PPE CASE

Personal Protective Equipment Conformity Assessment Studies and Evaluations

Point-of-Use Assessment for Self-Contained Self-Rescuers 

Randomly Sampled from Mining Districts: Third Phase 

Sample Period: February 2013 to December 2014

Gary Walbert and Bill Monaghan

National Institute for Occupational Safety and Health

National Personal Protective Technology Laboratory

Abstract 

An ongoing Long-Term Field Evaluation (LTFE)1 study, carried out jointly by the National Personal Protective 

Technology Laboratory (NPPTL), a laboratory in the National Institute for Occupational Safety and Health 

(NIOSH) and the Mine Safety and Health Administration (MSHA), evaluates 

the long-term field performance and reliability of self-contained self-rescuer 

(SCSR) units deployed in U.S. underground coal mines. The LTFE study

provides performance, reliability, and user maintenance compliance data 

on field-deployed SCSR units. 

This report presents findings from the third phase long-term random (LTR3) 

testing of SCSR units that was conducted between February 2013 and 

December 2014. Prior to collection, MSHA provided a copy of the SCSR 

inventory from which NIOSH compiled a statistically-significant random list 

of 620 SCSR units to target for collection. NIOSH returned 319 SCSR units to 

the laboratory when the collection effort ended. Three hundred ten (310) 

SCSR units that passed the manufacturers’ recommended visual inspections

were subsequently tested using an automated breathing and metabolic 

simulator (ABMS). The tests performed in this study are not approval tests; 

however, products that exhibit any suspected nonconforming

characteristics during their inspection and testing at NPPTL are identified. A 

certified product investigation process (CPIP) may subsequently be opened 

to determine the impact of observed performance degradation or potential 

nonconformance of deployed SCSR units. It was not necessary to open a CPIP audit for SCSR nonconformance 

issues in this phase of the LTFE study.

 

1 A list of acronyms and abbreviations is available in Appendix A.

NIOSH’s point-of-use 

assessments for selfcontained self-rescuers 

(SCSRs) found that mine 

operators are largely 

compliant with SCSR 

manufacturer-specified 

requirements and the 

devices tested appear to be 

sufficiently designed for 

mining use conditions.
2

Twenty-five of the targeted SCSR units failed the manufacturers’ recommended visual inspections either at the 

mine or at NIOSH. LTR3 sample test results suggest that SCSR units that pass the manufacturers’ recommended 

inspection criteria and breathing and metabolic simulation (BMS) testing can be relied upon to provide life 

support for mine escape. Although deployment in the mining environment caused some performance 

degradation in most of the SCSRs tested during LTR3, all retained their ability to preserve life in the event of an 

emergency. 

As in the first phase long-term random (LTR1) SCSR unit collection efforts, NIOSH failed to collect 100 of each 

NIOSH-approved SCSR model deployed in United States underground coal mines. A revised strategy to meet this 

study design goal is being formulated and will be enacted for future LTFE collection phases in order to retain the 

desired statistical validity of the study. 

Introduction 

Coal mine operators in the United States are required to make SCSR units available to each underground coal 

miner. Additional SCSR units are required to be cached on working settings and in escape ways. Title 30, Code of 

Federal Regulations (30 CFR) §75.1714 requires that each person in an underground coal mine wear, carry, or 

have ready access to a device approved by NIOSH and MSHA. The device must provide respiratory protection with 

an oxygen (O2) source for at least one hour. In some mines, shorter duration SCSR units are worn, while cached 

one-hour units provide the additional duration. SCSRs are sealed for protection from the underground mining 

environment. The sealed case protects the apparatus from environmental and physical damage, but makes it 

difficult to inspect the unit for damage. Unlike open-circuit, self-contained breathing apparatus employed in fire 

services and general industry, no functional assessment can be made prior to actual use. For these reasons, NIOSH 

NPPTL, in cooperation with MSHA, conducts an ongoing, long-term field evaluation of SCSR units deployed in 

underground coal mines to assess their reliability and performance. 

The objective of the LTFE program is to evaluate how well SCSR units endure the underground coal mining 

environment with regard to both physical damage and the effects of aging. In order to protect miners’ safety, 

mines must conduct regular inspections of deployed units to ensure readiness. The criteria for these inspections 

are established by the manufacturers and include damage assessment of specific components by either visual 

inspection or nondestructive testing. Among the visual inspection criteria are evaluation of heat and humidity 

indicators on pressure gauges, verification of the remaining service time based on the manufacturing date, 

assurance that the case seal is intact, and visual assessment of physical indications of wear or damage. All inservice units must comply with the manufacturer’s specified conditions for storage and use. SCSR units failing 

inspection or not in compliance with the conditions of storage and use, no longer conform with NIOSH/MSHA 

approval criteria and must be removed from service. 

During the first ten phases of the LTFE program, referred to as LTFE 1 through LTFE 10, NIOSH NPPTL (and during 

the early phases, the U.S. Bureau of Mines) collected SCSR units mines were willing to surrender for replacement 

units. Reports published that describe the findings of LTFE 1 through LTFE 10 (Kyriazi et al. 1986; Kyriazi and 

Shubilla 1992, 1994, 1996, 2000, 2002, 2004, 2006, 2008) were successful at identifying performance and 

reliability issues, resulting in SCSR product improvements. However, the SCSR sample size and collection criteria 

limited how well the results represented the deployed SCSR population. 

In 2009, a new sampling strategy was implemented. The new strategy involved randomizing the SCSR population 

to identify a statistically valid sample, rather than a convenience sample collected under the previous strategy. In 

keeping with this strategy for LTR3, NIOSH compiled a random list of approximately 620 SCSRs from the MSHA 

SCSR Inventory and Report, representing all 11 MSHA mining districts. From this list, NIOSH attempted to collect 

all SCSR units that would pass manufacturers’ recommended visual inspections at the mine. This sampling strategy 

attempted to improve the significance of test results by sampling a broader range of SCSR deployment types and 
3

Photo by NPPTL

Figure 1. Ocenco EBA 6.5 self-rescuer

Photo by NPPTL

Figure 2. Ocenco M-20 self-rescuer

environments. Since 2009, NPPTL has referred to the LTFE collections as LTR1, LTR2, LTR3, etc., to indicate the 

randomization of the sampling operation and phase of the collection. NIOSH based LTR1, LTR2, and LTR3 

collections on this random sampling protocol that typically targets the same number of each SCSR model currently 

approved for use in underground coal mines. Beginning with the LTR1 collection phase and continuing with the 

LTR3 collection phase, NIOSH subjected the SCSR units to strict visual inspection. The intent was to collect 

performance test data only for units that passed the visual inspection. 

The Automated Breathing and Metabolic Simulator (ABMS) machine is used to assess the performance of SCSR 

units collected for the LTR3 study and provides a reproducible measure for comparison. All tests are conducted at 

a constant work rate until the oxygen supply is expended in order to facilitate duration comparisons between 

NIOSH NPPTL stored and deployed units. Test data is averaged over the first 60 (for one-hour SCSR units) or ten

(for ten-minute SCSR units) minutes of testing to eliminate the test duration variability effect in the determination 

of stressor levels. The SCSR units tested in this phase were not NIOSH-approved using the ABMS. 

All of the SCSR units tested as part of LTR3 have been approved by both NIOSH and MSHA under the requirements 

of Title 42, Code of Federal Regulations, Part 84 (42 CFR, Part 84), Subpart H. It is important to keep in mind that 

the tests performed as part of LTR3 are focused on detecting any change in the performance of deployed 

respirators. Tests conducted as part of LTR3 are not performed as part of Subpart H certification. LTR3 test 

conditions and endpoints are also different from tests conducted in Subpart H certification. Unlike the Subpart H 

certification testing which relies solely on human subjects to evaluate the SCSR units, LTR3 tests are performed 

using an ABMS. The LTR3 breathing and metabolic simulation (BMS) tests are designed to be highly reproducible 

so comparisons between new and old units are valid. Although human-facilitated and machine results are similar, 

they are not exactly the same and the data reported from machine testing is not to be considered a direct 

equivalent to a Subpart H certification man test. The BMS tests are also intended to stress the functionality of the 

SCSR units towards the high end of their life support capabilities. While this report offers results that are 

sometimes less than optimal, it is important to remember that one of the goals is to assure that SCSR units, as 

found in mines, will provide the expected life-support capacity when they are properly used and cared for. Unless 

specifically noted otherwise, the report should be viewed as providing that evidence.

Methods

SCSRs Collected and Evaluated

The SCSR units evaluated in the LTR3 study included units manufactured by Ocenco Incorporated, CSE 

Corporation, and Dräger. The Ocenco EBA 6.5 and the Ocenco M-20 (Figures 1 and 2) are compressed-oxygen 

SCSR units. 
4

Photo by NPPTL

Figure 3. CSE SRLD self-rescuer

Photo by Dräger

Figure 4. Dräger Oxy K Plus (top) and Oxy K Plus S

(bottom) self-rescuers

The EBA 6.5 has an approved duration of 60 minutes; the M-20 has an approved duration of 10 minutes. The CSE 

SRLD (Figure 3), Dräger Oxy K Plus (top of Figure 4), and Dräger Oxy K Plus S (bottom of Figure 4) are chemicaloxygen-SCSR units that employ an oxygen gas starter for initial operation while chemical oxygen is subsequently

generated through chemical reaction as the sorbent absorbs carbon dioxide from the user’s exhaled breath. The 

Oxy K Plus and Oxy K Plus S are the same SCSR but have different case opening mechanisms and procedures 

(demonstrated in Figure 4). The SRLD and Oxy K Plus/Oxy K Plus S SCSR units both have approved durations of 

60 minutes. 

Sampling Strategy

For statistical analysis purposes, NIOSH NPPTL attempted to collect at least 100 of each NIOSH-approved SCSR 

model deployed in United States underground coal mines for the LTR3 study. To obtain the units, NIOSH

requested a list from MSHA of all units currently in mine use. In response, using the MSHA SCSR Inventory and 

Report, MSHA generated a list of approximately 25,000 SCSR unit serial numbers across all 11 mining districts. 

From the list, NIOSH NPPTL compiled a random list of at least 140 units of each model. Targeting more SCSR

units for collection than was needed was necessary in case there were issues with obtaining specific SCSRs. This 

approach increased the likelihood of collecting at least 100 units of each model for laboratory testing. Despite 

this strategy, slightly less than 100 of each SCSR model were collected mostly due to SCSR units not passing 

visual inspection, mine closures, and SCSR units found to be missing upon collection attempt. Table 1 lists the 

number of each SCSR model returned to NIOSH NPPTL for testing during the LTR3 collection phase along with 

their manufacturing date ranges. 

