................................3 

SCOPE OF WORK .......................................................................................................................................................5 

OBJECTIVES OF THE FIELD EVALUATION....................................................................................................................5 

FACILITY SELECTION PROCESS...................................................................................................................................5 

SCHEDULING AND COORDINATION.............................................................................................................................7 

DATA COLLECTION PROCESS .....................................................................................................................................8 

LIMITATIONS OF DATA COLLECTION..........................................................................................................................9 

UST SENSOR FIELD EVALUATION SURVEY..............................................................................................................10 

DATA ANALYSIS ......................................................................................................................................................10 

FINDINGS ..................................................................................................................................................................16 

A. SENSOR DESIGN AND PERFORMANCE ...............................................................................................................16 

B. SECONDARY CONTAINMENT PERFORMANCE AND COMPLIANCE ISSUES...........................................................18 

C. OVERSIGHT AND QUALIFICATIONS ...................................................................................................................19 

D. SENSOR FIELD-CERTIFICATION AND TESTING PROCEDURES ............................................................................20 

E. MAINTENANCE AND PROGRAMMING ................................................................................................................21 

F. DISCRIMINATING SENSORS...............................................................................................................................22 

G. OTHER OBSERVATIONS NOT RELATING TO SENSORS .......................................................................................24 

RECOMMENDATIONS.............................................................................................................................................25 

A. SENSOR DESIGN AND PERFORMANCE ...............................................................................................................25 

B. SECONDARY CONTAINMENT PERFORMANCE AND COMPLIANCE ISSUES...........................................................26 

C. OVERSIGHT AND QUALIFICATIONS ...................................................................................................................26 

D. SENSOR FIELD-CERTIFICATION AND TESTING PROCEDURES ............................................................................27 

E. MAINTENANCE AND PROGRAMMING ................................................................................................................27 

F. DISCRIMINATING SENSORS...............................................................................................................................28 

CONCLUSION ...........................................................................................................................................................30 

APPENDICES.............................................................................................................................................................33 

APPENDIX I SUMMARY OF PHASE I TESTING (VEEDER-ROOT DISCRIMINATING SENSORS) 

APPENDIX II WORKPLAN FOR THE FIELD EVALUATION

APPENDIX III LOCATION OF FACILITIES INVOLVED IN THE FIELD EVALUATION

APPENDIX IV FIELD DATA COLLECTION FORMS

APPENDIX V SENSOR SURVEY DISTRIBUTION LETTER, SURVEY FORM, RESULTS, AND COMMENTS

APPENDIX VI FIELD DATA

APPENDIX VII DISCUSSION OF POINT LIQUID AND POLYMER STRIP DISCRIMINATING SENSORS

EXECUTIVE SUMMARY

State Water Resources Control Board (SWRCB) staff have been conducting a comprehensive 

evaluation of the effectiveness of underground storage tank (UST) and piping systems, and 

associated leak detection equipment. The evaluation includes: a field-based research project to 

determine the frequency and source of releases from single and double-walled UST systems, a 

field evaluation of automatic tank gauges and automatic line leak detectors, a survey of statistical 

inventory reconciliation service providers, and a field evaluation of leak detection sensors. This 

report contains the findings of the field evaluation of leak detection sensors, which are the 

primary form of leak detection in double-walled UST systems. California’s UST population 

currently consists of roughly 75% double-walled systems, making sensor performance a key 

element in the detection of leaks from UST systems statewide. The importance of sensors will 

only increase as older single-walled systems are phased out of service and replaced by doublewalled systems. 

Leak detection sensors are typically located in tank interstitial spaces, piping sumps, underdispenser containment, and monitoring wells within excavation liners. They may also be located 

in groundwater monitoring wells or soil-vapor monitoring wells surrounding the tank system, 

although no such facilities were included in this field evaluation. California regulations require 

that all leak detection equipment be functionally tested and certified by an authorized service 

technician on an annual basis. This report was based largely on data collected from 789 sensors 

at 124 UST facilities during routine annual testing and certification. Also discussed in this report 

are 71 responses to an on-line survey on sensor performance, completed by service technicians 

and inspectors. It is important to note that federal regulations and other state UST programs do 

not require annual certification of monitoring equipment. One may assume that the sensor 

performance problems identified in this field evaluation would be significantly more common if 

California did not require the annual certification of monitoring equipment. 

Federal and California regulations require that leak detection equipment be evaluated by an 

independent third-party testing organization in accordance with recognized protocols. However, 

these evaluation protocols are designed only to test sensor functionality in a laboratory setting. 

The objective of this field evaluation was to assess sensor functionality under field conditions. 

We also set out to determine the adequacy of annual certification testing procedures, and to 

determine whether sensors in the field perform in a manner consistent with the specifications 

outlined in their third-party evaluations. 

The data collected in this field evaluation demonstrate that sensors can be a reliable form of leak 

detection only when properly installed, programmed, maintained, and operated. Most problems 

observed in this field evaluation are due to improper installation and programming of sensors, 

poor or infrequent maintenance at UST facilities, ignoring alarms, and tampering with monitoring 

equipment. Poor design, construction, and maintenance of secondary containment systems were 

also common. Additionally, sensor design and materials played a role in some of the failures 

observed. 

 

SWRCB 1 August 2002 
Findings - Effective performance of sensors is also dependent upon the performance of the 

secondary containment in which they are installed. Therefore, this report’s findings are 

presented in two categories: sensor performance and secondary containment performance. 

Sensor Performance - Approximately 12% of sensors had one or more problems at the time 

of testing. The most common problems observed were sensors raised from the low point of 

the secondary containment, sensors failing to alarm when tested, and sensors failing to shut 

down the turbine pump in the event of an alarm (when programmed to do so). 

Secondary Containment System Performance - Problems with the performance of secondary 

containment were more common than problems with sensors. Secondary containment must 

be kept clean and dry in order for sensors to perform properly; however, water was found in 

over 10% of secondary containment systems. Liquid product was present in an additional 

3.5% of systems. Overall, 31% of the facilities visited in this field evaluation had water or 

product in one or more areas of the secondary containment system. 

Recommendations - Based on the findings of this field evaluation, we propose the following 

recommendations to improve sensor performance and the effectiveness of leak detection 

programs based on the use of sensors: 

1. Periodic inspection and functional testing of sensors and secondary containment are essential 

to reliable performance. California currently requires annual certification of monitoring 

equipment, and triennial integrity testing of all secondary containment. The United States 

Environmental Protection Agency (U.S. EPA) and states not currently requiring annual 

certification of monitoring equipment and periodic testing of secondary containment should 

consider implementing such requirements. 

2. Sensor manufacturers should continue to refine sensor design and field testing procedures. 

Sensors must be designed to reliably operate under the conditions found within the secondary 

containment of an UST. Field testing procedures should involve functional testing of the 

sensor, and should accurately determine the ability of the sensor to detect a release. 

3. Standard third-party evaluation protocols for sensors should be revised to better reflect 

operating conditions found in the field. SWRCB UST program staff has been active in the 

efforts of the National Workgroup on Leak Detection Evaluations to improve the evaluation 

and review process. 

4. Regulatory agencies should call for more thorough training of personnel who install, service, 

and operate UST leak detection systems. A recent California statute requires training for 

these individuals, and the SWRCB is currently developing regulations to implement a 

training standard statewide.

5. Regulatory agencies must have authority to take enforcement action against UST owners and 

operators who tamper with leak detection equipment. The SWRCB has proposed legislation 

that would grant regulators administrative enforcement authority, and allow them to “redtag” facilities that are significantly out of compliance. 

 

SWRCB 2 August 2002 
INTRODUCTION 

Secondary containment for most UST systems has been required in California since January 1, 

19841

. These “double-walled” systems employ liquid sensors in the interstitial space of UST 

components, the space between the inner and outer wall of the component. Sensors are designed 

to detect the presence of liquid in the interstitial space, providing the primary (and often only) 

form of leak detection in double-walled UST systems. Therefore, their reliable performance is a 

critical factor in preventing the release of hazardous substances into the environment. 

To comply with regulations and provide the most effective leak detection, sensors should be 

installed at the low point of the secondary containment [i.e., at the bottom of the tank interstice, 

in turbine sumps (where liquid from leaks in double-walled piping will collect), and in underdispenser containment (where under-dispenser leaks collect)]. Sensors can also be found in fill 

sumps, monitoring wells, or anywhere else leaking liquid from the primary containment may 

collect. Regardless of location, all sensors are designed to perform the same task: to alert the 

UST operator that liquid is present in the monitored area. This alert is typically accomplished 

either by activating an audible and visual alarm at a control panel, or by stopping the flow of 

product through automatic valve closure or pump/dispenser shutdown. 

California regulations require that all UST monitoring equipment installed on a UST system

(including sensors) be tested and certified annually by a qualified technician2

. Testing and 

certification are often witnessed by an inspector from one of the 104 local government agencies 

throughout the state that implement the UST regulations. The local regulatory agencies 

implement the statewide UST program, which is overseen by the SWRCB. As the statewide 

regulatory agency, SWRCB staff often receive comments from technicians and inspectors about 

the effectiveness of UST monitoring equipment, especially if the equipment is not performing 

properly. During Spring of 2000, inspectors brought the following specific concerns to our 

attention: 

• The inability of discriminating sensors to detect a layer of hydrocarbon-based product (i.e. 

gasoline) floating on top of water and to properly distinguish between water and product; 

• The inability of polymer-strip hydrocarbon detecting elements to quickly and reliably 

alarm; and 

• The inability of polymer-strip hydrocarbon detecting elements to return to effective 

operation (recover) after exposure to hydrocarbons. 

To determine how pervasive the problems were, SWRCB staff launched a field evaluation of 

sensors. The first phase (Phase I) of this evaluation was a cooperative effort between SWRCB 

staff, Veeder-Root representatives, and UST inspectors from the Santa Ana Fire Department, 

City of Santa Monica, and Oakland Fire Department. Phase I focused exclusively on 

discriminating sensors manufactured by Veeder-Root. Data were collected from 67 Veeder-Root 

discriminating sensors at 18 UST facilities in Phase I, between August 2000 and November 

2000. Sensors were evaluated for their ability to detect and discriminate between product and 

 

1

 California Health and Safety Code, Chapter 6.7, Section 25291(a) 2

 California Code of Regulations, Title 23, Section 2637(b) 

 

SWRCB 3 August 2002 
water, using a test method proposed by UST inspectors and further refined by Veeder-Root and 

SWRCB staff. The information collected provided a clearer picture of how sensors perform in 

the field. Although a great deal of information was collected in Phase I, the data was limited to 

Veeder-Root discriminating sensor models only. 

With funding from U.S. EPA, we were able to conduct a second phase of field evaluations 

(Phase II). Phase II was conducted to evaluate the functionality of all types of liquid sensors 

used to monitor UST systems, including discriminating and non-discriminating sensors of all 

makes and models. The range of objectives for Phase II was broader than that of Phase I. Field 

data for Phase II was collected between June 2001 and October 2001. This report includes the 

findings of both phases, but focuses primarily on Phase II. A summary of Phase I testing results 

is included in Appendix I.

 

SWRCB 4 August 2002 
SCOPE OF WORK 

Objectives of the Field Evaluation 

The purpose of this field evaluation was to assess the functionality of liquid sensors used to 

monitor UST systems. The focus was on “real world” effectiveness, with testing performed at 

operating UST facilities. The field evaluation was designed to: 

• evaluate the functionality of sensors; 

• check the adequacy of field-testing procedures for sensors (or work with manufacturers to 

develop field-testing procedures if they were not already available); 

• determine whether sensors in the field perform consistently with their third-party evaluations; 

and 

• determine whether the standard U.S. EPA third-party evaluation protocols for sensors are 

appropriate for each of the sensor types evaluated. 

A copy of the workplan for Phase II is included in Appendix II. 

Facility Selection Process

For the first phase of this field evaluation, all facilities were located within the jurisdiction of 

three agencies assisting in the project; Oakland, Santa Ana, and Santa Monica. All facilities 

were equipped with Veeder-Root discriminating sensors, and all were owned by major oil 

companies. In contrast to Phase I, Phase II data were collected from a variety of sensors at a 

variety of facilities throughout California. An effort was made to include a wide variety of 

geographic locations, facility ownership types, tank system configurations, sensor manufacturers, 

sensor applications, and sensor operating mechanisms. 

Facility Ownership

Of the 124 facilities in this field evaluation, 76 retail fueling facilities owned by major oil 

companies and 23 were retail fueling facilities owned by independent marketers. Other types of

UST facilities were also included, such as emergency generator fueling facilities, fleet fueling 

facilities, unmanned card-lock facilities, and government facilities. Figure 1 shows the 

distribution of facilities in this field evaluation, by ownership. 

 

Figure 1 - Facility Ownership

Major Oil Company

61%

Independent Oil

Company

19%

Governmental

Agency

13%

Other

7%

SWRCB 5 August 2002 
Geographic Location

Data from facilities within 28 local regulatory jurisdictions throughout the state were included in 

the field evaluation. Table 1 lists the various regulatory agencies and associated number of 

facilities evaluated in the field evaluation. A map of California showing the distribution of test 

facility locations is included in Appendix III.

Table 1 - Distribution of Test Facilities, 

by Regulatory Agency Jurisdictions

Agency # of 

Facilities 

Anaheim Fire Department 2 

Butte County Environmental Health Division 1 

Calaveras County Environmental Health Department 1 

Orange City Fire Department 1 

Colusa County Environmental Health 1 

Contra Costa Hazardous Materials Program 3 

Fremont Fire Department 2 

Fullerton Fire Department 5 

Long Beach Fire Department 2 

Los Angeles County Department of Public Works 5 

Mendocino County Environmental Health Department 1 

Mountain View Fire Department 16 

Napa County Hazardous Materials Section 3 

Newark Fire Department 1 

Oakland Fire Department 13 

Placer County Department of Environmental Health 3 

Sacramento County Environmental Health Department 15 

San Bernardino Fire Department 11 

San Diego County Department of Environmental Health Services 1 

San Francisco Department of Public Health 2 

San Leandro Fire Department 1 

San Mateo County Environmental Health Department 2 

Santa Ana Fire Department 3 

Santa Monica Environmental Program Division 7 

Solano County Environmental Health Services 16 

Torrance Fire Department 2 

Yolo County Environmental Health Department 3 

Yuba County Emergency Services 1 

Total # of Facilities 124 

Sensor Location

Since all monitoring equipment is functionally tested during the annual certifications at which 

field data was collected, sensors from various locations within the tank system are included in 

this field evaluation. Figure 2 shows the distribution of sensors, by location within the tank 

system. Note that no groundwater monitoring well or soil-vapor monitoring well sensors are 

included in this field evaluation. While we did not specifically exclude such sensors, they are 

very rarely used in California. 

 

 

SWRCB 6 August 2002 
Figure 2 - Distribution of Sensor Locations

Under Dispenser 

Containment

15%

Turbine Sump

38%

Tank Interstice

34%

Excavation Liner

1%

Piping Transition 

Sumps

1%

Fill/Vapor Sump

11%

Sensor Manufacturer and Operating Mechanisms

Facilities for Phase II were selected with the intention of including a wide variety of sensor 

manufacturers and operating mechanisms. Overall, sensor selection represented 8 different 

operating mechanisms and 15 different manufacturers. Figure 3 shows a distribution of sensors 

in this field evaluation, by operating mechanism. Figure 4 shows a distribution of sensors in this 

field evaluation, by manufacturer. In spite of our efforts to include a wide variety, the majority 

of sensors tested were float switches manufactured by Veeder-Root. Such sensors are by far the 

most prevalent in California.

Figure 3 - Sensors Tested, by Operating Mechanism

Float Switch,

Product Permeable

12%

Float Switch

68%

Ultrasonic and 

Product Permeable

5%

Optical

5%

Thermal

Conductivity

5%

Ultrasonic,

Capacitance Change

3%

Conductivity

1% Metal Oxide

Semiconductor

1%

 

SWRCB 7 August 2002 
Figure 4 - Sensors Tested, by Manufacturer

Ronan

11%

Veeder-Root

66%

Gilbarco

7%

Universal Sensors

4%

Emco Electronics

2%

Beaudreau

3%

Other

3%

Red Jacket

2%

Incon

2%

Note: Veeder-Root and Gilbarco sensors are produced by the same manufacturer 

Scheduling and Coordination 

As part of the annual monitoring system certification required for UST systems in California, a 

qualified technician must functionally test each leak detection component. To minimize the 

impact on UST facility operations during Phase II data collection, SWRCB staff accompanied 

service technicians and regulatory agency inspectors during scheduled annual monitoring system

certifications. Field data were collected while the technician performed this testing, and the 

technician’s routine test procedures were not interrupted. 

Many inspectors and service technicians provided insightful information and data that would not 

have otherwise been obtained. In total, inspectors were present at 79 of the 106 facilities (75%) 

evaluated in Phase II. In cases where regulatory agencies do not routinely have inspectors 

witness annual monitoring systems certifications, SWRCB staff coordinated with the service 

technicians directly. In total, technicians from 19 service companies performed the sensor 

testing in this field evaluation. 

Data Collection Process 

Data for Phase II were collected from 722 sensors in the field between May 2001 and February 

2002. Where applicable in data analysis, data from the 67 sensors tested during Phase I were also 

included. During Phase II, SWRCB staff used a Sensor Data Collection Form to record the 

make, model, location, condition, response, and recovery times for each sensor tested. Data 

about facility location, UST system construction type, and personnel present were recorded on 

the Site Data Collection Form. All field data collected in Phase I was recorded on the VeederRoot Discriminating Sensor Field Performance Test Form. A copy of each form is included in 

Appendix IV. 

 

SWRCB 8 August 2002 
Limitations of Data Collection 

Because all Phase II data were collected with the intent of minimum impact on the operation of 

the UST facility, not all of the desired tests were performed. For example, we suggested that 

discriminating sensors should be tested both in product and water, and that non-discriminating 

sensors be tested in water. However, many discriminating sensors were not tested in product, but 

rather by inverting or submersing the sensor in water. Non-discriminating float switch sensors 

were often tested by inverting the sensors, rather than by submersing them in water. 

When possible, sensor response time was measured from the time the sensor was immersed in 

liquid (or flipped in the case of some float switch sensors) to the time an alarm was activated at 

the control panel. In cases where the control panel could not be seen or heard from the sensor 

location, the time from sensor immersion/flip to the time of pump shutdown occurred was used. 

In cases where the control panel could not be seen or heard from the sensor location and the 

monitoring system was not programmed for pump shutdown, field staff would move between the 

sensor location and the control panel, making their best estimate as to the actual sensor response 

time. 

Several SWRCB staff were involved in field data collection. To reduce subjectivity during data 

collection, staff met periodically throughout the evaluation to discuss the standards used in 

recording data. These meetings helped minimize the impact that inconsistent standards may 

have had on the data collection process. For example, some sensors were found near, but not 

quite at the lowest point of the secondary containment. One person might consider this sensor to 

be raised from the lowest point, while another person might consider it close enough to the 

proper location to record it as being at the lowest point. Through periodic staff meetings, 

standards were agreed upon and applied uniformly by all staff involved in data collection. 

Another factor that may have impacted the results of this field evaluation is the practice of 

performing maintenance at a facility just prior to the annual monitoring certification. Some

inspectors have stated that service technicians often perform these “pre-tests” to assure that the 

facility will be in regulatory compliance and the monitoring equipment will pass the annual 

certification. Problems such as failed sensors and water or product in sumps may have been 

corrected during a “pre-test”, meaning they would not show up during our field evaluation. If 

“pre-testing” occurred at facilities covered in this field evaluation, failure rates would be 

artificially lowered. Although SWRCB staff are not aware that any “pre-testing” took place, the 

possibility cannot be ruled out. 

While the findings of this field evaluation are applicable to UST systems throughout the nation, 

it is important to note that our field data were collected exclusively in California, where annual 

certification of monitoring equipment is required. This means that a technician had already 

certified all leak detection equipment at the facilities as operational within the year prior to the

data collection. It is reasonable to assume that failure rates may be higher in states where annual 

certification of monitoring equipment is not required, although such data are not available. 

 

SWRCB 9 August 2002 
UST Sensor Field Evaluation Survey

To supplement the field data, inspectors and service technicians were polled to provide their 

personal experiences with sensor performance. Sensor surveys were distributed to regulatory 

agencies and UST service technicians who work with sensors on a regular basis. With the help 

of the California Certified Unified Program Agency (CUPA) Forum, an online version of the 

survey was also made available. A total of 71 surveys were completed, with 63 submitted by 

inspectors and 8 by service technicians. Copies of the survey and transmittal letter are included 

in Appendix V. 

Data Analysis 

To prepare this report, data from both phases of field evaluation were entered into a database. 

Additional information from sensor manufacturers’ installation, testing, and operations manuals 

have also been used as reference materials. Sensor survey results have been reviewed, and in 

most instances they validate the field findings. However, the results of the survey are not always 

consistent with field data. In such cases, it is possible that survey respondents may have negative 

experiences with a specific sensor model’s performance, which could cause them to believe that 

a particular problem is more widespread than it actually is. It is also possible that we were 

unable to collect sufficient field data to yield reliable findings in a particular area. In such 

instances, additional research may be needed to discover why field results differ from survey 

results. 

Although the data collection forms and sensor surveys were designed to adequately record most 

data, there were many instances where important information could not be captured on a form. 

In these cases, the “comments” section was used. On the data collection forms, comments 

describe unique facility layouts, special testing procedures, and additional details on sensor 

condition and performance. On the sensor survey, the comments include respondents’ 

observations of sensor performance, and suggestions on sensor improvements. Comments from

the field data collection can be found in Appendix VI. Comments from the sensor survey can be 

found in Appendix V. 

Failure Rates, by Sensor Make and Model 

One objective of this field evaluation was to quantify failure rates for each sensor make, model, 

and operating principle. We attempted to locate and include facilities with a variety of

monitoring equipment. Although 59 sensor models from 15 manufacturers were tested, it was not 

possible to test a statistically significant number of each model. Therefore, no statistically valid 

comparison can be made between manufacturers’ products. Data on makes and models tested are 

summarized in Table 2. Sensor performance data by manufacturer are detailed in Table 3. 

Failure Rates, by Sensor Operating Mechanisms 

Efforts were made to collect enough performance data from sensors so that statistically valid 

determinations about operating mechanisms could be made. Sufficient data were gathered for 

float switch, optical, ultrasonic, and product permeable sensors. However, only a handful of 

capacitance change, thermal conductivity, or metal-oxide semiconductor sensors were included 

in the field evaluation. Therefore, the limited data may not be a statistically valid to determine 

the reliability of these latter operating mechanisms. Sensor performance data by operating 

mechanism is detailed in Table 4.

 

SWRCB 10 August 2002 
Table 2 - Number of Sensors Tested and Failures, by Model 

Manufacturer Model Tested Failed 

Alpha Wire Unknown 2 

Beaudreau 404 1

406 24 3

Emco Q0003-010 2 

Q0003-001 5

Q0003-002 6

Q0003-006 4

Gilbarco PA02591144000 24 1

PA02592000000 8

PA02592000010 16 1

PA0259300000-2 2

Incon TS-ILS 1

TSP-DIS 1

TSP-HIS 2

TSP-ULS 15 1

Mallory Controls Pollulert FD 221GTRA 3 

Pollulert MD 241RRA 6 1 

Mine Safety Appliances Tankgard 482607 5 2 

Owens-Corning Tank FHRB 810 1 

PermAlert PSTV 1

Pneumeractor LS 600LD 3

Red Jacket RE400-111-5 6 

RE400-203 6

Liquid Refraction (Unknown) 1 

Unknown 1

Ronan LS-30 5

LS-3 59 4

LS-7 18

Unknown 1

Universal Sensors LAVS-1 1 1 

LALS-1 29 2

LS 03875 STP 3 

Veeder-Root 330212-001 7

331102-002 2

794380-208 171 3

794380-209 3

794380-300 1

794380-301 3

794380-302 8

794380-320 2

794380-322 1

794380-341 26 11

794380-350 39 4

794380-352 52 1

794380-408 4

794380-500 1

794390-205 40

794390-352 33 2

794390-407 20 2

794390-409 22 2

794390-420 80 2

794390-460 4

847990-001 6

Warrick Controls DLP-1-NC 2 1 

Total 789 44

(Note: Veeder-Root and Gilbarco sensors are produced by the same manufacturer)

 

SWRCB 11 August 2002 
Table 3 - Sensors Failing to Alarm, by Manufacturer 

Manufacturer Sensors 

Tested 

Failures Failure 

Rate (%) 

Alpha Wire 2 0 0 

Beaudreau 25 3 12

Emco 17 0 0

Gilbarco 54 2 4

Incon 19 1 5

Mallory Controls 9 1 11 

Mine Safety Appliances 5 2 40 

Owens-Corning Tank 1 0 0 

PermAlert 1 0 0

Pneumeractor 3 0 0

Red Jacket 14 0 0 

Ronan 83 4 5

Universal Sensors and Devices 33 3 9 

Veeder-Root 521 27 5

Warrick Controls 2 1 50 

TOTAL 789 44 5.6 

Table 4 - Sensors Failing to Alarm, by Operating Mechanism 

Operating Mechanism Sensors 

Tested 

Failures Failure 

Rate (%) 

Conductivity 9 1 11

Float Switch 539 17 3 

Float Switch, Product Permeable 97 3 3 

Metal Oxide Semiconductor 1 1 100 

Optical 39 3 8

Thermal Conductivity 37 4 11 

Ultrasonic and Capacitance Change* 26 11 42 

Ultrasonic and Product Permeable 41 4 10 

Total 789 44 5.6 

* All sensors in this category were Veeder-Root model 794380-341 

 

SWRCB 12 August 2002 
Failure Rates, by Facility Ownership 

The quality of installation and maintenance procedures at a UST facility is expected to affect 

sensor reliability. An assumption was made that the quality of maintenance and installation 

would vary depending on the type of facility ownership. Therefore, an attempt was made to 

gather and compare data from a variety of types of facility ownership. The distribution of

sensors by facility ownership is shown in Table 5. 

Table 5 - Number of Sensors Tested, 

by Facility Ownership

Ownership # of 

Facilities 

# of 

Sensors 

Major Oil Company 76 504 

Independent Oil Company 23 177 

Governmental Agency 16 61 

Other* 9 47

Total 124 789 

* Other includes emergency generator fueling systems,

chemical storage tanks, and fleet fueling facilities. 

Field data shows that failure rates were similar among major oil and independent owners. Other 

facility ownership types had a failure rate of roughly twice that of the major and independent oil 

marketers, although the sample size for “other ownership” was somewhat limited. Independently 

owned facilities had a noticeably higher rate of raised sensors and water or product in the 

secondary containment. This may be attributed to less stringent construction standards, or less 

frequent visual inspection of the secondary containment. Sensor performance data by facility 

ownership is shown in Figure 5. 

 





 







 



 





 









 











 

 



 

















 



 





 



 













 





Figure 5 - Sensor Performance, by Facility Ownership

5.3 6.2

12

5.5

9

20

3.3

1.6

13

10.6

4.3

6.4

0

5

10

15

20

25

Sensor Failures Raised Sensors** Water/Product in

Containment**

(%)













Major Oil Company

Independent Oil

Company Governmental Agency

Other

**Calculations based on the 722 sensors tested in Phase II, since data on raised sensors and 

water/product in the containment were not recorded in Phase I.

 

SWRCB 13 August 2002 
Performance of Discriminating Sensors Compared to Non-Discriminating Sensors 

SWRCB staff have received many comments from inspectors and contractors, stating that 

discriminating sensors do not perform reliably in the field. Responses to the sensor survey 

echoed these comments. We targeted as many facilities with discriminating sensors as possible, 

collecting data on a total of 182 discriminating sensors, including the 67 tested during the Phase 

I. Of these 182 discriminating sensors, 132 were tested in both water and product. Figures 6a, 

6b, and 6c show a comparison between discriminating sensors tested in water only, 

discriminating sensors tested in both water and product, and non-discriminating sensors. 

Because the Veeder-Root model 794380-341 discriminating sensors have such high failure rates, 

and because Veeder-Root has since that time specified that all model 794380-341 sensors should 

be programmed as non-discriminating, the performance of discriminating sensors excluding the 

model 794380-341 have also been included for comparison. 

Figure 6a - Number of Sensors Tested

50

132

106

607

0 100 200 300 400 500 600 700

Discriminating in Water Only

Discriminating in Water and Product

Discriminating in Water and Product (excluding model -341)

Non-Discriminating Sensors

Figure 6b - Perecntage of Sensors Failing to Alarm Properly When Tested

2%

14%

7%

4%

0% 2% 4% 6% 8% 10% 12% 14%

Discriminating in Water Only

Discriminating in Water and Product

Discriminating in Water and Product (excluding model -341)

Non-Discriminating Sensors

Figure 6c - Percentage of Sensors Not at Low Point

1%

8%

0% 2% 4% 6% 8% 10% 12% 14%

Discriminating

Sensors

Non-Discriminating

Sensors

 

SWRCB 14 August 2002 
Field data shows that, when excluding the Veeder-Root model 794380-341 sensor, 

discriminating sensors failed to alarm properly only slightly more frequently than nondiscriminating sensors. It is also important to note that discriminating sensors appear to be less 

likely to be raised from their proper location. In contrast to these findings, 77% of survey 

respondents stated that discriminating sensors were less reliable than non-discriminating sensors. 

This may be due to their negative experiences with the model 794380-341 sensor. It may also 

reflect the fact that our field data has an important limitation. Due to contractors’ reluctance to 

test discriminating sensors in product3

 and the difficulty in locating a wide selection of 

makes/models, many discriminating sensors were not tested in product. Without test data on 

more makes and models, and without the ability to test these sensors both in product and water, it 

is difficult to make a statistically valid statement regarding the relative reliability of

discriminating versus non-discriminating sensors. Table 6 lists the failure rates for all 

discriminating sensors tested in product, sorted by make and model. 

