May 2008
Disclaimer 

This publication was prepared for the Canadian Association of Petroleum Producers, the Gas 

Processing Association Canada, the Alberta Department of Energy, the Alberta Energy 

Resources and Conservation Board, Small Explorers and Producers Association of Canada and 

Natural Resources Canada by CETAC-West. While it is believed that the information contained 

herein is reliable under the conditions and subject to the limitations set out, CETAC-West and the 

funding organizations do not guarantee its accuracy. The use of this report or any information 

contained will be at the user’s sole risk, regardless of any fault or negligence of CETAC-West or 

the sponsors.

Acknowledgements

This Fuel Gas Efficiency Best Management Practice Series was developed by CETAC WEST 

with contributions from: 

• Accurata Inc. 

• Clearstone Engineering Ltd. 

• RCL Environmental 

• REM Technology Inc. 

• Sensor Environmental Services Ltd. 

• Sirius Products Inc. 

• Sulphur Experts Inc. 

• Amine Experts Inc. 

• Tartan Engineering 

CETAC-WEST is a private sector, not-for-profit corporation with a mandate to encourage 

advancements in environmental and economic performance in Western Canada. The corporation 

has formed linkages between technology producers, industry experts, and industry associates to 

facilitate this process. Since 2000, CETAC-WEST has sponsored a highly successful ecoefficiency program aimed at reducing energy consumption in the Upstream Oil and Gas Industry.

Head Office

# 420, 715 - 5th Ave SW 

Calgary, Alberta 

Canada T2P2X6 

Tel: (403) 777-9595 

Fax: (403) 777-9599 

cetac@cetacwest.com
Table of Contents 

1. Applicability and Objectives 1 

2. Basic Improvement Strategies 3 

 2.1 Technology and Equipment 

 2.2 Efficiency Assessment 

 2.3 Training and Expertise 

3. Inspection, Monitoring and Record Keeping 5 

4. Rapid Feasibility Assessment 6 

4.1 Types of Pneumatic Devices 

 4.2 Performance of Pneumatic Instrumentation 

5. Operational Checks, Testing and Adjustments 11 

5.1 Field Survey 

5.2 Field Measurement 

5.3 Data Review 

5.4 Economic/Environmental Evaluation 

5.5 Implementation 

6. Appendices 17 

Appendix A Types of Pneumatic Devices and Uses 

Appendix B Instrument Characteristics 

Appendix C Field Survey 

Appendix D Flowchart 

Appendix E Case Study 

Appendix F References 
Figures 

Figure 1 Flapper Nozzle Control Loop 

Figure 2 Wellmark 2001NB Snap Acting Pilot 

Figure 3 Common Pressure Controller 

Figure 4 Pressure Control Loop 

Figure 5 Level Control Loop 
Background 

The issue of fuel gas consumption is increasingly important to the oil and gas 

industry. The development of this Best Management Practice (BMP) Module is 

sponsored by the Canadian Association of Petroleum Producers (CAPP), the 

Gas Processing Association Canada (GPAC), the Alberta Department of Energy, 

Small Explorers and Producers Association of Canada (SEPAC), Natural 

Resources Canada (NRC) and the Energy Resources and Conservation Board 

(ERCB) to promote the efficient use of fuel gas in pneumatic instruments used in 

the upstream oil and gas sector. It is part of a series of 17 modules addressing 

fuel gas efficiency in a range of devices. 

This BMP Module: 

• identifies the typical impediments to achieving high levels of operating 

efficiency with respect to fuel gas consumption, 

• presents strategies for achieving cost effective improvements through 

inspection, maintenance, operating practices and the replacement of 

underperforming components, and 

• identifies technical considerations and limitations. 