Table 1. Summary of LTR3 SCSR Collection

Manufacturer Model Number of units collected Manufacture date range

CSE SRLD 84 11/2011 – 07/2012

Dräger Oxy K Plus 35 06/2006 – 12/2010

Dräger Oxy K Plus S 44 12/2010 – 10/2011

Ocenco EBA 6.5 70 12/2003 – 06/2012

Ocenco M-20 86 11/2006 – 06/2012
5

Tests and Evaluations

The following tests and evaluations were conducted on each SCSR unit obtained: (1) visual inspection that 

miners are required to make before each shift; (2) phenolphthalein indicator check; (3) quantitative leak test; (4) 

oxygen flow test; and (5) BMS test. In addition to the visual checks, the CSE and Dräger inspection manuals state 

that the SRLD and Oxy K Plus/Oxy K Plus S SCSR units, respectively, be tested in the field every 90 days with a 

solids movement sound detector to determine the condition of the chemical bed used to remove carbon dioxide 

and generate oxygen. This test is normally performed at NIOSH NPPTL using laboratory-scale solids movement 

sound detectors as a final screening just prior to testing. However, the equipment to assess the Dräger SCSR 

units’ chemical bed integrity was not available at NIOSH NPPTL during LTR3 testing and the equipment to assess

the CSE SRLD SCSR units’ chemical bed integrity wasn’t available until early in the supplemental testing period 

conducted in 2017. Therefore, NIOSH performed this assessment for only a small portion of the CSE SRLD units 

evaluated for LTR3. While the units were provided to NIOSH with the understanding that they should have 

passed the mine’s solids movement sound detector assessment, we acknowledge that unassessed, or even 

improperly assessed bed degradation could have had a negative impact on at least some of the results being 

reported herein.

Visual Inspection

Three hundred nineteen (319) SCSR units passed the manufacturers’ recommended visual inspections at the 

mines and were collected for further evaluation by NIOSH, including a second visual inspection at NIOSH NPPTL 

prior to BMS testing. Manufacturers’ recommended visual inspections focus on the integrity of the case, seal, 

latches, and indicators that are viewable without opening or activating the respirator. The cases of the CSE SRLD 

and Dräger Oxy K Plus chemical units have moisture and heat indicators to signify water penetration or excessive 

temperature exposure, respectively. Ocenco Incorporated compressed-gas oxygen units have pressure 

indicators that indicate oxygen cylinder pressure. Damage to the case, missing case latches, broken seals, 

excessive heat exposure, or low O2 gauge pressures are reasons for a unit to fail the visual inspection. The SCSR 

is safe for use if all visual inspections pass. If a unit does not meet the manufacturer’s prescribed limits for these 

indicators when inspected at the mine, it must be taken out of service. SCSR units that failed the visual 

inspection at NIOSH NPPTL were also removed from the study. It should be noted that NIOSH only performed

the same visual inspections that a miner is required to conduct prior to using the unit or taking it underground.

Phenolphthalein Indicator Check

Upon opening the SCSR case and removing the mouthpiece plug, for those having a mouthpiece plug, each 

mouthpiece and inner portion of the breathing tube was wiped with a swab soaked in phenolphthalein. This 

action indicated whether the granular sorbent/oxygen generator particles or chemical sorbent particles for 

oxygen-supplied SCSR units had broken down and entered the breathing circuit where it could be inhaled by the 

user. The phenolphthalein soaked swab changing to pink in color after swabbing indicates the presence of these 

granular particles in the breathing zone of the SCSR unit. 

Quantitative Leak Test

SCSR units that passed the visual inspection check proceeded to the quantitative leak test (QNT). This test 

assesses breathing circuit integrity but is not required for approval. The leak test employs a vacuum source to 

induce a vacuum of 300 mm H2O column within the SCSR breathing circuit while measuring the inward leakage 

rate with an in-line mass flow meter. The vacuum source’s gas return tubing is connected and sealed on its 

opposite end to the mouthpiece of the SCSR unit being tested. A mass flow meter is installed in the tubing 

between the vacuum source and the mouthpiece connector to measure the flow rate of gas being evacuated 

from the SCSR unit’s breathing circuit when the vacuum source is activated. 
6

As the vacuum is adjusted to and stabilizes at 300 mm H2O column, the evacuated gas flow rate decreases and 

stabilizes. The stable evacuated gas flow rate is considered to be the SCSR unit leak rate. At maximal work rates, 

inhalation pressure/vacuum should not exceed +300 or -300 mm H2O (Hodgson, 1993) and inward leakage rates 

should be less than 500 milliliters per minute (ml/min) to reasonably assure user protection for a period equal to 

or greater than the rated service time (https://www.cdc.gov/niosh/npptl/pdfs/PPEC-SCSR-Mining-SecondPhase508.pdf). 

Mouthpiece connectors shaped as closely as possible to the internal dimensions of the SCSR mouthpiece 

opening are used to seal the SCSR to the ABMS trachea. Custom fabrication of these mouthpieces to match the 

SCSR mouthpiece opening is required to optimize the fit and prevent the connection from being a source of 

inward leakage. Care is taken when inserting the connector into the SCSR mouthpiece to be tested and securing 

it tightly with a wire tie. Putty is used, as necessary, to enhance this seal and stop any residual inward leakage. 

The mouthpiece connector is tightly sealed to the vacuum source’s evacuated gas return tubing for the QNT. 

Leakage within the breathing circuit of the SCSR being tested under vacuum is confirmed by pinching and sealing 

the breathing hose just below the mouthpiece connector.

Oxygen Flow Test

After assessing the breathing circuit integrity, each Ocenco EBA 6.5 SCSR was tested for minimum sustained 

oxygen flow rate. This was performed by disconnecting the oxygen supply line from the breathing bag, 

connecting it to a flow meter, and fully opening the oxygen supply valve for approximately 30 seconds. The 

sustained oxygen flow rate was subsequently recorded and the supply valve was fully closed. The oxygen supply 

line was subsequently reattached securely to the breathing bag connector with a wire tie. 42 CFR, Part 84, 

§84.94, gas flow test for a closed-circuit apparatus, requires a minimum constant-flow rate of 1.5 L/min for 

combination constant flow and demand-flow SCSR units for their entire operation. Since it is not possible to 

measure the minimum sustained oxygen flow rate over the duration of the SCSR unit’s operation, a flow 

measurement greater than or equal to 1.5 L/min at the start of testing provides a partial indicator of 

conformance to this requirement. 

Acoustics Solids Movement Detector Test

The Acoustic Solids Movement Detector (ASMD) is a device used to identify loose particles that lead to 

channeling of breathing gas flow in the chemical bed of chemical-oxygen-generating CSE SRLD SCSR units. SRLD 

SCSR units with such damage promote a decrease in breathing gas residence time in the chemical bed and the 

hastening of CO2 breakthrough. The ASMD analyzes the sound induced in an SRLD SCSR unit by shaking it in a 

controlled manner. The sound level produced by the SRLD SCSR when shaken is used as an indicator of shock 

and vibration damage incurred by the chemical bed within the SCSR. In the field, this assessment is made

qualitatively using a handheld ASMD instrument. A laboratory version of the handheld ASMD rotates the SRLD 

SCSR at 10 rpm in an anechoic chamber to quantitatively measure sound levels in decibels (dB). A blank SCSR 

calibration unit filled with cement is used to measure a baseline sound level. This calibration unit is used to 

adjust the sound level measured for units under test. Mine-deployed SRLD SCSR units for which sound levels

higher than 60 dB are measured fail the test. NIOSH performs the laboratory version of the ASMD test as part of 

LTFE inspection of all chemical-oxygen generating CSE SRLD SCSR units. CSE SRLD SCSR units failing the ASMD 

test are not included for evaluation in the LTFE program study.

Breathing and Metabolic Simulation Test

The computer-controlled ABMS (Figure 5) injects CO2 into and removes O2 from its breathing circuit while 

operating at fixed breathing frequencies and tidal volumes to simulate human metabolic processes (Deno, 1984 

and Kyriazi, 1986). 
7

The ABMS machine is an ideal device for evaluating inspired CO2 and O2 concentrations in SCSR units due to its 

high degree of accuracy and repeatability in simulating human CO2 production and O2 consumption. By design, 

an ABMS replicates breathing ventilation (respiratory frequency, tidal volume, flow, temperature, and humidity), 

O2 consumption, and CO2 production. The National Instruments’ LabVIEW-based software application manages 

the operation of the ABMS. Test input parameters required to initiate a simulation operation include the VO2, 

VCO2, respiration rate, and tidal volume set points. LabVIEW software subroutines work to control the piston 

operation, and maintain the VO2 and VCO2 set points through the control of the injection rates of CO2 and N2

streams into the breathing circuit and the exhaust gas flow (containing O2) out of the breathing circuit. 

Measurements of respiratory gas constituents, O2 and CO2, breathing resistances, and wet and dry bulb 

temperatures are recorded at 60 Hz. These measurements are used to provide real-time test data displays and 

in the final analysis of test performance.

NIOSH tested the SCSR units on the ABMS using a constant average metabolic work rate test (Table 2). The 

constant average work rate used is similar to the 50th percentile miner (body weight of 87 kg or 192 lbs.) 

performing the one hour man test 4 as described in 42 CFR, Part 84, Subpart H. The ABMS was programmed to 

simulate human respiration at a VO2 of 1.35 L/min, VCO2 of 1.15 L/min, a ventilation rate of 30 L/min, and 

respiratory frequency of 18 breaths per minute. During testing, the ABMS monitored metabolic stressors which 

included inspired levels of CO2 and O2, inspired wet- and dry-bulb temperatures, and peak inhalation and 

exhalation breathing resistances (pressures) continuously until the test was terminated. Tests on the ABMS are 

terminated upon one of three endpoints: exhaustion of the O2 supply as indicated by inhalation pressures 

reaching -200 mm H2O, coinciding with an empty breathing bag; average inspired CO2 levels exceeding 10%; or 

inspired O2 levels falling below 15%. When these limits are exceeded, the ABMS gas metabolism is compromised 

and further data are not acceptable for analysis.

Although the average work rate is the same, LTR testing is not equivalent to Subpart H approval testing. Human 

subjects may differ from each other and from BMS tests in terms of CO2 production rate, ventilation rate, and 

respiratory frequency. These parameters affect apparatus duration as well as all of the monitored variables. 

Treadmill tests cannot be considered equivalent to BMS tests, even though the O2 consumption rate is the same. 

However, BMS tests can be used to provide an indication of SCSR duration performance (i.e., the length of time 

that an SCSR unit will operate at a constant work rate before the oxygen supply becomes fully expended). 

Approval testing under 42 CFR, Part 84, Subpart H using human subjects imposes high and low work rates that 

the average work rate used in LTR testing does not. Also, stressor levels are continuously monitored during LTR 

testing, whereas they are sampled only between work activities in approval testing. In addition, LTR testing 

continues until the apparatus breathing gas supply is expended or stressor levels exceed allowable parameters, 

whereas testing during approval ends at the rated duration, even if the capacity of the apparatus exceeds it.
8

Photo by NPPTL

Figure 5. Automated Breathing and Metabolic 

Simulator

Table 2. Constant Average Metabolic Work Rate

Metabolic workload Rate

O2 Consumption 1.35 L/min

CO2 Production Rate 1.15 L/min

Ventilation Rate 30 L/min

Tidal Volume 1.68 l/breath

Respiratory Frequency 17.9 breaths/min

Peak Respiratory Flow Rate:

 Peak Inhalation 89 L/min

 Peak Exhalation 71 L/min

In Storage Unit Evaluations

SCSR units maintained in storage at NIOSH NPPTL for the next phase of the LTFE program were evaluated using 

the ABMS for performance comparisons with deployed units. Twelve CSE SRLD, eight Dräger Oxy K Plus, nine 

Ocenco EBA 6.5, and eight Ocenco M-20 SCSR units were tested between January 21 and February 19, 2016 

using the same work rate at which the deployed SCSR units were tested. Prior to evaluation, manufacturers’ 

recommended visual inspections were performed on the stored SCSR units to ensure qualification for BMS 

testing.