Table 6 - Performance Data for Discriminating Sensors, by Make and Model 

Make Model # of

Sensors 

Tested in 

Product 

# of

Failures 

when

Tested in 

Product 

Failure 

Rate when 

Tested in 

Product 

(%) 

# of

Sensors 

Tested in 

Water 

Only

# of Failures 

when Tested 

in Water 

Only

Failure 

Rate when 

Tested in 

Water 

Only (%) 

Total # 

of

Sensors 

Tested 

Total # 

of

Failures 

Total 

Failure 

Rate 

(%) 

Alpha Wire Unknown 0 - - 2 0 0 2 0 0

Emco Electronics Q0003-001 0 - - 5 0 0 5 0 0

Q0003-002 0 - - 6 0 0 6 0 0

Incon TSP-DIS 0 - - 1 0 0 1 0 0

Mallory Controls Pollulert FD 

221GTRA 

3 0 0 0 - - 3 0 0

Pollulert MD

241RRA

6 1 17 0 - - 6 1 17

Red Jacket RE400-203 0 - - 6 0 0 6 0 0

Veeder-Root 794380-320 2 0 0 0 - - 2 0 0

794380-322 0 - - 1 0 0 1 0 0

794380-341 26 11 42 0 - - 26 11 42

794380-350 39 4 10 0 - - 39 4 10

794380-352 56 2 4 29 1 3 85 3 4

Total 132 18 13.5 50 1 2 182 19 10 

Total Excluding Model 794380-341 106 7 6.5 50 1 2 156 8 5 

 

Determining the Reason for Sensor Failures 

It is important to understand what causes failures of sensors in the field. However, the reasons 

are not always apparent. When possible, SWRCB staff and the technician performing the test 

attempted to determine the cause of failure. In cases where the cause of failure could not be 

determined, SWRCB staff followed up with the proper regulatory agency and/or service 

technician to verify that the failure was repaired and the system was verified functional. 

 

3

 Many contractors state that testing polymer strip discriminating sensors in product is impractical due to excessive 

response and recovery times. Further, some sensors may not recover after repeated or prolonged exposure to

product, thus requiring replacement. 

 

SWRCB 15 August 2002 
FINDINGS 

The findings of this report have been sorted into six general categories: Sensor Design and 

Performance, Secondary Containment Performance and Compliance Issues, Oversight and 

Qualifications, Sensor Field-Certification and Testing Procedures, Maintenance and 

Programming, and Discriminating Sensors. These categories reflect the fact that the condition 

of secondary containment, the frequency and quality of maintenance and testing, the level of 

training among operators and service technicians, and the quality of regulatory oversight will all 

impact the effectiveness of sensors as a leak detection method. The Sensor Design and 

Performance section contains findings applicable to all sensors, while findings pertaining 

specifically to discriminating sensors have been included as a separate section for easy reference. 

A section covering Other facility Observations Not Relating to Sensors has also been included. 

However, there is only limited discussion on these observations, since they are beyond the scope 

of this field evaluation. 

A. Sensor Design and Performance 

1. Observation: Sensors failed to alarm properly for 5.6% of sensors tested (44 out of 789)4. 

A list of sensor failures, by make and model, is included in Appendix VI.

Likely Cause: Causes varied, but failures are either due to defects in the sensors themselves, 

or defective/corroded wiring between the sensor and the control panel. 

Consequences: Sensors failing to alarm when tested would likely also fail to alarm in the 

event of a leak, leading to an increased risk of release to the environment. 

2. Observation: Sensors can corrode over time. Corrosion interferes with sensor performance 

in a variety of ways. A common form of corrosion was observed with Veeder-Root 794380-

420 float switch sensors installed in the interstitial space of double-walled steel tanks. These 

sensors have steel housings, which were frequently observed to be cracked. Corrosion can 

also affect the internal components of a sensor. The field evaluation showed that the moving 

parts of float switches could become lodged in place due to corrosion. In rare instances, the 

float had fallen off due to corrosion of the pin that holds the float in place.

Likely Cause: Materials used in the manufacture of sensors are not always compatible with 

the stored substances, moisture, and materials found in the secondary containment of UST 

systems. 

Consequences: Since there is limited space in the interstice of steel tanks, a cracked sensor 

casing can make it impossible to remove the sensor for testing. Technicians have said that 

such sensors occasionally have to be abandoned in the tank interstice, with new sensors 

installed above them. Corrosion of internal sensor components can result in missed detection 

of product in the secondary containment. 

 

3. Observation: Interstitial sensors in double-walled fiberglass tanks can become lodged 

between the inner and outer tank walls. 

 

4

 This value includes 2 float switch sensors that were in water within the sump prior to testing, but were not in

alarm. Although these sensors eventually alarmed when shaken vigorously, they were recorded as failures. 

 

SWRCB 16 August 2002 
Likely Cause: Sensors are designed to be inserted into a small channel and wrapped around 

the tank, so that the sensor rests at the low point of the interstice. A pull string is used to 

position the sensor into the proper position within the tightly confined tank interstice. In 

some instances, the sensor becomes lodged. Several technicians commented that this might 

be due to the inner tank settling under the weight of the product stored, effectively pinching 

the sensor between the inner and outer walls. 

Consequences: When a sensor becomes lodged in the interstitial space, it cannot be removed 

for testing. If sensors cannot be removed for testing, their functionality cannot be verified. 

Without verifying functionality, a faulty sensor could go undetected, leaving the secondary 

containment unmonitored. Further, installation of a new sensor is impractical, since the same

physical barrier preventing removal of the old sensor will also prevent proper installation of a 

replacement sensor. 

4. Observation: Float switches that alarm when tested may not alarm under leak conditions. At 

two facilities with float switch sensors, a sensor was sitting in sufficient liquid within a sump

to activate an alarm, but was not in alarm. Another two facilities had sensors with stuck 

floats. The sensors went into alarm once the technician removed and shook them vigorously.

Likely Cause: When inspecting turbine sumps, staff discovered that movement of some

floats was hindered by debris, preventing the alarm from being activated until a technician 

removed and shook the sensor. 

Consequences: Sensors that do not go into alarm because floats are lodged by debris can 

result in missed detection of product in the secondary containment.

5. Observation: Sensors failing to activate alarms when immersed in liquid was observed at 

several stations.

Likely Cause: The leading cause appeared to be faulty wiring, which was either installed 

incorrectly or had degraded over time. Another cause was faulty sensors. At one facility, 

three of four Beaudreau model 406 sensors installed within the under-dispenser containment 

failed due to faulty dispenser cut-offs, (similar to a control panel, but designed to cut power 

to the dispenser when the sensor detects liquid). 

Consequences: Sensors failing to activate alarms when immersed in liquid can result in 

missed detection of product in the secondary containment.

6. Observation: At two facilities in the field evaluation, sensors activated alarms when tested 

but did not come out of alarm.

Likely Cause: While further follow-up is required to determine the exact cause, technicians 

at the facility suspected a short in the wiring between the sensor and the control panel. 

Consequences: Leak detection equipment malfunctioning in this manner needs immediate 

service. Facilities with pump shutdown will be out of service until the problem is fixed. At 

facilities without pump shutdown, an operator may choose to ignore the alarm. This leaves 

the monitored area with no leak detection, and, therefore, poses a risk of release. 

 

SWRCB 17 August 2002 
B. Secondary Containment Performance and Compliance Issues 

1. Observation: Approximately 6.5% of sensors tested (46 of 722) were not properly located at 

the lowest point of the secondary containment5

. For the purposes of this field evaluation, 

sensors were recorded as “not at lowest point” if they appeared to have intentionally been 

raised from their proper location, or if they could not be placed in the proper location due to 

insufficient length of wiring or a similar reason.

Likely Cause: In some cases, facility operators may have been raising sensors to avoid 

having to respond to frequent alarms caused by surface water and/or ground water ingress 

into the secondary containment. In other cases, the design of the secondary containment may 

have made it difficult to place the sensor in the proper location, since other components may 

be in the way. Sumps that have a designated location for mounting the sensor (such as a pipe 

mounted to the sump wall) reduced the likelihood of raised sensors. 

Consequences: California regulations state that sensors should be able to detect leaks at the 

earliest possible opportunity6

. Raised sensors are unable to detect liquid in the secondary 

containment at the earliest opportunity, placing the facility out of regulatory compliance and 

increasing the threat of a release to the environment. By raising sensors, facility owners and 

operators may also be subject to penalties for tampering with monitoring equipment.

2. Observation: Water ingress into at least one portion of the secondary containment occurred 

at 31% of facilities (33 of 106) tested in Phase II. Water ingress was most common in tanktop sumps; 18% (64 of 353) contained water. Water ingress was observed only occasionally 

in the tank interstice and under-dispenser containment. In 22 of the 75 cases where water 

was present in the secondary containment, the sensor was raised to prevent alarm. The depth 

of water in the secondary containment varied from less than one inch to almost two feet.

Likely Cause: Construction of some secondary containment systems allows surface water 

ingress. Groundwater may also be entering into improperly constructed secondary 

containment. 

Consequences: Water in the secondary containment leads to alarms, which may prompt the 

UST operator to raise or disable the sensors. Water also occupies volume in the secondary 

containment, reducing its ability to contain product in the event of a release from the primary 

containment. Further, water may accelerate deterioration of UST components and leak 

detection equipment since they are not generally designed to be wet for an extended period of 

time. 

3. Observation: 11% of facilities (12 of 106) tested in Phase II had product present in at least 

one portion of the secondary containment. The presence of product was most common in 

tank-top sumps, where nearly 7% (24 of 353) contained product. Waste oil tanks often 

contained product in fill sumps. The depth of product varied from less than 1 inch to 

approximately 18 inches.

Likely Cause: Releases from primary containment will collect in the secondary containment. 

In turbine sumps, the apparent cause of most leaks was faulty seals within the pump heads. 

Diesel fuel was observed most often, likely due to its slow evaporation rate. Careless filling 

practices are the most likely cause of product in fill sumps. 

 

5

 Calculations based on the 722 sensors tested in Phase II only, since this information was not recorded in Phase I. 6

 California Code of Regulations, Title 23, Section 2630(d) 

 

SWRCB 18 August 2002 
Consequences: Product in the secondary containment poses a significant fire hazard, as well 

as an increased risk of release to the environment. 

4. Observation: Monitoring systems at 2 of the 106 facilities tested in Phase II were in alarm

when the service technician arrived to conduct testing. The staff on-site had not taken action 

in response to these alarms.

Likely Cause: UST operators may not have been trained in the proper response to alarms. 

Repeated false alarms may lead operators to ignore them, believing that proper alarm

response is not important. 

Consequences: Failure to respond to alarms leads to an increased risk of release to the 

environment. 

5. Observation: Some sensors are being used in applications for which they have not been 

designed. Sensors were used to monitor products for which they are not certified, such as 

solvents, caustic chemicals, and waste oil. In one case, an interstitial sensor intended for use 

in a steel tank had been installed in a fiberglass tank.

Likely Cause: Inadequate training of inspectors and installers plays a likely role in the 

improper application of sensors. Inspectors and contractors may not know that a sensor 

designed for use in unleaded fuel may not be effective in waste oil or certain chemicals. 

Consequences: Sensors used with incompatible products may deteriorate more quickly, or 

be unable to detect a release from the primary containment. A steel tank sensor is not 

designed to fit within the interstice of a fiberglass tank. Steel tank sensors must operate in a 

vertical position, but a fiberglass tank interstice is designed to be monitored with a sensor 

that is installed horizontally. Sensors used in applications for which they have not been 

designed may not reliably detect a release from the primary containment.

6. Observation: Degradation of the tank interstice made it impossible to remove/test sensors in 

some fiberglass tanks. It is often difficult (and sometimes impossible) to remove sensors 

from the annular space of fiberglass tanks for inspection/testing. 

Likely Cause: The pull-string used to install and remove sensors from the tank interstice was 

often missing or broken, making it difficult for technicians to replace the sensors once they 

were removed. The primary tank tends to settle within the secondary tank over time, 

effectively pinching the sensor between the walls of the primary and secondary containment. 

Consequences: When sensors cannot be tested, it is impossible to verify that they are 

functioning properly. For sensors that are removed but cannot be replaced, the tank interstice 

is not monitored.

C. Oversight and Qualifications 

1. Observation: Inspectors were present for observation and data collection at 79 of the 106 of 

facilities evaluated in Phase II (75%). This rate of participation was higher than average due 

to interest in the field evaluation, and the fact that the inspectors had assisted SWRCB staff 

in coordinating inspections. The rate of inspector oversight during annual monitoring 

equipment testing and certification is generally lower. 

Likely Cause: The regulatory agency’s resources do not always allow inspectors to oversee 

monitoring equipment certifications at every facility in their jurisdictions. Furthermore, it 

may be difficult to coordinate the inspection with the technician conducting the certification. 

 

SWRCB 19 August 2002 
Consequences: Coordination of annual facility inspection and the monitoring certification 

allows inspectors to visually inspect sensor locations, and to verify that technicians are 

conducting the monitoring certification properly. Problems noted by an inspector can often 

be remedied immediately, using the skills of the service technician already present. These 

benefits are lost if inspection and monitoring certification are not performed simultaneously. 

 

2. Observation: A wide range of knowledge and experience with sensors was observed among 

technicians and inspectors. Technicians had experience working in the UST field ranging 

from a few months to over 25 years. 

Likely Cause: The level of knowledge seems directly related to experience. Inspectors and 

technicians that are new to the UST field are not as knowledgeable about the regulations and 

equipment as those with many years of experience. Inspector expertise may also depend on 

the structure of the regulatory agency. Some agencies have inspectors dedicated exclusively 

to the UST program, while other agencies cross-train inspectors in a variety of programs.

Consequences: Inspectors and service technicians play a key role in ensuring that a UST 

facility is properly maintained and regulated. Lack of proper training for the inspector or 

service technician increases the likelihood of non-compliant or substandard UST systems 

remaining in operation. Such systems may pose an increased risk of release to the 

environment. 

3. Observation: Some technicians performing annual certification of monitoring equipment do 

not repair or replace faulty sensors at the time of testing. Regulatory agencies may specify 

that sensors be repaired or replaced within a specified amount of time, generally 30 days.

Likely Cause: Some technicians who conduct the annual certification of monitoring 

equipment do not have contracts specifying that they perform repairs. Their responsibility is 

to test the equipment and report on its functionality. In other cases technicians may have 

contracts to perform repairs as needed, but do not have the necessary replacement parts or 

diagnostic equipment. 

Consequences: Facilities may be allowed to operate without functional monitoring 

equipment for 30 days or longer while repairs are scheduled and completed. 

D. Sensor Field-Certification and Testing Procedures 

1. Observation: Float switch sensors are often tested by flipping them rather than immersing 

them in liquid. Some sensors that had been immersed in water without activating an alarm

were found to activate an alarm when flipped.

Likely Cause: Flipping or shaking a float switch sensor can free up a float that may be 

clogged by dirt or debris. Some technicians believe that immersing the sensor in water 

during testing promotes corrosion, thus reducing the effective life of the sensor. 

Consequences: Manually flipping a float switch sensor is an effective method of activating 

an alarm condition, and verifying that monitoring system responds accordingly. However, 

flipping a sensor over does not accurately simulate the conditions a sensor encounters in the 

event of a leak. 

 

SWRCB 20 August 2002 
2. Observation: Under-dispenser containment (UDC) boxes with mechanical floats and chains 

(i.e. Bravo Boxes) are not commonly tested. The inspector required functional testing of the 

float-and-chain UDC leak detection device at only one of the 106 facilities tested in Phase II, 

and no test results were recorded or included in our database. Occasionally during this field 

evaluation, inspectors looked to see that the chains were connected. According to the few 

inspectors who routinely require testing of float-and-chain UDC leak detection devices, the 

failure rate is high. 

Likely Cause: The common reasons given by service technicians and inspectors for not 

testing these sensors is that the process takes too long or is too difficult. 

Consequences: Without periodic testing, faulty equipment may go unnoticed. This 

equipment may not function properly in the event of a leak from the primary containment, 

leading to an increased risk of release. Additionally, undetected releases from primary 

containment may accumulate in secondary containment and pose a significant risk of fire, 

particularly in the UDC. 

3. Observation: Old equipment is still in use at a number of facilities, even though the 

manufacturers are out of business or no longer support the product.

Likely Cause: As long as their old leak detection equipment continues to function and is in 

compliance with regulatory requirements, there is no incentive for an owner to replace these 

devices. 

Consequences: Although this equipment may still be functioning, it poses a number of 

potential problems. Technicians may not be familiar with operation and testing procedures 

for obsolete systems. If the manufacturer is no longer in business, there is generally no 

service technician training available. Technicians may also be hesitant to test equipment for 

which replacement parts are unavailable. 

4. Observation: Test procedures are inconsistent. Procedures vary from one contractor to the 

next and from one regulatory agency jurisdiction to the next. For example, some technicians 

tested float switch sensors by inverting them, while others dipped them in water. Some

thermal conductivity sensors were tested in liquid, while other technicians blew on the sensor 

to activate an alarm. 

Likely Cause: Many manufacturers do not provide detailed step-by-step field testing 

procedures and training. Some technicians may not have received training from

manufacturers on field testing procedures. In addition, some inspectors may not believe that 

manufacturers’ procedures are adequate and may require sensors be tested in a way other 

than that recommended by the manufacturer. 

Consequences: Without standard testing procedures, the possibility exists that inadequate 

procedures may be used. In such cases, there is no assurance that the sensors would reliably 

detect releases from the primary containment. 

E. Maintenance and Programming 

1. Observation: The pump shutdown (PSD) feature is not always functional. Additionally, we 

observed a wide range of pump shutdown response times. Times ranged from nearly 

instantaneous to several minutes. 

 

SWRCB 21 August 2002 
Likely Cause: Technicians in the field attribute PSD failure to sticky relays. Factors 

affecting shutdown time include control panel model, software version (particularly with the 

Veeder-Root/Gilbarco panels), and complexity of leak detection equipment at the facility. 

(For example, the more sensors at a facility, the slower the shutdown). 

Consequences: Pump shutdown failure could result in piping sumps or under-dispenser 

containment overflowing in the event of a catastrophic piping failure. 

2. Observation: In many instances, a console had not been programmed according to the 

facility monitoring plan. 

Likely Cause: Many monitoring equipment manufacturers provide the user with a variety of 

set-up and alarm options for their facilities. These options include activating pump 

shutdown, indicating a warning instead of an alarm, or dialing out to a remote location in the 

event of an alarm condition. In cases where the console set-up did not match the monitoring 

plan, it is possible that the console was not programmed correctly at the time of installation. 

Programming may also have been changed, intentionally or inadvertently, either at the 

console or remotely via a modem connection. 

Consequences: Programming of the monitoring console affects sensor performance and the 

ability to properly alert an operator in the event of a problem. Improper programming may 

also place a facility out of regulatory compliance.

F. Discriminating Sensors 

1. Observation: Although field staff requested that discriminating sensors be tested in water 

and product, this was only done 56% of the time (65 of 115 discriminating sensors)7

. 

Likely Cause: Many technicians and inspectors are hesitant to test discriminating sensors in 

product due to the long response and recovery times. There is also a concern that the sensors 

may not recover after being exposed to product, and will have to be replaced. 

Consequences: Unless a discriminating sensor is tested in product, the functionality of one 

of its operating modes is not verified. Since the sensor’s full performance is not determined, 

there is an increased possibility of missed detection. 

2. Observation: Many of the Veeder-Root 794380-341 sensors (shown in Figure 8) exposed to 

product indicated a water alarm. This problem was observed in 13 of 26 model 794380-341 

sensors in the first phase of testing, and 9 of 17 in the second phase. Overall, the model 

794380-341 sensor failed to alarm properly approximately 50% of the time.

Likely Cause: Since this problem is specific to the model 794380-341 sensor, there is likely 

a design or manufacturing flaw. 

Consequences: UST owners and operators generally consider response to water less urgent 

response than product alarms. Therefore, product in the interstitial space that is falsely 

identified by the sensor as water may pose an increased risk of release to the environment. 

3. Observation: Response and recovery times of the polymer strip element when exposed to 

fuel were sometimes excessive, and not always consistent with third-party claims. Response 

times in a gasoline/water mixture ranged from 5 to 12 minutes, with an average of 

 

7

 Does not include sensors tested during Phase I, since testing in product was mandated during that phase. 

 

SWRCB 22 August 2002 
approximately 7 minutes. Recovery times in gasoline ranged from 1 minute to over 50 

minutes, with an average of approximately 17 minutes (see Figure 7).8

 

Likely Cause: The fuel alarm is activated only after enough fuel has permeated the polymer 

strip to raise its electrical resistance to a set value. Typically the resistance in the strip did not 

begin to change appreciably for several minutes. 

Consequences: A primary concern with polymer strip discriminating sensors is the amount 

of time they take to alarm. In the event of a catastrophic leak from pressurized piping, the 

slow response time could allow for a large release of fuel into the UDC or containment sump

before the alarm sounds. When the liquid level reaches the high-level liquid set point, a 

high-level water alarm will sound. It could still be many minutes before the polymer strip 

reacts to the fuel and activates a fuel alarm. This could be a major concern if the system is 

not configured for turbine shutdown when the high-level water alarm is activated. An 

additional concern is the wide variation in response times from one sensor to another. With 

such variation, it is difficult to determine exactly how long a polymer-strip sensor should 

typically take to alarm once exposed to fuel, to establish field-testing guidelines, or to 

determine if a sensor is actually non-functional or just slow to respond. 

Figure 7 - Response and Recovery Times for Veeder-Root Model 794380-352

Polymer Strip Discrminiating Sensors Tested in Gasoline/Water Mix (Phase I)

0

8

16

24

32

0 5 10 15 20 25 30 35 40 45

Sensors

Time (min.)

Time to Alarm

Time to Recover

Third-Party

Value for

Recovery Time

(17.2 minutes)

Third-Party

Value for

Reponse Time

(10 minutes)

Max Value: 52 Minutes 

 

SWRCB 23 August 2002 

 

8

 A thorough discussion on response and recovery of polymer strip discriminating sensors can be found in the 

“Summary of Test Results from Phase I Testing,” which is included in Appendix I. 
4. Observation: Current third-party protocols may not be appropriate for polymer-strip sensors.

Likely Cause: Third-party evaluators have been using a standard liquid point detection 

protocol to evaluate polymer-strip sensors. These protocols are designed for mechanical or 

electrical switching devices that do not use chemical reactions like the polymer strips. The 

protocol does not take into account factors that may affect polymer-strip sensors. The ability 

to alarm and recover in a variety of environmental conditions is not assessed. The impact on 

response time and recovery time after repeated fuel exposure of these sensors is not 

evaluated. 

Consequences: Sensors may fail to detect a product release in the field, not respond quickly 

under certain conditions, and not recover once exposed to product.

5. Observation: Some discriminating sensors may not be able to detect product floating on 

water.

Likely Cause: Hydrocarbons typically float on water, and most discriminating sensor 

designs require the sensor to be in contact with product in order to detect it. Therefore, some

discriminating sensors will not detect product release when sufficient water is present. The 

level of water that will result in a missed detection varies depending on sensor design. 

Designs can be divided into two general categories: Point Liquid Type and Polymer Strip 

Type. Each of these categories has distinct capabilities and limitations, as described in 

Appendix VII. 

Consequences: Sensors may not detect a product release when water is present in the 

secondary containment, which may pose an increased risk of release to the environment. 

G. Other Observations Not Relating to Sensors 

The following observations do not directly relate to the effectiveness of sensors as a method of 

leak detection, but are compliance related items that pose an increased environmental risk. 

Discussion of these observations is limited because they are beyond the scope of this field 

evaluation, but follow-up and enforcement action may be appropriate. 

1. Line leak detectors (LLDs) have a high failure rate when tested with a 3.0 gallons per hour at 

10 pounds per square inch leak rate. All staff collecting data for this field evaluation 

observed failures, although LLD failure data were not recorded. In general, mechanical 

LLDs failed more frequently than electronic LLDs. SWRCB staff are currently evaluating 

the effectiveness of LLDs in the field as part of a separate project.

2. Some UST facilities had recently installed under-dispenser containment (UDC), but did not 

install monitoring devices as required by California regulations9

. In one case, a small leak 

from the dispenser piping had resulted in nearly 18 inches of diesel fuel in the UDC. In this 

case, it appeared that the presence of UDC prevented a release to the environment. However, 

the leak had gone undetected for some unknown time period, and would have remained 

undetected if the annual facility compliance inspection were not being performed that day. 

3. The overfill prevention devices had been tampered with at one facility. Long sticks had been 

inserted and left in the fill pipes, effectively disabling the fill tube positive overfill protection 

device. Comments from technicians and inspectors indicate that this is not uncommon. 

 

9

 California Code of Regulations, Title 23, Section 2636(f) 

 

SWRCB 24 August 2002 
RECOMMENDATIONS 

The following recommendations are designed to improve the effectiveness of sensors as a leak 

detection method by addressing specific issues observed during this field evaluation. Just like 

the “findings” section of this report, recommendations are organized into six categories: Sensor 

Design and Performance, Secondary Containment Performance and Compliance Issues, 

Oversight and Qualifications, Sensor Field-Certification and Testing Procedures, Maintenance 

and Programming, and Discriminating Sensors. The Sensor Design and Performance section 

contains recommendations applicable to all sensors, while issues pertaining specifically to 

discriminating sensors have been included as a separate section for easy reference. Note that no 

specific recommendations have been made to address the findings listed under Other Facility 

Observations Not Relating to Sensors, since these are beyond the scope of work for this report. 

A. Sensor Design and Performance 

• Improvement in the design and manufacture of sensors is needed. The results of this 

field evaluation indicate that the environment in which UST leak detection sensors operate 

can degrade their performance over time. Manufacturers should design sensor housings, 

wiring, and functional elements to endure UST system conditions for the anticipated life of 

the sensor. 

• Float switch sensor design should allow for free movement of the float. For a float 

switch sensor to operate effectively, the float must be free to move up and down in response 

to the presence of liquid in the secondary containment. Manufacturers should produce float 

switch sensors that are not easily obstructed by dirt and debris, or are in an enclosed housing 

that keeps debris away from the float mechanism.

• All sensors should be evaluated under field-representative conditions. Standard U.S. 

EPA evaluation protocols should be re-evaluated by a workgroup of inspectors, 

manufacturers, and third-party evaluators. Modifications to the protocols should be made to 

assure that the evaluation challenges the sensor’s performance under conditions likely to be 

encountered in the field. Once the new protocol is in place, only sensors that have been 

evaluated by an independent third party in accordance with the revised protocol should be 

approved for new installations.

• Sensors should not be used as the sole method of leak detection for double-walled 

pressurized piping. This field evaluation has shown that, for a variety of reasons, sensors 

may fail to detect a release from the primary containment. Therefore, a line leak detector or 

other leak detection should be used as a backup. This will reduce the risk of release to the 

environment in the event of a catastrophic failure of the primary piping. 

 

SWRCB 25 August 2002 
B. Secondary Containment Performance and Compliance Issues 

• Secondary containment should be designed and constructed to prevent the ingress of 

surface and ground water. Preventing water ingress will reduce the frequency of water 

alarms from sensors in the secondary containment. It will also help reduce the tendency of 

facility operators to raise their sensors to avoid water alarms, and would reduce the amount 

of water that has to be removed from the containment and disposed of properly. Finally, any 

adverse impact that water may have on sensors (such as corrosion or accelerated failure of 

internal components) would be minimized by keeping water out of the secondary 

containment.

• Secondary containment should be tested periodically. Testing will verify that the 

containment is capable of holding product in the event of a release. Testing will also identify 

points where groundwater may enter the containment. Once identified, these points can be 

repaired in order to prevent groundwater intrusion into the secondary containment.

 

C. Oversight and Qualifications 

• UST operators should be trained about their role in effective leak prevention. The most 

common problem observed in this field evaluation was raised sensors. In many of these 

cases it is likely that the facility operator raised the sensor in order to disable it, or to take it 

out of alarm when liquid was in the secondary containment. Tampering with leak detection 

is a regulatory violation, and individuals caught doing so may be subject to penalties and 

fines. Raising sensors makes the leak detection system less effective, thus increasing the risk 

of release of hazardous substances to the environment. Training UST owners and operators 

on proper alarm response and the consequences of tampering with monitoring equipment will 

help reduce this problem.

• Enforcement action should be taken against those who intentionally hinder the 

effectiveness of leak detection equipment. This includes tampering with sensors, ignoring 

alarms, turning off monitoring systems, or failing to take action when product or water is 

present within secondary containment. Enforcement action may also be appropriate for other 

violations that increase the risk of release to the environment, such as tampering with overfill 

prevention equipment.

• UST inspectors would benefit from additional training on the limitations and proper 

application of sensors. Some sensors were installed incorrectly for the specific conditions at 

a particular UST facility. Facility-specific conditions included the type of product stored and 

the size or shape of the monitored space. By better understanding how each type of sensor 

operates, regulators can make more informed decisions about the appropriate application and 

placement of specific sensors when reviewing and approving monitoring plans. 

 

SWRCB 26 August 2002 
D. Sensor Field-Certification and Testing Procedures 

• All sensors should be functionally tested at least annually. This annual testing should 

include under-dispenser containment boxes with mechanical floats and chains (i.e. Bravo 

Boxes). Testing procedures should also include verification of alarms and pump shutdown 

where applicable. Monitoring systems that provide shutdown of the pumping system when 

sensors are disconnected and/or when the monitoring system loses power should also be 

functionally tested.