The aim is to provide practical guidance to operators for achieving fuel gas 

efficient operation while recognizing the specific requirements of individual 

pneumatic instruments and their service requirements. 
EFFICIENT USE OF FUEL GAS 

IN THE UPSTREAM OIL AND GAS INDUSTRY 

MODULE 3 of 17: Pneumatic Instruments 

FIELD

5. Chemical Injection Pumps

1. Gathering Systems6. Fired Heaters4. Flaring

3. Pneumatic Instruments

2. Pumpjacks

7. Engines

10. Desiccant Dehydrators

8. Compression

9. Glycol Dehydrators

11. Fuel Gas Measurement

SOUR GAS PLANTS

17. Acid Gas Injection

15. Sulphur Recovery

14. Amine

13. Refrigeration12. Fractionation

5. Chemical Injection Pumps

6. Fired Heaters4. Flaring

3. Pneumatic Instruments

7. Engines

10. Desiccant Dehydrators

8. Compression

9. Glycol Dehydrators

11. Fuel Gas Measurement

16. Tail Gas Incineration

SWEET GAS PLANTS

13. Refrigeration12. Fractionation

5. Chemical Injection Pumps

6. Fired Heaters4. Flaring

3. Pneumatic Instruments

7. Engines

10. Desiccant Dehydrators

8. Compression

9. Glycol Dehydrators

11. Fuel Gas Measurement

16. Tail Gas Incineration
Efficient Use of Fuel Gas Pneumatic Instruments Rev Date 27/05/2008 

Module 3 of 17 Page 1 of 28 

1. Applicability and Objectives 

Pneumatic instruments of all types are used throughout the oil and gas industry 

to perform the necessary functions which enable the production, processing, 

transfer and refining of petroleum products. Instrumentation is used to take 

measurements and control processes typically by sending a signal to a valve to 

adjust its position based on changes in the process conditions. Controllers can 

be used to control the process based on pressure, temperature, flow or liquid 

level. Because of the simplicity and reliability of pneumatic instrumentation as 

well as the lack of available electricity in many locations, pneumatic 

instrumentation has become the standard in the industry. 

Pneumatic instruments may be powered by compressed air, natural gas or 

propane. However, the ready availability of pressurized natural gas has made it 

the energy of choice for instrumentation. In spite of the cost of natural gas and 

emissions to the atmosphere, its use as an energy source continues to dominate 

for the following reasons: 

• Pneumatic instrumentation is simple and reliable, making it easy for field 

operators to adjust and repair. 

• Reliable electricity is not available or economical at many locations. 

• Electrical instrumentation can be many times the cost and in some cases 

does not meet the process control requirements. 

• Low Bleed instrumentation is now available. 

• Retrofit kits are available for high bleed instrumentation still in place. 

• Conversion to air at larger facilities still requires pneumatic 

instrumentation. 

• Most operators have considerable experience with pneumatic instruments. 

There has long been a misunderstanding in the industry that the amount of gas 

pneumatic controllers bleed is insignificant. Work performed for the United 

States Environmental Protection Agency has shown that the largest source of 

methane emissions in the industry comes from pneumatic instrumentation. Fifty 

percent of all vented gas and 15 to 20 percent of total emissions in the United 

States (U.S.) are said to come from pneumatic instrumentation. The production 

segment accounts for 69 percent of these emissions in the US and it is likely that 

a similar percentage applies in Canada. Gas storage and transmission account 

for most of the remainder. In the US, venting from pneumatic instruments is 

estimated to be in the order of 61 billion standard cubic feet (Bscf) per year. In 

Canada the estimate is between 12 and 25 Bscf per year of gas being vented to 

the atmosphere through pneumatic instrumentation. Assuming a price of CDN$6 

per 1000 scf, the value of vented gas is between $75 and $150 million dollars per 

year. 
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There are about 100,000 gas wells in Western Canada, the majority in remote 

locations without power. Although pressurized natural gas is the primary power 

source for pneumatic controllers, about 30 percent of the wells are sour gas wells 

which use bottled propane as the energy source to drive the pneumatics. 

Propane venting, like natural gas, adds to both the cost and environmental 

impact of operating pneumatic devices. In many cases propane is much more 

costly than natural gas due to trucking and logistics. 

Typical pneumatic instruments used in the Canadian oil and gas industry are 

listed in the Instrument Table (Appendix B) and in general vent between 3 and 50 

standard cubic feet per hour (scfh). A single device venting at 30 scfh will use 

262,500 ft3

 in a year, more than $1,500 per year in lost reserves (assuming a gas 

price of CDN$6 per 1000scf) in addition to approximately 97 tonnes of CO2

equivalent (CO2E) emissions. The several hundred thousand pneumatic 

controllers in operation today, present a significant opportunity to reduce 

emissions and increase sales of natural gas. 