SCSR Stressor Test Data

NIOSH averaged the minute-average values of the stressors monitored during the BMS testing of each SCSR over 

its rated service time in order to enable comparison with other SCSR units of the same type. Use of full test 

duration results introduces stressor data variances that prevent valid comparisons between individual tests. 

NIOSH plotted all stressor data as a function of SCSR manufacturing date in order to determine if deployment 

time effects existed. 
9

All average stressor data from the testing of deployed units and new units stored at NIOSH NPPTL for each SCSR 

type were averaged to obtain a composite average to detect any change in performance of deployed SCSR units. 

This information, along with stressor minimums and maximums for each set of tests, was tabulated to assess the 

deployed units’ performance.

Results and Discussion

SCSR Collection

NIOSH NPPTL targeted collection of 620 units deployed in United States underground coal mines for LTR3. On 

the randomly generated collection lists, 140 units represented CSE SRLD, 140 units represented Ocenco EBA 6.5, 

200 units represented Ocenco M-20, and 140 units represented Dräger Oxy K Plus/Oxy K Plus S models. Of the 

620 units targeted, NPPTL collected 335 SCSR units at the mines. After identifying 16 visual inspection failures, 

319 SCSR units were returned to NIOSH NPPTL for testing, yielding an overall collection rate of 51.5%. Figure 6

depicts the status of the 620 SCSRs targeted in the LTR3 collection. A total of 285 targeted SCSR units were 

either missing or not available for various reasons including mine closures, removed from service, or not feasible 

to be collected (Figure 6). This amounts to 46.0% of the SCSRs on the targeted collection list.

A revised LTFE collection strategy will be implemented for future collection phases. Part of this new strategy will 

include determining the quantity of each SCSR type required to achieve the desired statistical validity for the 

study. NIOSH will work closely with MSHA to develop the design study goal once this quantity is determined. 

NIOSH will also explore improved communication strategies for confirming SCSR status prior to collection, and a 

means to reach smaller mines that may only have one unit to collect.

From the 319 collected SCSR units, 9 additional units failed the visual inspection at NIOSH NPPTL leaving 310

units that qualified for BMS testing. The SCSRs that qualified for BMS testing included: 84 CSE SRLD, 79 Dräger 

Oxy K Plus/Oxy K Plus S, 69 Ocenco EBA 6.5, and 78 Ocenco M-20 SCSR units (Figure 7).

319

162

18 38

16 22

45

Collected

Missing

Removed from Service

Not Available

Failed inspection at

mine

Not feasible to be

collected

Mine

Closed/Abandoned

Figure 6. LTR3 Collection Dispersion
10

Figure 7. Dispersion of SCSRs Qualified for BMS Testing

When LTR3 collection and testing began in May 2013, NIOSH collected all SCSR units that the mines and MSHA 

District Offices deemed as passing visual inspection. Of the 335 SCSRs (Table 3) collected at the mines, 16 (4.8%) 

failed mine visual inspection for reasons including failure of the solids movement sound detector test of the 

chemical bed, damage to the case or case seal, and activation of moisture penetration or excessive heat 

indicators. Out of 319 SCSRs collected and transported to NIOSH NPPTL, an additional nine SCSRs (2.7%) failed 

visual inspection when applying the manufacturer’s criteria upon test initiation in the laboratory for reasons 

including mine dust penetration into the case, white powder in the breathing hose, and case damage. From the 

310 qualifying SCSR units, NPPTL obtained 286 valid sets of data.

Table 3. Test Summary for SCSRs Passing Visual Inspection at the Mine, MSHA District Office, and 

NIOSH Test Laboratory

SCSR Model Targeted Collected 

at Mine

Passed Visual 

Inspection at 

Mine

Passed Visual 

Inspection at 

NIOSH Test 

Laboratory

Tested

Obtained 

Valid Test 

Data

CSE SRLD 140 95 84 84 84 65

Dräger Oxy K Plus 60 35 35 35 35 34

Dräger Oxy K Plus

S 80 47 44 44 44 41

Ocenco EBA 6.5 140 72 70 69 69 69

Ocenco M-20 200 86 86 78 78 77

Totals 620 335 319 310 310 286

As noted in Table 3, 310 out of 335 (92.5%) of SCSR units collected at the mine passed the manufacturers’ visual 

inspections performed by NIOSH. This visual inspection failure frequency (7.5%) indicates a need to further train 

miners/mine operators who use/own these SCSR units to fulfill the requirements of the manufacturers’ 

0

10

20

30

40

50

60

70

80

90

CSE SRLD Dräger Oxy K

Plus/Oxy K Plus S

Ocenco EBA 6.5 Ocenco M20

84 79

69

78
11

recommended visual inspections. The 25 SCSR units that failed the visual inspection should have been removed 

from service and would not have been available to collect if the proper visual inspections had been adequately 

performed by their users. 

Units not passing the manufacturers’ recommended visual inspections, exhibiting defects, or not meeting the 

rated duration were referred for investigation into the cause of these results and to determine if any further 

action was warranted. None of the LTR3 SCSR units referred for review were deemed to require further action.

CSE SRLD SCSR

Eighty-four of the 140 CSE SRLD SCSR units listed on the LTR3 targeted collection list were returned to NIOSH 

NPPTL for testing. LTR3 collection methods called for the collection of 100 units, yielding a collection rate of 

84%. Challenges affecting the collection of CSE SRLD SCSR units included missing units or units listed as not

available accounting for 34 units. These two challenges resulted in 24.3% of CSE SRLD SCSR units on the targeted 

collection list being unavailable for testing. The remaining units were not collected for reasons listed as failure of 

visual inspection at the mine (11), not feasible to collect (6), out of service (3), idle (1), and database collection 

error (1). Visual inspection failures at the mines included failure of the handheld sound level test, excessive heat 

indication, damage to the case, and broken case seal.

All CSE SRLD SCSR units tested passed the manufacturer’s recommended visual inspection at NIOSH NPPTL 

(Figure 8). Valid test data was obtained for 65 of the 84 CSE SRLD SCSR units. The 19 invalid data sets were 

mainly the result of ABMS operational issues caused by test operator error. ABMS operational issues included

excessive leaks at the fixture connection to the mouthpiece, test termination as a result of excessively low 

pressure, test termination as a result of inadequate O2 level, excessively high pressure, and lack of breathable 

volume. These latter four operational issues were deemed to be due to improper start-up procedures employed 

by the test operator. None of the CSE SRLD SCSR units returned for testing failed the phenolphthalein indicator 

test.

Photo by NPPTL

Figure 8. Areas of Visual Inspection for CSE SRLD
12

The breathing circuit integrity check of the CSE SRLD SCSR using the QNT leak test procedure showed that all 84 

SCSR units tested had a leak rate less than 500 ml/min (i.e., passed).

After test initiation on the ABMS, all SCSR units continued operating until the breathing gas supply was 

expended. All SCSR units but one met or exceeded the NIOSH-approved 60-minute service time. The average 

duration for CSE SRLD SCSR units tested was 67 minutes.

All CSE SRLD SCSRs tested provided acceptable oxygen levels during the entire 60-minute service time. 

Inspired CO2 levels measured for six of the 65 valid mine-deployed SRLD SCSR unit tests exceeded 4% prior to 

reaching the 60-minute NIOSH-approved service time (Table 4). As shown in Table 4, inspired CO2 levels 

measured for 27 of the remaining 59 valid mine-deployed SCSR unit tests exceeded 4% after the 60-minute 

service time was reached but prior to the expenditure of oxygen. These results are important to note because 

NIOSH has established a 4.0% inspired CO2 pass/fail limit for LTFE testing. However, continuous inspired CO2

measurements were not taken near the end of the 60-minute service time during approval testing of SCSR units 

under Subpart H. Therefore, the excursions in inspired CO2 measured near the end of service time and after the 

service time had been reached for these tests could not have been detected had they occurred. For most users, 

elevated inspired CO2 would most typically cause no more than an elevated ventilation rate, which would likely 

lead to elevated breathing resistance, both of which may cause the user to stop using the unit sooner than if the 

inspired CO2 remained low.
13

Table 4. CSE SRLD SCSR 4% Carbon Dioxide Breakthrough Times

NIOSH NPPTL averaged the minute-average values of the stressors monitored during BMS testing of minedeployed CSE SRLD SCSR units over the first 60 minutes of the test and the results are presented graphically in 

Appendix B (Figures 15 through 20). Sixty-minute data averaging, consistent with service time, was chosen to 

eliminate the test duration variability effect in the determination of stressor levels. NIOSH NPPTL sorted the 

mine-deployed CSE SRLD SCSR unit stressor results within each composite graph by manufacturing dates which 

range in age from oldest to newest, left to right. The stressor value data points for testing of CSE SRLD SCSR units 

in storage at NIOSH NPPTL are shown in red for comparison with the mine-deployed units on these plots. 

A linear regression is fit to each stressor plotted from testing of mine-deployed CSE SRLD SCSR units to draw out 

the effects of deployment time. No trends in measured stressors attributable to deployment time were

identified.

4% Inspired CO2 Test Duration, Mine-Deployed or Inspired CO2 Maximum Inspired CO2,

Breakthrough Time, minutes minutes In Storage at 60 minutes Volume %

40 59 Mine-Deployed NA 9.70

47 66 Mine-Deployed 6.33 9.43

50 65 Mine-Deployed 6.04 7.90

51 62 Mine-Deployed 7.34 7.96

57 66 Mine-Deployed 4.66 6.58

59 65 Mine-Deployed 4.28 6.25

61 68 Mine-Deployed 3.89 6.38

61 62 Mine-Deployed 3.74 4.34

61 73 Mine-Deployed 4.00 8.70

62 74 Mine-Deployed 3.72 9.81

62 67 Mine-Deployed 3.80 5.98

62 68 Mine-Deployed 3.68 6.07

63 63 Mine-Deployed 3.53 4.32

63 66 Mine-Deployed 3.38 5.02

63 65 Mine-Deployed 3.52 4.59

63 65 Mine-Deployed 3.60 4.86

64 67 Mine-Deployed 3.46 5.10

64 69 Mine-Deployed 3.35 5.87

65 66 Mine-Deployed 3.16 4.49

65 69 Mine-Deployed 3.26 5.39

65 65 Mine-Deployed 3.07 4.25

66 68 Mine-Deployed 2.96 4.71

66 70 Mine-Deployed 3.06 6.02

67 67 Mine-Deployed 2.56 4.09

67 68 Mine-Deployed 2.62 4.54

68 72 Mine-Deployed 2.48 6.15

68 70 Mine-Deployed 2.76 5.02

69 72 Mine-Deployed 2.44 4.99

69 71 Mine-Deployed 2.90 4.66

71 76 Mine-Deployed 2.41 5.88

71 71 Mine-Deployed 2.33 4.14

71 76 Mine-Deployed 2.65 5.83

74 74 Mine-Deployed 2.44 4.23
14

Test duration and composite mean stressor levels, including FIO2 (mole fraction inspired oxygen), FICO2 (mole 

fraction inspired carbon dioxide), PEPRS CMH2O (peak expired pressure, cm H2O column), PIPRS CMH2O (peak 

inspired pressure, cm H2O column), and TAVGDB (average inspired dry bulb temperature), are shown for in 

storage and mine-deployed CSE SRLD SCSR units tested in Table 5. The percent difference between minedeployed unit mean stressor values and in storage unit mean stressor values, relative to mine-deployed unit 

mean stressor values, is also shown in Table 5. Mole fraction, as used, is defined as moles of breathing gas 

constituent, O2 or CO2, per 100 moles of breathing gas.