• Testing should be conducted by a qualified service person. Service technicians should be 

knowledgeable about UST monitoring systems, and should be trained the manufacturers of 

the equipment they are working with. Periodic testing should verify functionality of the 

sensor, and should be conducted in accordance with the manufacturer’s recommended 

protocols, in a manner consistent with all applicable regulations. 

• A standard field test procedure should be developed for each sensor technology. The 

procedures should demonstrate each sensor’s ability to reliably detect a leak (for example, 

float switch sensors should be tested in liquid rather than by flipping). Manufacturers should 

work with technicians and regulators to develop these testing procedures, and should train 

service technicians to perform the testing properly. Technicians should be required to 

conduct testing in accordance with standard procedures once such procedures are in place.

E. Maintenance and Programming 

• Secondary containment should be inspected frequently to verify that it is clean and free 

of liquid (water and product) and debris. This field evaluation showed that, due to a 

variety of factors, sensors were not 100% effective at detecting liquid in secondary 

containment. Therefore, it is important to perform frequent visual inspection of these areas. 

We recommend that visual inspections be conducted on at least a monthly basis. 

• Float sensors should be inspected frequently (more than once a year) to verify that they 

are functional. Float sensors may not work properly if debris and dirt within the secondary 

containment interferes with the movement of the float mechanism. In order to have effective 

monitoring of secondary containment using float sensors, frequent inspections and 

maintenance is important. This recommendation is particularly significant given the 

prevalence of float sensors (68% of sensors in this field evaluation). 

 

• Sensors installed in piping sumps to monitor pressurized piping should be programmed 

to shut down the pump when product is detected. Most monitoring systems are capable of 

this function if they are programmed accordingly. Programming the monitoring system to 

shut down the pump when a leak is detected in the piping is a simple, inexpensive way to 

reduce the risk of release of hazardous substances to the environment.

 

SWRCB 27 August 2002 
F. Discriminating Sensors 

• Veeder-Root model 794380-341 sensors should not be used as discriminating sensors. 

The field testing demonstrated they are unable to discriminate between water and product 

nearly half of the time. However, they were able to reliably determine the presence of liquid. 

Therefore, all alarms from the model 794380-341 sensors, whether water or product, should 

be treated identically. Consoles should be programmed accordingly, and Veeder-Root has 

issued a statement to this effect. We further recommend that all model 794380-341 sensors 

that fail the annual monitoring certification be replaced with a different model. 

• Discriminating sensors should be tested in water and product as part of the annual 

monitoring certification. Since discriminating sensors are programmed to respond 

differently in product than in water, and since different alarms may receive different 

responses from on-site staff, it is important to verify that the water and product detection 

capabilities of the sensor are functional. If long response and recovery times make such 

testing impracticable, the use of a different type of sensor should be considered. 

• A new evaluation protocol should be developed to effectively evaluate polymer strip 

sensors10 under field-representative conditions that may impact their performance. The 

protocol should assess the sensor’s ability to respond to hydrocarbons in a variety of 

environmental conditions, and the impact that repeated/prolonged exposure to product may 

have on the sensor’s ability to alarm and recover from alarm reliably. Since current 

evaluation protocols do not cover these key performance factors, no new polymer strip 

sensors should be installed until new evaluation protocols are in place and the sensors have 

been certified in accordance with those protocols. 

• Water alarms from point liquid discriminating sensors should receive a rapid response. 

Since point liquid discriminating sensors can only respond to the liquid directly in contact 

with the detection element, they are unable to detect a product release floating on an existing 

pool of water whose height exceeds the level of the detection element. To minimize the risk 

of missed product detection with these sensors, it is important that water alarms be responded 

to promptly and owners and operators be trained on the limitations of these type of 

discriminating sensors. Regulatory agencies should consider the limitations of these sensors 

when reviewing monitoring plans. 

• When installed in turbine sumps and UDC, polymer strip discriminating sensors with 

low and high level liquid alarms should activate pump shutdown for both product and 

high-level liquid alarm. Once the water level has risen above the high-level float, floating 

product will not come in contact with the polymer cable or strip. There is essentially no leak 

detection once water reaches the high-level float, so all sensors of this type which are 

monitoring pressurized piping should be programmed to shutdown the pump at high liquid 

level. Proper console configuration and operation of the pump shutdown feature should be 

verified during the annual monitoring certification. 

 

10 See Appendix VII for a description of polymer strip and point liquid sensors. 

 

SWRCB 28 August 2002 
• Longer response times associated with polymer strip discriminating sensors may make 

them inappropriate for use in certain applications. Polymer strip discriminating sensors 

are much slower to respond to hydrocarbons than other sensor types. Therefore, care must be 

taken when considering their use. Polymer strip discriminating sensors should not be used as 

the sole monitoring method for double-walled pressurized piping unless they are 

programmed to shut down the pump when exposed to water or product.

• Polymer strip discriminating sensors should not be used in UST systems storing diesel. 

Since diesel fuel is not as volatile as unleaded fuel, polymer strips respond much more slowly 

(response times in diesel fuel may be 12 hours or more.) The lengthy response time of 

polymer-strip sensors in diesel fuel poses an increased risk of release to the environment. 

• Monitoring plans for facilities with discriminating sensors should include response 

plans for both water and product alarms. Leaving water in the secondary containment for 

an extended time period is unacceptable. The most appropriate solution for dealing with 

water in the secondary containment is to make the containment systems water tight. 

California’s program of periodic integrity testing of secondary containment systems should 

help minimize water intrusion problems, by identifying and repairing leaks through which 

groundwater may enter. Regulatory agencies should review response plans to assure that 

response times for water and product alarms are appropriate based on facility-specific 

conditions.

• Discriminating sensors may be reprogrammed as non-discriminating if needed. In 

response to the recommendations of this report, or to comply with local ordinances, UST 

operators may wish to replace their discriminating sensors with a non-discriminating model. 

As an alternative to replacement, many discriminating sensors can be reprogrammed to 

operate as non-discriminating. Reprogramming can be a cost-effective solution for 

discriminating sensors that may not be providing effective leak detection or satisfying local 

ordinances. Note that only a representative authorized by the manufacturer should perform

this reprogramming.

 

SWRCB 29 August 2002 
CONCLUSION 

The results of this field evaluation indicate that sensors can be an effective form of leak detection 

only when properly installed, programmed, and maintained. Improper operation, poor 

installation and maintenance practices, deficiencies in the construction of secondary 

containment, and poor design of some sensors was observed during the field evaluation. When 

including instances of water or product in the secondary containment, raised sensors, ignored 

alarms, and failure of the pump shutdown feature, 12% of the sensors tested had a problem. The 

problems identified may well be even more common in states not requiring annual certification 

of monitoring equipment. 

To make sensors a more effective form of leak detection, improvements are needed in the 

following areas: 

Functionality of Sensors

 Manufacturers should consider improving sensor design and materials to make them

more durable. Sensors should be designed and manufactured to operate under the 

conditions present at operating UST facilities. 

 Sensors should not be used as the sole form of monitoring for double-walled pressurized 

piping. Line leak detectors should be required as additional protection, to reduce the risk 

of release to the environment in the event of a catastrophic release from the primary 

piping. 

 Polymer strip discriminating sensors should not be used to monitor for the presence of 

less volatile hydrocarbons, such as diesel and waste oil. 

Field Testing Procedures

 Periodic functional testing of sensors is critical to their effectiveness. Functional testing 

should be performed at least on an annual basis. However, more frequent visual 

inspection and preventative maintenance is recommended for all float switch sensors. 

 Manufacturers should develop standard field testing procedures, and technicians should 

be trained on how to conduct field testing properly. Once test procedures are in place, 

technicians should be required to follow them. Test procedures should demonstrate a 

sensor’s ability to detect a release (for example: testing in liquid for float switch sensors, 

and testing in both water and product for discriminating sensors). 

Third-Party Evaluation of Sensors 

 Current third-party certification test protocols for sensors should be modified to better 

and more thoroughly evaluate sensors, and subject them to the parameters present at 

operating UST facilities. 

Regulatory and Technical Oversight

 Training is needed for UST owners, operators, installers, service technicians, and 

inspectors. Training should cover proper application, installation, testing, programming, 

and operation of sensors, as applicable. 

 

SWRCB 30 August 2002 
 Enforcement action should be taken against those who tamper with sensors, ignore 

alarms, turn off monitors, or fail to take action where product or water is present within 

secondary containment. 

Design and Construction of Secondary Containment 

 Secondary containment should be designed, installed, and maintained to be water tight. 

This will help reduce the frequency of raised sensors and water alarms, and help prevent 

deterioration of the sensors and secondary containment. 

 Secondary containment should be tested periodically. Periodic testing will help assure 

that secondary containment can prevent groundwater ingress and contain product in the 

event of a leak. 

 

SWRCB 31 August 2002 
Winston H. Hickox

Secretary for

Environmental

Protection

Gray Davis

Governor

FIELD EVALUATION OF

UNDERGROUND STORAGE TANK SYSTEM

LEAK DETECTION SENSORS

- Appendices -

August 2002

State Water Resources Control Board

Underground Storage Tank Program

P.O. Box 944212

Sacramento, CA 94244

www.swrcb.ca.gov/cwphome/ust/
TABLE OF CONTENTS

APPENDIX I

Summary of Phase I Testing (Veeder-Root Discriminating Sensors)

APPENDIX II

Workplan for the Field Evaluation

APPENDIX III

Location of Facilities Involved in the Field Evaluation

APPENDIX IV

Field Data Collection Forms

APPENDIX V

Sensor Survey Distribution Letter, Survey Form, Results, and Comments

APPENDIX VI

Field Data

APPENDIX VII

Discussion of Point Liquid and Polymer Strip Discriminating Sensors
A

Summary of Phase I Testing (Veeder-Root Discriminatin
November, 2000

Appendix I, Phase I Testing Summary Page 1 of 9

Figure I - A typical multi-element discriminating sensor

with float switches and a product solubility element.

Phase I Testing Summary

(Field Evaluation of Veeder-Root Discriminating Sensors)

Introduction

Sensors are used in a variety of places within a UST system to detect a release of product. For

double-wall systems, they are either located inside the secondary containment (sumps and under

dispenser pans) or in the space between the primary and secondary containment of the tank or

piping, known as the interstitial space. Field experience has shown that due to numerous design,

installation, and maintenance issues these areas are often not kept clean of water intrusion or

excessive condensation. This has led the industry to introduce sensors that are capable of

differentiating between water and hydrocarbons. These sensors are referred to as “discriminating

sensors.”

Discriminating sensors can provide distinct alarms for water or product. Some even offer

distinct alarms for low and high levels of water. Depending on how the control panel is

programmed, a product or water (low or high level) detection can activate a warning, alarm, or

pump shutdown. Typically, sensors are programmed to provide a warning when water is

detected, which still allows the UST system to operate. Product detection is typically

programmed to activate a fuel alarm, and may also automatically shut down the pump.

There are two basic approaches to discriminating sensors, as described in the following

paragraphs. One approach to discriminating sensors is to combine two or more sensing elements

into a single unit (See Figure I). This approach is well suited for sumps where surface water is

prone to leak in, presenting the possibility of product floating on water. Sensing elements (most

often a float switch) are used to detect low and high liquid levels. If the level rises above a

preset point, the sensor notifies the operator by activating an alarm or warning message on a

control panel. A hydrocarbon-sensing element (such as a product permeability sensor) is also

incorporated to detect the presence of product. The combination of these multiple sensing

elements into a single unit makes a discriminating sensor able to determine the presence of water

versus hydrocarbons. There are several combinations of detection mechanisms that may be

incorporated in a single unit to produce a discriminating sensor.
November, 2000

Appendix I, Phase I Testing Summary Page 2 of 9

The second type of discriminating sensor uses only one detection mechanism, but is able to

discern between product and other liquids based on some specific property of the liquid. Some

adsistor, capacitance change, electrical conductivity, fiber optic chemical, and thermal

conductivity sensors are sophisticated enough to distinguish between product and water.

Purpose of the Project

This report is based on testing performed only on discriminating sensors manufactured by

Veeder-Root, as they are the most prevalent in California. We initiated a field study of

discriminating sensors in response to local agency concerns that some of these sensors did not

appear to operate properly when annual maintenance certification and inspections were

conducted. Particular items of concern brought to our attention by local agency inspectors were:

• The inability of discriminating sensors to detect a layer of hydrocarbon-based product (i.e.

gasoline) floating on top of water and to properly distinguish between water and product; 

• The inability of polymer-based hydrocarbon detecting elements to alarm in a reasonable

amount of time; and

• The inability of polymer-based hydrocarbon detecting elements to return to effective

operation (recover) after exposure to hydrocarbons.

While this project was initially designed to address the aforementioned local agency concerns,

we enlisted the help of discriminating sensor manufacturers and local agency inspectors to

expand the scope of the study. The scope of the study included: 

• Evaluating the functionality of discriminating sensors used in California (in response to

the above listed concerns of local agency inspectors);

• Checking the adequacy of field-testing procedures for discriminating sensors (or work

with manufacturers to develop field-testing procedures if they are not already available);

• Determining if discriminating sensors in the field perform consistently with the

specifications outlined in their third-party evaluations; and

• Determining if the third-party evaluation protocol currently used is suitable for the sensor

types tested using that protocol.

Coordination of the Field Testing

Since the focus of the testing was on the performance of sensors in the field, it was necessary to

conduct testing at operating facilities where the sensors are installed. Three local agencies

representing a cross section of California’s UST population local regulatory governments

volunteered to assist with this project. The City of Santa Ana, City of Santa Monica, and City of

Oakland helped us to identify facilities within their jurisdictions that were using Veeder-Root

discriminating sensors. In order to minimize the impact on owners, operators, and local

agencies, we scheduled our field testing to coincide with the required annual inspections. The

maintenance contractor performed the testing for the sensors while completing all the other

scheduled annual certification work. Manufacturer’s representatives were on hand to observe

the testing, assist with the advanced setup and diagnostic features of the sensor control panel, and

to answer technical questions.

Testing Procedure

In order to test the sensors during this evaluation, Veeder-Root prepared a draft testing

procedure. We reviewed and provided comments on the draft test procedures, which were then
November, 2000

Appendix I, Phase I Testing Summary Page 3 of 9

modified by Veeder-Root and re-submitted as a second draft. The second draft was the testing

procedure used in our field evaluation. Modifications were made throughout the study, as

deemed necessary by our staff on site. Modifications were included to minimize station

downtime, and to test possible improvements to the protocol (such as the cleansing of sensors in

white gas1 to accelerate recovery of polymer strips.) 

The basic test procedure was to immerse the discriminating sensor in fuel, water, or a fuel/water

mixture to see if it alarmed appropriately (e.g., water and/or fuel). We modified the procedure

by using a stopwatch to determine the length of time between sensor immersion and alarm, and

the length of time for the sensor to recover after being removed from the liquid. We also noted

the type and the depth of the liquid in which a sensor was immersed, as well as the type of alarm

(fuel, water, or both water and fuel) the sensor registered.

Test procedures varied slightly between sensor models, due to differences in detection

mechanisms. Veeder-Root’s discriminating sensors can be classified in two general families

based upon their fuel-sensing mechanisms: Ultrasonic sensors (model 794380-341), and Polymer

Strip Sensors (all other models tested). Table I lists the Veeder-Root discriminating sensors

tested in this study, including the mechanisms each sensor model uses to determine the presence

of liquid and/or fuel, and the testing procedure used in our study.

TABLE I - Veeder-Root’s Discriminating Sensors

Model

Number

Application VR Test

Procedure

Water Sensing

Mechanism

Fuel Sensing Mechanism

794380-320 Dispenser Pan A Ultrasonic Polymer Strip

794380-350 Sump (Pump or Piping) A Ultrasonic Polymer Strip

794380-322 Dispenser Pan A Float Switch Polymer Strip

794380-352 Sump (Pump or Piping) A Float Switch Polymer Strip

794380-360 Fiber Trench A Ultrasonic Polymer Strip

794380-361 Fiber Trench A Ultrasonic Polymer Strip

794380-362 Fiber Trench A Ultrasonic Polymer Strip

794380-341 Interstitial B Ultrasonic Capacitance Change

Data Collection

City of Santa Ana

SWRCB staff, local agency inspectors, maintenance contractors, and Veeder-Root

representatives collected data for this project. Data collection began in Santa Ana in August

2000, where the local agency inspector, maintenance contractor, Veeder-Root representatives

were present at each testing site. SWRCB staff was present at some of the Santa Ana sites.

Veeder-Root representatives recorded the test data in Santa Ana. This data was forwarded to us

for analysis. (See Table II for a summary of this data.)

 

1 Since the time of testing we have heard from other manufacturers of polymer strip sensors that this practice,

although common among service technicians, may have an adverse effect on the polymer strip sensor’s continued

functionality. SWRCB staff does not recommend cleansing sensors with white gas unless specifically instructed to

do so by the sensor manufacturer.
November, 2000

Appendix I, Phase I Testing Summary Page 4 of 9

SWRCB staff did not always witness testing in Santa Ana. Additionally, we were still refining

the scope of data to be collected, testing procedures, and protocol for data collection. For these

reasons, results of testing in Santa Ana were usually considered only when making general

observations and conclusions in this report, not in making any specific calculations. An

exception to this is test data for model 794380-341 sensors. Santa Ana test data for this model

has been included in the calculations of this report, since the sample size in Santa Monica and

Oakland was so small. The local agency inspector present at all Santa Ana sites furnished us

with his reports on the sites equipped with model 794380-341 sensors, and this data was used in

calculating pass/fail rates for that model.

 

City of Oakland and City of Santa Monica

Testing was conducted in Oakland and Santa Monica in October and November 2000. Local

agency inspectors, Veeder-Root personnel, service technicians, and SWRCB staff were present

at all facilities tested. SWRCB staff recorded all test data. Upon completion of testing, the data

collected from Oakland and Santa Monica was compiled in a data table, which is summarized in

Table III.

Table II - Summary of Veeder-Root Test Data from Santa Ana*

Dates of Testing August 21st–25th, 2000

Number of Facilities Tested 8

Number of Sensors Tested (model 794380-208) = 18

(model 794380-320) = 3

(model 794380-341) = 13

(model 794380-350) = 26

(model 794380-352) = 5

(model 794380-362) = 1

(model 794380-40x) = 10

Total Number of Sensors Tested 76

*Detailed test information not available for Santa Ana facilities

Table III - Summary of Test Data from Oakland and Santa Monica

Number of Facilities Tested 18

Number of Sensors Tested (model 794380-320) = 2

(model 794380-322) = 1

(model 794380-341) = 6

(model 794380-350) = 8

(model 794380-352) = 49

(model 794380-360) = 1

Total Number of Sensors Tested 67

Pass/Fail Data for Model 794380-341 4 passes, 2 failures

Range of Response Times in Fuel and Fuel/Water Mix (794380-350) 3:26 to 42:50 (min:sec)

Range of Recovery Times in Fuel and Fuel/Water Mix (794380-350) 19:49 to 70:40 (min:sec)

Range of Response Times in Water (794380-352) 2 to 18 seconds

Average Response Time in Water (794380-352) 8 seconds

Range of Response Times in Fuel and Fuel/Water Mix (794380-352) 4:59 to 12:10 (min:sec)

Average Response Time in Fuel and Fuel/Water Mix (794380-352) 7 minutes, 15 seconds

Range of Recovery Times in Fuel and Fuel/Water Mix (794380-352) 0:27 to 52:29 (min:sec)

Average Recovery Time in Fuel and Fuel/Water Mix (794380-352) 17 minutes, 26 seconds
November, 2000

Appendix I, Phase I Testing Summary Page 5 of 9

Discussion

Since the operating mechanism and testing procedure of the Veeder-Root model 794380-341

sensor are different than all the other sensors in our study, it is reasonable to divide the

“discussion” section into two parts: one part for the 794380-341 (ultrasonic mechanism), and one

for all of the other sensors in our study (polymer-strip mechanism).

Ultrasonic Mechanism (Veeder-Root Model 794380-341)

Our testing showed the 794380-341 interstitial fiberglass tank sensor performed unsatisfactorily.

Eleven of 20 model 794380-341 sensors failed when tested in the field2. Usually, the sensors

detected the presence of liquid, but were unable to discriminate between fuel and water. VeederRoot determined the failures are due to a faulty solder joint within the sensor, and is planning to

make design changes to eliminate the problem. Since the sensor cannot reliably discriminate

between fuel and water, Veeder-Root intends to reclassify the current 794380-341 sensor as nondiscriminating3

.

When testing the 794380-341 sensors in Santa Ana, we observed that they often came out of the

tanks wet. The moisture was a clear, odorless and somewhat gooey film. When the film dried, it

became milky white4. There appeared to be moisture in the interstitial spaces of the tanks these

sensors are monitoring, but not enough to activate an alarm. Follow-up information from Santa

Ana indicates that these sensors had to be cleaned before they would alarm properly when tested,

and that this is a common occurrence observed by inspectors during routine sensor field

certifications.

Polymer-Strip Mechanism (Veeder-Root Models 794380-320, 794380-322, 794380-350,

794380-352, 794380-360, 794380-361, and 794380-362)

The polymer-strip discriminating sensors consist of three separate sensing elements. The low

and high liquid detectors are float switches or ultrasonic sensors depending on the model. The

product-sensing element is a polymer strip that absorbs hydrocarbons. The strip is imbedded

with small particles of conductive material (See Figure II). As the strip absorbs hydrocarbons,

the material expands and the strip becomes less conductive (e.g. the resistance rises). When the

resistance reaches a certain level (for Veeder-Root sensors this is set at approximately 250 kΩ to

500 kΩ) an alarm is activated.

 

2 Includes data supplied by the local agency inspector present at Santa Ana test sites. 3 Veeder-Root has completed reclassification of the model 794380-341 sensor since this summary was originally

prepared.

4 The local agency inspector present at these facilities was concerned that the liquid may include resin or adhesive

used in construction of the fiberglass tanks where these sensors are installed.

Figure II – Polymer strip used in discriminating sensors
November, 2000

Appendix I, Phase I Testing Summary Page 6 of 9

The low and high-level liquid sensors proved to be generally effective. They typically activated

a liquid alarm in less than the third-party specified time. On the few occasions that a sensor did

not respond properly, the problem was usually diagnosed as faulty wiring or improper

programming of the console and not a design problem.

While our field-testing showed the low and high level liquid sensors to be effective, several

issues concerning the polymer strip were raised which may be cause for concern and further

investigation. Other issues, such as control panel configuration and testing protocols, were also

brought to light in the course of field-testing. The following paragraphs discuss these concerns

in detail.

1. Response and recovery times of the polymer strip element when exposed to fuel were

sometimes excessive, and not always consistent with third-party claims. Primary concerns

include the length and variation of response and recovery times, as discussed below:

(a) Length of Response Times 

The fuel alarm is activated only after enough fuel has permeated the polymer strip to

raise its electrical resistance to a value of 250 kΣ-500 kΣ. The time required to reach the

necessary electrical resistance varied from 5 to 12 minutes, with an average of just above

7 minutes. Typically the resistance in the strip did not change appreciably for several

minutes. In the event of a catastrophic leak, this response time could lead to large

amounts of fuel in the dispenser pan or containment sump. As the liquid level reaches

the high-level liquid sensor a high level water alarm will sound, but it could still be many

minutes before the polymer strip reacts to the fuel and activates a fuel alarm. This would

be a major concern if the system is not configured for turbine shutdown when the high

level water alarm is activated.

(b) Variation of Response Times 

With the wide variation in response times between sensors of the same model tested in

the same product, it is difficult to say exactly how long a polymer-strip sensor should

typically take to alarm once exposed to fuel. This makes it difficult to establish fieldtesting guidelines, or to determine if a sensor is actually non-functional or just slow to

respond.

(c) Length of Recovery Times 

Recovery times often exceeded the third-party value of 17.17 minutes. Values ranged

from under 1 minute to over 52 minutes, with an average of more than 17 minutes. Like

a sponge in water, the strip swells when exposed to fuel. It must completely dry out and

return to its original shape in order to come out of alarm. This can take quite awhile,

depending on how saturated the strip is and how volatile the liquid is. In the interest of

time, our test procedure called for a minimum amount of fuel, and for the sensor to be

removed from fuel as soon as it alarmed. We even experimented with removing the

sensor from fuel before it had alarmed in hopes of decreasing recovery times. Even so,

the recovery times were high. Although the test protocol used in this study did not

include long-term immersion of sensors in fuel, it is reasonable to believe that sensors

immersed in fuel for extended periods of time (as would be the case in the event of an

actual leak) would take even longer to recover, or may not recover at all.
November, 2000

Appendix I, Phase I Testing Summary Page 7 of 9

2. Response and recovery times seem to vary with weather conditions.

(a) Warm and dry vs. cool and wet conditions

Although it is difficult to substantiate with hard data due to the inconsistency of our

testing procedures5, the polymer strips tended to respond and recover more quickly in

warmer weather. We observed that sensors tested in the sun and sensors tested during

dry conditions recovered more quickly than sensors tested in rainy or colder weather.

This may be due to the fact that in colder or more humid weather fuel is less volatile. 

(b) Very cold conditions

The correlation between temperature and response/recovery time may become a major

factor at extremely low temperatures. In our field evaluation, we did not test sensors in

freezing conditions, so we do not know if the polymer strips are still effective at these

temperatures. Is fuel volatile enough during freezing temperatures for the sensor to

absorb the hydrocarbons and go into alarm? We posed this question to Veeder-Root in a

letter. Nowhere in the third-party evaluation is temperature or humidity considered. We

simply do not know how effective these sensors will be in extreme temperatures.

In addition to the polymer strips, we are also concerned about the functionality of float

switches in freezing conditions, especially those monitoring shallow sumps and shallow

under-dispenser containment boxes. It may be possible for condensation to freeze on a

float switch and render it inoperable.

3. The frequency of data transmittal between the sensor and the control console is a factor in

response and recovery times. 

The console (e.g., TLS 350) “looks” at the status of each sensor or leak detection element

in the UST system. It cycles through each sensor and element in the system before

returning to the beginning. If multiple sensors and elements are built into the

programming, it may take more time for the console to return to a particular sensor. As a

result, facilities with a large number of sensors may take longer to activate an alarm at the

console than those with a small number of sensors.

4. Alarm Settings and Pump Shutdown Features.

Many of Veeder-Root’s polymer-strip discriminating sensors have three different types of

alarms: a low liquid alarm, a high liquid alarm, and a fuel alarm. 

• The low liquid alarm is triggered by a float switch or ultrasonic mechanism

located at or near the bottom of the sensor housing. This mechanism will “trip”

whenever it is covered with fluid. It does not discriminate between water and

fuel. This mechanism activates a warning (yellow light) at the control panel. 

• The high liquid alarm is also triggered by a float switch or an ultrasonic

mechanism, which is located a few inches from the top of the sensor housing.

 

5 In warm weather, the thin layer of fuel used on top of water evaporated completely before the sensor alarmed. The

service person conducting the test had to add more fuel several minutes into the testing, causing very long response

times. Therefore the correlation between temperature and response time which might otherwise have been evident is

not readily recognized.
November, 2000

Appendix I, Phase I Testing Summary Page 8 of 9

Again, this mechanism cannot discriminate between water and fuel. This

mechanism activates an alarm (red light) at the control panel. 

• A fuel alarm is triggered by a polymer strip that runs the length of the sensor

housing, from the bottom of the sensor to the top float switch. Unless the polymer

strip detects hydrocarbons, alarms from this mechanism are considered an

indication of water intrusion. This mechanism activates an alarm (red light) at the

control panel.

Both warnings and alarms are designed to alert the operator that there is something wrong

with the UST system. Each requires investigation, and should receive an appropriate

response from the operator. Warnings and alarms may also be programmed to activate

pump shut-down, which turns off the turbine so that the UST cannot operate. Pump shutdown is generally only done with alarms. 

If warnings or alarms are ignored and the liquid level exceeds the height of the top float

switch, the sensor no longer detects additional fuel or water entering the sump. The

sensor becomes ineffective and no longer provides leak detection; therefore, pump shut

down at the high level alarm is a must.

5. High Vapor Mode

Another feature of the Veeder-Root control panel is the “High Vapor Mode.” This

operating mode is designed for use in areas where background levels of hydrocarbon

vapors are high enough to activate the fuel alarm, even though the UST system is not

leaking. This may be due to a previous release of product, or possibly the materials and

adhesives used in the construction of the UST itself may release vapors. “High Vapor

Mode” is a tool used to eliminate false alarms. When the console is configured in “High

Vapor Mode,” the sensor will not sound a fuel alarm unless it detects both the presence of

liquid and hydrocarbons. The low liquid alarm mechanism must be triggered and the

resistance in the polymer strip must be high enough to trigger a fuel alarm. 

Although the sensors we tested in “High Vapor Mode” seemed to be generally effective,

they have not been third-party certified for operation in “High Vapor Mode” versus “Low

Vapor Mode.”

6. Lack of Field Testing Procedures.

Although each manufacturer may provide its own manual of procedures for testing

discriminating sensors, there are several different tests a technician can run. Some

agencies require a test of the low and high liquid alarms only. Some agencies require

testing the sensors in fuel and water separately. And some agencies require each sensor

to be tested in fuel, in water, and in a fuel/water mixture.

Based on the results of our field testing, we determined that it is necessary to periodically

test all sensors in fuel. Even though the consoles are designed to run diagnostics on the

sensors, the consoles do not always recognize problems with sensors or their wiring. We

encountered two or three sensors that were either not programmed properly or had wiring

problems. These programming or wiring problems were only discovered through
November, 2000

Appendix I, Phase I Testing Summary Page 9 of 9

physical testing of the sensors in fuel. We might also benefit from testing sensors in a

water/product mixture, since it simulates more accurately conditions encountered in parts

of the UST system that are prone to water intrusion.