Technology exists today to dramatically reduce this venting and at the same time 

have a positive economic impact on oil and gas operations. In addition to the 

large economic benefits there are many side benefits including: 

• reducing emissions of GHGs, 

• reducing odors which reduces landowner complaints, 

• increasing worker safety, and 

• reducing fire hazards. 

This document discusses the different types of pneumatic instrumentation, gas 

consumption from these devices, and field optimization to improve both the 

economics and environmental aspects of operating pneumatic instrumentation. 

The best management practices presented here, both in text and in the form of a 

flowchart, are practical steps to minimize the amount of venting from pneumatic 

devices. 
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2. Basic Improvement Strategy 

The critical factors to ensuring a successful long term strategy to optimize fuel 

gas consumption from field wide operations are to educate personnel to 

recognize opportunities, and to perform field optimization using logical steps. 

Efficient operation of pneumatic devices requires: 

 

• a database or inventory of pneumatic devices, 

• knowledge of the instrumentation, typical field bleed rates and 

alternatives, 

• routine maintenance and repair of any problems, and 

• optimization of existing equipment performance by implementing 

appropriate technology. 

2.1 Technology and Equipment 

When looking at the basic improvements to reduce fuel gas consumption it is 

imperative that there is understanding of the device, its application, limitations 

and the operational conditions that may affect its performance. This information 

provides the basis for an assessment on an individual device. Appendix A 

provides background on pneumatic devices; types, applications, fuel gas 

consumption and performance. 

2.2 Efficiency Assessment 

In order to optimize the performance of pneumatic instrumentation, it is 

recommended that the followings steps be implemented. 

• Conduct a comprehensive Field Survey. 

• Undertake Field Measurements to establish vent rates. 

• Review data to identify opportunities for improvement. 

• Evaluate Economic and Environmental options. 

• Implement preferred options. 

Section 5 provides details on each step and an easy to follow flowchart. 
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2.3 Training and Expertise 

Pneumatic instruments are not complicated. However, they do control important 

processes which must be understood prior to working on an individual device. 

The basic assessment of the equipment should be performed by someone with 

adequate background in instrumentation, or by an experienced operator who 

understands pneumatic instruments. Prior to performing large scale field 

optimization both operational personnel and a local pneumatic instrumentation 

specialist should be involved. 
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3. Inspection, Monitoring and Record Keeping 

Operators should record the pneumatic instruments testing and improvement 

program. Proper record keeping should assist in ensuring that sub-optimal 

instrumentation and devices are identified and that appropriate follow-up actions 

are implemented. This information will also assist in establishing the 

checking/testing frequency, to achieve cost-effective fuel gas efficiency 

improvements. 

Although each company will define its record keeping system, consideration 

should be given to recording and retaining the following information: 

• data sheets for each type of instrument in service, 

• expected fuel gas consumption by device or system, 

• records of changes/upgrades that have been performed, 

• test results, and 

• the economic analysis performed on high bleed instruments, where they 

have been adjusted/modified on economic grounds. 

Appendix B provides the expected fuel gas consumption for the most common 

instruments and devices that are in use in the upstream oil and gas (UOG) 

industry. 
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4. Rapid Feasibility Assessment 

4.1 Types of Pneumatic Devices 

Pneumatic devices can be divided into three principle categories: Continuous 

Bleed, Intermittent Bleed, and No-Bleed. These categories are important when 

looking at the potential opportunity for optimizing your processes in terms of 

reducing gas venting.

 

The design of the instrumentation is a major factor in how much the device will 

vent or bleed. Both continuous bleed and intermittent bleed devices can be 

either high bleeders or low bleeders. In general terms high bleed devices have 

been categorized as those that bleed more than 6 scfh. This bleed rate does not 

include vent gas from any actuators. The instrument table in Appendix B outlines 

the devices that are throttling (continuous bleed) and snap acting (intermittent 

bleed) as well as manufactured specified bleed rates and where available field 

measured bleed rates. It is important to be aware that not all manufacturers use 

the same standards to measure bleed rates in the laboratory and typically results 

in field applications will be higher. 