Table 5. CSE SRLD Duration and Composite Mean Stressor Levels

CSE SRLD SCSR – Supplemental Testing

Evaluation of 41 additional CSE SRLD SCSR mine-deployed units was performed May 9 through November 8, 

2017 using the ABMS to investigate elevated inspired CO2 nonconforming test results observed during original 

LTR3 testing. CSE SRLD SCSR units tested in the supplemental study were identified randomly through a search 

of MSHA’s SCSR Inventory and Report for MSHA Mining Districts 2 and 3. Testing focused on checking for the 

recurrence of one-minute average inspired CO2 levels exceeding 4.0% before reaching the 60-minute service 

time. CSE SRLD SCSR units in storage at NPPTL were also evaluated as part of the LTR3 supplemental testing for 

comparison purposes. One CSE SRLD SCSR in storage unit was tested for each mine-deployed unit tested. 

Forty-one of the 94 CSE SRLD SCSR units listed on the LTR3 supplemental testing targeted collection list were 

returned to NIOSH NPPTL. This yielded a collection rate of 43.6%. NIOSH collected a sufficient number of SRLD 

SCSR units for evaluation to elicit a recurrence of elevated inspired CO2 nonconforming test results, based on the 

rates of occurrence during original LTR3 testing. Challenges affecting the collection of CSE SRLD SCSR units for 

supplemental LTR3 testing included units that were not available/unable to be found (31) and mine closures

(22). The supplemental LTR3 collection effort is summarized in Table 6.

Table 6: Test Summary for Supplemental CSE SRLD SCSR Units Passing Visual Inspection at the Mine, MSHA 

District Office, and NIOSH Test Laboratory

SCSR Model Targeted Collected 

at Mine

Passed Visual 

Inspection at 

Mine

Passed Visual 

Inspection at 

NIOSH Test 

Laboratory

Tested

Obtained 

Valid Test 

Data

CSE SRLD 94 41 41 40 40 40

Sound level assessments were performed at the mine on the 41 CSE SRLD SCSR units collected using a portable, 

handheld ASMD provided by CSE. This screening is performed to disqualify those SCSR units that fail this test 

through the detection of loose sorbent particles in the SCSR canister bed that could lead to channeling of 

DURATION FIO2 FICO2 PEPRS CMH2O PIPRS CMH2O TAVGDB

MIN 59 0.6081 0.0114 41.53 -80.11 37.02

MAX 76 0.9243 0.0411 62.97 -53.33 45.73

AVERAGE 67.2 0.7256 0.0183 53.27 -66.24 42.02

% Difference 2.60 -7.89 2.12 5.36 -1.57 -0.04

MIN 63 0.7461 0.0156 45.42 -73.65 39.96

MAX 68 0.8360 0.0201 55.24 -59.87 43.47

AVERAGE 65.5 0.7878 0.0179 50.56 -67.30 42.04

SRLD Deployed Unit Data (65 tests)

SRLD NIOSH In Storage Unit Data (12 tests)
15

breathing gas flow and inefficient CO2 absorption/O2 generation. All of the units collected at the mine passed 

this initial screening test. All but one CSE SRLD SCSR unit was qualified for testing at NIOSH NPPTL. This one 

disqualification was due to the unit failing the sound level test using the laboratory ASMD. Valid test data was 

obtained for all 40 units that qualified for BMS testing. 

NIOSH tested the last 32 units collected from the mines on the laboratory ASMD to obtain sound level 

measurements. During this testing, the sound level measured for one SCSR unit exceeded 60 dB, the pass/fail 

limit for this test as established by CSE. This unit is not included in this study and is identified as failing visual 

inspection at NIOSH NPPTL in Table 6. Sound levels measured for most of the 31 remaining mine-deployed units 

using the laboratory ASMD were less than 30 dB (See Figure 9). Sound levels measured for all 32 in storage CSE 

SRLD SCSR units evaluated on the ASMD were also less than 30 dB (Figure 10). The laboratory ASMD was not

operational for sound level measurements for the first nine mine-deployed and in storage units tested. 

Figure 9. ASMD Sound Level Measurements – 

Supplemental LTR3 Testing of Mine-Deployed CSE SRLD SCSR Units

Figure 10. ASMD Sound Level Measurements – 

Supplemental LTR3 Testing of In Storage CSE SRLD SCSR Units

18

66

18181821181818231818251818181818

47

2327

18231825302421

40

18

27

18

Sound Level, decibels

1 2 3 4 5 6 7 8 9 1011121314151617181920212223242526272829303132

CSE SRLD Unit Test Number

ASMD Sound Level Measurements -

Supplemental LTR3 Testing of Mine-Deployed 

CSE SRLD SCSR Units

27

23

27

2123

181818181818

27

23

18181818

2324

18181818181818181818211818

Sound Level, decibels

1 2 3 4 5 6 7 8 9 1011121314151617181920212223242526272829303132

CSE SRLD Unit Number

ASMD Sound Level Measurements -

Supplemental LTR3 Testing of In Storage CSE 

SRLD SCSR Units
16

The breathing circuit integrity check of mine-deployed CSE SRLD SCSR units using the QNT leak test procedure 

showed that all had leak rates less than 500 ml/min. The breathing circuit integrity check of in storage CSE SRLD 

SCSR units also showed that all in storage units had leak rates less than 500 ml/min.

After test initiation on the ABMS, all mine-deployed and in storage CSE SRLD SCSR units continued operating 

until the breathing gas supply was expended. All mine-deployed and in storage SCSR units met or exceeded the 

NIOSH-approved 60-minute service time. The average duration for mine-deployed and in storage CSE SRLD SCSR

units was 69 and 68 minutes, respectively.

All CSE SRLD SCSR units tested provided acceptable inspired oxygen levels during the entire 60-minute service 

time. Inspired CO2 levels measured for three of the 40 mine-deployed SRLD SCSR units tested exceeded 4% 

prior to reaching the 60-minute NIOSH-approved service time (Table 7). As shown in Table 7, inspired CO2 levels 

measured for nine of the remaining 37 mine-deployed SCSR units tested exceeded 4% after the 60-minute 

service time was reached but prior to the expenditure of oxygen. These results are important to note because 

NIOSH has established a 4.0% inspired CO2 pass/fail limit for LTFE testing. However, continuous inspired CO2

measurements were not taken near the end of the 60-minute service time during approval testing of SCSR units 

under Subpart H. Therefore, the excursions in inspired CO2 measured during the latter portion of service time

and after the service time had been reached for these tests would not have been detected had they occurred. 

For most users, elevated inspired CO2 would most typically cause no more than an elevated ventilation rate, 

which would likely lead to elevated breathing resistance, both of which may cause the user to stop using the 

unit sooner than if the inspired CO2 remained low.

Table 7. CSE SRLD SCSR 4% Carbon Dioxide Breakthrough Times – Supplemental Testing

Inspired CO2 levels were compared to sound level measurements obtained from testing on the laboratory ASMD

for all mine-deployed units (Figure 11). As can be seen, the three highest 60-minute average inspired CO2 levels 

4% Inspired CO2 Test Duration, Mine-Deployed or Inspired CO2 Maximum Inspired CO2,

Breakthrough Time, minutes minutes In Storage at 60 minutes Volume %

54 72 Mine-Deployed 4.98 9.39

56 70 Mine-Deployed 5.04 9.43

57 71 Mine-Deployed 4.53 9.54

61 69 Mine-Deployed 4.03 6.19

66 73 Mine-Deployed 3.03 6.10

66 68 Mine-Deployed 2.92 4.88

66 72 In Storage 3.18 6.45

67 76 In Storage 3.20 7.51

67 73 In Storage 3.05 7.01

67 75 Mine-Deployed 3.09 8.33

68 72 Mine-Deployed 3.04 5.34

68 73 Mine-Deployed 2.65 6.80

68 70 In Storage 2.62 4.92

69 71 In Storage 3.91 5.05

69 70 In Storage 2.63 4.74

70 74 In Storage 2.81 5.82

70 72 Mine-Deployed 2.87 4.66

70 72 In Storage 2.31 5.29

72 73 Mine-Deployed 2.55 4.49

73 80 Mine-Deployed 2.12 9.56
17

were measured for the CSE SRLD SCSR units that had the three highest sound level measurements (≥30 dB). In 

addition, one-minute average inspired CO2 levels for these same three units exceeded 4.0% prior to reaching the 

60-minute service time. Sound level measurements for all remaining mine-deployed units and all in storage 

units were ≤27 dB.

Figure 11. 60-Minute Average Inspired CO2 Levels vs. ASMD Sound Level Measurements for

31 Mine-Deployed Units – Supplemental Testing

NIOSH NPPTL averaged the minute-average values of the stressors monitored during supplemental LTR3 BMS 

testing of CSE SRLD SCSR units over the first 60 minutes of each test and the results are presented graphically in 

Appendix C (Figures 21 through 26 for mine-deployed and Figures 27 through 32 for in storage units). NIOSH 

sorted the mine-deployed CSE SRLD SCSR unit stressor results within each composite graph by manufacturing 

dates which range in age from oldest to newest, left to right. In storage unit stressor value data points were 

plotted in the order in which each unit was tested. A linear regression is fit to each stressor plotted from testing 

of mine-deployed CSE SRLD SCSR units to draw out the effects of deployment time. No trends in the measured 

stressors attributable to deployment time were identified.

Test results from in storage unit testing were used to validate results from mine-deployed unit testing. SCSR test 

duration and composite mean stressor levels, including FIO2, FICO2, PEPRS CMH2O, PIPRS CMH2O, TAVGDB, 

and TAVGWB (average inspired wet bulb temperature,) are shown for the in storage and deployed CSE SRLD 

SCSR units in Table 8. The percent difference between deployed-unit mean stressor values and in storage unit 

mean stressor values, relative to deployed-unit mean stressor values, is shown in Table 8. As can be seen, all 

stressor differences are less than 2%.