7. Degradation of Polymer Strips

Our testing provided no conclusive information as to the long-term reliability of polymerstrip sensors in harsh environments, or after repeated/prolonged exposure to

hydrocarbons. Results of testing showed a wide variation in the response and recovery

times for the polymer strip sensors. In many cases these times exceeded the third-party

specifications. 

The manufacturers of polymer strips claim the strips are testable and reusable, but each

time the strip comes in contact with fuel, it apparently either retains some of the volatile

compounds within its material or its elasticity is compromised after repeated/prolonged

hydrocarbon exposure. Once exposed to fuel, the sensor is no longer “good as new.”

Eventually, the sensor will degrade so much that either it may not recover from an alarm

condition (the resistance will not drop to the point that it comes out of alarm), or the

probability of false alarms will be very high. We do not know how many testing cycles a

sensor can reasonably accommodate.

8. Volatility of Stored Product

The polymer strip is most readily activated by volatile hydrocarbons, with unleaded fuel

and white gas producing the most rapid responses. The sensors also recovered from

exposure to these fuels fairly consistently. Diesel fuel would activate an alarm, but not

nearly as quickly as the more volatile unleaded fuel. Recovery times were very slow.

Veeder-Root suggested cleaning sensors exposed to diesel fuel with white gas in order to

speed up recovery. Technicians told us that sensors exposed to diesel must often be airdried for days, and even then, sometimes never recover.

 Although we encountered some waste oil UST systems being monitored by Veeder-Root

discriminating sensors, we did not test the sensors in waste oil. Veeder-Root’s sensors

are not third-party evaluated for use in waste oil applications. We are concerned that

waste oil may not be volatile enough to trigger an alarm from polymer strip sensors.

9. Third-Party Protocol is Inappropriate for Polymer Strip Sensors

Third-party testers have been using standard liquid point detection protocols to evaluate

the polymer-strip sensors. These protocols are usually designed for mechanical or

electrical switching devices that do not use chemical reactions like the polymer strips. It

may be necessary to develop a protocol that takes into account the unique aspects of

polymer-strip sensors. Ability to alarm and recover in a variety of environmental

conditions should be assessed. The impact of repeated exposure of these sensors to fuel

on response time and recovery time should also be evaluated.
A

Workplan for Phase II of the Field 
Appendix II, Workplan Page 1 of 1

SWRCB Sensor Field Evaluation Workplan (Phase II) – July 3, 2001

Team Members

Project Supervisor: Shahla Farahnak, P.E.

Project Coordinator: Scott Bacon

Assistant Coordinator: Raed Mahdi

Field Testing Staff: Raul Barba, Eric Luong, and Jennifer Redmond

Purpose of the Project

This project is intended to evaluate the functionality of liquid and vapor sensors used to monitor UST

systems. The focus will be on “real world” effectiveness, with testing performed at operating facilities

where the sensors are currently installed. The study is designed to:

• Evaluate the functionality of sensors used in California;

• Check the adequacy of field-testing procedures for sensors (or work with manufacturers to

develop field-testing procedures if they are not already available);

• Determine if sensors in the field perform consistently with the specifications outlined in their

third-party evaluations; and

• Determine if the third-party evaluation protocol currently used is suitable for each of the sensor

types evaluated with that protocol.

Coordinating Field Efforts

In order for us to test at a UST facility, several people must be present or notified. At a minimum, this

will include SWRCB staff and a service technician on site, as well as notification of the facility

owner/operator. Additionally, local agency inspectors and sensor manufacturers may be present. We

plan to work with local agencies and maintenance contractors to coincide our testing with the required

annual maintenance inspections already scheduled at the facilities

Data Collection Process

• Field Testing Method – Experienced service technicians will conduct the testing. They will

access sensors in sumps, tank interstice, dispenser pans, excavation linings, and monitoring wells.

The sensors will be immersed in water at a depth corresponding to their third-party evaluation. In

addition, discriminating sensors will be tested in fuel and/or a fuel/water mixture. 

• Data Recording – Our staff will observe the testing and record data. We will record sensor

response and recovery time, as well as information about the sensor make, model, and

application. Additionally, we will record data about the facility and the condition of the area the

sensor is located in. Through careful collection and analysis of data, we hope to determine what

factors may adversely effect sensor performance.

• Industry Professional’s Survey - In addition to the data collected from field-testing, we will

survey experienced maintenance technicians and inspectors. Their responses will be used to

supplement our field data and give us a clearer picture of sensor effectiveness.

Safety Considerations

Qualified contractors will perform all hands-on testing. They have been trained to safely deal with the

equipment and hazardous substances found at the facilities where our testing will take place. Our staff

will only observe and record data, but all applicable standards of safety will be adhered to. This includes,

but is not limited to, proper securing of the work area from traffic hazards. 

Final Report/Summary

A thorough report will be completed at the end of field-testing. It will detail our testing activities and

present the data collected from both the tests and completed surveys. In addition, the report will state

conclusions and recommendations based on the results of our study. 
AP

Location of Facilities Included in the Field 
Appendix III, Location of facilities included in the field evaluation Page 1 of 1

Location of Facilities Included in the Field 

Evaluation of Underground Storage Tank 

System Leak Detection Sensors 
AP

Field Data Collec
Appendix IV, Field Data Collection Forms Page 1 of 3

SWRCB SENSOR FIELD EVALUATION

SITE DATA COLLECTION FORM

Site # ________________________

SITE INFORMATION

Date: Time Testing Begins: Time Testing Ends:

Facility Name: Address:

Facility Ownership: Major Oil  Independent Oil  Government Agency 

Other:

Tank Type: Single-Wall  Double-Wall  Steel  Fiberglass  Dry  Hydrostatic 

Piping Type: Single-Wall  Double-Wall  Pressurized  Suction 

Steel  Fiberglass  Flex  Fiber Trench 

# of Tanks: # of Sumps: # of Dispensers:

STAFF

SWRCB Staff Present:

Local Agency Staff

Present

Agency:

Service Technician(s) Conducting Test:

Contractor: Years in Industry:

Manufacturer’s

Representatives:

Manufacturer:

WEATHER CONDITIONS

Temperature at Start of Testing: Temperature at End of Testing:

Humidity at Start of Testing: Humidity at End of Testing:

General Sunny  Cloudy  Windy  Light Rain 

Conditions: Heavy Rain  Fog  Other:

COMMENTS:
Appendix IV, Field Data Collection Forms Page 2 of 3

SWRCB SENSOR FIELD EVALUATION, SENSOR DATA COLLECTION FORM

EQUIPMEMNT INFORMATION

Sensor Make: Sensor Model:

Sensor Serial #: Sensor Manufacture Date:

Control Panel Make: Control Panel Model:

Control Panel Serial #: Control Panel

Manufacture Date:

Operating Principle: Float Switch  Ultrasonic  Product Permeable  Optical 

Capacitance Change  Product Soluble  Thermal Conductivity  Conductivity 

Discriminating? Y N Continuous? Y N Reusable? Y N Listed in LG-113? Y N

APPLICATION INFORMATION

Sensor Location: Tank Interstice  Pump Sump  Fill Sump  UDC 

Vapor Well  Groundwater Well  Trench Liner 

Is Sensor at Lowest Point? 

Yes No NA

Is Wiring Connected Properly?

Yes No NA

Total # of Sensors

Recorded on this Form:

Sensor Location... Is Clean and Dry  Contains Water  Contains Debris  Brine-Filled 

(check all that apply) Contains Product  Contains Backfill  Has Strong Vapor Smell 

Sensor is Monitoring for Regular Unleaded  Mid-Grade Unleaded  Premium Unleaded  Water 

the Presence of... Diesel  Brine  Waste Oil  Other:

Tank/Sump/UDC Steel  PVC/Plastic  Fiberglass 

Monitored by Sensor is... Membrane/Liner  HDPE  Other:

Tank/Sump/UDC Manufacturer:

WATER TEST (Low)

Water Height: Response Time

Recovery Time Pump Shut-Down Yes No NA

Alarm Activated: Water Product Both None Test Result: Pass Fail

WATER TEST (High)

Water Height: Response Time

Recovery Time Pump Shut-Down Yes No NA

Alarm Activated: Water Product Both None Test Result: Pass Fail

PRODUCT TEST Product Used:

Product Height: Response Time

Recovery Time: Pump Shut-Down Yes No NA

Alarm Activated: Water Product Both None Test Result: Pass Fail

PRODUCT ON WATER TEST

Water Height: Product Thickness:

Response Time: Recovery Time:

Alarm Activated: Water Product Both None Pump Shut-Down Yes No NA

Product Used: Test Result: Pass Fail

After testing this sensor was: Repaired1  Replaced  Re-Tested2  Re-Installed 

COMMENTS: 

 

1 Describe repairs in Comments section

2 If the sensor is re-tested, record test data in another sensor form and attach it to the back of this form
1) Sensor Location: T1 to T4 are sensors in tanks 1-4, S1 to S4 are sensors in the turbine sumps of tanks 1-4, additional sensor locations should be included in the “co

2) Alarm Type: W = Water, F = Fuel, N = None. Include both W and F if applicable.

3) Times: All times will be taken from the moment the sensor is placed in the fluid. The clock will not be zeroed between alarm activation and recovery.

4) Indicate any sensors that were replaced, noting the model # of the old and new sensors as well as the reason for replacement.

Appendix IV, Field Data Collection Forms 

Veeder-Root Discriminating Sensor Field Performance Test

Site Address: Date:Testing Contractor: SWRCB Staff:Weather Conditions: Diameter of test apparatus (in.): S

High Water Level Fuel Water/Fue

Response Response 

Sensor

Model

Water

Level

(in.)

Time to

Alarm

(mm:ss)

Alarm

Type

(WFN)

Recovery

Time

(mm:ss)

Fuel

Level

(in)

Time in

Fuel

(mm:ss)

Time to

Alarm

(mm:ss)

Alarm

Type

(WFN)

Recovery

Time

(mm:ss)

Water

Level

(in.)

Fuel

Thickness

(in.)

Time in

Liquid

(mm:ss)

S1S2S3S4

T1T2T3T4

Comments:
A

Sensor Survey Distribution Letter, Survey Form, Results, and 
State Water Resources Control Board

Division of Clean Water Programs

1001 I Street • Sacramento, California 95814 • (916) 341-5871

Mailing Address: P.O. Box 944212 • Sacramento, California • 94244-2120

FAX (916) 341-5808 • Internet Address: http://www.swrcb.ca.gov

California Environmental Protection Agency

 Recycled Paper

Winston H. Hickox

Secretary for

Environmental

Protection

Gray Davis

Governor

October 24, 2001

TO: Interested Parties

SURVEY FORM FOR SENSOR FIELD STUDY

We are sending this letter to you, as someone who may have expertise in the performance of the various

sensors used in UST systems. We are concerned about the performance of these sensors, specifically

those in tank-top sumps, tank annular spaces, and under dispenser containment. As you know, their

performance is critical in detecting leaks. Therefore, we have initiated our own study to evaluate their

effectiveness under actual operating conditions.

We plan to visit 200 operating UST facilities and collect data on sensor performance. However, we

recognize that our field study is limited and would be incomplete without input from those who have

valuable first-hand experience with these sensors. Therefore, we are requesting your assistance to

complete the enclosed survey form and return it to us. This will allow us to incorporate your knowledge

and experience into our study. We estimate it will take approximately 30 minutes to complete the entire

survey, however we are interested in your views even if you can only complete a portion. 

Please distribute the survey to anyone in your organization who routinely works with UST leak detection

sensors. This includes, but is not limited to, service technicians, inspectors, installers, and environmental

managers. Please return the completed surveys by November 15, 2001 to:

Attention: Scott Bacon

State Water Resources Control Board

Department of Clean Water Program

P.O. Box 944212

Sacramento, CA 94244-2120

Fax: (916) 341-5808

If you prefer, you may complete and submit the survey online at:

http://www.calcupa.net/support/index.htm

If you have any questions regarding this survey, please contact Scott Bacon at (916) 341-5873 or email:

bacons@cwp.swrcb.ca.gov.

Sincerely,

- ORIGINAL SIGNED BY -

Shahla Dargahi Farahnak, P.E., Chief

Engineering Unit 2

Underground Storage Tank Program

Enclosure
Appendix V, Survey Page 1 of 3

UST SENSOR STUDY SURVEY

STATE WATER RESOURCES CONTROL BOARD

(Please answer all the questions that are applicable based on your experience in the field)

Information provided by: – (Leave blank if you prefer to submit this survey anonymously) 

Name: _________________________________ Company/Agency: _____________________________

Address: _______________________________________________ Telephone: ____________________

GENERAL INFORMATION

1. What is your affiliation?  Local Agency Inspector  Technician  Consultant

 Owner/Operator  Other (Specify) _______________________

2. How many years of experience do you have in the UST field? ___________

3. Average number of UST facilities you inspect/service monthly? _______  Not applicable

OVERALL SENSOR INFORMATION

4. Do you perform/require a functional test (i.e. accessing the sensors and activating an alarm by flipping

them over, immersing them in liquid, etc.) of all sensors during the annual UST monitoring equipment

certification?  Yes  No

5. What percentage of the sensors you encounter in the field are failing the functional tests?

 <5%  5-10%  10-20%  20-30%  30-40%  40-50%  >50%

6. What percentage of the sensor failures are due to the following factors:

a) Poor design:  <5%  5-10%  10-20%  20-30%  30-40%  40-50%  >50%

b) Installation:  <5%  5-10%  10-20%  20-30%  30-40%  40-50%  >50%

c) Maintenance:  <5%  5-10%  10-20%  20-30%  30-40%  40-50%  >50%

d) Programming: <5%  5-10%  10-20%  20-30%  30-40%  40-50%  >50%

e) Tampering:  <5%  5-10%  10-20%  20-30%  30-40%  40-50%  >50%

f) Other:  <5%  5-10%  10-20%  20-30%  30-40%  40-50%  >50%

7. Sensor failure is most common in:  Steel Tanks  Dry Interstice Fiberglass Tank 

 Wet Interstice Fiberglass Tank  Tank-Top (pump/fill) Sumps

 Under Dispenser Containment  Location is not a factor in sensor failure
Appendix V, Survey Page 2 of 3

SENSOR COMPARISON

8. Please complete this section to the best of your knowledge:

Float

switch

Polymer

strip

Optical Prism Ultrasonic Conductivity Capacitance

change

% failure rate

* Indicate most

common reason(s)

for failure

*Failure Reasons: P = Programming M = Maintenance I = Installation T = Tampering

PD = Poor Design Other = Please indicate

9. What specific make(s) and/or model(s) of sensor are most reliable? _____________________________

_______________________________________________________________________________________

10. What specific make(s) and/or model(s) of sensor are least reliable? ______________________________

_______________________________________________________________________________________

DISCRIMINATING SENSORS

11. What percentage of the sensors you use/inspect/service are discriminating sensors? 

- Tank Interstice:  <5%  5-10%  10-20%  20-30%  30-40%  40-50%  >50%

- Turbine Sumps:  <5%  5-10%  10-20%  20-30%  30-40%  40-50%  >50%

- Under Dispenser:  <5%  5-10%  10-20%  20-30%  30-40%  40-50%  >50%

12. Based on your experience, discriminating sensors are ________________ when compared to nondiscriminating sensors?

 More reliable  Less reliable  Equally reliable

13. For discriminating sensors using polymer strip, what is the typical time for each of the following?

a) response in unleaded fuel:

 <30sec  30-60sec  1-3min  3-5min  5-10min  10-20min  >20min

b) recovery in unleaded fuel:

 <1min  1-3min  3-5min  5-10min  10-20min  >20min  Not reusable

c) response in diesel fuel:

 <30sec  30-60sec  1-3min  3-5min  5-10min  10-20min  >20min

d) recovery in diesel fuel:

 <1min  1-5min  5-15min  15-30min  30-60min  >60min  Not reusable
Appendix V, Survey Page 3 of 3

14. Is there a change in response times for polymer strip sensors after repeated exposure to fuel?

 Response time for polymer-strip sensors increases after repeated exposure to hydrocarbons.

 Response time for polymer-strip sensors decreases after repeated exposure to hydrocarbons.

 Response time for polymer strip sensors does not change after repeated exposure to hydrocarbons.

15. Which of the following methods do you most often use/require when testing discriminating sensors?

 Test in water only  Test in product only  Test in both product and water

 Flip sensor over  I do not test/require testing of discriminating sensors

PUMP SHUT-DOWN FEATURE

16. What is the typical time delay between sensor activation and pump shut-down?

 <5sec  5-10sec  10-30sec  30-45sec  45-60sec  1-2min  >2min

17. For sensors programmed for pump shut-down, what percent of them shut down the pump?

 <5%  5-10%  10-20%  20-30%  30-40%  40-50%  >50

18. What are the most common reason(s) for failure of the pump shut-down? 

 Programming  Maintenance  Installation  Tampering

 Relay box (Equipment problems)  Other (Specify) __________________

ADDITIONAL INFORMATION

19. What changes can be made to improve sensor reliability?______________________________________

____________________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

20. Do you have any other comments you would like to share with us? _____________________________

____________________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________
Number of UST Facilities Inspected/Serviced

by Respondent

0

0.5 1 2 3 4 5 6 7 8 10 12 15 20 25 30 35 50 60

UST Facilities per Month

Responses

Experience of Survey Respondents

0

0.5 1 2 3 4 5 6 7 9 10 11 12 13 15 17 20 21 30

Years Experience

Responses

ABOUT THE RESPONDENTS

SWRCB Sensor Field Evaluation, Survey Results

71 local agency inspectors and service technicians responded to the survey. The following tables summarize their responses to a variety

of questions on UST leak detection sensors.

1

4

12

10

6

5

1

2

1

6

1

3

4

3

1 1 1 1

2

4

6

8

10

12

14

1

3

4

2

3

6

5 5

1

7

5

8

2

9

1

2

1 1

1

2

3

4

5

6

7

8

9

10

Appendix V, Survey Results Page 1 of 6
Do you Require Functional Test of Sensors? Percentage of Sensors Failing Functional Test

< 5%

5 to 10%

10 to 20%

20 to 30%

30 to 40%

40 to 50%

> 50%

1

64

Responses

33

16

10

4

0

2

0

0 5 10 15 20 25 30

What Percentage of Sensor Failures are Due to

Poor Design?

21

8

2

3

3

2

6

Responses

Responses

No

Yes

0 10 20 30 40 50

0 2 4 6 8 10 12 14 16 18 20 22

< 5%

5 to 10%

10 to 20%

20 to 30%

30 to 40%

40 to 50%

> 50%

What Percentage of Sensor Failures are Due to

Poor Installation?

18

7

6

4

2

1

5

Responses

0 2 4 6 8 10 12 14 16 18 20 22

< 5%

5 to 10%

10 to 20%

20 to 30%

30 to 40%

40 to 50%

> 50%

60 70 35 Percentage

PercentagePercentage

Appendix V, Survey Results Page 2 of 6

GENERAL SENSOR INFORMATION
Location Where Sensor Failure is Most Common

Dry Interstice

Fiberglass Tank

Location is not a

factor in sensor failure

Steel Tanks

Tank-Top (pump/fill)

Sumps

Under Dispenser

Containment

< 5%

5 to 10%

10 to 20%

20 to 30%

30 to 40%

40 to 50%

> 50%

What Percentage of Sensor Failures are Due to

Tampering?

13

4

3

2

0

1

1

Responses

0 2 4 6 8 10 12 14 16 18 20 22

15

21

1

16

2

Responses

0 2 4 6 8 10 12 14 16 18 20 22

< 5%

5 to 10%

10 to 20%

20 to 30%

30 to 40%

40 to 50%

> 50%

What Percentage of Sensor Failures are Due to

Poor Maintenance?

15

8

6

5

2

4

1

Responses

0 2 4 6 8 10 12 14 16 18 20 22

< 5%

5 to 10%

10 to 20%

20 to 30%

30 to 40%

40 to 50%

> 50%

What Percentage of Sensor Failures are Due to

Improper Programming?

14

13

4

6

1

3

2

Responses

0 2 4 6 8 10 12 14 16 18 20 22

PercentagePercentage

Percentage

Appendix V, Survey Results Page 3 of 6
Equally Reliable

Less Reliable

More Reliable

Reliability of Discriminating Sensors

as Compared to Non-Discriminating

10

41

2

Responses

0 5 10 15 20 25 30 35 40 45

< 5%

5 to 10%

10 to 20%

20 to 30%

30 to 40%

40 to 50%

> 50%

Percentage of Discriminating Sensors in Tank Interstice

39

6

4

5

3

1

0

Responses

0 5 10 15 20 25 30 35 40

< 5%

5 to 10%

10 to 20%

20 to 30%

30 to 40%

40 to 50%

> 50%

Percentage of Discriminating Sensors in Turbine Sumps

28

8

7

7

4

1

4

Responses

0 5 10 15 20 25 30 35 40

< 5%

5 to 10%

10 to 20%

20 to 30%

30 to 40%

40 to 50%

> 50%

Percentage of Discriminating Sensors in UDC

29

10

6

4

4

1

3

Responses

0 5 10 15 20 25 30 35 40

PercentagePercentage

Percentage

Appendix V, Survey Results Page 4 of 6

DISCRIMINATING SENSOR INFORMATION
Discriminating Sensor Response Time in Unleaded Fuel

4

6

9

4

7

2

3

Responses

Discriminating Sensor Recovery Time in Unleaded Fuel

1

5

2

4

10

9

3

0 2 4 6 8 10 12

< 1 min

3 to 5 mins

10 to 20 mins

not reusable

Discriminating Sensor Response Time in Diesel Fuel

2

6

4

2

3

4

10

< 30 secs

30 to 60 secs

1 to 3 mins

3 to 5 mins

5 to 10 mins

10 to 20 mins

> 20 mins

Responses

Discriminating Sensor Recovery Time in Diesel Fuel

1

3

0

0

3

11

6

Time TimeTime Time

1 to 3 mins

5 to 10 mins

> 20 mins

Responses

0 2 4 6 8 10 12

Responses

< 1 min

3 to 5 mins

10 to 20 mins

not reusable

1 to 3 mins

5 to 10 mins

> 20 mins

0 2 4 6 8 10 12

< 30 secs

30 to 60 secs

1 to 3 mins

3 to 5 mins

5 to 10 mins

10 to 20 mins

> 20 mins

0 2 4 6 8 10 12

Appendix V, Survey Results Page 5 of 6
Installation

Maintenance

Programming

Relay Box

Tampering

Other

How are Discriminating Sensor Being Tested?

8

21

10

9

0 5 10 15 20 25

Flip Sensor

Over

Test in

Product Only

Pump Shut-Down Delay Time

12

16

19

11

4

2

1

< 5 secs

5 to 10 secs

1 to 2 mins

> 2 mins

Responses

Reason for Failure of Pump Shutdown

2

8

11

28

8

3

Time

Test in Both

Product and Water

Test in

Water Only

Responses

0 5 10 15 20 25 30

Responses

0 5 10 15 20

Changes in Response Time for Polymer Strips After

Repeated Exposure to Fuel

14

11

7

Responses

0 2 4 6 8 10 12 14 16

increases

decreases

does not change

10 to 30 secs

30 to 45 secs

45 to 60 secs

Appendix V, Survey Results Page 6 of 6

PUMP SHUT-DOWN INFORMATION
Appendix V, Survey Comments and Recommendations page 1 of 3

Online Survey Comments and Recommendations for the Sensor Field

Evaluation of Underground Storage Tanks:

This is a compilation of comments and recommendations we received from our survey participants. These

comments represent the views of the participants surveyed and may not reflect the opinions of the SWRCB.

• Discriminating sensors must be able to be tested in the actual product and must clear within a few

minutes.

• Improve maintenance of sensors and replace outdated ones.

• The polymer strip type sensor appears to be a poor design for immediate identification of a leak.

Remove this type from the approval list.

• Do not allow the use of sensors associated with the MSA Tankguard. I'm not sure, but I believe that

they are polymer strip discriminating sensors. They have an extremely low response and recovery time

of about 15-20 minutes. Also the sensitivity of the MSA Tankguard can be adjusted and always seems

to need to be adjusted at each inspection. The alarm may not sound when the sensor is being tested in

liquid, but then sound when it is not being tested. I do not trust the reliability of these sensors.

• Operator training, proper maintenance and tamper proofing.

• Eliminate discriminating sensors altogether in annular spaces. Heck, eliminate them everywhere.

They are only good for sumps and containment areas that are so poorly constructed that liquid

intrusion is a constant problem. Repairing the sumps would be a better solution to liquid intrusion

problems.

• The positive shut down sump sensors are plastic and they stick open. Some type of new stick product

is needed.

• You might want to require that all sensors be replaced regularly every 2-3 years.

• Eliminate discriminating sensors unless they have <5sec-response time. They need to be designed so

that corrosion and sticking do not occur. Needs to be such that maintenance is minimized since this is

only done annually.

• Require quarterly maintenance and inspection of sensors.

• Make them simple and easy to place. The Tri-State feature is best on systems that have no maintenance

crew.

• Overall experience with discriminating sensors is minimal, but due to survey set cases/problems, we do

not allow or will approve them for use in the city. Result is problematic.

• Better design, stronger materials, and no resistors at sensor end.

• Improve design on brands listed in question 10. Discriminating sensors are not practical. I do not test

them due to recovery time. Sometimes they do not recover.

• I don't know if it is possible, but what if they made a sensor that was non-stick so that sludge would not

hold the float, making it stuck. The contact points would also need to be sludge proof.

• Better installation practices. Sensors are not being hung at the correct location, i.e. at the bottom of the

tank or sump.
Appendix V, Survey Comments and Recommendations page 2 of 3

• Eliminate discriminating sensors or improve technology. Operate and test sensors under various

simulated conditions. Improve technology of annular float sensors in FG tanks to improve

accessibility/visual inspection/simulated testing.

• Be there at the annual maintenance checks. You learn a lot, see a lot of the important violations and

disrupt the business only once. The entire focus of my inspections is the leak detection systems for

piping and tanks. They must work. Operators do not like to do leak detection manually. Pushing

toward all electronic monitoring is essential for the future. Get the operators out of it. Have the ATG

print out the monthly .2 gph-passing test for tanks at least once a month automatically. Then the

operator saves this record for the inspection.

• Testers hate to test the discriminating sensors with product because they know they will have problems

getting them cleared, if at all. If the sensors won't clear, then it must be replaced, and tested. On one

occasion, the technician did not have a discriminating sensor replacement with him so he had to call

his shop and have someone drive one out to the site. This kept that product offline for several hours.

The facility operator was not happy.

• Get rid of sacrificial sensors, and require secondary containment for all piping!!!

• My primary objective in completing this survey is to expose the problems that I have encountered in

trying to test the sensors for the MSA Tankguard system. All other sensors that I have encountered are

sufficiently reliable.

• The compatibility of simple contact switch sensors with the control panels is not a major issue or an

operational problem. The use of discriminating sensors is a major issue even when these sensors are

used with a compatible control panel.

• We hardly see discriminating sensors. The alarm needs to go through a central alarm system in which

case we will know of any release. Tampering defeats the purpose of monitoring. We find improper

positioning of the probe/ raised probe 80 % of the sites. Water intrusion a real problem.

• A tank system that is properly constructed and maintained should never have liquid intrusion problems

and therefore there is no need for discriminating sensors.

• Owners need a good, simple manual on the tank system components, requirements, and

responsibilities: like "straight talk on tanks" in more detail. So many stations change hands and so

many employees are dueless, that comprehensive explanation of UST's is desperately needed to start to

get an unformed constituency.

• Bravo box float mechanisms for dispenser containment monitoring were not mentioned in this survey

but have about a 50% failure rate due to debris or loose chains. SFSFD water tests all float monitored

dispenser pans.

• Sensor reliability or rather the lack there of, has caused local agencies to all other leak detection and

testing requirements to UST's. The confidence level in the sensors functioning properly at any given

time is low, Because of this the confidence in our UST programs goal of preventing and detecting

releases is also somewhat low. Why spend a lot of time and resources when the devices are

unreliable? Also, this didn't address mechanical systems. The Bravo Float system has chronic

problems with not functioning properly after more than a year. The float does not leave very much

room for sidewalls of channels so dirt freezes the movement. Tampering by loosening chains is

extremely common. We dislike this design.

• Phasing out existing monitoring systems. I.e. pollulert, petrometer, leak-x, petrovend, etc. Notion

current LG-113 should be an eventually to start planning for now.
Appendix V, Survey Comments and Recommendations page 3 of 3

• Discriminating sensors add approximately 10 min. per sensor for testing and returning to operability.

That adds about 2 hours to a standard gas station monitoring certification inspection.

• Question 13(d)- recovery time for diesel fuel is greater than 60 minutes.

• Please remove discriminating sensors from approved method. They are not reliable and/or do not sense

for reasonable system monitoring (if located in sump bottom with water in sump a full leak will not be

detected if the water level is above the sensor). Question 7-Sensor failure is most common in Tank Top

(pump/fill) Sumps and Under Dispenser Containment.

• This survey should allow free-text answers. Some pick-list choices are inadequate. At the very least,

there should be a "unknown" response.

• In the past when we arrived on site for an inspection, the maintenance contractor or operator may have

already tested and replaced any faulty sensors. This will skew the data you collect from inspectors,

indicating higher performance rates.

• People raising probes due to surface water infiltration via rain or steam cleaning the parking lot, which

violates many laws.