Continuous Bleed Devices or Throttling Devices 

These include controllers, transducers and positioners. These devices are used 

to control flow, pressure, temperature and liquid level. Continuous bleed 

instrumentation is necessary for proportional control of the process, and is 

suitable where a steady state environment is desired. 

Throttling devices continuously bleed because the design requires a constant 

supply and venting of gas in order for the controller to function. This bleed rate is 

steady when the process is steady and will change when the process changes. 

In addition to the continuous bleed of the controller, additional venting occurs 

when the actuator strokes. 

Figure 1 demonstrates how a continuous bleed device known as a “flappernozzle” arrangement functions. The flapper-nozzle designed pressure controller 

(item e) gets its constant feed of supply gas from a pressure regulator (item f). 

This gas is used to operate the controller. For the controller to function properly it 

requires a constant source of supply pressure. The industry standard is either 20 

or 35 psi. The controller is connected to the pipeline (item b) and the control 

valve (item c). The pipeline connection is where the measuring takes place. A 

measuring device, in this case a bourdon tube (item h), is attached to a flapper 

assembly (item i). As pressure increases or decreases the, bourdon tube reacts 

by moving the flapper assembly either closer or further away in relation to a fixed 

nozzle assembly (item k). When the pressure increases the bourdon tube will 

move the flapper closer to the fixed nozzle assembly creating a restriction of gas 

flow coming from the nozzle. Back pressure created in the nozzle will be 
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transmitted to a relay device through the outlet (item j), opening a valve within 

that device, allowing output pressure to be diverted to the control valve. The 

valve opens according to the amount of output pressure transmitted. This allows 

pipeline pressure to decrease back to the desired set point predetermined inside 

the controller, bringing balance to the process loop (item a). 

Figure 1 

Flapper Nozzle Control Loop 

Intermittent Bleed or Snap Acting Devices 

These devices bleed only when the process requires a change. These devices 

are typically used for level control, or emergency shut down (ESD) operations. 

When no action is required no gas is used. When a situation occurs requiring a 

valve to operate this type of device reacts by sending a full output signal to the 

valve. Intermittent Bleed and snap acting devices are “all or nothing” controllers, 

that is, they are either on or off, no proportionality. 
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Refer to Figure 2 as an example of a snap acting device. When no action is 

required the supply valve is seated against the supply port prohibiting the 

movement of instrument gas, thus creating a no bleed situation. As level rises in 

the tank the flapper bar also rises. When the flapper bar rises it lifts the exhaust 

valve, pushing the supply valve 

upward. This action results in the 

closing of the exhaust port and the 

opening of the supply port, allowing 

gas to flow freely from the supply 

port through the output port to the 

control valve. At this time no gas 

has been vented to the 

atmosphere. With the liquid in the 

tank now flowing through the 

control valve, the level decreases. 

A decrease in level will eventually 

lower the flapper bar causing the 

exhaust valve to lower, allowing the 

supply valve to reseat the supply 

port, prohibiting the flow of supply gas. This action will also result in the opening 

of the exhaust port allowing the gas that was used to open the control valve to 

escape or bleed to atmosphere, eventually closing the valve and completing the 

cycle. 

No Bleed or Self Contained Devices 

These devices include regulators, and most switches. These will not be 

discussed as they do not vent to the atmosphere. 

4.2 Performance of Pneumatic Instrumentation 

The amount an individual instrument vents is dependent on several factors, some 

of which we have control over after the instrument is purchased and some of 

which we do not. The factors affecting bleed rates of individual instruments are 

listed below in order of importance: 

 

Instrument Design 

The design of any instrument dictates how the device will bleed (Intermittent or 

Continuous) and how much it will bleed. As discussed above, instruments are 

classified as either high bleed or low bleed devices. High bleed, meaning they 

bleed at over 6 scfh and in some cases over 100 scfh. The design can be 

altered using a low bleed retrofit kit that is adaptable to many instruments, in 

effect changing the design and lowering the bleed rate. These low bleed retrofit 

kits are available from several manufacturers. Field results have shown that 

between 10 and 60 scfh is the typical saving after implementing a replacement 

Figure 2 

Wellmark 2001NB Snap Acting Pilot 
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low bleed device or retrofitting an existing device. In general these devices 

reduce gas consumption from 65 to 95 percent. 