1.00

1.20

1.40

1.60

1.80

2.00

2.20

2.40

2.60

2.80

0.00 10.00 20.00 30.00 40.00 50.00

Average Inspired CO2, Volume %

ASMD Sound Level Measurement, decibels

CSE SRLD 60-minute Average Inspired CO2 Levels vs. ASMD 

Sound Level Measurements for 31 Mine-Deployed Units
18

Table 8. CSE SRLD Duration and Composite Mean Stressor Levels – Supplemental Testing

SCSR test duration and composite mean stressor levels for supplemental and original LTR3 testing of minedeployed CSE SRLD SCSR units are shown in Table 9. The percent difference between supplemental LTR3 testing 

mean stressor values and original LTR3 testing mean stressor values of mine-deployed units, relative to 

supplemental LTR3 testing mean stressor values, is also shown. 

Table 9. Mine-Deployed CSE SRLD Duration and Composite Mean Stressor Levels – 

Supplemental vs. Original LTR3 Testing

Dräger Oxy K Plus/Plus S SCSR

Seventy-nine of the 140 Oxy K Plus/Oxy K Plus S SCSR units listed on the LTR3 targeted collection list were 

received at NIOSH NPPTL for testing. LTR3 methods called for the collection of 100 units, yielding a collection 

rate of 79%. Challenges affecting the collection of Dräger Oxy K Plus/Oxy K Plus S SCSR units included the closure 

of mines, leading to the unavailability of 25 SCSR units, and 26 units identified as missing. These two challenges 

resulted in 36.4% of Dräger Oxy K Plus/Oxy K Plus S SCSR units on the targeted collection list being unavailable. 

The remaining units were not collected for reasons listed as unfeasible to collect (6), failure of visual inspection 

at the mine (3), and out of service (1). The reasons for failure of the visual inspection included moisture indicator 

collar missing, metal lock clamp missing, and damage to the case.

All 79 Dräger Oxy K Plus/Oxy K Plus S SCSR units tested passed the manufacturer’s visual inspection at NIOSH 

NPPTL (Figure 12). Valid test data was obtained for 75 of the 79 Dräger Oxy K Plus/Oxy K Plus S SCSR units. The 

four invalid data sets were due to ABMS operational issues. None of the Dräger Oxy K Plus/Oxy K Plus S SCSR 

units returned to NIOSH NPPTL for testing failed the phenolphthalein indicator test.

DURATION FIO2 FICO2 PEPRS CMH2O PIPRS CMH2O TAVGDB TAVGWB

MIN 62 0.7346 0.0148 32.54 -75.42 40.56 32.56

MAX 80 0.8231 0.0265 58.57 -54.05 45.30 38.07

AVERAGE 69 0.7930 0.0185 46.64 -66.31 42.99 35.42

% Difference 0.9 -0.4 1.8 1.3 0.7 -0.4 -1.2

MIN 63 0.7648 0.0161 37.67 -74.14 41.45 33.74

MAX 76 0.8196 0.0205 55.39 -59.40 44.57 37.55

AVERAGE 68 0.7964 0.0181 46.06 -65.85 43.18 35.87

SRLD Mine-Deployed Unit Data - Supplemental Testing (40 tests)

SRLD NIOSH In Storage Unit Data (41 tests)

DURATION FIO2 FRAC FICO2 FRAC PEPRS CMH2O PIPRS CMH2O TAVGDB

MIN 62 0.7346 0.0148 32.54 -75.42 40.56

MAX 80 0.8231 0.0265 58.57 -54.05 45.30

AVERAGE 69.0 0.7930 0.0185 46.64 -66.31 42.99

% Difference 2.68 9.29 1.09 -12.45 0.11 2.31

MIN 59 0.6081 0.0114 41.53 -80.11 37.02

MAX 76 0.9243 0.0411 62.97 -53.33 45.73

AVERAGE 67.2 0.7256 0.0183 53.27 -66.24 42.02

SRLD Deployed Unit Data - Supplemental LTR3 Testing (40 tests)

SRLD Deployed Unit Data - Original LTR3 Testing (65 tests)
19

Photo by NPPTL 

Figure 12. Areas of Visual Inspection for Dräger Oxy K Plus

The breathing circuit integrity check of the Dräger Oxy K Plus using the QNT leak test procedure showed that 34

of 35 SCSR units had leak rates less than 500 ml/min. The breathing circuit integrity check of the Dräger Oxy K 

Plus S using the QNT leak test procedure showed that all 44 units had leak rates less than 500 ml/min.

After test initiation on the ABMS, all SCSRs continued operating until the breathing gas supply was expended. All 

SCSRs met or exceeded the NIOSH-approved 60-minute service time. The average duration for Dräger Oxy K Plus

and Dräger Oxy K Plus S SCSR units was 73.0 and 79.2 minutes, respectively. 

NIOSH NPPTL personnel averaged the minute-average values of the stressors monitored during BMS testing of 

the Dräger Oxy K Plus/Oxy K Plus S SCSR units over the first 60 minutes of the test and the results are presented 

graphically in Appendix D (Figures 33 through 38). The mine-deployed Dräger Oxy K Plus/Oxy K Plus S SCSR unit 

stressor results were sorted within each composite graph by manufacturing dates which ranged in age from 

oldest to newest, left to right. The stressor value data points for the Dräger Oxy K Plus S SCSR units in storage at 

NIOSH NPPTL are shown in red for comparison with the mine-deployed units. A linear regression is fit to each 

stressor plotted from Dräger Oxy K Plus/Oxy K Plus S SCSR unit testing to draw out the effects of deployment 

time. No trends in measured stressors attributable to deployment time were identified.

Test duration and composite mean stressor levels, including FIO2, FICO2, PEPRS CMH2O, PIPRS CMH2O, and 

TAVGDB, are shown for the in storage Dräger Oxy K Plus S and mine-deployed Dräger Oxy K Plus/Oxy K Plus S

SCSRs in Table 10. The percent difference between mine-deployed unit mean stressor values versus in storage 

unit mean stressor values, relative to deployed unit mean stressor values, is also shown in Table 10. 
20

Table 10. Dräger Oxy K Plus Duration and Composite Mean Stressor Levels

Ocenco EBA 6.5 SCSR

Of the 140 EBA 6.5 SCSR units listed on the LTR3 targeted collection list, 70 were returned to NIOSH NPPTL for 

testing. LTR3 collection methods called for the collection of 100 units, yielding a collection rate of 70%. 

Challenges affecting the collection of Ocenco EBA 6.5 SCSR units included the closure of mines, leading to the 

unavailability of eight SCSRs, and 54 missing or unavailable units. These two challenges resulted in 44.3% of 

Ocenco EBA 6.5 SCSR units on the targeted collection list being unavailable. The remaining units were not 

returned for reasons listed as unfeasible to collect (5), failure of visual inspection at the mine (2), and out for 

service (1). The reasons for failure of the visual inspection included a crimped hose and damage to the case.

All but one of the 70 Ocenco EBA 6.5 SCSR units returned for testing passed the manufacturer’s visual inspection 

at NIOSH NPPTL. The one failure was due to the presence of a large crack on the back of the case. This means 

that 98.6% of the EBA 6.5 SCSR units that passed the manufacturer’s recommended visual inspection at the 

mine also passed visual inspection at NIOSH NPPTL. Valid test data was obtained for the 69 Ocenco EBA 6.5 SCSR

units that were tested. None of the Ocenco EBA 6.5 SCSR units returned to NIOSH NPPTL for testing failed the 

phenolphthalein indicator test. 

The breathing circuit integrity check of the Ocenco EBA 6.5 using the QNT procedure showed that 54 of 69 SCSR 

units had leak rates of less than 500 ml/min. The units with high leak rates were rechecked and leakage at the 

juncture of the plastic valve frame and the mouthpiece (Figure 13) was identified as the cause. This was 

discovered by pressing the junction (where the wire tie is connected) of the check valve frame and observing a 

reduction in the leak rate. Sealing the hoses below the collar confirmed the location of the leak as no reduction 

in leak rate was observed when this action was performed.

DURATION FIO2 FICO2 PEPRS CMH2O PIPRS CMH2O TAVGDB

MIN 67 0.7723 0.0073 31.43 -49.82 34.69

MAX 87 0.8804 0.0144 48.54 -40.78 40.16

AVERAGE 73.0 0.8189 0.0127 35.53 -45.70 37.35

% Difference 2.56 -2.54 -9.13 4.98 7.08 5.86

MIN 68 0.6986 0.0092 25.99 -94.66 30.94

MAX 92 0.8465 0.0157 48.79 -40.85 40.67

AVERAGE 79.2 0.7993 0.0119 36.17 -45.81 35.54

% Difference 10.25 -5.05 -16.37 6.68 7.32 1.09

MIN 70 0.8192 0.0127 30.96 -44.40 33.83

MAX 73 0.8689 0.0166 37.71 -41.10 36.11

AVERAGE 71.1 0.8397 0.0138 33.76 -42.46 35.16

Oxy K Plus Deployed Unit Data (34 tests)

Oxy K Plus S NIOSH In Storage Unit Data (8 tests)

Oxy K Plus S Deployed Unit Data (41 tests)
21

Photo by NPPTL

Figure 13. Ocenco EBA 6.5 Junction of Check Valves at Mouthpiece

After test initiation on the ABMS, all SCSR units continued operating until the breathing gas supply was 

expended. All SCSR units met or exceeded their NIOSH-approved 60-minute service time with no critical failures. 

The average duration for all Ocenco EBA 6.5 SCSRs was 99 minutes.

All Ocenco EBA 6.5 SCSR units were subsequently evaluated for minimum sustained oxygen flow rate. The flow 

rates ranged from 1.67 to 2.0 liters per minute at ambient temperature and pressure.

NIOSH NPPTL averaged the minute-average values of the stressors monitored during BMS testing of the Ocenco 

EBA 6.5 SCSRs over the first 60 minutes of the test and the results are presented graphically in Appendix E 

(Figures 39 through 44). NIOSH sorted the mine-deployed Ocenco EBA 6.5 SCSR unit stressor results within each 

composite graph by manufacturing dates which range in age from oldest to newest, left to right. The stressor 

value data points for Ocenco EBA 6.5 SCSR units in storage at NPPTL are shown in red for comparison with the 

deployed units. A linear regression is fit to each stressor plotted from SCSR testing to draw out the effects of 

deployment time. As can be seen in Figures 43 and 44, breathing resistance increased as a function of 

deployment time for the Ocenco EBA 6.5 SCSR.

Test duration and composite average stressor levels, including FIO2, FICO2, PEPRS CMH2O, PIPRS CMH2O, and 

TAVGDB, are shown for the in storage and mine-deployed Ocenco EBA 6.5 SCSR units in Table 11. The percent 

difference between mine-deployed unit mean stressor values versus in storage unit mean stressor values, 

relative to deployed unit mean stressor values, is also shown in Table 11. 