• Alternate technologies should be available for positive shutdown, which do not rely on the relay boxes.
AP
Appendix VI, Definitions and List of Acronyms Page 1 of 1

Sensor Field Data Tables

List of Acronyms 

Acronym Meaning

MR Sensor is manually reset after an alarm

MSA Mine Safety Appliances

NA Not applicable to the sensor being tested

NP Not programmed for pump shut-down

NT Not tested

PSD Pump shut-down

Rec Recovery time (in seconds)

Resp Response time (in seconds)

UDC Under-dispenser containment

Unk Unknown. Data was unavailable

List of Definitions

Term Definition

Flip Test Sensor was tested by flipping it over

Heights All liquid levels are reported in inches

High Test High-level water testing

Low Test Low-level water testing. For single-level

sensors tested in water, test data will be

recorded in this column

Product Sensor was tested in product

Site ID #200 The 67 sensors tested during Phase I (VeederRoot discriminating sensors) are included in

this database under Site ID# 200

Times All response and recovery times are reported

in seconds
APPENDIX V

Summary of A
TABLE 1 - Summary of All Failures

Make At Low 

Point

Flip Test 

Result

Low Test Result

Site ID / Model

Low PSD High Test 

Result

High 

PSD

Pr

R

Wired 

Properly

Discriminating Flip PSD

Al

pha wire

92 Unk Yes Fail NT Yes NT NA NA 

NP 

Beaudreau

82 406 No NA NT Yes NT NA NA 

NA 

10 406 Yes NA Fail Yes NA NA NA 

NA 

Led indicator light was working on sensor, indicating that the wiring was properly connected. Sensor was reinstalled, meaning local agency has to follow up.

10 406 Yes NA Fail Yes NA NA NA 

NA 

Led indicator light was working on sensor, indicating that the wiring was properly connected. Sensor was reinstalled, meaning local agency has to follow up.

10 406 Yes NA Fail Yes NA NA NA 

NA 

Led indicator light was working on sensor, indicating that the wiring was properly connected. Sensor was reinstalled, meaning local agency has to follow up.

Gilbarco

28 PA02591144000 Yes Fail NT Yes NT NA NA 

NP 

Sensors was replaced by contractor two days after the inspection.

28 PA02592000000 Yes Fail NT Yes NT NA NA 

No 

Sensors was replaced by contractor two days after the inspection and positive shut down was rewired.

28 PA02592000000 Yes Fail NT Yes NT NA NA 

No 

Sensors was replaced by contractor two days after the inspection and positive shut down was rewired.

98 PA02592000010 No NT Pass Yes Yes NA NA 

NT 

3-4 inches of water on both sides of sump (low spots of tank top).

98 PA02592000010 No NT Pass Yes Yes NA NA 

NT 

2-3 inches of water on both sides of sump (low spots of tank top).

24 PA02592000010 Yes Fail NT Yes NT NA NA 

No 

Relay was stuck, so the PSD failed when tested. It passed when re-tested.

Incon

16 TSP-ULS No NT NT No NT Fail Yes 

NT 

Sensor was turned off when technician conducted the test. Sensor appears to have been turned due to water in the UDC. After turning the sensor on, it passed.

35 TSP-ULS No Pass NT Yes NT NA NA 

Yes 

The sump was full of diesel approximately 9 1/2 inches deep. The sensor was set at the top of the sump to avoid alarming.

Mallor

y Controls

92 Pollulert MD 241RRA Yes NA NT Yes NT NA NA 

NA 

Sensor failed the test, but the company is out of business.So, owner might have to change the system. Inspector gave the owner two weeks to fix it or replace It.

All times are recorded in seconds, heights are recorded in inches. Appendix VI, 
Make At Low 

Point

Flip Test 

Result

Low Test Result

Site ID / Model

Low PSD High Test 

Result

High 

PSD

Pr

R

Wired 

Properly

Discriminating Flip PSD

MSA

17 Tankgard 482607 No NA NT No NT NA NA 

NA 

Sensor initially turned off. Appears to have been turned off due to product in the sump. Sensor worked when turned on; sensor not at lowest point - about 8" above.

17 Tankgard 482607 Yes NA NT Yes NT NA NA 

NA 

Had to leave site before witnessing removal or re-installation of sensor.

Red Jacket

20 Liquid Refraction Sensor No Pass NT Yes NT NA NA 

Yes 

Sensor has been pulled up due to high water in the fill/vapor sump.

Ronan

20 LS-3 No Fail NT Yes NT NA NA 

No 

Sensor appears to be good during a continuity test, but appears not to be hooked up to the control panel.

47 LS-3 Yes Fail NT No NT NA NA 

Yes 

Sensor would not come out of alarm after testing. Pump would not come on. Contractor repaired the facility. Problem was wiring inside the building, near the control panel.

20 LS-3 Yes Fail NT No NT NA NA 

No 

Sensor appeared to be functional when technician tested for continuity, but did not activate an alarm at the panel. Tech suspects problem with wiring between sensor and panel.

32 LS-3 Yes Fail NT Yes NT NA NA 

NP 

Float was stuck. Technician had to shake it to loosen it, then sensor went into alarm.

1 LS-7 No Pass NT Yes NT NA NA 

NP 

The sensor could not be taken out of the tank interstice; therefore the sensor was activated within the tank.

Universal

94 LALS-1 Yes Fail NT Yes NT NA NA 

NA 

Contractor waited for 2 minutes for the sensor to response, but never did. Sensor had to be replaced.

95 LALS-1 Yes NA Fail Yes No NA NA 

NA 

Sensor was not tested because it was stuck in the interstitial space.

94 LAVS-1 Yes NA Fail Yes No NA NA 

NA 

Veeder-Root

85 794380-208 No Fail NT Yes NT NA NA 

No 

The contractor decided to stop testing the sensor after it failed to respond for more than 2 minutes and replace it with a new sensor.

10 794380-208 No Fail NT Yes NT NA NA 

No 

Alarm activated at the control panel, but no pump shutdown. ( printer said pump shutdown occurred, but pump continued to run. Picture of sensor is site 7 #2.). Follow up was dothat the PSD is functioning properly.

91 794380-208 No NT Pass Yes Yes NA NA 

NT 

Fill bucket was detached. Stick was in the product line (to prevent the flapper from shutting down the flow)

All times are recorded in seconds, heights are recorded in inches. Appendix VI, 
Make At Low 

Point

Flip Test 

Result

Low Test Result

Site ID / Model

Low PSD High Test 

Result

High 

PSD

Pr

R

Wired 

Properly

Discriminating Flip PSD

91 794380-208 No NT Pass Yes Yes NA NA 

NT 

Fill bucket was detached. Stick was in the product line (to prevent the flapper from shutting down the flow)

91 794380-208 No NT Pass Yes Yes NA NA 

NT 

Fill bucket was detached. Stick was in the product line (to prevent the flapper from shutting down the flow)

91 794380-208 No NT Pass Yes Yes NA NA 

NT 

Sensor timed out & Technician had to go and re-set it to shut down the pump.

91 794380-208 No NT Pass Yes Yes NA NA 

NT 

Fill bucket was detached. Stick was in the product line (to prevent the flapper from shutting down the flow). Most of sensors timed out & Technician had to go and re-set it to shut 

91 794380-208 No NT Pass Yes Yes NA NA 

NT 

Sensor timed out & Technician had to go and re-set it to shut down the pump.

91 794380-208 No NT Pass Yes Yes NA NA 

NT 

Sensor timed out & Technician had to go and re-set it to shut down the pump.

91 794380-208 No NT Pass Yes Yes NA NA 

NT 

Sensor timed out & Technician had to go and re-set it to shut down the pump.

42 794380-208 No Pass NT Yes NT NA NA 

NP 

Contains a substantial amount of water.

76 794380-208 No Pass NT Yes NT NA NA 

NP 

73 794380-208 No Pass NT Yes NT NA NA 

Yes 

Sensor was raised about 4 inches from the bottom of the sump.

33 794380-208 No Pass NT Yes NT NA NA 

NP 

33 794380-208 No Pass NT Yes NT NA NA 

NP 

33 794380-208 No Pass NT Yes NT NA NA 

NP 

33 794380-208 No Pass NT Yes NT NA NA 

NP 

33 794380-208 No Pass NT Yes NT NA NA 

NP 

33 794380-208 No Pass NT Yes NT NA NA 

NP 

79 794380-208 No Pass NT Yes NT NA NA 

Yes 

Product is leaking out of the top of the turbine pump.

79 794380-208 No Pass NT Yes NT NA NA 

Yes 

Product is leaking out of the top of the turbine pump.

79 794380-208 No Pass NT Yes NT NA NA 

Yes 

Product is leaking out of the top of the turbine pump.

42 794380-208 No Pass NT Yes NT NA NA 

Yes 

The sensor was not located at the lowest point in the tank. Technician lowered it and activetd an alarm.

All times are recorded in seconds, heights are recorded in inches. Appendix VI, 
Make At Low 

Point

Flip Test 

Result

Low Test Result

Site ID / Model

Low PSD High Test 

Result

High 

PSD

Pr

R

Wired 

Properly

Discriminating Flip PSD

76 794380-208 No Pass NT Yes NT NA NA 

NP 

62 794380-208 No Pass NT Yes NT NA NA 

NP 

2-3 gallons of product in the sump. Sensor was raised above the product level. Sensor in pump sump was not programmed to shut down pump.

62 794380-208 No Pass NT Yes NT NA NA 

NP 

2-3 gallons of product in the sump. Sensor was raised above the product level. Sensor in pump sump was not programmed to shut down pump.

42 794380-208 No Pass NT Yes NT NA NA 

Yes 

85 794380-208 No Pass NT Yes NT NA NA 

Yes 

There was a hole in the sump, approximately 1 1/2" diam. Electrical wiring below penetration lines. Hydrostatic test was performed to the highest penetration lines at 16 minutes p

12 psi. Fill sump is not clean..

10 794380-208 No Pass NT Yes NT NA NA 

Yes 

2 sensors, 1 raised in sump and the other was a the lowest point. Both responded and activated pump shut off. Picture of sensor was taken.

88 794380-208 Yes Fail NT Yes NT NA NA 

No 

Technician waited for over 2 minutes, but sensor did not alarm. Finally inspector decided to call the test off and replace the sensor. Testing was done on the new sensor and it pass

200 794380-341 Unk NA Unk Unk Unk NA NA 

NA 

200 794380-341 Unk NA Unk Unk Unk NA NA 

NA 

19 794380-341 Yes NA NT Yes NT NA NA 

NA 

Replaced with same type of sensor.

38 794380-341 Yes NA NT Yes NT NA NA 

NA 

Sensor was tested with both unleaded gasoline and waste oil. Both cases, water alarms were observed. Sensor was not approved for use in waste oil. After testing, sensor was repla

38 794380-341 Yes NA Pass Yes NA NA NA 

NA 

Sensor sets water alarm for product test. After testing the sensor was replaced and the new sensor was setting the right alarm.

38 794380-341 Yes NA Pass Yes NA NA NA 

NA 

Sensor sets water alarm for product test. After testing, sensor was replaced and the new sensor was setting the right alarm.

64 794380-341 Yes NA Pass Yes Yes NA NA 

NA 

Detected product as water. Since pump shuts down for product or water, Local Agency did not require sensor to be changed. Owner will replace sensor or re-program as non-disc

77 794380-341 Yes NA Pass Yes Yes NA NA 

NA 

Technician had to clean the sensor with a rag completely (especially in the small window at sensor's center) before fuel could be detected. After cleaning sensor did detect fuel.

64 794380-341 Yes NA Pass Yes Yes NA NA 

NA 

Detected product as water. Since pump shuts down for product or water, Local Agency did not require sensor to be changed. Owner will replace sensor or reprogram as non-discr

77 794380-341 Yes NA Pass Yes Yes NA NA 

NA 

Technician had to clean the sensor with a rag completely (especially in the small window at sensor's center) before fuel could be detected. After cleaning sensor did detect fuel.

77 794380-341 Yes NA Pass Yes Yes NA NA 

NA 

Technician had to clean the sensor with a rag completely (especially in the small window at sensor's center) before fuel could be detected. After cleaning sensor did detect fuel.

84 794380-350 Yes NA Pass Yes NA Pass Yes 

NA 

Sensor did not come out of alarm after being tested in product, so technician replaced it.

All times are recorded in seconds, heights are recorded in inches. Appendix VI, 
Make At Low 

Point

Flip Test 

Result

Low Test Result

Site ID / Model

Low PSD High Test 

Result

High 

PSD

Pr

R

Wired 

Properly

Discriminating Flip PSD

84 794380-350 Yes NA Pass Unk NA Fail No 

NA 

Technician suspected a problem with the wiring at this site.

84 794380-350 Yes NA Pass Unk NA Fail No 

NA 

Sensor alarmed, but failed PSD. Problem with the relay is suspected.

84 794380-350 Yes NA Pass No NA Fail No 

NA 

Sensor did not respond during high water or product testing. Technician suspected wiring problem, since sensor was replaced but test results did not change.

22 794380-352 No NT Fail Yes No Pass Yes 

NT 

Sensor's low float did not activate (would not reset). Sensor was replaced by the owner without informing the local agnecy nor the contractor who does the routine inspection. App

functinality.

200 794380-352 Unk NT Unk Unk Unk Pass Unk 

NT 

200 794380-352 Unk NT Unk Unk Unk Pass Unk 

NT

82 794380-352 Yes NT NT No NT NT NT 

NT 

Wiring malfunctioning.

82 794380-352 Yes NT NT No NT NT NT 

NT 

Wiring malfunctioning.

65 794390-205 No NT NT Yes NT NA NA 

NT 

Sump had oil in it. Sensor was raised above the oil, but alarmed when technician lowered it into the oil. Contractor was notified to pump out the oil that day.

46 794390-205 No Pass NT Yes NT NA NA 

Yes 

Sensor was raised approximately 1 foot from bottom of the sump.

29 794390-407 No NT NT No NT NA NA 

NT 

The sensor was located at the top of the tank, at the access port. The pull-string was broken. Inspector said sensor must be fixed immediately. The sensor was not functionally teswas done & sensor was repaired.

73 794390-407 Yes Fail NT Yes NT NA NA 

NP 

Sensor would not go into alarm until the techician shook it vigorously. Float was stuck. Interstice was moist, but not enough liquid to activate an alarm.

73 794390-407 Yes Fail NT Yes NT NA NA 

NP 

Sensor would not go into alarm until the techician shook it vigorously. Float was stuck.

81 794390-409 Unk Fail NT Unk NT NA NA 

NP 

Sensor was wedged between the primary and secondary tank walls and cannot be removed to verify sensor type. Alarm was not set at the control panel by pulling it like the prevou

81 794390-409 Unk Fail NT Yes NT NA NA 

NP 

Sensor was wedged between the primary and secondary tank walls and cannot be removed to verify sensor type. Alarm was set at the control panel by pulling it. The response time 

of knowing when sensor was triggered.

51 794390-420 NA Fail NT Yes NT NA NA 

NP 

The sensor was missing the float. Follow up was made with local agency and confirmed that the technician repaired the sensor. However, inspector did not peform re-inspection.

55 794390-420 No Pass NT Yes NT NA NA 

NP 

This sensor is for steel tanks, and could not be wrapped around the FG tank. Local agency instructed owner to replace.

All times are recorded in seconds, heights are recorded in inches. Appendix VI, 
Make At Low 

Point

Flip Test 

Result

Low Test Result

Site ID / Model

Low PSD High Test 

Result

High 

PSD

Pr

R

Wired 

Properly

Discriminating Flip PSD

89 794390-420 No Pass NT Yes NT NA NA 

Yes 

Interstitial space is full of water. Technician could not put back the sensor without calling the maintenance to remove water. Sensor was not at lowest point and wire was wrapped u

99 794390-420 No Pass NT No NT NA NA 

NP

Waste oil contained oil/water around the tank sump. The sensor was not located in the lowest point.

89 794390-420 No Pass NT Yes NT NA NA 

Yes 

23 794390-420 Yes Fail NT Yes NT NA NA 

NP 

Original sensor was stuck in the interstice because of rust on casing; sensor was replaced. New sensor passed test.

Warrick Controls

7 DLP-1-NC Yes Fail NT Yes NT NA NA 

NP 

Sensor was sitting in water and not alarmed. Contractor shook sensor and float moved activating the alarm. Sensor passed retest after 1-2 second alarm response.

All times are recorded in seconds, heights are recorded in inches. Appendix VI, 
APPENDIX V

Field Data for Non-discriminatin
TABLE 2 - Field Data for Non-Discriminating Sen

Sensor 

Location

Panel 

Make

Panel 

Model

At Low 

Point

Wiring 

OK

Condition 

of Location Resp Rec Alarm PSD Result Resp R

Liquid Testing 

Sensor Make: Beaudreau

Sensor Model: 404 Operating Principle: Float Switch

UDC Veeder-Root TLS-300 Yes Yes Clean/Dry 3 1 Product NA Pass NT N

Sensor Model: 406 Operating Principle: Optical

UDC Beaudreau 404-4 Cut-off Yes Yes Clean/Dry 1 2 Both NA Pass NA N

Sensor shuts off power to dispenser.

UDC Beaudreau 404-4 Cut-off Yes Yes Clean/Dry 1 2 Both NA Pass NA N

Sensor shuts off power to dispenser.

UDC Beaudreau 404-4 Cut-off Yes Yes Clean/Dry 2 2 Both NA Pass NA N

Sensor shuts off power to dispenser.

UDC Beaudreau 404-4 Cut-off Yes Yes Clean/Dry 2 2 Both NA Pass NA N

Sensor shuts off power to dispenser.

UDC Beaudreau 404-4 Cut-off Yes Yes Clean/Dry 2 2 Both NA Pass NA N

Sensor shuts off power to dispenser.

UDC Beaudreau 404-4 Cut-off No Yes Debris NT NT NT NT NT NA NUDC Beaudreau 404-4 Cut-off Yes Yes Clean/Dry None NA None NA Fail NA N

Led indicator light was working on sensor, indicating that the wiring was properly connected. Sensor was reinstalled, meaning local agency has to follow up.

UDC Beaudreau 404-4 Cut-off Yes Yes Clean/Dry None NA None NA Fail NA N

Led indicator light was working on sensor, indicating that the wiring was properly connected. Sensor was reinstalled, meaning local agency has to follow up.

UDC Beaudreau 404-4 Cut-off Yes Yes Clean/Dry None NA None NA Fail NA N

Led indicator light was working on sensor, indicating that the wiring was properly connected. Sensor was reinstalled, meaning local agency has to follow up.

UDC Beaudreau 404-4 Cut-off Yes Yes Clean/Dry 1 2 Both NA Pass NA N

Sensor shuts off power to dispenser.

UDC Beaudreau 404-4 Cut-off Yes Yes Clean/Dry 1 1 Both NA Pass NA N

The sensor was tested in a cup for total darkness and shut off the valve at the dispenser.

UDC Beaudreau 404-4 Cut-off Yes Yes Clean/Dry 2 5 Both NA Pass NA NUDC Beaudreau 404-4 Cut-off Yes Yes Debris NT NT NT NT NT NA N

Debris and dust accumulated over the years.

All times are recorded in seconds and heights in inches. Appe
Sensor 

Location

Panel 

Make

Panel 

Model

At Low 

Point

Wiring 

OK

Condition 

of Location Resp Rec Alarm PSD Result Resp R

Liquid Testing 

UDC Beaudreau 404-4 Cut-off Yes Yes Clean/Dry 15 1 Both NA Pass NA NUDC Beaudreau 404-4 Cut-off Yes Yes Clean/Dry 1 1 Both Yes Pass NA N

Sensor failed testing 6 weeks earlier. Technician replaced control module (located under dispenser) and now sensor worked.

UDC Beaudreau 404-4 Cut-off Yes Yes Clean/Dry 1 1 Both Yes Pass NA N

Sensor failed testing 6 weeks earlier. Technician replaced control module (located under dispenser) and now sensor worked.

UDC Beaudreau 404-4 Cut-off Yes Yes Clean/Dry 1 1 Both Yes Pass NA N

Sensor failed testing 6 weeks earlier. Technician replaced control module (located under dispenser) and now sensor worked.

UDC Beaudreau 404-4 Cut-off Yes Yes Clean/Dry 1 1 Both Yes Pass NA N

Sensor failed testing 6 weeks earlier. Technician replaced control module (located under dispenser) and now sensor worked.

UDC Beaudreau 404-4 Cut-off Yes Yes Clean/Dry 1 1 Both NA Pass NA NUDC Beaudreau 404-4 Cut-off Yes Yes Clean/Dry 1 1 Both NA Pass NA NUDC Beaudreau 404-4 Cut-off Yes Yes Clean/Dry 1 1 Both NA Pass NA NUDC Beaudreau 404-4 Cut-off Yes Yes Clean/Dry 1 1 Both NA Pass NA NUDC Beaudreau 404-4 Cut-off Yes Yes Clean/Dry 1 1 Both NA Pass NA NUDC Beaudreau 404-4 Cut-off Yes Yes Clean/Dry 1 1 Both NA Pass NA N

Sensor Make: Emco

Sensor Model: Q0003-006 Operating Principle: Optical

Tank Interstice Emco EECO 3000 Yes Yes Clean/Dry 60 60 Product NA Pass NA NTank Interstice Emco EECO 3000 Yes Yes Clean/Dry 60 60 Product NA Pass NA NTank Interstice Emco EECO 3000 Yes Yes Clean/Dry 60 60 Product NA Pass NA NTank Interstice Emco EECO 3000 Yes Yes Clean/Dry 60 60 Product NA Pass NA N

Sensor Model: Q0003-010 Operating Principle: Optical

Pump Sump Emco Wheaton Leak Sensor II Yes Yes Clean/Dry NT NT NT NT NT NA N

~8 oz water in cup; panel did not support ATG, only good for open/close sensor response; pressure operating principle?

Tank Interstice Emco Wheaton Leak Sensor II Yes Yes Clean/Dry NT NT NT NT NT NA N

~8 oz water in cup; panel did not support ATG, only good for open/close sensor response; pressure operating principle?

Sensor Make: Gilbarco

Sensor Model: PA02591144000 Operating Principle: Float Switch

All times are recorded in seconds and heights in inches. Appe
Sensor 

Location

Panel 

Make

Panel 

Model

At Low 

Point

Wiring 

OK

Condition 

of Location Resp Rec Alarm PSD Result Resp R

Liquid Testing 

Pump Sump Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 5 5 

Sensor is Gilbarco equivalent of VR model -208.

Pump Sump Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 5 5 

Sensor is Gilbarco equivalent of VR model -208.

Pump Sump Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 5 5 

Sensor is Gilbarco equivalent of VR model -208.

Tank Interstice Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 360 1 

Unable to remove and observe waste oil UST overfill sesor. Technician was able to to activate sensor within the tank.

Tank Interstice Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 720 1 Tank Interstice Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 1 1 Tank Interstice Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 720 1 

Mid-grade and Premium share the same annular space; some condensation; sensor casing split.

Tank Interstice Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 1 1 Tank Interstice Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 1 1 Tank Interstice Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 1 1 Tank Interstice Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 1 1 Tank Interstice Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 1 1 Tank Interstice Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 1 1 Tank Interstice Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT None N

Sensors was replaced by contractor two days after the inspection.

Tank Interstice Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 1 1 Tank Interstice Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 5 5 

This was a two-compartment tank (midgrade and premium). The casing of the sensor was split and took the form of a bell.

Tank Interstice Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 5 5 Tank Interstice Gilbarco EMC Yes Yes Clean/Dry 8 5 Product NA Pass NT NTank Interstice Gilbarco EMC Yes Yes Clean/Dry 9 5 Product NA Pass NT N

Soil in the access area for this sensor was stained dark with diesel fuel from unknown source. Possibly overfill or surface water ingress.

Tank Interstice Veeder-Root TLS-350 Yes Yes Water NT NT NT NT NT Unk Un

Alarm was set during the removal of the sensor from the tank interstice. Sensor was also covered with dirty water.

Tank Interstice Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 1 1 

All times are recorded in seconds and heights in inches. Appe
Sensor 

Location

Panel 

Make

Panel 

Model

At Low 

Point

Wiring 

OK

Condition 

of Location Resp Rec Alarm PSD Result Resp R

Liquid Testing 

Tank Interstice Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 5 5 

Sensor is Gilbarco equivalent of VR model -420.

Tank Interstice Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 5 5 

Sensor is Gilbarco equivalent of VR model -420.

Tank Interstice Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 5 5 

Sensor is Gilbarco equivalent of VR model -420.

Sensor Model: PA02592000000 Operating Principle: Float Switch

Pump Sump Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 840 5 

LLD failed the 3 gph leak test. Needs replacement.

Pump Sump Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 5 5 

Sensors was replaced by contractor two days after the inspection and positive shut down was rewired.

Pump Sump Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 5 5 

Sensors was replaced by contractor two days after the inspection and positive shut down was rewired.

Pump Sump Gilbarco EMC Yes Yes Product NT NT NT NT NT 5 5 Pump Sump Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 10 1 Pump Sump Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 840 5 Pump Sump Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 840 5 Pump Sump Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 5 5 

Sensor Model: PA02592000010 Operating Principle: Float Switch

Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 Pump Sump Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 5 5 Pump Sump Gilbarco EMC Yes Yes Product NT NT NT NT NT 10 1 Pump Sump Gilbarco EMC Yes Yes Product NT NT NT NT NT 10 1 Pump Sump Gilbarco EMC Yes Yes Product NT NT NT NT NT 30 1 

Relay was stuck, so the PSD failed when tested. It passed when re-tested.

Pump Sump Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 5 5 Pump Sump Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 5 5 Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 Pump Sump Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 5 5 

All times are recorded in seconds and heights in inches. Appe
Sensor 

Location

Panel 

Make

Panel 

Model

At Low 

Point

Wiring 

OK

Condition 

of Location Resp Rec Alarm PSD Result Resp R

Liquid Testing 

Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 Pump Sump Gilbarco EMC No Yes Water 5 5 Product Yes Pass NT N

3-4 inches of water on both sides of sump (low spots of tank top).

Pump Sump Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 7 1

Flip test used since cable was too short to remove from sump for water test.

Pump Sump Gilbarco EMC No Yes Water 8 8 Product Yes Pass NT N

2-3 inches of water on both sides of sump (low spots of tank top).

Pump Sump Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 5 5 Pump Sump Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 5 5 Pump Sump Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 5 5 

Sensor Model: PA0259300000-2 Operating Principle: Float Switch

Tank Interstice Gilbarco EMC NA Yes Brine-Filled 5 5 Product Yes Pass NT N

Pump shut down on high and low level alarms.

Tank Interstice Gilbarco EMC NA Yes Brine-Filled 5 5 Product Yes Pass NT N

Pump shut down on high and low level alarms.

Sensor Make: Incon

Sensor Model: TS-ILS Operating Principle: Optical

Tank Interstice Incon 1000ER Yes Yes Clean/Dry NT NT NT NT NT NA N

Sensor Model: TSP-HIS Operating Principle: Float Switch

Tank Interstice Incon TS-1000 Yes Yes Brine-Filled NT NT NT NT NT 15 Un

The sensor is Incon (double floats) continuously monitors the interstitial space.It was tested for both high level and low level alarms.

Tank Interstice Incon TS-1000 Yes Yes Brine-Filled NT NT NT NT NT 10 Un

Sensor Model: TSP-ULS Operating Principle: Float Switch

Fill Sump Incon TS-1000 No Yes Product NT NT NT NT NT 1 1

The sump was full of diesel approximately 9 1/2 inches deep. The sensor was set at the top of the sump to avoid alarming.

Fill Sump Incon TS-1000EFI Yes Yes Clean/Dry NT NT NT NT NT 5 Un

Pump Sump Incon Unk Yes Yes Clean/Dry NT NT NT NT NT 2 2 

Small metal casing with holes at bottom of sensor for liquid to enter; console had printer and ATG capability.

All times are recorded in seconds and heights in inches. Appe
Sensor 

Location

Panel 

Make

Panel 

Model

At Low 

Point

Wiring 

OK

Condition 

of Location Resp Rec Alarm PSD Result Resp R

Liquid Testing 

Pump Sump Incon Unk Yes Yes Clean/Dry NT NT NT NT NT 2 2 

Small metal casing with holes at bottom of sensor for liquid to enter; console had printer and ATG capability.

Pump Sump Incon 1000ER Yes Yes Clean/Dry NT NT NT NT NT NT NPump Sump Incon TS-1000 Yes Yes Clean/Dry NT NT NT NT NT 5 Un

This facility does not have a positive shut-down feature.

Pump Sump Incon TS-1000 Yes Yes Clean/Dry NT NT NT NT NT 5 UnPump Sump Incon TS-1000EFI Yes Yes Clean/Dry NT NT NT NT NT 25 UnPump Sump Incon TS-1000 Yes Yes Water NT NT NT NT NT 1 1

Tank Interstice Incon 1000ER Yes Yes Clean/Dry NT NT NT NT NT NT NTank Interstice Incon TS-1000 NA Yes Clean/Dry NT NT NT NT NT 1 1Tank Interstice Incon Unk Yes Yes Clean/Dry NT NT NT NT NT 2 2 

Small metal casing with holes at bottom of sensor for liquid to enter; console had printer and ATG capability.

Tank Interstice Incon Unk Yes Yes Clean/Dry NT NT NT NT NT 2 2 

Small metal casing with holes at bottom of sensor for liquid to enter; console had printer and ATG capability.

UDC Incon TS-1000 Yes Yes Product NT NT NT NT NT 1 1

There was a substantial amount of product in the UDC. There seemed to be a leak in the piping under the dispenser. It was in alarm on arrival.

UDC Incon 1000ER No No Water NT NT NT NT NT NT N

Sensor was turned off when technician conducted the test. Sensor appears to have been turned due to water in the UDC. After turning the sensor on, it passed.

Sensor Make: MSA

Sensor Model: Tankgard 482607 Operating Principle: Thermal Conductivity

Pump Sump MSA Tankguard Yes Yes Water NT NT NT NT NT NA NPump Sump MSA Tankguard No No Water NT NT NT NT NT NA N

Sensor initially turned off. Appears to have been turned off due to product in the sump. Sensor worked when turned on; sensor not at lowest point - about 8" above.