Appendix E is a case study describing two applications of low bleed retrofits. 

This case study was chosen as it contains both a typical controller and one not 

very typical which has a very low bleed rate for its design. Both have very good 

gas reductions but the lower bleed device would have a slower payback. 

Device Condition 

Device condition is a very important factor in keeping the bleed rates low. If the 

instrument is not maintained the parts will become dirty and worn. Dirt and 

particles in the moving parts will cause the device to operate out of its designed 

parameters and typically result in excessive venting. Field results have 

demonstrated that instrumentation in poor condition bleed 5 to 10 scfh more than 

they should. Typical problems include: 

• worn seals, gaskets, and diaphragms resulting in leaks, 

• nozzle corrosion or wear from poor quality gas leading to increased flow, 

and 

• loose control tube fittings. 

Gas Supply Pressure 

The supply gas pressure directly affects the bleed rate of instrumentation. The 

supply pressure should be either 20 pounds per square inch (psi) (for 3-15 psi 

signal) or 35 psi (for 6-30 psi signal) depending on the instrument design. 

However it is common to see pressures significantly higher than the design of the 

instrument resulting in excess gas being vented through the device. The 

regulator must be set to the proper supply pressure. In some cases the process 

may have changed significantly and where once a 35 psi signal 6-30 output was 

needed for proper control, a 20 psi signal 3-15 psi output can now achieve the 

same result. This will have a significant effect on venting rates. 

Controller Tuning 

Controllers out of tune are more active, resulting in non-steady state operation, 

causing higher bleed rates from both the controller and the actuator. Tuning 

controllers on a periodic basis will maintain optimal conditions and reduce 

emissions. 
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Controller Features 

The number of internal 

controls such as 

proportional band and 

reset contribute to the 

overall bleed rate of a 

controller. The common 

pressure controller shown 

in Figure 3 has several 

adjustments. Depending 

on the application these 

internal controls may play 

a significant role in the 

bleed rate of the controller. 

In many applications the 

reset valve can be 

removed resulting in less 

bleeding while still 

permitting proper control. 

Age of Instruments 

The age of the instrument can be a factor in vent rates although not as important 

as condition. Worn parts are typically a sign of age which may increase venting; 

however, if the device has been properly maintained and tuned then age have 

less effect on emission rates. 

Figure 3 

Common Pressure Controller 
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5. Operational Checks, Testing and Adjustments

In order to optimize the performance of pneumatic instrumentation, it is 

recommended that a program including the followings steps be implemented: 

• Conduct a comprehensive field survey. 

• Undertake field measurements to establish vent rates. 

• Data review to identify opportunities for improvement. 

• Perform economic/environmental evaluation of options. 

• Implementation of preferred options. 

5.1 Field Survey 

Before starting a field survey a rough calculation can be made to determine the 

field wide opportunity for fuel gas savings. An approximation of the gas 

consumption can be obtained by taking the number of control loops and 

multiplying it by 60 scfh per control loop. Using this information as a rough guide 

gives a sense of the opportunity available for reducing emissions. 

To determine what the opportunity in any field or operation may be, the first step 

is to understand what instrumentation is currently in place. The most efficient 

way to do this is to assign a person familiar with the field and instrumentation to 

complete a table similar to that below. The table should allow additional room for 

notes as shown in Appendix C (Field Survey). Keeping the table short and 

concise allows the operator to be efficient during the field survey process. The 

task should be focused on getting all the correct information as efficiently as 

possible. 

The field survey should be restricted to the following pneumatic instrument types: 

pressure, temperature, level, differential pressure controllers, transducers, 

positioners and transmitters. 