Table 11. Ocenco EBA 6.5 Duration and Composite Mean Stressor Levels

DURATION FIO2 FICO2 PEPRS CMH2O PIPRS CMH2O TAVGDB

MIN 83 0.3245 0.0007 32.32 -113.10 32.59

MAX 107 0.9475 0.0070 98.73 -38.03 42.34

AVERAGE 99.3 0.7168 0.0028 47.16 -49.71 38.90

% Difference 3.40 27.29 2.59 1.41 8.71 -0.69

MIN 98 0.5171 0.0025 40.00 -54.60 37.90

MAX 108 0.6205 0.0032 59.04 -40.33 40.38

AVERAGE 102.8 0.5631 0.0027 46.51 -45.73 39.17

EBA 6.5 Deployed Unit Data (69 tests)

EBA 6.5 NIOSH In Storage Unit Data (9 tests)
22

Photo by NPPTL 

Figure 14. Ocenco M-20 Security Latch

Ocenco M-20 SCSR

Eighty-six of the 200 Ocenco M-20 SCSR units listed on the LTR3 targeted collection list were returned to NIOSH 

NPPTL. LTR3 methods called for the collection of 100 units, yielding a collection rate of 86%. The main challenge 

affecting the collection of Ocenco M-20 SCSR units was the identification of 77 units as missing. This challenge 

resulted in 38.5% of Ocenco M-20 SCSR units on the targeted collection not being available for testing. The 

remaining units not returned for testing included reasons listed as out of service (13), mine closures (12), 

unavailable (9), and security latch missing (3). The security latch for the Ocenco M-20 is shown in Figure 14. 

 

All but eight of the 86 Ocenco M-20 SCSR units returned for testing passed the manufacturer’s recommended 

visual inspection at NIOSH NPPTL. Six visual inspection failures were due to the presence of mine dust inside the 

case, on the outside of the unit and mouthpiece. Two other visual inspection failures were due to white powder 

at the breathing bag entrance and in the bag, respectively. This means that 91% of the Ocenco M-20 SCSR units 

that passed the manufacturer’s visual inspection at the mine also passed visual inspection at NIOSH NPPTL. Valid 

test data was obtained for 77 of the 78 Ocenco M-20 SCSRs tested. One data set was deemed invalid after it was 

determined that the unit tested was new and just out of the box. One of the Ocenco M-20 SCSR units returned 

to NIOSH NPPTL for testing failed the phenolphthalein indicator test. This wasn’t surprising given the discovery 

of white powder and mine dust within the breathing bag and in the case, respectively, for several units. This 

unit subsequently continued in the circuit of tests and all stressors were measured within normal limits. 

The breathing circuit integrity check of the Ocenco M-20 SCSR units using the QNT procedure showed that 50 of 

78 SCSR units tested had a leak rate less than 100 ml/min, and 72 of 78 SCSR units tested had a leak rate of less 

than 500 ml/min.

After test initiation on the ABMS, all but one Ocenco M-20 SCSR continued operating until the breathing gas 

supply was exhausted. Testing of this one unit was stopped after 14 minutes because the breathing bag was 

empty and the percent inspired O2 level had decreased to less than 7.0%. All M-20 SCSR units exceeded the 

NIOSH-approved 10-minute service time. The average duration for all Ocenco M-20 SCSR units was 16 minutes.
23

While all 77 SCSR units provided acceptable inspired CO2 levels for the NIOSH-approved service time of 10

minutes, 12 of the 77 M-20 SCSR units exceeded 4% CO2 prior to oxygen expenditure (Table 12). However, none 

of the 12 exceeded 4% CO2 before the 10-minute service time was reached.

Table 12. Ocenco M-20 SCSR 4% Carbon Dioxide Breakthrough Times

4% CO2 Breakthrough Test Maximum CO2,

Time, minutes Duration, minutes Volume %

12 14 4.87

15 17 5.64

15 18 6.3

16 18 4.88

16 18 5.48

16 16 4.26

16 19 7.3

17 18 5.47

18 19 5.8

18 18 4.44

19 19 4.38

19 20 4.8

NIOSH averaged the minute-average values of the stressors monitored during BMS testing of the Ocenco M-20 

SCSR units over the first 10 minutes of the test. The results appear graphically in Appendix F (Figures 45 through 

50). Ten-minute data averaging, consistent with service time, was chosen to eliminate the test duration 

variability effect in the determination of stressor levels. NIOSH NPPTL sorted the mine-deployed Ocenco M-20 

SCSR unit stressor results within each composite graph by manufacturing dates which range in age from oldest 

to newest, left to right. Stressor value data points for Ocenco M-20 SCSR units in storage at NIOSH NPPTL are 

shown in red for comparison with the mine-deployed units. A linear regression is fit to each stressor plotted 

from Ocenco M-20 SCSR testing to draw out the effects of deployment time. No major trends in measured 

stressors that could be attributed to deployment time are identified. An increase in inspired breathing resistance 

as a function of increased deployment time is suggested in Figure 49.

Test duration and composite average mean stressor levels, including FIO2, FICO2, PEPRS, PIPRS, and TAVGDB, 

are shown for the in storage and mine-deployed Ocenco M-20 SCSR units in Table 13. The percent difference 

between mine-deployed unit mean stressor values versus in storage unit stressor mean values, relative to minedeployed unit mean stressor values, is also shown in Table 13. 
24

Table 13. Ocenco M-20 Duration and Composite Mean Stressor Levels

Conclusion

Mine Operators

All 326 SCSR units for which valid test data was obtained (286 original and 40 supplemental) demonstrated the 

expected life support capacity over the course of the manufacturers’ specified service time. Breathing 

resistances measured for all SCSRs tested were well within limits accepted as tolerable (-300 to +200 mm H2O) 

based on research conducted at Noll Laboratory at Penn State University. As 7.5% of the SCSR units collected at 

the mines did not meet the visual inspections, miners should continue to inspect their units daily to ensure 

those not meeting visual inspection requirements are removed from the mines. Overall, very little degradation 

in SCSR performance due to deployment time in the mines was observed.

Manufacturers

Significant differences observed in measured stressor levels between deployed units and stored units may be

due to the smaller sample of stored units tested. During supplemental LTR3 testing of CSE SRLD SCSR units, one 

stored unit was tested for each of 40 deployed units tested and very minor differences (<1.8%) in all measured 

stressor levels were observed. This observation provides some support for the need to perform more frequent 

stored unit testing. Future LTFE evaluations will incorporate additional contemporaneous testing of stored units 

to validate deployed unit test results. The frequency of in storage unit testing is to be determined. 

During 65 original LTR3 tests, inspired CO2 levels for six mine-deployed CSE SRLD SCSR units exceeded 4.0% prior 

to the 60-minute service time being reached. During 40 supplemental tests, inspired CO2 levels for three 

additional mine-deployed CSE SRLD SCSR units exceeded 4.0% prior to reaching the 60-minute service time. 

Thus, supplemental test results corroborated these original results at the same rate of occurrence (7.5%). 

Twenty-nine of the last 32 mine-deployed CSE SRLD SCSR units and 32 of the last in storage CSE SRLD SCSR units 

tested during supplemental LTR3 testing had quantitative sound level measurements ≤27 dB. Inspired CO2 levels 

measured for these 53 tests ranged from 1.48% to 2.05%. Inspired CO2 levels for the three remaining minedeployed CSE SRLD SCSR units with the three highest quantitative sound level measurements were >2.45%. This 

suggests direct correlation between quantitative sound level measurements and inspired CO2 levels for these 

units. It is further observed that a reduction in the current pass/fail level (cited as 60 dB by CSE), while 

eliminating more units capable of keeping CO2 concentrations in the desired range, has at least the potential to 

eliminate units likely to yield CO2 concentrations above that range. 

DURATION FIO2 FICO2 PEPRS CMH2O PIPRS CMH2O TAVGDB

MIN 11 0.2352 0.0022 23.57 -82.73 34.84

MAX 20 0.8080 0.0159 57.05 -40.37 44.38

AVERAGE 16.2 0.4977 0.0062 31.11 -54.39 38.92

% Difference 17.90 9.65 -4.49 12.62 1.37 -3.89

MIN 18 0.3893 0.0052 16.33 -64.14 39.34

MAX 20 0.5053 0.0078 31.93 -44.30 41.49

AVERAGE 19.0 0.4538 0.0065 27.62 -53.66 40.49

M-20 Deployed Unit Data (77 tests)

M-20 NIOSH In Storage Unit Data (8 tests)
25

Consistent operation of the ABMS and simulation of the manufacturer’s start-up procedure for the SCSR being 

tested is critical in obtaining valid and consistent test data for future LTFE studies. NIOSH NPPTL has prepared 

detailed work instructions for these test processes which will be reviewed and updated as necessary. Training of 

ABMS test operators in these work instructions will be performed on a regular basis to assure the ABMS is 

consistently operated per these procedures.

There are numerous challenges associated with collecting a statistically valid sample of units, testing those units, 

and reporting on the results in a timely manner. Consequently, NIOSH NPPTL has initiated an effort to explore

alternative collection and reporting strategies with the objectives of positively impacting mine operator and user 

safety and influencing manufacturer technology improvements. 
26

Appendix A: Acronyms and Abbreviations 

Acronyms and Abbreviations

ABMS

BMS 

CFR 

CO

CO2 

CPIP

dB

FICO2

FIO2

LTFE

LTR

MSHA

N2

NIOSH

NPPTL

O2

OSHA

QNT

PEPRS CMH20

PIPRS CMH20

SCSR

TAVGDB

TAVGWB

TLV

VCO2 

VO2

automated breathing and metabolic simulator

breathing and metabolic simulation

code of federal regulations 

carbon monoxide

carbon dioxide

certified product investigation process

decibels

mole fraction inspired carbon dioxide

mole fraction inspired oxygen

long-term field evaluation

long-term random field evaluation

Mine Safety and Health Administration

Nitrogen

National Institute for Occupational Safety and Health 

National Personal Protective Technology Laboratory

oxygen

Occupational Safety and Health Administration

quantitative leak test

peak expired pressure, centimeters of water column

peak inspired pressure, centimeters of water column

self-contained self-rescuer

average dry bulb temperature over inspired breath, o

C 

average wet bulb temperature over inspired breath, o

C 

threshold limit value

volume of carbon dioxide

volume of oxygen
27

Unit of Measure Abbreviations

breaths/min

kg

L 

L/breath

lb

LPM

mL/min

mm

mm H2O 

% 

ppm

breaths per minute

kilogram(s)

liter(s)

liter(s) per breath

pound(s)

liter(s) per minute

milliliter(s) per minute

millimeter(s)

millimeter(s) of water pressure

percent

parts per million
28

Appendix B: BMS Testing of the CSE SRLD SCSRs Stressors 

Figure 15. Duration of Deployed and New CSE SRLD Self-Contained Self-Rescuers

Figure 16. 60-Minute Average Percent Inspired Carbon Dioxide of Deployed and New CSE SRLD 