Pump Sump MSA Tankguard Yes Yes Clean/Dry NT NT NT NT NT NA N

Had to leave site before witnessing removal or re-installation of sensor.

Tank Interstice MSA Tankguard Unk Unk Water NT NT NT NT NT NA N

Sensor also is monitoring the presense of antifreeze, which shared the tank with the waste oil.

Tank Interstice MSA Tankguard Yes Yes Clean/Dry NT NT NT NT NT NA N

Sensor Make: Owens-Corning Tank

All times are recorded in seconds and heights in inches. Appe
Sensor 

Location

Panel 

Make

Panel 

Model

At Low 

Point

Wiring 

OK

Condition 

of Location Resp Rec Alarm PSD Result Resp R

Liquid Testing 

Sensor Model: FHRB 810 Operating Principle: Float Switch

Tank Interstice Veeder-Root TLS-350 NA Yes Brine-Filled NT NT NT NT NT 20 Un

This single sensor monitors the regular-mid-premium tanks; two reservoirs are used (left and right) and both must be activated for the alarm to go off.

Sensor Make: PermAlert

Sensor Model: PSTV Operating Principle: Float Switch

Tank Interstice Red Jacket PPM 4000 Yes Yes Clean/Dry NT NT NT NT NT 3 Un

Sensor Make: Pneumeractor

Sensor Model: LS 600LD Operating Principle: Float Switch

Pump Sump Pneumeractor LC-1000 Yes Yes Clean/Dry NT NT NT NT NT 2 2 

Unknown sensor type, photo taken. Flip test was done because sensor wiring prevented removal of the sensor ( wiring too short).

Pump Sump Pneumeractor LC-1000 Unk Yes Water NT NT NT NT NT 2 Un

Water in sumps was below level of the sensor. Flip test was done due to wiring being too short. No labels or markings on the sensor. Picture was taken.

Pump Sump Pneumeractor LC-1000 Unk Yes Water NT NT NT NT NT 2 Un

Sensor Make: Red Jacket

Sensor Model: Liquid Refraction Sensor Operating Principle: Optical

Fill Sump Red Jacket PPM 4000 No Yes Water/Debris NT NT NT NT NT 2 Un

Sensor has been pulled up due to high water in the fill/vapor sump.

Sensor Model: RE400-111-5 Operating Principle: Float Switch

Pump Sump Red Jacket STL 1801 Yes Yes Clean/Dry NT NT NT NT NT 1 1 Pump Sump Red Jacket STL 1401 Yes Yes Clean/Dry NT NT NT NT NT 1 1 Pump Sump Red Jacket STL 1401 Yes Yes Clean/Dry NT NT NT NT NT 1 1 Pump Sump Red Jacket STL 1801 Yes Yes Clean/Dry NT NT NT NT NT 1 1 Pump Sump Red Jacket STL 1401 Yes Yes Clean/Dry NT NT NT NT NT 1 1 Pump Sump Red Jacket STL 1801 Yes Yes Clean/Dry NT NT NT NT NT 1 1 

Sensor Model: Unk Operating Principle: Float Switch

Pump Sump Veeder-Root TLS-300 Yes Yes Clean/Dry NT NT NT NT NT 2 2 

All times are recorded in seconds and heights in inches. Appe
Sensor 

Location

Panel 

Make

Panel 

Model

At Low 

Point

Wiring 

OK

Condition 

of Location Resp Rec Alarm PSD Result Resp R

Liquid Testing 

Sensor Make: Ronan

Sensor Model: LS-3 Operating Principle: Float Switch

Fill Sump Ronan X76S Yes Yes Clean/Dry NT NT NT NT NT 1 1 

Float was stuck. Technician had to shake it to loosen it, then sensor went into alarm.

Fill Sump Ronan X761VCS-3LXi Yes Yes Clean/Dry NT NT NT NT NT 2 2 Fill Sump Ronan X761VCS-3LXi Yes Yes Clean/Dry NT NT NT NT NT 2 2 Fill Sump Ronan X76S Yes Yes Clean/Dry NT NT NT NT NT 1 1 Fill Sump Ronan X76S Yes Yes Clean/Dry NT NT NT NT NT 1 1 Fill Sump Ronan X76S Yes Yes Water NT NT NT NT NT 1 1 

Slight amount of water in fill sump. Not enough to activate an alarm.

Fill Sump Ronan X761VCS-3LXi Yes Yes Clean/Dry NT NT NT NT NT 2 2 Fill Sump Ronan X76S Yes Yes Clean/Dry NT NT NT NT NT 1 1 Fill Sump Red Jacket PPM 4000 No Yes Water/Debris NT NT NT NT NT Unk Un

Sensor appears to be good during a continuity test, but appears not to be hooked up to the control panel.

Monitoring Well EBW AutoStik Jr. 4 Yes Yes Backfill NT NT NT NT NT 1 1 

Sensor is a custom version of the LS3-A. It is made of stainless steel and is resistant to the chemicals stored in the system.

Monitoring Well EBW AutoStik Jr. 4 Yes Yes Backfill NT NT NT NT NT 1 1 

Sensor is a custom version of the LS3-A. It is made of stainless steel and is resistant to the chemicals stored in the system.

Monitoring Well EBW AutoStik Jr. 4 Yes Yes Backfill NT NT NT NT NT 1 1 

Sensor is a custom version of the LS3-A. It is made of stainless steel and is resistant to the chemicals stored in the system.

Monitoring Well EBW AutoStik Jr. 4 Yes Yes Backfill NT NT NT NT NT 1 1 

Sensor is a custom version of the LS3-A. It is made of stainless steel and is resistant to the chemicals stored in the system.

Monitoring Well EBW AutoStik Jr. 4 Yes Yes Backfill NT NT NT NT NT 1 1 

Sensor is a custom version of the LS3-A. It is made of stainless steel and is resistant to the chemicals stored in the system.

Monitoring Well EBW AutoStik Jr. 4 Yes Yes Backfill NT NT NT NT NT 1 1 

Sensor is a custom version of the LS3-A. It is made of stainless steel and is resistant to the chemicals stored in the system.

Monitoring Well EBW AutoStik Jr. 4 Yes Yes Backfill NT NT NT NT NT 1 1 

Sensor is a custom version of the LS3-A. It is made of stainless steel and is resistant to the chemicals stored in the system.

Monitoring Well EBW AutoStik Jr. 4 Yes Yes Backfill NT NT NT NT NT 1 1 

Sensor is a custom version of the LS3-A. It is made of stainless steel and is resistant to the chemicals stored in the system.

All times are recorded in seconds and heights in inches. Appe
Sensor 

Location

Panel 

Make

Panel 

Model

At Low 

Point

Wiring 

OK

Condition 

of Location Resp Rec Alarm PSD Result Resp R

Liquid Testing 

Pump Sump Ronan X76-4X Yes Yes Clean/Dry NT NT NT NT NT 1 1 Pump Sump Ronan X76S Yes Yes Water NT NT NT NT NT 2 2 Pump Sump Ronan X76S Yes Yes Clean/Dry NT NT NT NT NT 1 1 

Fail-safe was verified operational.

Pump Sump Ronan X76VS Yes Yes Clean/Dry NT NT NT NT NT 2 1 Pump Sump Ronan X76S Yes Yes Clean/Dry NT NT NT NT NT 1 1 

Fail-safe was verified operational.

Pump Sump Ronan X76S Yes No Clean/Dry NT NT NT NT NT 3 N

Sensor would not come out of alarm after testing. Pump would not come on. Contractor repaired the facility. Problem was wiring inside the building, near the control panel.

Pump Sump Ronan X76S Yes Yes Water NT NT NT NT NT 1 1 Pump Sump Ronan X76S Yes Yes Water NT NT NT NT NT 1 1 Pump Sump Ronan X76S Yes Yes Clean/Dry NT NT NT NT NT 1 1 

Fail-safe was verified operational.

Pump Sump Red Jacket PPM 4000 Yes No Water NT NT NT NT NT none N

Sensor appeared to be functional when technician tested for continuity, but did not activate an alarm at the panel. Tech suspects problem with wiring between sensor and panel.

Pump Sump Ronan Unk Yes Yes Clean/Dry NT NT NT NT NT 2 2 

This site has a suction system and a tank sump.

Pump Sump Ronan X761VCS-3LXi Yes Yes Clean/Dry NT NT NT NT NT 2 2 Pump Sump Red Jacket PPM 4000 Yes Yes Clean/Dry NT NT NT NT NT 3 Un

After follow up with local agency, inspector confirmed that the technician replaced fill sump sensor and replaced the broken wire in the monitor.

Pump Sump Ronan X76LVC Yes Yes Clean/Dry NT NT NT NT NT 1 1 Pump Sump Ronan X76LVC Yes Yes Clean/Dry NT NT NT NT NT 1 1 Pump Sump Ronan X76VS Yes Yes Clean/Dry NT NT NT NT NT 2 1 Pump Sump Ronan X76S Yes Yes Water NT NT NT NT NT 1 2 Pump Sump Ronan X76S Yes Yes Water NT NT NT NT NT 2 2 Pump Sump Ronan X76VS Yes Yes Clean/Dry NT NT NT NT NT 2 1 

Sensor was on its side and slightly upside-down, but not in alarm. Sensor did alarm when fully flipped over. Tech re-installed sensor properly after testing.

Pump Sump Ronan X76LVC Yes Yes Clean/Dry NT NT NT NT NT 5 5 Pump Sump Ronan X761VCS-3LXi Yes Yes Water NT NT NT NT NT 2 2 Pump Sump Ronan X76LVC Yes Yes Clean/Dry NT NT NT NT NT 1 1 

All times are recorded in seconds and heights in inches. Appe
Sensor 

Location

Panel 

Make

Panel 

Model

At Low 

Point

Wiring 

OK

Condition 

of Location Resp Rec Alarm PSD Result Resp R

Liquid Testing 

Pump Sump Ronan X76S Yes Yes Water NT NT NT NT NT 2 2 Pump Sump Ronan X76LVC Yes Yes Clean/Dry NT NT NT NT NT 5 5 Pump Sump Ronan X761VCS-3LXi Yes Yes Clean/Dry NT NT NT NT NT 2 2 Pump Sump Ronan X76-4X Yes Yes Clean/Dry NT NT NT NT NT 1 1 Pump Sump Ronan X76-4X Yes Yes Clean/Dry NT NT NT NT NT 1 1 

Tank Interstice Ronan X76S Yes Yes Clean/Dry NT NT NT NT NT 2 2 Tank Interstice Ronan X76LVC Yes Yes Clean/Dry NT NT NT NT NT 1 1 Tank Interstice Ronan X76S Yes Yes Clean/Dry NT NT NT NT NT 1 1 Tank Interstice Ronan X76S Yes Yes Clean/Dry NT NT NT NT NT 1 1 Tank Interstice Red Jacket PPM 4000 Yes Yes Clean/Dry NT NT NT NT NT 3 UnTank Interstice Ronan X76S Yes Yes Clean/Dry NT NT NT NT NT 2 2 Tank Interstice Ronan X76S Yes Yes Clean/Dry NT NT NT NT NT 1 1 

UDC Ronan X76-4X Yes Yes Clean/Dry NT NT NT NT NT 1 1 UDC Ronan X76-4X Yes Yes Clean/Dry NT NT NT NT NT 1 1 UDC Ronan X76-4X Yes Yes Clean/Dry NT NT NT NT NT 1 1 UDC Ronan X76-4X Yes Yes Clean/Dry NT NT NT NT NT 1 1 UDC Ronan X76-4X Yes Yes Clean/Dry NT NT NT NT NT 1 1UDC Ronan X76-4X Yes Yes Clean/Dry NT NT NT NT NT 1 1 UDC Ronan X76-4X Yes Yes Clean/Dry NT NT NT NT NT 1 1 UDC Ronan X76-4X Yes Yes Clean/Dry NT NT NT NT NT 1 1 

Sensor Model: LS-30 Operating Principle: Float Switch

Tank Interstice Ronan X76S NA Yes Brine-Filled NT NT NT NT NT 2 2 Tank Interstice Ronan X76S NA Yes Brine-Filled NT NT NT NT NT 2 2 Tank Interstice Ronan Unk NA Yes Unk 3 3 Water NA Pass NT N

Ronan- LS-30 hydrostatic in generator tank.

Tank Interstice Ronan X76S NA Yes Brine-Filled NT NT NT NT NT 2 2 Tank Interstice Ronan X76S NA Yes Brine-Filled NT NT NT NT NT 2 2 

All times are recorded in seconds and heights in inches. Appe
Sensor 

Location

Panel 

Make

Panel 

Model

At Low 

Point

Wiring 

OK

Condition 

of Location Resp Rec Alarm PSD Result Resp R

Liquid Testing 

Sensor Model: LS-7 Operating Principle: Float Switch

Tank Interstice Ronan X76S Yes Yes Clean/Dry NT NT NT NT NT 1 1 

Technician pulled wire and pull string at the same time. This lifts the sensor off the bottom of the tank interstice and allows the float to fall, activating the alarm.

Tank Interstice Ronan X76S Yes Yes Clean/Dry NT NT NT NT NT 1 1 

Technician pulled wire and pull string at the same time. This lifts the sensor off the bottom of the tank interstice and allows the float to fall, activating the alarm.

Tank Interstice Ronan X76S Yes Yes Clean/Dry NT NT NT NT NT 1 1 

Technician pulled wire and pull string at the same time. This lifts the sensor off the bottom of the tank interstice and allows the float to fall, activating the alarm.

Tank Interstice Ronan X76S Yes Yes Clean/Dry NT NT NT NT NT 3 1 Tank Interstice Ronan X76S Yes Yes Clean/Dry NT NT NT NT NT 3 1 Tank Interstice Ronan X76LVC Yes Yes Clean/Dry NT NT NT NT NT 4 4 Tank Interstice Ronan X76-4X Yes Yes Clean/Dry NT NT NT NT NT 1 1 Tank Interstice Ronan X76VS Yes Yes Clean/Dry NT NT NT NT NT 1 1 

Alarm was activated by shaking sensor while still in tank interstice.

Tank Interstice Ronan X76LVC No Yes Clean/Dry NT NT NT NT NT 5 5 

The sensor could not be taken out of the tank interstice; therefore the sensor was activated within the tank.

Tank Interstice Ronan X76VS Yes Yes Clean/Dry NT NT NT NT NT 1 1 

Sensor had to be re-installed with a fish-tape because the string was broken. This took the contractor about 1 hour.

Tank Interstice Ronan X76S Yes Yes Clean/Dry NT NT NT NT NT 3 1 Tank Interstice Ronan X76LVC Yes Yes Clean/Dry NT NT NT NT NT 5 5 Tank Interstice Ronan X76VS Yes Yes Clean/Dry NT NT NT NT NT 1 1 

Alarm was activated by shaking sensor while still in tank interstice.

Tank Interstice Ronan X76LVC Yes Yes Clean/Dry NT NT NT NT NT 3 3 Tank Interstice Ronan X76-4X Yes Yes Clean/Dry NT NT NT NT NT 1 1 Tank Interstice Ronan X76-4X Yes Yes Clean/Dry NT NT NT NT NT 1 1 Tank Interstice Ronan X76LVC NA Yes Clean/Dry NT NT NT NT NT 5 5 Tank Interstice Ronan X76VS Yes Yes Clean/Dry NT NT NT NT NT 1 1 

Alarm was activated by shaking sensor while still in tank interstice.

Sensor Model: Unk Operating Principle: Float Switch

Tank Interstice Veeder-Root TLS-300 NA Yes Clean/Dry NT NT NT NT NT 2 2 

All times are recorded in seconds and heights in inches. Appe
Sensor 

Location

Panel 

Make

Panel 

Model

At Low 

Point

Wiring 

OK

Condition 

of Location Resp Rec Alarm PSD Result Resp R

Liquid Testing 

Sensor Make: Universal

Sensor Model: LALS-1 Operating Principle: Thermal Conductivity

Fill Sump Universal Leak Alert LA-08 Yes Yes Clean/Dry 1 Unk Both Yes Pass NA N

Sensor activates an audible alarm and shuts down pump at the dispenser.

Fill Sump Universal Leak Alert LA-08 Yes Yes Clean/Dry 1 Unk Both Yes Pass NA N

Sensor activates an audible alarm and shuts down pump at the dispenser.

Piping Sump Universal Leak Alert LA-08 Yes Yes Clean/Dry 1 Unk Both Yes Pass NA N

Sensor activates an audible alarm and shuts down pump at the dispenser.

Pump Sump Universal Leak Alert LA-08 Yes Yes Clean/Dry 2 Unk Product NA Pass NA NPump Sump Universal Leak Alert LA-08 Yes Yes Clean/Dry 3 2 Water Yes Pass NA NPump Sump Universal Leak Alert LA-08 Yes Yes Clean/Dry 2 2 Water Yes Pass NA NPump Sump Universal Leak Alert LA-08 Yes Yes Vapor Odor NT NT NT NT NT 1 1 

Contractor blows on the sensor to activate the alarm. Sensor responds instantly. Sumps had been recently refinished and had strong chemical smell, not fuel.

Pump Sump Universal Leak Alert LA-08 Yes Yes Clean/Dry 2 Unk Product NA Pass NA NPump Sump Universal Leak Alert LA-08 Yes Yes Vapor Odor NT NT NT NT NT 1 1 

Contractor blows on the sensor to activate the alarm. Sensor responds instantly. Sumps had been recently refinished and had strong chemical smell, not fuel.

Pump Sump Universal Leak Alert LA-08 Yes Yes Clean/Dry 2 Unk Product NA Pass NA N

Tank Interstice Universal Leak Alert LA-08 Yes Yes Clean/Dry 8 10 Water Yes Pass NA NTank Interstice Universal Leak Alert LA-08 Yes Yes Clean/Dry 15 15 Water NA Pass NA N

Emergency generator with 1000 gallon tank.

Tank Interstice Universal Leak Alert LA-08 Yes Yes Clean/Dry 5 3 Water Yes Pass NA NTank Interstice Universal Leak Alert LA-08 Yes Yes Clean/Dry 4 4 Water Yes Pass NA NTank Interstice Universal Leak Alert LA-08 Yes Yes Clean/Dry NT NT NT NT NT 3 3 

Contractor blows on the sensor to activate the alarm.

Tank Interstice Universal Leak Alert LA-08 Yes Yes Clean/Dry NT NT NT NT NT 1 1 

Contractor blows on the sensor to activate the alarm. Sensor responds instantly.

Tank Interstice Universal Leak Alert LA-08 Yes Yes Clean/Dry NT NT NT NT NT 1 1 

Contractor blows on the sensor to activate the alarm. Sensor responds instantly.

Tank Interstice Universal Leak Alert LA-08 Yes Yes Clean/Dry NT NT NT NT NT 1 1 

Contractor blows on the sensor to activate the alarm. Sensor responds instantly.

All times are recorded in seconds and heights in inches. Appe
Sensor 

Location

Panel 

Make

Panel 

Model

At Low 

Point

Wiring 

OK

Condition 

of Location Resp Rec Alarm PSD Result Resp R

Liquid Testing 

Tank Interstice Universal Leak Alert LA-08 Yes Yes Clean/Dry 2 Unk Product NA Pass NA NTank Interstice Universal Leak Alert LA-08 Yes Yes Clean/Dry 2 Unk Product NA Pass NA NTank Interstice Universal Leak Alert LA-08 Yes Yes Clean/Dry NT NT NT NT NT 2 2 

Contractor blows on the sensor to activate the alarm.

Tank Interstice Universal Leak Alert LA-08 Yes Yes Clean/Dry NT NT NT NT NT 3 3 

Contractor blows on the sensor to activate the alarm.

Tank Interstice Universal Leak Alert LA-08 Yes Yes Clean/Dry 3 3 None Yes Pass NA NTank Interstice Universal Leak Alert LA-08 Yes Yes Clean/Dry NT NT NT NT NT 3 3 

Contractor blows on the sensor to activate the alarm.

Tank Interstice Universal Leak Alert LA-08 Yes Yes Clean/Dry 1 Unk Both Yes Pass NA N

Sensor activates an audible alarm and shuts down pump at the dispenser.

Tank Interstice Universal Leak Alert LA-08 Yes Yes Clean/Dry 1 Unk Both Yes Pass NA N

Sensor activates an audible alarm and shuts down pump at the dispenser.

Tank Interstice Universal Leak Alert LA-08 Yes Yes Clean/Dry NT NT NT NT NT None No

Contractor waited for 2 minutes for the sensor to response, but never did. Sensor had to be replaced.

Tank Interstice Universal Leak Alert LA-08 Yes Yes Clean/Dry None NA None No Fail NA N

Sensor was not tested because it was stuck in the interstitial space.

Tank Interstice Universal Leak Alert LA-08 Yes Yes Clean/Dry 2 Unk Product NA Pass NA N

Sensor Model: LAVS-1 Operating Principle: Metal Oxide Semiconductor

Tank Interstice Universal Leak Alert LA-08 Yes Yes Clean/Dry Unk Unk Unk No Fail NA N

Sensor Model: LS 03875 STP Sensor Operating Principle: Thermal Conductivity

Pump Sump Universal Leak Alert LA-08 Yes Yes Clean/Dry 2 33 Product Yes Pass NA N

There was no light bulb on the monitoring panel, but alarm activated.

Pump Sump Universal Leak Alert LA-08 Yes Yes Clean/Dry 2 11 Product Yes Pass NA N

There was no light bulb on the monitoring panel, but alarm activated.

Pump Sump Universal Leak Alert LA-08 Yes Yes Clean/Dry 2 15 Product Yes Pass NA N

There was no light bulb on the monitoring panel, but alarm activated.

Sensor Make: Veeder-Root

Sensor Model: 330212-001 Operating Principle: Float Switch

UDC Veeder-Root Dispenser cut-off Yes Yes Clean/Dry NT NT NT NT NT 2 2 

All times are recorded in seconds and heights in inches. Appe
Sensor 

Location

Panel 

Make

Panel 

Model

At Low 

Point

Wiring 

OK

Condition 

of Location Resp Rec Alarm PSD Result Resp R

Liquid Testing 

UDC Veeder-Root Dispenser cut-off Yes Yes Clean/Dry NT NT NT NT NT 1 M

Sensor cuts power to dispenser, which must be manually reset.

UDC Veeder-Root Dispenser cut-off Yes Yes Clean/Dry NT NT NT NT NT 2 1 UDC Veeder-Root Dispenser cut-off Yes Yes Clean/Dry NT NT NT NT NT 2 2 UDC Veeder-Root Dispenser cut-off Yes Yes Clean/Dry NT NT NT NT NT 2 2 UDC Veeder-Root Dispenser cut-off Yes Yes Clean/Dry NT NT NT NT NT 1 M

Sensor cuts power to dispenser, which must be manually reset.

UDC Veeder-Root Dispenser cut-off Yes Yes Clean/Dry NT NT NT NT NT 10 M

Sensor cuts power to dispenser, which must be manually reset.

Sensor Model: 331102-002 Operating Principle: Float Switch

Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 8 1 

Sensor has double float alarm (high/low). Service technician decided only to do the flip test.

Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 1 

Sensor has double float alarm (high/low). Service technician decided only to do the flip test.

Sensor Model: 794380-208 Operating Principle: Float Switch

ATG Sump Veeder-Root TLS-350 Yes Yes Water NT NT NT NT NT Unk Un

Sump contains dirty water. Alarm was set at the control panel.

ATG Sump Veeder-Root TLS-350 Yes Yes Water NT NT NT NT NT Unk Un

Sump contains dirty water. Alarm was set at the control panel.

ATG Sump Veeder-Root TLS-350 Yes Yes Water NT NT NT NT NT Unk Un

Sump contains dirty water. Alarm was set at the control panel

ATG Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 1 ATG Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 1 ATG Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 1 

Fill Sump Veeder-Root TLS-350 Yes Yes Water NT NT NT NT NT 3 3 

Fill sump contains water, dirt, and corrosion.

Fill Sump Veeder-Root TLS-350 Yes Yes Debris NT NT NT NT NT 3 2 Fill Sump Veeder-Root TLS-350 Yes Yes Product NT NT NT NT NT 2 2 

Sensor was in alarm when technician arrived to conduct inspection. Technician called to have the product removed.

Fill Sump Veeder-Root TLS-350 No Yes Water NT NT NT NT NT 2 2 

All times are recorded in seconds and heights in inches. Appe
Sensor 

Location

Panel 

Make

Panel 

Model

At Low 

Point

Wiring 

OK

Condition 

of Location Resp Rec Alarm PSD Result Resp R

Liquid Testing 

Fill Sump Veeder-Root TLS-350 No Yes Product NT NT NT NT NT 2 2 Fill Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 2 2 Fill Sump Veeder-Root TLS-350 Yes Yes Water NT NT NT NT NT 10 2 Fill Sump Veeder-Root TLS-350 Yes Yes Debris NT NT NT NT NT 2 2 Fill Sump Veeder-Root TLS-350 Yes Yes Clean/Dry 5 Unk Product NA Pass NT NFill Sump Veeder-Root TLS-350 Yes Yes Product NT NT NT NT NT 8 Un

Fill sump contains waste oil.

Fill Sump Veeder-Root TLS-350 Yes Yes Product NT NT NT NT NT 8 UnFill Sump Veeder-Root TLS-350 Yes Yes Product NT NT NT NT NT 8 UnFill Sump Veeder-Root TLS-350 Yes Yes Product NT NT NT NT NT 8 UnFill Sump Veeder-Root TLS-350 Yes Yes Clean/Dry 10 5 Product Yes Pass NT NFill Sump Veeder-Root TLS-350 Yes Yes Clean/Dry 5 5 Product Yes Pass NT NFill Sump Veeder-Root TLS-350 Yes Yes Clean/Dry 8 5 Product Yes Pass NT NFill Sump Veeder-Root TLS-350 Yes Yes Clean/Dry 5 5 Product Yes Pass NT NFill Sump Veeder-Root TLS-350 Yes Yes Clean/Dry 5 5 Product Yes Pass NT NFill Sump Veeder-Root TLS-350 No Yes Clean/Dry NT NT NT NT NT 1 1 Fill Sump Veeder-Root TLS-350 No Yes Clean/Dry NT NT NT NT NT 1 1 Fill Sump Veeder-Root TLS-350 Yes Yes Water NT NT NT NT NT none N

Technician waited for over 2 minutes, but sensor did not alarm. Finally inspector decided to call the test off and replace the sensor. Testing was done on the new sensor and it pass

Fill Sump Veeder-Root TLS-350 No Yes Clean/Dry NT NT NT NT NT 1 1 Fill Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 1 Fill Sump Veeder-Root TLS-350 Yes Yes Water NT NT NT NT NT 5 1 Fill Sump Veeder-Root Unk Yes Yes Clean/Dry NT NT NT NT NT 5 6 Fill Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 12 2 Fill Sump Veeder-Root TLS-350 No Yes Water NT NT NT NT NT 15 1 

The sensor was not located at the lowest point in the tank. Technician lowered it and activetd an alarm.

Fill Sump Veeder-Root Unk Yes Yes Water NT NT NT NT NT 5 6 

All times are recorded in seconds and heights in inches. Appe
Sensor 

Location

Panel 

Make

Panel 

Model

At Low 

Point

Wiring 

OK

Condition 

of Location Resp Rec Alarm PSD Result Resp R

Liquid Testing 

Fill Sump Veeder-Root TLS-350 No Yes Water NT NT NT NT NT 5 1 

Contains a substantial amount of water.

Fill Sump Veeder-Root Unk Yes Yes Clean/Dry NT NT NT NT NT 5 6 Fill Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 1 

The sensor was not at the lowest point in the tank.

Fill Sump Veeder-Root Unk Yes Yes Water NT NT NT NT NT 5 5 

Sump has 4-5 inches of water. Technician was waiting for maintinance to clean the water before putting back the sensor.

Fill Sump Veeder-Root Unk Yes Yes Water NT NT NT NT NT 5 5 

Sump has 4-5 inches of water. Technician was waiting for maintinance to clean the water before putting back the sensor.

Piping Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 6 4 

Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT Unk Un

Alarm was set at the control panel.

Pump Sump Veeder-Root TLS-350 Yes Yes Water 5 2 Product Yes Pass NT NPump Sump Veeder-Root TLS-350 Yes Yes Water 5 2 Product Yes Pass NT NPump Sump Veeder-Root TLS-350 Yes Yes Water 5 2 Product Yes Pass NT NPump Sump Veeder-Root TLS-350 Yes Yes Water NT NT NT NT NT 10 1

Flip Test- estimated response of 10 seconds.

Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 10 1

Flip Test- estimated response of 10 seconds

Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT Unk Un

Alarm was set at the control panel.

Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 8 2 Pump Sump Veeder-Root TLS-350 Yes Yes Water NT NT NT NT NT 6 2 Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry 5 5 Product Yes Pass NT NPump Sump Veeder-Root TLS-350 Yes Yes Product NT NT NT NT NT 5 2 Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 10 5 Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 

The cable is too short to test sensor in liquid, Instead perform a flip test.

Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 8 2 

All times are recorded in seconds and heights in inches. Appe
Sensor 

Location

Panel 

Make

Panel 

Model

At Low 

Point

Wiring 

OK

Condition 

of Location Resp Rec Alarm PSD Result Resp R

Liquid Testing 

Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 10 1

Flip Test- estimated response of 10 seconds

Pump Sump Veeder-Root TLS-350 No Yes Clean/Dry NT NT NT NT NT 1 1 Pump Sump Veeder-Root TLS-350 Yes Yes Water NT NT NT NT NT 5 1 Pump Sump Veeder-Root TLS-350 No Yes Product NT NT NT NT NT 5 1 Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 1 Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 1 Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry 10 4 Product Yes Pass NT NPump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry 12 4 Product Yes Pass NT NPump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT Unk Un

Alarm was set at the control panel.