A quick check to ensure all field data has been collected prior to leaving a 

location is to count the pneumatic operated valves and compare it with the 

number of control devices; they should be the same. 
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Location 

LSD

Facility 

Description Manufacturer Model Output 

Range

Supply 

Pressure

Throttle

or Snap Condition Gas 

Type Retrofit

Location LSD - This is the Land Survey Description. 

Facility Description - Type of facility: well site, metering station, plant, 

separator, etc. 

Manufacturer - The manufacturer of the instrument should be on the 

identification plate. 

Model - This is also located on the identification plate. 

Output Range - This can also be found on the identification plate. 

Supply Pressure - If there is a gauge downstream of the regulator read the 

supply pressure here, otherwise it can be taken from the controller. Many times 

the controller gauges are inaccurate; however it may be the only option. Ensure 

the units (kPa or psi) are recorded. 

Throttle or Snap Acting - This is important for level control only and indicates 

the design style of the controller. This may be indicated on the pilot or relay with 

an “S” for snap or “T” for throttle. The indication may also be located on the 

identification plate. 

Condition - The condition of the controller should be indicated by either good or 

poor. 

• Good - clean, no visible signs of wear and tear, gauges operating 

properly, no irregular sound or feel due to excessive venting of gas. 

• Poor - any signs of wear and tear, dirty, fluid in controller, louder than 

normal venting, venting can be felt with fingers and is clearly high, door 

gasket in poor condition, non functioning gauges, visible corrosion around 

nozzle/pilot device. 

Gas Type - This will typically be either fuel gas, propane, or air. 
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Retrofit - Has the device already been retrofitted with a low bleed kit? The 

retrofit may be located on the tubing between the instrument and the valve or 

directly inside the controller. Some training will be required to recognize these 

devices. 

5.2 Field Measurements 

The most accurate information for quantifying bleed rates from pneumatic 

instruments comes from field measurements, but this data is not always 

available. The Instrument Table in Appendix B outlines the field data available 

for many instruments. If there is no field data for your particular instrument, and 

you have a significant number of these devices, then you should perform field 

measurements to obtain accurate data. Statistical methods can be applied to 

ensure that a representative sample is taken. 

Different field measurement techniques have been used to quantify the amount 

of vent gas coming from pneumatic instrumentation and some are more accurate 

than others. Because of the relatively low emission rates and pressures from 

individual instruments it is important to ensure that proper methodology is 

followed and accurate instruments are used when gathering data from these 

devices. When dealing with low volumes a small mistake can lead to a large 

error in measurement. 

Vent gas from controllers does not necessarily leave the controller through the 

vent line. In many cases the controller will be leaking gas around the door or 

through fittings attached to the controller body. Not understanding this may lead 

to erroneous results when measuring vent gas. To ensure that all of the gas is 

vented through the vent line when measuring vent rates, the instrument needs to 

be bagged. A plastic bag encloses the instrument and is taped tightly using duct 

tape to force any fugitive emissions through the vent line. This ensures an 

accurate measure of the total venting from the controller. 

An accurate meter needs to be selected that measures very low flow at near 

atmospheric pressure. The meter should be attached to the vent line and the 

fittings “snooped” to ensure no leaks are present. The total flow should be 

measured over as long a time as practical (at least one hour) to ensure accuracy 

of the data. A longer time will give a more representative measure of any flow 

rate changes that may occur as a result of process variations. 

The data should then be converted to standard conditions of pressure and 

temperature and presented in terms of scfh. 
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5.3 Data Review 

After the survey is complete the data needs to be reviewed to assess the 

opportunity for reducing emissions. By comparing the collected field data with 

the Instrument Table in Appendix B, you can determine how many high bleed 

devices are in the field. The Instrument Table provides bleed rates for these 

devices based on both manufacturer specifications and field data gathered from 

various sources. Experience suggests that manufacturer bleed rates are 

understated so field measurement data should be used when possible. If there is 

no field data available, field measurements should be performed on your 

instruments; however, it will be impractical to physically measure all bleed rates 

from all instruments. Focus should be applied to the instruments of which there 

are significant numbers in the field. 

 

To begin the assessment of the field data refer to the flowchart in Appendix D. 