Self-Contained Self-Rescuers

y = 0.0115x - 402.68

55

60

65

70

75

80

9/14/2011 12/3/2011 2/21/2012 5/11/2012 7/30/2012 10/18/2012

Duration, minutes

Manufacturing Date

Duration of CSE SRLD SCSR

y = -0.0001x + 7.1059

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

9/14/2011 12/3/2011 2/21/2012 5/11/2012 7/30/2012 10/18/2012

Average Inspired CO2, Volume %

Manufacturing Date

Average % Inspired CO2 of CSE SRLD SCSR
29

Figure 17. 60-Minute Average Percent Inspired Oxygen of Deployed and New CSE SRLD

Self-Contained Self-Rescuers

Figure 18. 60-Minute Average Dry-Bulb Temperatures of Deployed and New CSE SRLD

Self-Contained Self-Rescuers

y = -7E-05x + 75.399

0

10

20

30

40

50

60

70

80

90

100

9/14/2011 12/3/2011 2/21/2012 5/11/2012 7/30/2012 10/18/2012

Average Inspired O2, Volume %

Manufacturing Date

Average % Inspired O2 of CSE SRLD SCSR

y = 0.0019x - 37.062

20

25

30

35

40

45

50

Average Dry Bulb Temperatures, 

9/14/2011 12/3/2011 2/21/2012 5/11/2012 7/30/2012 10/18/2012

oC

Manufacturing Date

Average Dry Bulb Temperatures of CSE SRLD SCSR

Dry Bulb Temperature New DB Temperature
30

Figure 19. 60-Minute Average Peak Inspired Pressure of Deployed and New CSE SRLD Self-Contained 

Self-Rescuers

Figure 20. 60-Minute Average Peak Expired Pressure of Deployed and New CSE SRLD Self-Contained 

Self-Rescuers

y = 0.0039x - 226.96

-120

-100

-80

-60

-40

-20

0

Average Peak Inspired Pressure, mm H

9/14/2011 12/3/2011 2/21/2012 5/11/2012 7/30/2012 10/18/2012

2O

Manufacturing Date

Average Peak Inspired Pressure of CSE SRLD SCSR

y = 0.0066x - 219.91

0

20

40

60

80

100

120

9/14/2011 12/3/2011 2/21/2012 5/11/2012 7/30/2012 10/18/2012

Average Peak Expired Pressure, mm 

H2O

Manufacturing Date

Average Peak Expired Pressure of CSE SRLD SCSR
31

Appendix C: BMS Testing of the CSE SRLD SCSRs Stressors – 

Supplemental LTR3 Testing 

Figure 21. Duration of Deployed CSE SRLD Self-Contained Self-Rescuers – Supplemental LTR3 Testing

Figure 22. 60-Minute Average Percent Inspired Carbon Dioxide of Deployed CSE SRLD Self-Contained 

Self-Rescuers – Supplemental LTR3 Testing

y = 0.0033x - 68.428

55.00

60.00

65.00

70.00

75.00

80.00

85.00

90.00

95.00

100.00

7/10/2012 1/26/2013 8/14/2013 3/2/2014 9/18/2014 4/6/2015 10/23/2015 5/10/2016 11/26/2016

Duration, minutes

Manufacturing Date

Duration of Mine-Deployed CSE SRLD SCSR - Supplemental LTR3 

Testing

y = 0.0001x - 2.77

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

7/10/2012 1/26/2013 8/14/2013 3/2/2014 9/18/2014 4/6/2015 10/23/2015 5/10/2016 11/26/2016

Average Inspired CO2, Volume %

Manufacturing Date

Average % Inspired CO2 of Mine-Deployed CSE SRLD SCSR -

Supplemental LTR3 Testing
32

Figure 23. 60-Minute Average Percent Inspired Oxygen of Deployed CSE SRLD Self-Contained 

Self-Rescuers – Supplemental LTR3 Testing

Figure 24. 60-Minute Average Dry/Wet-Bulb Temperatures of Deployed CSE SRLD Self-Contained 

Self-Rescuers – Supplemental LTR3 Testing

y = 0.0008x + 45.711

0

10

20

30

40

50

60

70

80

90

100

7/10/2012 1/26/2013 8/14/2013 3/2/2014 9/18/2014 4/6/2015 10/23/2015 5/10/2016 11/26/2016

Average Inspired O2, Volume %

Manufacturing Date

Average % Inspired O2 of Mine-Deployed CSE SRLD SCSR -

Supplemental LTR3 Testing

y = 0.0004x + 26.001

y = -0.0005x + 56.032

20

25

30

35

40

45

50

7/10/2012 1/26/2013 8/14/2013 3/2/2014 9/18/2014 4/6/2015 10/23/2015 5/10/2016 11/26/2016

Average Dry/Wet Bulb Temperatures, oC

Manufacturing Date

Average Inspired Dry/Wet Bulb Temperatures of MIneDeployed CSE SRLD SCSR - Supplemental LTR3 Testing

Dry Bulb Temperature Wet Bulb Temperature

Linear (Dry Bulb Temperature) Linear (Wet Bulb Temperature)
33

Figure 25. 60-Minute Average Peak Inspired Pressure of Deployed CSE SRLD Self-Contained 

Self-Rescuers – Supplemental LTR3 Testing

Figure 26. 60-Minute Average Peak Expired Pressure of Deployed SRLD Self-Contained Self-Rescuers 

– Supplemental LTR3 Testing

y = -0.0023x + 30.287

-120

-100

-80

-60

-40

-20

0

7/10/2012 1/26/2013 8/14/2013 3/2/2014 9/18/2014 4/6/2015 10/23/2015 5/10/2016 11/26/2016

Average Peak Inspired Pressure, mm 

H2O

Manufacturing Date

Average Peak Inspired Pressure of Mine-Deployed CSE SRLD 

SCSR - Supplemental LTR3 Testing

y = -0.002x + 129.26

0

20

40

60

80

100

120

Average Peak Expired Pressure, mm H

7/10/2012 1/26/2013 8/14/2013 3/2/2014 9/18/2014 4/6/2015 10/23/2015 5/10/2016 11/26/2016

2O

Manufacturing Date

Average Peak Expired Pressure of Mine-Deployed CSE SRLD 

SCSR - Supplemental LTR3 Testing
34

Figure 27. Duration of In Storage CSE SRLD Self-Contained Self-Rescuers – Supplemental LTR3 Testing

Figure 28. 60-Minute Average Percent Inspired Carbon Dioxide of In Storage CSE SRLD Self-Contained 

Self-Rescuers – Supplemental LTR3 Testing

y = 0.0496x + 66.986 55.00

60.00

65.00

70.00

75.00

80.00

85.00

90.00

95.00

100.00

0 1 2 3 4 5 6 7 8 9 101112131415161718192021222324252627282930313233343536373839404142

Duration, minutes

Test Number

Duration of In Storage CSE SRLD SCSR - Supplemental LTR3 

Testing

y = 0.0009x + 1.794

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0 1 2 3 4 5 6 7 8 9 101112131415161718192021222324252627282930313233343536373839404142

Average Inspired CO2, Volume %

Test Number

Average % Inspired CO2 of In Storage CSE SRLD SCSR -

Supplemental LTR3 Testing
35

Figure 29. 60-Minute Average Percent Inspired Oxygen of In Storage CSE SRLD Self-Contained

Self-Rescuers – Supplemental LTR3 Testing

Figure 30. 60-Minute Average Dry/Wet-Bulb Temperatures of In Storage CSE SRLD Self-Contained 

Self-Rescuers – Supplemental LTR3 Testing

y = 0.0261x + 79.094

0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5 6 7 8 9 101112131415161718192021222324252627282930313233343536373839404142

Average Inspired O2, Volume %

Test Number

Average % Inspired O2 of In Storage CSE SRLD SCSR - Supplemental 

LTR3 Testing

20

25

30

35

40

45

50

55

0 1 2 3 4 5 6 7 8 9 101112131415161718192021222324252627282930313233343536373839404142

Average Dry/Wet Bulb Temperatures, oC

Test Number

Average Inspired Dry/Wet Bulb Temperatures of In Storage CSE 

SRLD SCSR - Supplemental LTR3 Testing

Dry Bulb Temperature Wet Bulb Temperature
36

Figure 31. 60-Minute Average Peak Inspired Pressure of In Storage CSE SRLD Self-Contained 

Self-Rescuers – Supplemental LTR3 Testing

Figure 32. 60-Minute Average Peak Expired Pressure of In Storage SRLD Self-Contained Self-Rescuers 

– Supplemental LTR3 Testing

-120

-100

-80

-60

-40

-20

0

Average Peak Inspired Pressure, mm H

0 1 2 3 4 5 6 7 8 9 101112131415161718192021222324252627282930313233343536373839404142

2O

Test Number

Average Peak Inspired Pressure of In Storage CSE SRLD SCSR -

Supplemental LTR3 Testing

0

20

40

60

80

100

120

0 1 2 3 4 5 6 7 8 9 101112131415161718192021222324252627282930313233343536373839404142

Average Peak Expired Pressure, mm H2O

Test Number

Average Peak Expired Pressure of In Storage CSE SRLD SCSR -

Supplemental LTR3 Testing
37

Appendix D: BMS Testing of the Dräger Oxy K Plus SCSRs Stressors

Figure 33. Duration of Field Deployed and New Dräger Oxy K Plus Self-Contained Self-Rescuers

Figure 34. 60-Minute Average Percent Inspired Carbon Dioxide of Field Deployed and New Dräger 

Oxy K Plus Self-Contained Self-Rescuers

y = -0.0026x + 180.65

55

60

65

70

75

80

85

90

95

9/5/2005 10/10/2006 11/14/2007 12/18/2008 1/22/2010 2/26/2011 4/1/2012

Duration, minutes

Manufacturing Date

Duration of Dräger Oxy K Plus SCSR - LTR3

y = 8E-05x - 1.8323

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

9/5/2005 10/10/2006 11/14/2007 12/18/2008 1/22/2010 2/26/2011 4/1/2012

Average Inspired CO2, Volume %

Manufacturing Date

Average % Inspired CO2 of Dräger Oxy K Plus SCSR - LTR3
38

Figure 35. 60-Minute Average Percent Inspired Oxygen of Field Deployed and New Dräger Oxy K 

Plus Self-Contained Self-Rescuers

Figure 36. 60-Minute Average Dry-Bulb Temperatures of Field Deployed and New Dräger Oxy K Plus 

Self-Contained Self-Rescuers

y = 0.0003x + 70.565

0

10

20

30

40

50

60

70

80

90

100

9/5/2005 10/10/2006 11/14/2007 12/18/2008 1/22/2010 2/26/2011 4/1/2012

Average Inspired O2, Volume %

Manufacturing Date

Average % Inspired O2 of Dräger Oxy K Plus SCSR - LTR3

y = 0.0001x + 32.246

20

25

30

35

40

45

50

9/5/2005 10/10/2006 11/14/2007 12/18/2008 1/22/2010 2/26/2011 4/1/2012

Average Dry Bulb Temperatures, oC

Manufacturing Date

Average Dry-Bulb Temperatures of Dräger Oxy K Plus SCSR -

LTR3

Dry Bulb Temperature New DB Temperature
39

Figure 37. 60-Minute Average Peak Inspired Pressure of Field Deployed and New Dräger Oxy K Plus 