Pump Sump Veeder-Root TLS-350 No Yes Clean/Dry NT NT NT NT NT 1 1 Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 8 4 Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry 10 4 Product Yes Pass NT NPump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 6 4 Pump Sump Veeder-Root TLS-350 No Yes Clean/Dry NT NT NT NT NT 1 1 Pump Sump Unk Unk Yes Yes Clean/Dry NT NT NT NT NT 6 6 Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry 5 5 Product Yes Pass NT NPump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 2 UnPump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 2 UnPump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry 8 4 Product Yes Pass NT NPump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 10 1Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry 7 5 Product Yes Pass NT NPump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry 10 5 Product Yes Pass NT NPump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 

Cable was too short to allow for testing in liquid. Flip test was used.

Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 

Cable was too short to allow for testing in liquid. Flip test was used.

All times are recorded in seconds and heights in inches. Appe
Sensor 

Location

Panel 

Make

Panel 

Model

At Low 

Point

Wiring 

OK

Condition 

of Location Resp Rec Alarm PSD Result Resp R

Liquid Testing 

Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 

Cable was too short to allow for testing in liquid. Flip test was used.

Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT Unk Un

Tested 4 of VR 208 sensors, all 4 alarms were set.

Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT Unk UnPump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT Unk UnPump Sump Veeder-Root Unk Yes Yes Water NT NT NT NT NT 5 6 Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 10 1Pump Sump Veeder-Root TLS-350 No Yes Product NT NT NT NT NT 3 3 

2-3 gallons of product in the sump. Sensor was raised above the product level. Sensor in pump sump was not programmed to shut down pump.

Pump Sump Veeder-Root Unk No Yes Water 25 17 Water Yes Pass NT N

Fill bucket was detached. Stick was in the product line (to prevent the flapper from shutting down the flow)

Pump Sump Veeder-Root Unk No Yes Water 20 20 Water Yes Pass NT N

Fill bucket was detached. Stick was in the product line (to prevent the flapper from shutting down the flow)

Pump Sump Veeder-Root Unk No Yes Water 20 20 Water Yes Pass NT N

Fill bucket was detached. Stick was in the product line (to prevent the flapper from shutting down the flow)

Pump Sump Veeder-Root Unk No Yes Water 20 15 Water Yes Pass NT N

Sensor timed out & Technician had to go and re-set it to shut down the pump.

Pump Sump Veeder-Root Unk No Yes Water 25 30 Water Yes Pass NT N

Sensor timed out & Technician had to go and re-set it to shut down the pump.

Pump Sump Veeder-Root Unk No Yes Water 20 30 Water Yes Pass NT N

Sensor timed out & Technician had to go and re-set it to shut down the pump.

Pump Sump Veeder-Root Unk No Yes Water 20 20 Water Yes Pass NT N

Sensor timed out & Technician had to go and re-set it to shut down the pump.

Pump Sump Veeder-Root Unk No Yes Water 20 15 Water Yes Pass NT N

Fill bucket was detached. Stick was in the product line (to prevent the flapper from shutting down the flow). Most of sensors timed out & Technician had to go and re-set it to shut 

Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT Unk UnPump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 3 5 Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 3 3 Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 2 2 Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 

All times are recorded in seconds and heights in inches. Appe
Sensor 

Location

Panel 

Make

Panel 

Model

At Low 

Point

Wiring 

OK

Condition 

of Location Resp Rec Alarm PSD Result Resp R

Liquid Testing 

Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 Pump Sump Veeder-Root TLS-350 No Yes Water NT NT NT NT NT 2 Un

2 sensors, 1 raised in sump and the other was a the lowest point. Both responded and activated pump shut off. Picture of sensor was taken.

Pump Sump Veeder-Root TLS-350 Yes Yes Water NT NT NT NT NT 2 UnPump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry 15 5 Product Yes Pass NT NPump Sump Veeder-Root TLS-350 No Yes Clean/Dry NT NT NT NT NT 5 5 

Sensor was raised about 4 inches from the bottom of the sump.

Pump Sump Veeder-Root TLS-350 No Yes Product NT NT NT NT NT 3 3 

2-3 gallons of product in the sump. Sensor was raised above the product level. Sensor in pump sump was not programmed to shut down pump.

Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 15 1Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 12 1Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 10 1Pump Sump Veeder-Root TLS-350 No Yes Product NT NT NT NT NT 8 1

Product is leaking out of the top of the turbine pump.

Pump Sump Veeder-Root TLS-350 No Yes Product NT NT NT NT NT 8 1

Product is leaking out of the top of the turbine pump.

Pump Sump Veeder-Root TLS-350 No Yes Product NT NT NT NT NT 8 1

Product is leaking out of the top of the turbine pump.

Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 6 UnPump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 6 UnPump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 10 1Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 3 5 Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 4 4 

Noticed a 1" hole in the sump, which will need to be repaired in order to have tight secondary containment.

Pump Sump Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 5 5 Pump Sump Veeder-Root TLS-300 Yes Yes Clean/Dry NT NT NT NT NT 30 Un

All times are recorded in seconds and heights in inches. Appe
Sensor 

Location

Panel 

Make

Panel 

Model

At Low 

Point

Wiring 

OK

Condition 

of Location Resp Rec Alarm PSD Result Resp R

Liquid Testing 

Pump Sump Veeder-Root TLS-350 No Yes Clean/Dry NT NT NT NT NT 4 5 

There was a hole in the sump, approximately 1 1/2" diam. Electrical wiring below penetration lines. Hydrostatic test was performed to the highest penetration lines at 16 minutes pebelow 12 psi. Fill sump is not clean..

Pump Sump Veeder-Root TLS-350 No Yes Clean/Dry NT NT NT NT NT er 2 m N

The contractor decided to stop testing the sensor after it failed to respond for more than 2 minutes and replace it with a new sensor.

Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 4 4 Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 3 3 Pump Sump Unk Unk Yes Yes Clean/Dry NT NT NT NT NT 5 5 Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 4 4 Pump Sump Veeder-Root Unk Yes Yes Clean/Dry NT NT NT NT NT 5 8 Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 1 Pump Sump Veeder-Root Unk Yes Yes Water NT NT NT NT NT 5 5 

Sump has 4-5 inches of water. Technician was waiting for maintinance to clean the water before putting back the sensor.

Pump Sump Veeder-Root Unk Yes Yes Water NT NT NT NT NT 5 5 

Sump has 4-5 inches of water. Technician was waiting for maintinance to clean the water before putting back the sensor.

UDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 10 1UDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 15 UnUDC Veeder-Root TLS-350 Yes Yes Clean/Dry 10 5 Product Yes Pass NT NUDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 6 4 UDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 6 4 UDC Veeder-Root TLS-350 Yes Yes Clean/Dry 15 10 Product Yes Pass NT NUDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 10 1UDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 6 4 UDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 10 1UDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 10 1UDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 8 2 UDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 15 UnUDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 15 Un

All times are recorded in seconds and heights in inches. Appe
Sensor 

Location

Panel 

Make

Panel 

Model

At Low 

Point

Wiring 

OK

Condition 

of Location Resp Rec Alarm PSD Result Resp R

Liquid Testing 

UDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 15 Un

Tested six dispensers, all passed-alarms set (total of six triggers), all six sensors (VR 208) are working.

UDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 10 1

Flip Test- estimated response of 10 seconds

UDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 8 2 UDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 8 2 UDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 8 2 UDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 8 2 UDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 8 2 UDC Veeder-Root TLS-350 Yes Yes Clean/Dry 15 10 Product Yes Pass NT NUDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 6 4 UDC Veeder-Root TLS-350 Yes Yes Clean/Dry 10 5 Product Yes Pass NT NUDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 10 1

Flip Test- estimated response of 10 seconds

UDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 10 1

Flip Test- estimated response of 10 seconds

UDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 10 1UDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 10 1UDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 10 1UDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 6 4 UDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 6 4 UDC Veeder-Root Unk Yes Yes Clean/Dry 20 20 Water Yes Pass NT N

Sensor timed out & Technician had to go and re-set it to shut down the pump. Technician conducts water and flip test in some of the sensors because the wire did not reach te wate

UDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 15 UnUDC Veeder-Root Unk Yes Yes Clean/Dry 20 25 Water Yes Pass NT N

Sensor timed out & Technician had to go and re-set it to shut down the pump. Technician conducts water and flip test in some of the sensors because the wire did not reach te wate

UDC Veeder-Root Unk Yes Yes Clean/Dry 22 22 Water Yes Pass NT N

Sensor timed out & Technician had to go and re-set it to shut down the pump. Technician conducts water and flip test in some of the sensors because the wire did not reach the wat

UDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 15 Un

All times are recorded in seconds and heights in inches. Appe
Sensor 

Location

Panel 

Make

Panel 

Model

At Low 

Point

Wiring 

OK

Condition 

of Location Resp Rec Alarm PSD Result Resp R

Liquid Testing 

UDC Veeder-Root Unk Yes Yes Clean/Dry 22 22 Water Yes Pass NT NUDC Veeder-Root Unk Yes Yes Clean/Dry 21 21 Water Yes Pass NT N

Sensor timed out & Technician had to go and re-set it to shut down the pump. Technician conducts water and flip test in some of the sensors because the wire did not reach te wate

UDC Veeder-Root Unk Yes Yes Clean/Dry 25 22 Water Yes Pass NT N

Sensor timed out & Technician had to go and re-set it to shut down the pump. Technician conducts water and flip test in some of the sensors because the wire did not reach te wate

UDC Veeder-Root Unk Yes Yes Clean/Dry 22 22 Water Yes Pass NT NUDC Veeder-Root Unk Yes Yes Clean/Dry 20 20 Unk Unk Unk NT N

Sensor timed out & Technician had to go and re-set it to shut down the pump. Technician conducts water and flip test in some of the sensors because the wire did not reach te wate

Unk Veeder-Root TLS-350 No Yes Water NT NT NT NT NT 2 2 

Alarm activated at the control panel, but no pump shutdown. ( printer said pump shutdown occurred, but pump continued to run. Picture of sensor is site 7 #2.). Follow up was do

confirmed that the PSD is functioning properly.

Vault Gilbarco Unk Yes Yes Clean/Dry NT NT NT NT NT 2 2 

Single wall steel tank inside a Vault. Vapor recovery fill bucket is half way full of water.

Sensor Model: 794380-209 Operating Principle: Float Switch

Pump Sump Veeder-Root TLS-350 Yes Yes Water NT NT NT NT NT 12 UnPump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 12 UnPump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 12 Un

Sensor Model: 794380-300 Operating Principle: Float Switch

Tank Interstice Veeder-Root TLS-300 NA Yes Brine-Filled 2 2 Water NA Pass NT N

Sensor Model: 794380-301 Operating Principle: Float Switch

Tank Interstice Veeder-Root Simplicity Yes Yes Brine-Filled NT NT NT NT NT 6 1 Tank Interstice Veeder-Root Simplicity Yes Yes Brine-Filled NT NT NT NT NT 6 1 Tank Interstice Veeder-Root Simplicity Yes Yes Brine-Filled NT NT NT NT NT 6 1 

Sensor Model: 794380-302 Operating Principle: Float Switch

Tank Interstice Veeder-Root TLS-350 NA Yes Brine-Filled 20 15 Water NA Pass NT N

Technician lifted sensor out of brine reservoir to activate the "low water level" alarm.

Tank Interstice Veeder-Root TLS-350 NA Yes Brine-Filled 10 Unk Low Brine Level Yes Pass NT NTank Interstice Veeder-Root TLS-350 NA Yes Brine-Filled 10 Unk Low Brine Level Yes Pass NT N

All times are recorded in seconds and heights in inches. Appe
Sensor 

Location

Panel 

Make

Panel 

Model

At Low 

Point

Wiring 

OK

Condition 

of Location Resp Rec Alarm PSD Result Resp R

Liquid Testing 

Tank Interstice Veeder-Root TLS-350 NA Yes Brine-Filled 20 15 Water NA Pass NT N

Technician lifted sensor out of brine reservoir to activate the "low water level" alarm.

Tank Interstice Veeder-Root TLS-350 NA Yes Brine-Filled 30 10 Water NA Pass NT N

Technician lifted sensor out of brine reservoir to activate the "low water level" alarm.

Tank Interstice Veeder-Root TLS-350 NA Yes Brine-Filled 5 5 Product Yes Pass NT NTank Interstice Veeder-Root TLS-350 NA Yes Brine-Filled 10 Unk Low Brine Level Yes Pass NT NTank Interstice Veeder-Root TLS-350 NA Yes Brine-Filled 30 10 Water NA Pass NT N

Technician lifted sensor out of brine reservoir to activate the "low water level" alarm.

Sensor Model: 794380-408 Operating Principle: Float Switch

UDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 6 Un

Alarm set at the control panel, sensor is not programmed for pump shut down or dispenser shut down.

UDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 6 Un

Alarm set at the control panel, sensor is not programmed for pump shut down or dispenser shut down.

UDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 6 Un

Alarm set at the control panel, sensor is not programmed for pump shut down or dispenser shut down.

UDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 6 Un

Alarm set at the control panel, sensor is not programmed for pump shut down or dispenser shut down.

Sensor Model: 794380-500 Operating Principle: Float Switch

Tank Interstice Veeder-Root TLS-300 NA Yes Brine-Filled 2 2 Water NA Pass NT N

Sensor Model: 794390-205 Operating Principle: Float Switch

Fill Sump Veeder-Root TLS-350 No Yes Product NT NT NT NT NT NT N

Sump had oil in it. Sensor was raised above the oil, but alarmed when technician lowered it into the oil. Contractor was notified to pump out the oil that day.

Fill Sump Veeder-Root TLS-350 Yes Yes Clean/Dry 5 5 Product NA Pass NT NFill Sump Veeder-Root TLS-350 Yes Yes Clean/Dry 5 5 Product NA Pass NT NFill Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 UnFill Sump Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 10 1

Sensor was Gilbarco equivalent of Veeder Root Model 794380-205. Cable was too short to test the sensor in liquid, so flip test was used.

Fill Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 10 6 Fill Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 10 6 

All times are recorded in seconds and heights in inches. Appe
Sensor 

Location

Panel 

Make

Panel 

Model

At Low 

Point

Wiring 

OK

Condition 

of Location Resp Rec Alarm PSD Result Resp R

Liquid Testing 

Fill Sump Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 5 5 

Sensor was Gilbarco equivalent of Veeder Root Model 794380-205. Cable was too short to test the sensor in liquid, so flip test was used.

Pump Sump Veeder-Root TLS-350 Yes Yes Water NT NT NT NT NT 90 Un

sensor is not programmed for positive shut down, only sets an audible alarm.

Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 8 6 Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 10 6 Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 10 1Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 10 5 Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 25 5 

Some condensation on sump.

Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 90 Un

sensor is not programmed for positive shut down, only sets an audible alarm.

Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry 5 5 Product Yes Pass NT NPump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry 10 5 Product Yes Pass NT NPump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 90 Un

sensor is not programmed for positive shut down, only sets an audible alarm.

Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 15 5 Pump Sump Veeder-Root TLS-350 Yes Yes Product NT NT NT NT NT 5 1 

1 inch of kerosene in sump; this sensor was tested with just an alarm first; retesting while running pump and the pump did not shut off.

Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 20 5 Pump Sump Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 10 1

Sensor was Gilbarco equivalent of Veeder Root Model 794380-205. Cable was too short to test the sensor in liquid, so flip test was used.

Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 20 1Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 15 5 

For this tank, there are two sumps, but only one sensor (the sumps are linked).

Pump Sump Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 5 5 

Sensor was Gilbarco equivalent of Veeder Root Model 794380-205. Cable was too short to test the sensor in liquid, so flip test was used.

Pump Sump Veeder-Root TLS-350 No Yes Clean/Dry NT NT NT NT NT 15 1

Sensor was raised approximately 1 foot from bottom of the sump.

Pump Sump Veeder-Root TLS-350 Unk Yes Water NT NT NT NT NT 1 2 

All times are recorded in seconds and heights in inches. Appe
Sensor 

Location

Panel 

Make

Panel 

Model

At Low 

Point

Wiring 

OK

Condition 

of Location Resp Rec Alarm PSD Result Resp R

Liquid Testing 

Pump Sump Veeder-Root TLS-350 Unk Yes Water NT NT NT NT NT 5 2 Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 15 1Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 10 1Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 2 1 Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 1 1 Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 1 

Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 20 5 

Diesel tank interstice 50m from sump.

Tank Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 25 Un

Suction system with tank top sump.

UDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 4 1 UDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 4 1 UDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 4 1 UDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 4 1 UDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 4 1 

Sensor Model: 794390-407 Operating Principle: Float Switch

Tank Interstice Veeder-Root TLS-350 No No Clean/Dry NT NT NT NT NT NT N

The sensor was located at the top of the tank, at the access port. The pull-string was broken. Inspector said sensor must be fixed immediately. The sensor was not functionally tesup was done & sensor was repaired.

Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 

Wrap-around sensor. Techician moved sensor toward top of tank until alarm sounded. Did not completely remove the sensor.

Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 

Wrap-around sensor. Techician moved sensor toward top of tank until alarm sounded. Did not completely remove the sensor.

Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 

Wrap-around sensor. Techician moved sensor toward top of tank until alarm sounded. Did not completely remove the sensor.

Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 Tank Interstice Veeder-Root TLS-350 Yes Yes Unk NT NT NT NT NT 1 1 Tank Interstice Veeder-Root TLS-350 Yes Yes Water NT NT NT NT NT 5 5 

Sensor would not go into alarm until the techician shook it vigorously. Float was stuck. Interstice was moist, but not enough liquid to activate an alarm.

All times are recorded in seconds and heights in inches. Appe
Sensor 

Location

Panel 

Make

Panel 

Model

At Low 

Point

Wiring 

OK

Condition 

of Location Resp Rec Alarm PSD Result Resp R

Liquid Testing 

Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 10 1

Technician pulled sensor around the tank until alarm activated, but did not fully remove the sensor from the annular space.

Tank Interstice Veeder-Root TLS-350 NA Yes Clean/Dry NT NT NT NT NT 2 1Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT Unk Un

Alarm was set during the removal of the sensor from the tank interstice.

Tank Interstice Veeder-Root TLS-350 NA Yes Clean/Dry NT NT NT NT NT 2 1Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT Unk Un

Alarm was set during the removal of the sensor from the tank interstice.

Tank Interstice Veeder-Root TLS-350 Yes Yes Unk NT NT NT NT NT 1 1 Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 10 1

Technician pulled sensor around the tank until alarm activated, but did not fully remove the sensor from the annular space.

Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 

Sensor would not go into alarm until the techician shook it vigorously. Float was stuck.

Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 10 1

Technician pulled sensor around the tank until alarm activated, but did not fully remove the sensor from the annular space.

Tank Interstice Veeder-Root TLS-350 Yes Yes Unk NT NT NT NT NT 1 1 Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 10 1

Technician pulled sensor around the tank until alarm activated, but did not fully remove the sensor from the annular space.

Sensor Model: 794390-409 Operating Principle: Float Switch

Tank Interstice Veeder-Root TLS-350 NA Yes Clean/Dry NT NT NT NT NT 3 2 Tank Interstice Veeder-Root TLS-350 Unk Yes Clean/Dry NT NT NT NT NT 1 1 Tank Interstice Veeder-Root TLS-350 Unk Yes Clean/Dry NT NT NT NT NT 1 1 Tank Interstice Veeder-Root TLS-350 Yes Yes Water NT NT NT NT NT 2 2 Tank Interstice Veeder-Root TLS-350 Unk Yes Clean/Dry NT NT NT NT NT 1 1 Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 9 Un

Sensor is not set up for pump shut down.

Tank Interstice Veeder-Root Unk Yes Yes Clean/Dry NT NT NT NT NT 17 1

Three tanks ( 1 split gasoline tank & 2 diesel tanks)

Tank Interstice Veeder-Root Unk Yes Yes Clean/Dry NT NT NT NT NT 20 2

All times are recorded in seconds and heights in inches. Appe
Sensor 

Location

Panel 

Make

Panel 

Model

At Low 

Point

Wiring 

OK

Condition 

of Location Resp Rec Alarm PSD Result Resp R

Liquid Testing 

Tank Interstice Veeder-Root Unk Yes Yes Clean/Dry NT NT NT NT NT 20 2Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 15 UnTank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 15 Un

Tested 4 of 409 sensors, all appeared to be dry and clean; alarms set for all sensors.

Tank Interstice Veeder-Root TLS-350 Yes Yes Unk NT NT NT NT NT 10 1

Flip Test - Approximately 10 Seconds.

Tank Interstice Veeder-Root TLS-350 Yes Yes Unk NT NT NT NT NT 10 1

Flip Test - Approximately 10 Seconds.

Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 15 UnTank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 UnTank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 15 UnTank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 9 Un

Sensor is not set up for pump shut down.

Tank Interstice Veeder-Root TLS-350 Unk Yes Clean/Dry NT NT NT NT NT 75 Un

Sensor was wedged between the primary and secondary tank walls and cannot be removed to verify sensor type. Alarm was set at the control panel by pulling it. The response time 

no way of knowing when sensor was triggered.

Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 45 Un

Follow up was made on this site with the local agnecy and assured that next day, the contractor replaced the broken sensors. Inspector did not re-inspect, but received a report from 

sensor is working properly.

Tank Interstice Veeder-Root TLS-350 Unk Unk Clean/Dry NT NT NT NT NT None Un

Sensor was wedged between the primary and secondary tank walls and cannot be removed to verify sensor type. Alarm was not set at the control panel by pulling it like the prevou

Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 UnTank Interstice Veeder-Root TLS-350 Yes Yes Unk NT NT NT NT NT 10 1

Flip Test - Approximately 10 Seconds.

Sensor Model: 794390-420 Operating Principle: Float Switch

Piping Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 

3 small steel pipes (1 for each generator) were run within one large steel pipe. The sensor monitors the large pipe, which stays dry unless the small pipes leak.

Piping Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 

3 small steel pipes (1 for each generator) were run within one large steel pipe. The sensor monitors the large pipe, which stays dry unless the small pipes leak.

Piping Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 

3 small steel pipes (1 for each generator) were run within one large steel pipe. The sensor monitors the large pipe, which stays dry unless the small pipes leak.

Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 

All times are recorded in seconds and heights in inches. Appe
Sensor 

Location

Panel 

Make

Panel 

Model

At Low 

Point

Wiring 

OK

Condition 

of Location Resp Rec Alarm PSD Result Resp R

Liquid Testing 

Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 Pump Sump Veeder-Root TLS-350 No No Water NT NT NT NT NT 5 5 

Waste oil contained oil/water around the tank sump. The sensor was not located in the lowest point.

Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 4 2 

The sump contained product.

Pump Sump Veeder-Root TLS-320 Yes Yes Clean/Dry NT NT NT NT NT 4 2 Pump Sump Veeder-Root TLS-350 Yes Yes Water/Product NT NT NT NT NT 10 5 

Sensor was sitting in 3-4 inches of water/product but was not in alarm. However, sensor activated alarm when flipped.

Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 

Tank Interstice Veeder-Root TLS-350 NA NA Clean/Dry NT NT NT NT NT 5 3 Tank Interstice Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 5 5 Tank Interstice Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 1 1 Tank Interstice Veeder-Root TLS-350 Unk Yes Clean/Dry NT NT NT NT NT 1 1 Tank Interstice Veeder-Root TLS-350 Unk Yes Clean/Dry NT NT NT NT NT 1 1 Tank Interstice Veeder-Root TLS-350 NA NA Clean/Dry NT NT NT NT NT 5 3 Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 

Contractor mentioned that this type of sensors are constantly cracking and split out in age(chronic problem). Maybe it’s a design problem.Even when sensors are cracked, contracto

Tank Interstice Veeder-Root Unk No Yes Water NT NT NT NT NT 4 4 

Interstitial space is full of water. Technician could not put back the sensor without calling the maintenance to remove water. Sensor was not at lowest point and wire was wrapped u

Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry 5 5 Product Yes Pass NT NTank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 

Sensor casing was corroded and cracked. This is a chronic problem with this model. Even when cracked, contractor does not replace them because they all tend to be like that afte

Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry 5 5 Product Yes Pass NT NTank Interstice Veeder-Root Unk No Yes Water NT NT NT NT NT 4 4 Tank Interstice Veeder-Root TLS-350 NA NA Clean/Dry NT NT NT NT NT 5 3 Tank Interstice Veeder-Root Unk Yes Yes Clean/Dry NT NT NT NT NT 5 5 Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 25 UnTank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 10 Un

All times are recorded in seconds and heights in inches. Appe
Sensor 

Location

Panel 

Make

Panel 

Model

At Low 

Point

Wiring 

OK

Condition 

of Location Resp Rec Alarm PSD Result Resp R

Liquid Testing 

Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 2 2 Tank Interstice Pneumeractor LC-1000 Yes Yes Clean/Dry NT NT NT NT NT 2 2 Tank Interstice Pneumeractor LC-1000 Yes Yes Clean/Dry NT NT NT NT NT 2 2 Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 2 2 Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 2 2 Tank Interstice Veeder-Root TLS-350 Yes Yes Water NT NT NT NT NT 5 Un

Sensor was wet when removed from tank interstice. It is unknown how much liquid was in interstice.

Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 10 UnTank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 10 UnTank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry 5 5 Product Yes Pass NT NTank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 10 UnTank Interstice Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 5 5 Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 10 UnTank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 UnTank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 UnTank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 UnTank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry 5 5 Product NA Pass NT NTank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry 5 5 Product Yes Pass NT NTank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry 5 5 Product Yes Pass NT NTank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry 5 5 Product NA Pass NT NTank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry 3 3 Product NA Pass NT NTank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 10 Un

.

Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 1 1 Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 2 UnTank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 2 2 

All times are recorded in seconds and heights in inches. Appe
Sensor 

Location

Panel 

Make

Panel 

Model

At Low 

Point

Wiring 

OK

Condition 

of Location Resp Rec Alarm PSD Result Resp R

Liquid Testing 

Tank Interstice Veeder-Root TLS-300 No Yes Clean/Dry NT NT NT NT NT 30 Un

This sensor is for steel tanks, and could not be wrapped around the FG tank. Local agency instructed owner to replace.

Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 1 1 Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT None N

Original sensor was stuck in the interstice because of rust on casing; sensor was replaced. New sensor passed test.

Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry 5 5 Product Yes Pass NT NTank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry 5 5 Product Yes Pass NT NTank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 2 UnTank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 Tank Interstice Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 5 5 Tank Interstice Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 5 5 

Steel sensor casing was split.

Tank Interstice Gilbarco EMC Yes Yes Clean/Dry NT NT NT NT NT 5 5 

Steel sensor casing was split.

Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 2 2 Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 3 3 Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 1 1 Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 3 3 Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 3 3 Tank Interstice Veeder-Root TLS-350 NA Yes Clean/Dry NT NT NT NT NT None N

The sensor was missing the float. Follow up was made with local agency and confirmed that the technician repaired the sensor. However, inspector did not peform re-inspection.

Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 

All times are recorded in seconds and heights in inches. Appe
Sensor 

Location

Panel 

Make

Panel 

Model

At Low 

Point

Wiring 

OK

Condition 

of Location Resp Rec Alarm PSD Result Resp R

Liquid Testing 

Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 

Sensor housing (steel bell) was split.

Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 2 2 Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 2 2 Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 2 2 

Sensor Model: 794390-460 Operating Principle: Float Switch

Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 Tank Interstice Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 5 5 

UDC Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 4 1 

Sensor Model: 847990-001 Operating Principle: Float Switch

Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 20 5 Pump Sump Veeder-Root TLS-350 Yes Yes Clean/Dry NT NT NT NT NT 20 5 

UDC Dispenser Cut-off Unk Yes Yes Clean/Dry 1 MR Unk NA Pass NT N

The sensor cuts power to dispensers. Dispenser had to be manually reset to clear alarm.

UDC Dispenser Cut-off Unk Yes Yes Clean/Dry 2 MR Unk NA Pass NT N

The sensor cuts power to dispensers. Dispenser had to be manually reset to clear alarm.

UDC Dispenser Cut-off Unk Yes Yes Clean/Dry 3 MR Unk NA Pass NT N

The sensor cuts power to dispensers. Dispenser had to be manually reset to clear alarm.

UDC Dispenser Cut-off Unk Yes Yes Clean/Dry 2 MR Unk NA Pass NT N

The sensor cuts power to dispensers. Dispenser had to be manually reset to clear alarm.

Sensor Make: Warrick Controls

Sensor Model: DLP-1-NC Operating Principle: Float Switch

Pump Sump Warrick Unk Yes Yes Water NT NT NT NT NT None N

Sensor was sitting in water and not alarmed. Contractor shook sensor and float moved activating the alarm. Sensor passed retest after 1-2 second alarm response.

Pump Sump Warrick Unk Yes Yes Water NT NT NT NT NT Unk Un

All times are recorded in seconds and heights in inches. Appe
APPENDIX V

Field Data for Discriminatin
TABLE 3 - Field Data for Discriminating Sen

Resp Rec Alarm PSD Result Resp Rec Alarm PSD Result Resp Rec Alarm PSD Result Resp Re

Low Water Test High Water Test Product Testing 

Sensor Make: Alpha wire

Sensor Model UnkNT NT NT NT NT NA NA NA NA NA NT NT NT NT NT 60 60 NT NT NT NT NT NA NA NA NA NA NT NT NT NT NT None N

Sensor Make: Emco

Sensor Model Q0003-00160 Unk Water NA Pass 60 Unk Water Yes Pass NT NT NT NT NT NT NLocal agency did not require discriminating sensors to be tested in product.60 Unk Water NA Pass 60 Unk Water Yes Pass NT NT NT NT NT NT NLocal agency did not require discriminating sensors to be tested in product.60 Unk Water NA Pass 60 Unk Water Yes Pass NT NT NT NT NT NT NLocal agency did not require discriminating sensors to be tested in product.60 Unk Water NA Pass 60 Unk Water Yes Pass NT NT NT NT NT NT NLocal agency did not require discriminating sensors to be tested in product.60 Unk Water NA Pass 60 Unk Water Yes Pass NT NT NT NT NT NT NLocal agency did not require discriminating sensors to be tested in product.Sensor Model Q0003-00260 Unk Water NA Pass 60 Unk Water Yes Pass NT NT NT NT NT NT NLocal agency did not require discriminating sensors to be tested in product.60 60 Water NA Pass 60 60 Water Yes Pass NT NT NT NT NT NT NLocal agency did not require discriminating sensors to be tested in product.60 60 Water NA Pass 60 60 Water Yes Pass NT NT NT NT NT NT NLocal agency did not require discriminating sensors to be tested in product.60 Unk Water NA Pass 60 Unk Water Yes Pass NT NT NT NT NT NT NLocal agency did not require discriminating sensors to be tested in product.60 Unk Water NA Pass 60 Unk Water Yes Pass NT NT NT NT NT NT NLocal agency did not require discriminating sensors to be tested in product.60 Unk Water NA Pass 60 Unk Water Yes Pass NT NT NT NT NT NT NLocal agency did not require discriminating sensors to be tested in product.