The first step in the flowchart is to determine the feasibility of converting all 

instruments to compressed air. The electrical power source for the instrument air 

must also be reliable as instrument air is required continuously. Conversion to 

instrument air is most viable when a facility wide change is already planned. A 

second benefit is the extension of life of the instrumentation because, unlike 

natural gas, no by products are present in air, which can harm the instrument. 

No effort in this paper has been made to specify the economic feasibility of 

converting to instrument air because each facility is different. 

Knowing if an instrument is high or low bleed is the most relevant variable in 

assessing the opportunity for savings and the best return on investment. Low 

bleed devices in instrument air packages are also beneficial as maintenance 

costs can be reduced by reducing air consumption. If a field has already been 

converted to low bleed devices then tuning, and maintaining instruments will 

provide continuing benefits. 

By referencing the flowchart in Appendix C along with the field data a complete 

assessment of each device can be made. 

5.4 Economic/Environmental Evaluation 

After reviewing the field survey data, the opportunities for gas savings should be 

understood, and whether additional field measurements are required. The 

devices which need to be replaced, retrofitted or repaired should be listed. 

The primary driver is almost always economics. Using field measurements 

where possible, calculate the reduction in gas consumption based on either 

replacement to a low bleed device or retrofit with a low bleed conversion kit. 

Field measurements should be performed if measured data is not available. 
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Alternatively if you use manufacturers’ specifications you will likely be 

conservative with any savings. 

To calculate the amount of gas saved: 

Replacement with low bleed - Use the field data bleed rate in scfh from the 

existing device minus the field data bleed rate in scfh from the new low bleed 

device. 

S = [(scfh)old – (scfh)new] x 8,760hr/yr x P/1000. 

S = Savings in Canadian dollars for each year after installing the new 

device. Savings do not include the cost of replacement equipment or the 

additional savings from potential carbon credits. 

[(scfh) old = field data bleed rate of existing device in standard cubic feet 

per hour. 

(scfh) new = field data bleed rate of replacement low bleed device in 

standard cubic feet per hour. 

P = price of gas in Canadian dollars per thousand standard cubic feet. 

Retrofit with low bleed kit - use the field data bleed rate in scfh from the 

existing device multiplied by the percent reduction applicable to the retrofit 

package of choice. 

S = [(scfh) old x R percent] x 8,760hr/yr x P/1000. 

S = Savings in Canadian dollars for each year after retrofitting the old 

device. Savings do not include the cost of retrofit or the additional savings 

from potential carbon credits. 

[(scfh) old = field data bleed rate of existing device in standard cubic feet 

per hour. 

Percent = reduction in gas consumption applicable to the retrofit system you 

have chosen. For SER use 65% reduction (R=0.65) and for the Mizer use 

95% reduction (R=0.95). 

P = price of gas in Canadian dollars per thousand standard cubic feet. 

When performing these calculations you must include the field time to retrofit or 

replace the old device, typically about two hours, in addition to the cost of the 

retrofit kit or replacement device. When replacing a device there is also an 

environmental impact from the disposal of the older instrument. In general if a 

retrofit can be performed it is a more economical and environmentally beneficial 

way to cut emissions. 
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Field experience has demonstrated that over 80 percent of all high bleed 

controllers can be economically retrofitted to become low bleed, or replaced with 

low bleed controllers. In general payouts are between 3 and 9 months based on 

gas savings. Annual savings by retrofitting or converting a high bleed device, 

bleeding at 35 scfh (306 million standard cubic feet per year), to a low bleed 

device are in the order of 250 mscfy or $1,500 in addition to 94 tonnes CO2E. If 

CO2 credits are applied the payouts may drop by 50%. 

Maintenance and Repair - During the Field Study and Data Review many 

controllers will be found to require maintenance or repair. Prior to proceeding, 

the review should be completed to determine which instruments will need to be 

replaced or retrofitted. Due to the various types of instruments in the field it is 

difficult to provide a formula to assess the benefits of repairing a particular 

instrument. However, there is plenty of evidence to support the economics of a 

solid maintenance program. Field tests by various operators suggest that 

paybacks of less than 9 months are typical. 