Self-Contained Self-Rescuers

Figure 38. 60-Minute Average Peak Expired Pressure of Field Deployed and New Dräger Oxy K Plus 

Self-Contained Self-Rescuers

y = 0.0014x - 101.29

-120

-100

-80

-60

-40

-20

0

9/5/2005 10/10/2006 11/14/2007 12/18/2008 1/22/2010 2/26/2011 4/1/2012

Average Peak Inspired Pressure, mm H

O2

Manufacturing Date

Average Peak Inspired Pressure of Dräger Oxy K Plus SCSR -

LTR3

y = 0.0021x - 48.957

0

20

40

60

80

100

120

9/5/2005 10/10/2006 11/14/2007 12/18/2008 1/22/2010 2/26/2011 4/1/2012

Average Peak Expired Pressure, mm H

O2

Manufacturing Date

Average Peak Expired Pressure of Dräger Oxy K Plus SCSR -

LTR3
40

Appendix E: BMS Testing of the Ocenco EBA 6.5 SCSRs Stressors 

Figure 39. Duration of Field Deployed and New Ocenco EBA 6.5 Self-Contained Self-Rescuers

Figure 40. 60-Minute Average Percent Inspired Carbon Dioxide of Field Deployed and New Ocenco 

EBA 6.5 Self-Contained Self-Rescuers

y = -0.0006x + 121.96

55

65

75

85

95

105

115

10/6/2003 5/28/2005 1/18/2007 9/9/2008 5/2/2010 12/23/2011 8/14/2013

Duration, minutes

Manufacturing Date

Duration of Ocenco EBA 6.5 SCSR - LTR3

y = -1E-05x + 0.8174

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

10/6/2003 5/28/2005 1/18/2007 9/9/2008 5/2/2010 12/23/2011 8/14/2013

Average Inspired CO2, Volume %

Manufacturing Date

Average % Inspired CO2 of Ocenco EBA 6.5 SCSR - LTR3
41

Figure 41. 60-Minute Average Percent Inspired Oxygen of Field Deployed and New Ocenco EBA 6.5 

Self-Contained Self-Rescuers

Figure 42. 60-Minute Average Dry-Bulb Temperatures of Field Deployed and New Ocenco EBA 6.5 

Self-Contained Self-Rescuers

y = -0.0043x + 243.59

0

10

20

30

40

50

60

70

80

90

100

10/6/2003 5/28/2005 1/18/2007 9/9/2008 5/2/2010 12/23/2011 8/14/2013

Average Inspired O2, Volume %

Manufacturing Date

Average % Inspired O2 of Ocenco EBA 6.5 SCSR - LTR3

y = -0.0006x + 63.407

30

32

34

36

38

40

42

44

10/6/2003 5/28/2005 1/18/2007 9/9/2008 5/2/2010 12/23/2011 8/14/2013

Average Dry Bulb Temperatures, oC

Manufacturing Date

Average Dry-Bulb Temperatures of Ocenco EBA 6.5 SCSR -

LTR3

Dry Bulb Temperature New DB Temperature
42

Figure 43. 60-Minute Average Peak Inspired Pressure of Field Deployed and New Ocenco EBA 6.5 

Self-Contained Self-Rescuers

Figure 44. 60-Minute Average Peak Expired Pressure of Field Deployed and New Ocenco EBA 6.5 

Self-Contained Self-Rescuers

y = 0.0056x - 270.52

-120

-100

-80

-60

-40

-20

0

Average Peak Inspired Pressure, mm H

10/6/2003 5/28/2005 1/18/2007 9/9/2008 5/2/2010 12/23/2011 8/14/2013

O2

Manufacturing Date

Average Peak Insprired Pressure of Ocenco EBA 6.5 SCSR -

LTR3

y = -0.0044x + 219.76

0

20

40

60

80

100

120

Average Peak Expired Pressure, mm H

10/6/2003 5/28/2005 1/18/2007 9/9/2008 5/2/2010 12/23/2011 8/14/2013

O2

Manufacturing Date

Average Peak Expired Pressure of Ocenco EBA 6.5 SCSR -

LTR3
43

Appendix F: BMS Testing of the Ocenco M-20 SCSRs Stressors

Figure 45. Duration of Field Deployed and New Ocenco M-20 Self-Contained Self-Rescuers

Figure 46. 10-Minute Average Percent Inspired Carbon Dioxide of Field Deployed and New Ocenco 

M-20 Self-Contained Self-Rescuers

y = 0.0008x - 15.737

0

5

10

15

20

25

7/2/2006 6/17/2007 6/1/2008 5/17/2009 5/2/2010 4/17/2011 4/1/2012 3/17/2013

Duration, minutes

Manufacturing Date

Duration of Ocenco M-20 SCSR - LTR3

y = 6E-05x - 1.9635

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

7/2/2006 6/17/2007 6/1/2008 5/17/2009 5/2/2010 4/17/2011 4/1/2012 3/17/2013

Average Inspired CO2, Volume %

Manufacturing Date

Average % Inspired CO2 of Ocenco M-20 SCSR - LTR3
44

Figure 47. 10-Minute Average Percent Inspired Oxygen of Field Deployed and New Ocenco M-20 

Self-Contained Self-Rescuers

Figure 48. 10-Minute Average Dry-Bulb Temperatures of Field Deployed and New Ocenco M-20 

Self-Contained Self-Rescuers

y = -0.0021x + 136.32

0

10

20

30

40

50

60

70

80

90

100

7/2/2006 6/17/2007 6/1/2008 5/17/2009 5/2/2010 4/17/2011 4/1/2012 3/17/2013

Average Inspired O2, Volume %

Manufacturing Date

Average % Inspired O2 of Ocenco M-20 SCSR - LTR3

y = 0.0004x + 23.271

25

30

35

40

45

50

7/2/2006 6/17/2007 6/1/2008 5/17/2009 5/2/2010 4/17/2011 4/1/2012 3/17/2013

Average Dry Bulb Temperatures, oC

Manufacturing Date

Average Dry-Bulb Temperatures of Ocenco M-20 SCSR - LTR3

Dry Bulb Temperature New DB Temperature
45

Figure 49. 10-Minute Average Peak Inspired Pressure of Field Deployed and New Ocenco M-20 

Self-Contained Self-Rescuers

Figure 50. 10-Minute Average Peak Expired Pressure of Field Deployed and New Ocenco M-20 

Self-Contained Self-Rescuers

y = 0.0028x - 166.18

-120

-100

-80

-60

-40

-20

0

7/2/2006 6/17/2007 6/1/2008 5/17/2009 5/2/2010 4/17/2011 4/1/2012 3/17/2013

Average Peak Inspired Pressure, mm H

O2

Manufacturing Date

Average Peak Inspired Pressure of Ocenco M-20 SCSR - LTR3

y = -0.0006x + 57.222

0

20

40

60

80

100

120

7/2/2006 6/17/2007 6/1/2008 5/17/2009 5/2/2010 4/17/2011 4/1/2012 3/17/2013

Average Peak Expired Pressure, mm H

O2

Manufacturing Date

Average Peak Expired Pressure of Ocenco M-20SCSR - LTR3
46

Acknowledgements

Thanks are extended to the Mine Safety and Health Administration, The United Mine Workers of America, Mine 

Operators, Manufacturers, Mine Workers, and NIOSH NPPTL personnel that supported and continue to support 

the long-term field evaluation of SCSRs in U.S. underground coal mines. The authors gratefully acknowledge 

Courtney Neiderhiser2

, Nicholas Kyriazi2, and John P. Shubilla2 for their contributions on the Long-Term Field 

Evaluation Project that include developing the sampling strategy, arranging the collection from the various 

mines, and testing of SCSRs.

References

Ahlers, H. (2010, February 26). NIOSH Respirator User Notices. Retrieved December 19, 2013, from National 

Personal Protective Technology Laboratory: 

http://www.cdc.gov/niosh/npptl/usernotices/pdfs/CSEUserNotice02262010V4.pdf.

Ahlers, H. (2012, April 26). National Personal Protective Technology Laboratory. Retrieved December 19, 2013, 

from Respirators User Notice: 

http://www.cdc.gov/niosh/npptl/usernotices/notices/notice04262012.html. 

Berry Ann, R. (2013, December 23). NIOSH Respirator User Notice. Retrieved January 14, 2014, from The

National Personal Protective Technologies Laboratory: 

http://www.cdc.gov/niosh/npptl/usernotices/notices/notice12232013.html.

Electronic Code of Federal Regulations. (2014, August 27). Retrieved from U.S. Government Printing Office: 

http://www.ecfr.gov/cgi-bin/ECFR?page=browse. 

Fowler, B., Paul, M., Porlier, G., Elcombe, D., & Taylor, M. (1985; 28(5)). A reevaluation of the minimum altitude 

at which hypoxic performance decrements can be detected. Ergonomics, 781-791.

Hodgson, J. (1993). Physiological Costs and Consequences of Mine Escape and Rescue. University Park, PA: The 

Pennsylvania State University, Contract J0145038 and J0345327.

Kamon, E. D. (1984). Physiological Responses of Miners to Emergency. Vol. 1-Self-contained breathing apparatus 

stressors. University Park, PA: The Pennsylvania State University. U.S. Bureau of Mines contract No. 

J0100092.

Walbert, G. and Monaghan, W. (2018). Paragraph 3, Page 6; Point-of-Use Assessment for Self-Contained SelfRescuers Randomly Sampled from Mining Districts: Second Phase; Sample Period: January 2012 to June 

2013

 

2 Formerly of NIOSH, National Personal Protective Technology Laboratory
47

For more information related to personal protective equipment, visit the NIOSH website

https://www.cdc.gov/niosh/npptl

To receive documents or other information about occupational safety and health topics, contact NIOSH:

Telephone: 1–800–CDC–INFO (1–800–232–4636)

TTY: 1–888–232–6348

CDC INFO: https://www.cdc.gov/cdc-info/

or visit the NIOSH website at https://www.cdc.gov/niosh/

For a monthly update on news at NIOSH, subscribe to NIOSH eNews by visiting 

https://www.cdc.gov/niosh/eNews/

Disclaimer 

Mention of any company or product does not constitute endorsement by the National Institute for Occupational Safety and 

Health (NIOSH). In addition, citations to websites external to NIOSH do not constitute NIOSH endorsement of the 

sponsoring organizations or their programs or products. Furthermore, NIOSH is not responsible for the content of these 

websites. All web addresses referenced in this document were accessible as of the publication date. 

Suggested Citation

NIOSH [2019] PPE CASE: self-contained self-rescuer long-term field evaluation: third phase random sampling results. By

Walbert G, Monaghan W, and Coyne J. Pittsburgh, PA U.S. Department of Health and Human Services, Centers for Disease 

Control and Prevention, National Institute for Occupational Safety and Health, NPPTL Report Number P2019-0101.