Sensor Make: Incon

Sensor Model TSP-DIS4 Unk Both Yes Pass NA NA NA NA NA NT NT NT NT NT NA N

Sensor Make: Mallory Controls

All times are recorded in seconds and heights in inches. Appendix 
Resp Rec Alarm PSD Result Resp Rec Alarm PSD Result Resp Rec Alarm PSD Result Resp Re

Low Water Test High Water Test Product Testing 

Sensor Model Pollulert FD 221GTRA10 Dry Water NA Pass NA NA NA NA NA 10 Dry Product NA Pass NA NSensor had to be wiped dry to come out of alarm.10 Dry Water NA Pass NA NA NA NA NA 10 Dry Product NA Pass NA NSensor had to be wiped dry to come out of alarm.10 Dry Water NA Pass NA NA NA NA NA 10 Dry Product NA Pass NA NSensor had to be wiped dry to come out of alarm.Sensor Model Pollulert MD 241RRA10 Dry Water NA Pass NA NA NA NA NA 10 Dry Product NA Pass NA NSensor had to be wiped dry to come out of alarm.10 Dry Water NA Pass NA NA NA NA NA 10 Dry Product NA Pass NA NSensor had to be wiped dry to come out of alarm.10 Dry Water NA Pass NA NA NA NA NA 10 Dry Product NA Pass NA NSensor had to be wiped dry to come out of alarm.NT NT NT NT NT NA NA NA NA NA 10 10 Product Yes Pass NA NNT NT NT NT NT NA NA NA NA NA NA NA None No Fail NA NSensor failed the test, but the company is out of business.So, owner might have to change the system. Inspector gave the owner two weeks to fix it or replace It.

NT NT NT NT NT NA NA NA NA NA 20 10 Product Yes Pass NA N

Sensor Make: Red Jacket

Sensor Model RE400-2031 1 Water NA Pass NA NA NA NA NA NT NT NT NT NT NA N1 1 Water NA Pass NA NA NA NA NA NT NT NT NT NT NA N1 1 Water NA Pass NA NA NA NA NA NT NT NT NT NT NA N1 1 Water NA Pass NA NA NA NA NA NT NT NT NT NT NA N1 1 Water NA Pass NA NA NA NA NA NT NT NT NT NT NA N1 1 Water NA Pass NA NA NA NA NA NT NT NT NT NT NA N

Sensor Make: Veeder-Root

Sensor Model 794380-320Unk Unk Unk Unk Unk 2 5 Water Unk Pass 383 1030 Product Unk Pass NA NUnk Unk Unk Unk Unk 1 7 Water Unk Pass 395 962 Product Unk Pass NA NSensor Model 794380-3225 Unk Water NA Pass 5 5 Water Yes Pass NT NT NT NT NT NT NTechnician flipped the sensor, activating both low and high water alarms at the same time.

All times are recorded in seconds and heights in inches. Appendix 
Resp Rec Alarm PSD Result Resp Rec Alarm PSD Result Resp Rec Alarm PSD Result Resp Re

Low Water Test High Water Test Product Testing 

Sensor Model 794380-341NT NT NT NT NT 5 1 Water Yes Pass 5 1 Product Yes Pass NA NWhen placed in fuel, alarms went off as water - pump shut-down worked; waste oil sensor failed, replaced and recorded on separate sheet.10 10 Water Yes Pass NA NA NA NA NA 10 10 Water Yes Fail NA NTechnician had to clean the sensor with a rag completely (especially in the small window at sensor's center) before fuel could be detected. After cleaning sensor did detect fuel.

10 10 Water Yes Pass NA NA NA NA NA 10 10 Water Yes Fail NA NTechnician had to clean the sensor with a rag completely (especially in the small window at sensor's center) before fuel could be detected. After cleaning sensor did detect fuel.

10 10 Water Yes Pass NA NA NA NA NA 10 10 Water Yes Fail NA NTechnician had to clean the sensor with a rag completely (especially in the small window at sensor's center) before fuel could be detected. After cleaning sensor did detect fuel.

Unk Unk Unk Unk Unk NA NA NA NA NA NA NA None Unk Fail NA N

Unk Unk Unk Unk Unk NA NA NA NA NA 2 2 Product Unk Pass NA NUnk Unk Unk Unk Unk NA NA NA NA NA 2570 4240 Product Unk Pass NA NUnk Unk Unk Unk Unk NA NA NA NA NA 5 5 Product Unk Pass NA N3 3 Water Yes Pass NA NA NA NA NA 3 3 Product Yes Pass NA N12 1 Water NA Pass NA 0 NA NA NA 13 Unk Water No Fail NA NSensor sets water alarm for product test. After testing the sensor was replaced and the new sensor was setting the right alarm.NT NT NT NT NT 5 1 Water Yes Pass 5 1 Product Yes Pass NA NNT NT NT NT NT 5 1 Water Yes Pass 5 1 Product Yes Pass NA NNT NT NT NT NT NA NA NA NA NA Unk Unk None No Fail NA NReplaced with same type of sensor.3 2 Both Yes Pass NA NA NA NA NA 3 2 Both Yes Pass NA NSensor had been programmed to give the same alarm in water and product.3 2 Both Yes Pass NA NA NA NA NA 3 2 Both Yes Pass NA NSensor had been programmed to give the same alarm in water and product.3 2 Both Yes Pass NA NA NA NA NA 3 2 Both Yes Pass NA NSensor had been programmed to give the same alarm in water and product.3 3 Water Yes Pass NA NA NA NA NA 3 3 Water Yes Fail NA NDetected product as water. Since pump shuts down for product or water, Local Agency did not require sensor to be changed. Owner will replace sensor or re-program as non-disc

12 1 Water NA Pass NA 0 NA NA NA 13 Unk Product Yes Pass NA N

Unk Unk Unk Unk Unk NA NA NA NA NA 2 2 Product Unk Pass NA N12 1 Water NA Pass NA 0 NA NA NA 12 Unk Water No Fail NA NSensor sets water alarm for product test. After testing, sensor was replaced and the new sensor was setting the right alarm.NT NT NT NT NT NA 0 NA NA NA 13 Unk Water NA Fail NA NSensor was tested with both unleaded gasoline and waste oil. Both cases, water alarms were observed. Sensor was not approved for use in waste oil. After testing, sensor was replaUnk Unk Unk Unk Unk NA NA NA NA NA NA NA None Unk Fail NA NUnk Unk Unk Unk Unk 3 10 Water Unk Pass 358 2450 Product Unk Pass NA N

All times are recorded in seconds and heights in inches. Appendix 
Resp Rec Alarm PSD Result Resp Rec Alarm PSD Result Resp Rec Alarm PSD Result Resp Re

Low Water Test High Water Test Product Testing 

Unk Unk Unk Unk Unk NA NA NA NA NA 4 10 Product Unk Pass NA NUnk Unk Unk Unk Unk NA NA NA NA NA 417 1055 Product Unk Pass NA N3 3 Water Yes Pass NA NA NA NA NA 3 3 Water Yes Fail NA NDetected product as water. Since pump shuts down for product or water, Local Agency did not require sensor to be changed. Owner will replace sensor or reprogram as non-discrSensor Model 794380-3505 5 Water NA Pass 5 5 Water Yes Pass 360 465 Product Yes Pass NA NTechnician left sensor in product for 2min & 45sec. He rinsed the sensor with soapy water after alarm activated to speed up recovery time.

1 1 Water NA Pass 5 5 Water Yes Pass 360 765 Product Yes Pass NA NTechnician left sensor in product for 2min & 45sec. He rinsed the sensor with soapy water after alarm activated to speed up recovery time.

2 2 Water NA Pass 2 2 Water Yes Pass 300 480 Product Yes Pass NA N

2 2 Water NA Pass 2 Unk Water Yes Pass 480 Non Product Yes Fail NA NSensor did not come out of alarm after being tested in product, so technician replaced it.2 2 Water NA Pass None Non None No Fail none Unk None No Fail NA NSensor did not respond during high water or product testing. Technician suspected wiring problem, since sensor was replaced but test results did not change.

2 2 Water NA Pass 2 2 Water Yes Pass 180 NA Product Yes Pass NA N

2 2 Water NA Pass 2 2 Water No Fail Unk Unk Product No Fail NA NTechnician suspected a problem with the wiring at this site.5 5 Water NA Pass 5 5 Water NA Pass 480 300 Product Yes Pass NA NTechnician left sensor in product for 2min & 45sec. He rinsed the sensor with soapy water after alarm activated to speed up recovery time.

1 1 Water NA Pass 5 5 Water Yes Pass 330 600 Product Yes Pass NA NTechnician left sensor in product for 2min & 45sec. He rinsed the sensor with soapy water after alarm activated to speed up recovery time.

5 Unk Water NA Pass 2 2 Water Yes Pass 300 600 Product Yes Pass NA NSensors were left in fuel for 3 minutes. They alarm 2-5 minutes after being pulled from fuel. This speeds up recovery time.5 5 Water NA Pass 5 5 Water Yes Pass 300 360 Product Yes Pass NA NTechnician left sensor in product for 2min & 45sec. He rinsed the sensor with soapy water after alarm activated to speed up recovery time.

5 5 Water NA Pass 5 5 Water Yes Pass 330 420 Product Yes Pass NA NTechnician left sensor in product for 2min & 45sec. He rinsed the sensor with soapy water after alarm activated to speed up recovery time.

5 5 Water NA Pass 5 5 Water NA Pass 300 540 Product Yes Pass NA NTechnician left sensor in product for 2min & 45sec. He rinsed the sensor with soapy water after alarm activated to speed up recovery time.

5 5 Water NA Pass 5 5 Water NA Pass 720 360 Product Yes Pass NA NTechnician left sensor in product for 2min & 45sec. He rinsed the sensor with soapy water after alarm activated to speed up recovery time.

5 5 Water NA Pass 5 5 Water NA Pass 360 1500 Product Yes Pass NA NTechnician left sensor in product for 2min & 45sec. He rinsed the sensor with soapy water after alarm activated to speed up recovery time.

5 Unk Water NA Pass 2 2 Water Yes Pass 420 720 Product Yes Pass NA NSensors were left in fuel for 3 minutes. They alarm 2-5 minutes after being pulled from fuel. This speeds up recovery time.1 1 Water NA Pass 5 5 Water Yes Pass 300 540 Product Yes Pass NA NTechnician left sensor in product for 2min & 45sec. He rinsed the sensor with soapy water after alarm activated to speed up recovery time.

All times are recorded in seconds and heights in inches. Appendix 
Resp Rec Alarm PSD Result Resp Rec Alarm PSD Result Resp Rec Alarm PSD Result Resp Re

Low Water Test High Water Test Product Testing 

7 1 Water NA Pass 3 1 Water Yes Pass 360 720 Product Yes Pass NA NFor product test, sensor was left in fuel for 3 minutes.NT NT NT NT NT 5 1 Water Yes Pass 360 900 Product Yes Pass NA NNT NT NT NT NT 5 1 Water Yes Pass 360 900 Product Yes Pass NA NNT NT NT NT NT 5 1 Water Yes Pass 360 900 Product Yes Pass NA NNT NT NT NT NT 5 1 Water Yes Pass 840 Unk Product Yes Pass NA NTakes longer for this sensor to alarm because often left sitting in water.7 1 Water NA Pass 5 1 Water Yes Pass 300 300 Product Yes Pass NA NFor product test, sensor was left in fuel for 3 minutes.7 1 Water NA Pass 4 1 Water Yes Pass 360 590 Product Yes Pass NA NFor product test, sensor was left in fuel for 3 minutes.7 1 Water NA Pass 5 1 Water Yes Pass 360 660 Product Yes Pass NA NFor product test, sensor was left in fuel for 3 minutes.Unk Unk Unk Unk Unk 4 5 Water Unk Pass 238 3531 Product Unk Pass NA N7 1 Water NA Pass 6 1 Water Yes Pass 360 1020 Product Yes Pass NA NFor product test, sensor was left in fuel for 3 minutes.5 Unk Water NA Pass 2 2 Water Yes Pass 300 600 Product Yes Pass NA NSensors were left in fuel for 3 minutes. They alarm 2-5 minutes after being pulled from fuel. This speeds up recovery time.Unk Unk Unk Unk Unk 2 10 Water Unk Pass 365 1100 Product Unk Pass NA NUnk Unk Unk Unk Unk 4 7 Water Unk Pass 357 890 Product Unk Pass NA N2 2 Water NA Pass 2 2 Water No Fail Unk Unk Product No Fail NA NSensor alarmed, but failed PSD. Problem with the relay is suspected.Unk Unk Unk Unk Unk 3 9 Water Unk Pass 206 1390 Product Unk Pass NA N5 Unk Water NA Pass 2 2 Water Yes Pass 300 600 Product Yes Pass NA NSensors were left in fuel for 3 minutes. They alarm 2-5 minutes after being pulled from fuel. This speeds up recovery time.5 5 Water NA Pass 5 5 Water NA Pass 420 420 Product Yes Pass NA NTechnician left sensor in product for 2min & 45sec. He rinsed the sensor with soapy water after alarm activated to speed up recovery time.

Unk Unk Unk Unk Unk 5 10 Water Unk Pass 318 1189 Product Unk Pass NA N

5 Unk Water NA Pass 2 2 Water Yes Pass 420 720 Product Yes Pass NA NSensors were left in fuel for 3 minutes. They alarm 2-5 minutes after being pulled from fuel. This speeds up recovery time.7 1 Water NA Pass 6 1 Water Yes Pass 300 483 Product Yes Pass NA NFor product test, sensor was left in fuel for 3 minutes.Unk Unk Unk Unk Unk 4 9 Water Unk Pass 3009 6120 Product Unk Pass NA N5 Unk Water NA Pass 2 2 Water Yes Pass 300 600 Product Yes Pass NA NSensors were left in fuel for 3 minutes. They alarm 2-5 minutes after being pulled from fuel. This speeds up recovery time.Sensor Model 794380-3523 1 Both Yes Pass 3 1 Both Yes Pass NT NT NT NT NT NT N

All times are recorded in seconds and heights in inches. Appendix 
Resp Rec Alarm PSD Result Resp Rec Alarm PSD Result Resp Rec Alarm PSD Result Resp Re

Low Water Test High Water Test Product Testing 

6 1 Both Yes Pass NT NT NT NT NT NT NT NT NT NT NT NSensors were tested as a non-discriminating float sensor.6 1 Both Yes Pass NT NT NT NT NT NT NT NT NT NT NT NSensors were tested as a non-discriminating float sensor.NT NT NT NT NT 5 1 Both Yes Pass NT NT NT NT NT NT NThese sensors were located in the fill sump, in the overfill bucket.NT NT NT NT NT 1 1 Both Yes Pass NT NT NT NT NT NT NThese sensors were located in the fill sump, in the overfill bucket.NT NT NT NT NT 5 1 Both Yes Pass NT NT NT NT NT NT NThese sensors were located in the fill sump, in the overfill bucket.3 1 Both Yes Pass 3 1 Both Yes Pass NT NT NT NT NT NT N10 5 Water NA Pass 10 5 Water Yes Pass NT NT NT NT NT NT NFlip test activated both low and high liquid alarms. Technician did not test the sensor in product.10 5 Water NA Pass 10 5 Water Yes Pass NT NT NT NT NT NT NFlip test activated both low and high liquid alarms. Technician did not test the sensor in product.10 5 Water NA Pass 10 5 Water Yes Pass NT NT NT NT NT NT NFlip test activated both low and high liquid alarms. Technician did not test the sensor in product.15 5 Water NA Pass 15 5 Water Yes Pass NT NT NT NT NT NT NFlip test activated both low and high liquid alarms. Technician did not test the sensor in product. Water in sump was not high enough to activate the alarm.5 Unk Water NA Pass 5 Unk Water Unk Pass NT NT NT NT NT NT NLocal agency did not test discriminating sensors in product. Both low and high level alarms were activated by flipping the sensor.5 Unk Water NA Pass 5 Unk Water Unk Pass NT NT NT NT NT NT NLocal agency did not test discriminating sensors in product. Both low and high level alarms were activated by flipping the sensor.Unk Unk None No Fail 3 1 Both Yes Pass NT NT NT NT NT NT NSensor's low float did not activate (would not reset). Sensor was replaced by the owner without informing the local agnecy nor the contractor who does the routine inspection. App

functinality.

Unk Unk Unk Unk Unk 10 17 Water Unk Pass 425 2435 Product Unk Pass NT NCleaned in Coleman Fuel.Unk Unk Unk Unk Unk 8 16 Water Unk Pass 446 1548 Product Unk Pass NT NUnk Unk Unk Unk Unk 12 18 Water Unk Pass 468 960 Product Unk Pass NT NUnk Unk Unk Unk Unk 4 10 Water Unk Pass 452 960 Product Unk Pass NT NUnk Unk Unk Unk Unk 6 11 Water Unk Pass NA NA Water Unk Fail NT NUnk Unk Unk Unk Unk NT NT NT NT NT 543 570 Product Unk Pass NT NUnk Unk Unk Unk Unk 10 18 Water Unk Pass 275 2595 Product Unk Pass NT NCleaned in Coleman Fuel.6 1 Both Yes Pass NT NT NT NT NT NT NT NT NT NT NT NSensors were tested as a non-discriminating float sensor.Unk Unk Unk Unk Unk 7 13 Water Unk Pass 425 1413 Product Unk Pass NT N

All times are recorded in seconds and heights in inches. Appendix 
Resp Rec Alarm PSD Result Resp Rec Alarm PSD Result Resp Rec Alarm PSD Result Resp Re

Low Water Test High Water Test Product Testing 

Unk Unk Unk Unk Unk 6 16 Water Unk Pass 435 2040 Product Unk Pass NT NUnk Unk Unk Unk Unk 9 22 Water Unk Pass 530 2040 Product Unk Pass NT NCleaned in Coleman Fuel.Unk Unk Unk Unk Unk 4 14 Water Unk Pass 355 1640 Product Unk Pass NT NCleaned in Coleman Fuel.Unk Unk Unk Unk Unk 5 13 Water Unk Pass 414 1240 Product Unk Pass NT NUnk Unk Unk Unk Unk 5 12 Water Unk Pass 379 1143 Product Unk Pass NT NUnk Unk Unk Unk Unk 6 16 Water Unk Pass 429 1166 Product Unk Pass NT NUnk Unk Unk Unk Unk 8 21 Water Unk Pass 422 1320 Product Unk Pass NT NUnk Unk Unk Unk Unk 5 12 Water Unk Pass 425 1271 Product Unk Pass NT NUnk Unk Unk Unk Unk 4 9 Water Unk Pass 483 1229 Product Unk Pass NT NUnk Unk Unk Unk Unk 7 13 Water Unk Pass 299 573 Product Unk Pass NT NUnk Unk Unk Unk Unk 4 13 Water Unk Pass 318 481 Product Unk Pass NT NUnk Unk Unk Unk Unk 4 11 Water Unk Pass 397 690 Product Unk Pass NT NUnk Unk Unk Unk Unk 6 10 Water Unk Pass 489 1190 Product Unk Pass NT NUnk Unk Unk Unk Unk 5 11 Water Unk Pass 539 1631 Product Unk Pass NT NUnk Unk Unk Unk Unk 4 9 Water Unk Pass 474 1299 Product Unk Pass NT NUnk Unk Unk Unk Unk 9 15 Water Unk Pass 495 1256 Product Unk Pass NT NUnk Unk Unk Unk Unk 6 14 Water Unk Pass Unk 813 Product Unk Pass NT NUnk Unk Unk Unk Unk 6 16 Water Unk Pass 335 2010 Product Unk Pass NT NUnk Unk Unk Unk Unk 2 12 Water Unk Pass 470 1078 Product Unk Pass NT NUnk Unk Unk Unk Unk 4 11 Water Unk Pass 350 3499 Product Unk Pass NT NUnk Unk Unk Unk Unk 5 10 Water Unk Pass 459 1769 Product Unk Pass NT NUnk Unk Unk Unk Unk 6 14 Water Unk Pass 462 2206 Product Unk Pass NT NUnk Unk Unk Unk Unk 5 11 Water Unk Pass 453 930 Product Unk Pass NT NUnk Unk Unk Unk Unk 6 13 Water Unk Pass 440 1140 Product Unk Pass NT NUnk Unk Unk Unk Unk 8 19 Water Unk Pass 420 1851 Product Unk Pass NT NUnk Unk Unk Unk Unk 5 13 Water Unk Pass 540 1760 Product Unk Pass NT NUnk Unk Unk Unk Unk 9 11 Water Unk Pass 360 1500 Product Unk Pass NT NUnk Unk Unk Unk Unk 8 21 Water Unk Pass 354 1807 Product Unk Pass NT NNT NT NT NT NT 5 5 Water Yes Pass NT NT NT NT NT 5 5 Sensor was programmed for PSD on high-liquid only, not product. Technician re-programmed for PSD on low, high, and product.

All times are recorded in seconds and heights in inches. Appendix 
Resp Rec Alarm PSD Result Resp Rec Alarm PSD Result Resp Rec Alarm PSD Result Resp Re

Low Water Test High Water Test Product Testing 

NT NT NT NT NT 5 5 Water Yes Pass NT NT NT NT NT 3 5 Sensor was programmed for PSD on high-liquid only, not product. Technician re-programmed for PSD on low, high, and product.NT NT NT NT NT 5 5 Water Yes Pass NT NT NT NT NT 3 5 Sensor was programmed for PSD on high-liquid only, not product. Technician re-programmed for PSD on low, high, and product.NT NT NT NT NT 5 5 Water Yes Pass NT NT NT NT NT 5 5 Sensor was programmed for PSD on high-liquid only, not product. Technician re-programmed for PSD on low, high, and product.NT NT NT NT NT 5 5 Water Yes Pass NT NT NT NT NT 5 U10 2 Water NA Pass 2 2 Water Yes Pass 260 Unk Product Yes Pass NT NProgrammed for "high vapor mode".NT NT NT NT NT 5 5 Water Yes Pass NT NT NT NT NT 5 U3 3 Water NA Pass 2 2 Water Yes Pass 240 Unk Product Yes Pass NT NProgrammed for "high vapor mode". Sensor intermittently activated "sensor out" alarm when being moved. Technician suspected a short in wiring where cable attaches to sensor.Unk Unk Unk Unk Unk 5 14 Water Unk Pass 730 1276 Product Unk Pass NT NUnk Unk Unk Unk Unk 13 21 Water Unk Pass 480 600 Product Unk Pass NT NNT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NWiring malfunctioning.NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NWiring malfunctioning.NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NNT NT NT NT NT 60 5 Water Yes Pass NT NT NT NT NT NT NNT NT NT NT NT NA NA NA NA NA NT NT NT NT NT NT NHad 2 bad relays that had to be fixed.NT NT NT NT NT 10 5 Water Yes Pass NT NT NT NT NT 5 UUnk Unk Unk Unk Unk 10 24 Water Unk Pass 520 1769 Product Unk Pass NT NNT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NHad 2 bad relays that had to be fixed.Unk Unk Unk Unk Unk 13 24 Water Unk Pass 420 1978 Product Unk Pass NT NUnk Unk Unk Unk Unk 18 25 Water Unk Pass 385 1470 Product Unk Pass NT NUnk Unk Unk Unk Unk 12 25 Water Unk Pass 412 1920 Product Unk Pass NT NUnk Unk Unk Unk Unk 12 25 Water Unk Pass 400 1695 Product Unk Pass NT NUnk Unk Unk Unk Unk 15 28 Water Unk Pass 335 2281 Product Unk Pass NT NNT NT NT NT NT 5 5 Water Yes Pass NT NT NT NT NT 5 5 Sensor was programmed for PSD on high-liquid only, not product. Technician re-programmed for PSD on low, high, and product.Unk Unk Unk Unk Unk 16 30 Water Unk Pass Unk Unk Product Unk Pass NT NEmergency shut-off activated during testing, so no data was available.Unk Unk Unk Unk Unk 8 19 Water Unk Pass 420 1625 Product Unk Pass NT N

All times are recorded in seconds and heights in inches. Appendix 
Resp Rec Alarm PSD Result Resp Rec Alarm PSD Result Resp Rec Alarm PSD Result Resp Re

Low Water Test High Water Test Product Testing 

Unk Unk Unk Unk Unk 9 19 Water Unk Pass NA NA None Unk Fail NT NUnk Unk Unk Unk Unk 6 15 Water Unk Pass 600 2120 Product Unk Pass NT NUnk Unk Unk Unk Unk 10 18 Water Unk Pass 600 2120 Product Unk Pass NT N15 Unk Water NA Pass 5 Unk Water Yes Pass 300 Unk Product Yes Pass NT N15 Unk Water NA Pass 6 Unk Water Yes Pass 390 Unk Product Yes Pass NT N15 2 Water NA Pass 15 3 Water Yes Pass 270 Unk Product Yes Pass NT N2 2 Product Yes Pass 2 2 Product Yes Pass 3 Unk Product Yes Pass NT NProgrammed for "high vapor mode". Sensor was saturated with product vapors, so any liquid moving low or high float registrered as a product alarm.Unk Unk Unk Unk Unk 16 41 Water Unk Pass 450 1559 Product Unk Pass NT N

All times are recorded in seconds and heights in inches. Appendix 
AP

Discussion of Point Liquid and Polymer Strip Discriminati
Appendix VII, Discussion of Point Liquid and Polymer Strip Discriminating Sensors Page 1 of 1

Point Liquid and Polymer Strip Discriminating Sensors

Point liquid type sensors use solid state electronics, which measure a particular physical property or

properties of liquid that contacts the detection element. An example is capacitance change sensors, where

liquid contacting the detection element acts as the dielectric in a capacitor. Air (no liquid present at

sensor), hydrocarbon-based liquids, and water each have distinctly different dielectric constants. A

capacitance change sensor can detect this and respond differently when dry, or when exposed to water or

hydrocarbons. Different responses from the sensor are interpreted by the control panel, which activates

the appropriate alarm. 

Point liquid discriminating sensors are capable of responding only to liquids directly in contact with the

detection element. This means that product floating on water will produce a water alarm if only the water

is in contact with the detection element. The detection elements are usually quite small, meaning that it

does not take a great deal of water to potentially mask a product release. Point liquid discriminating

sensors tend to be smaller than the polymer strip type, and contain no moving parts. These attributes

allow them to be installed in a variety of orientations, and in tight spaces (such as a tank interstice) where

polymer strip sensors would not fit. Response time for this type of sensor varies by manufacturer and

model, but is generally quick (less than 1 minute).

In contrast to point liquid discriminating sensors, polymer strip sensors use two detection elements

combined in one housing to discriminate between product and water*

. The first detection element is a

float switch or ultrasonic detector that will activate a “low liquid level” alarm when in contact with any

liquid. It is located near the bottom of the sensor, and generally has a quick response time (less than 1

minute). The second detection element is a hydrocarbon-sensing cable or strip that will activate a

“product” alarm when exposed to hydrocarbon-based product. It will not respond to water. The cable or

strip typically runs from the bottom to the top of the sensor, and response times vary between

approximately 5 minutes and 20 minutes in unleaded fuel (may be 12 hours or more in diesel fuel).

 

It is only by combining the float or ultrasonic liquid-sensing element with the hydrocarbon-sensing

element (cable or strip) that the polymer strip type sensor is able to discriminate between product and

water. A liquid entering the area monitored by the sensor will first contact the lowest float or ultrasonic

detection element, activating a “low liquid level” alarm. This alarm alerts the UST operator that liquid is

present in the monitored area. If the liquid present is gasoline, the hydrocarbon-sensing element will

activate a “product” alarm approximately 5 to 20 minutes later (may be 12 hours or more for diesel fuel).

In this event, the UST operator knows that product is present in the area monitored by the sensor, not just

water.

Polymer strip discriminating sensors offer the benefit of being able to detect a layer of hydrocarbon

floating on water, as long as the water level is in contact with the hydrocarbon-sensing strip. This makes

them well suited for locations where water ingress is common. Many (but not all) of these sensors have

an additional float or ultrasonic liquid-sensing element located at the top end of the hydrocarbon-sensing

strip. This element activates a “high liquid level” alarm, which indicates that the liquid level has

exceeded the height of the hydrocarbon-sensing strip. Once water has reached this level, subsequent

product releases may float above and fail to contact the hydrocarbon-sensing strip, resulting in a missed

detection. Polymer strip type sensors are less likely to miss a layer of product on water than point liquid

discriminating sensors, but it is still a possibility that UST operators and inspectors should be aware of. 

 

* Examples of polymer strip discriminating sensors include Emco Electronics models Q0003-002 and -003, Incon

models TSP-DDS and TSP-DTS, and Veeder-Root models 794380-320, -322, -350, and –352).