5.5 Implementation 

The implementation of the plan is the most important part. Once the economic 

and technical justifications are complete and management has approved the 

project, implementation can start. Managing the implementation will be subject 

to individual operations and availability of skilled people to perform the tasks. 
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Figure 4 

Pressure Control Loop 

Appendix A 

 Types of Pneumatic Devices and Uses 

A typical process control loop consists of a control device (i.e. pressure, flow, 

level, or temperature controller), a controlled device (i.e. valve, choke, louver, or 

pump), and a pressure regulator, which supplies power to the control device, 

which in turn operates the controlled device. Pneumatic devices include 

controllers, switches, transducers, positioners, and transmitters. A brief 

description and application is outlined for each below: 

Controllers 

These devices typically have a built in sensing device which measures the 

process variable. This allows the controller to transmit a pneumatic signal to the 

final controlled device based on a predetermined set point. It is the difference 

between this pneumatic signal and the set point that determines how much the 

final device changes, such as a valve opening or closing. Controller types 

include pressure, differential pressure, temperature, and level control devices. 

Pressure Controller 

These devices are used to control process pressure. For example in Figure 4 

(Pressure Control Loop) below the controller and control valve are used to 

maintain the pressure in the pipeline 

based on a desired “set point” or 

process parameter. The pressure 

controller uses the supply gas from the 

regulator as its energy source for 

operation. The controller senses the 

pressure in the pipe line, and 

compares this pressure with the “set 

point”. The controller then sends a 

pressure signal to the actuator of the 

control valve causing the valve to 

open or close. This results in a 

change in process conditions to bring 

the actual pressure closer to the 

desired pressure or “set point”. In this 

process the valve is typically never 

fully open or closed. This type of 

process control is called proportional control and is achieved with a “throttling” 

controller. 
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Differential Pressure Controller 

A differential pressure controller operates in a similar fashion to the pressure 

controller. The differential pressure controller senses pressure from two points, 

typically across an orifice or nozzle. This measurement provides the information 

the controller needs to adjust a valve in order to maintain the set point. Typically 

differential pressure controllers are indirectly measuring and controlling flow in a 

process. 

Temperature Controller 

A temperature controller is used to control a process based on the difference 

between the “set point” and the process temperature. 

Level Controller 

These devices are typically 

used to control the level in a 

tank. For example Figure 5 

(Level Control Loop) below 

depicts a process where the 

tank level will fluctuate and the 

level controller will maintain a 

desired “set point” or tank level. 

The level controller has a float 

which rises with the liquid level 

in the tank. Once it rises to a 

certain limit the controller is 

tripped and the controller sends 

a signal for the valve to open. 

Fluid then leaves the tank until 

the level lowers to a certain 

level again tripping the 

controller. At this point the controller again sends a signal to close the valve. 

Transducers 

These devices are used to convert an electric signal, usually 4 to 20 mA to a 

pneumatic signal either 3 to 15 psi or 6 to 30 psi. In general the application is to 

allow a feedback from an electronic SCADA system to operate a pneumatic 

control valve. 

Positioners 

Used on some control valves to establish a certain amount of travel on the valve 

based on the output signal of the controller. Typically positioners are used on 

larger actuators to get more accurate control and a quicker response. Bleeding 

occurs at the positioner in addition to the controller. 

Figure 5 

Level Control Loop
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Switches 

These devices are typically used as a safety device to protect the process during 

upsets, or if control problems occur. These devices typically open or close based 

on level, pressure or temperature. 

Transmitters 

These are used to transmit pneumatic signals to a central control point but with 

the advancement of electronic technologies pneumatic transmitters have nearly 

all been replaced with no-bleed electronic transmitters. 
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Appendix B 

Instrument Characteristics 

Controller Model 

Signal 

Pressure (psi) 

Manufacturer 

Data (scfh) 

Field Data 

(scfh) 

Number 

in Field 

Throttling 

or snap 

Retrofit 

choices 

Low Bleed 

Alternatives 

 

PRESSURE CONTROLLERS 

Ametek Series 40 20 6 N/A low throttling 

 35 6 N/A low throttling 

Bristol Babcock Series 5453-Model 

10F 20 3 20 - 30 low throttling SER 

 35 3 20 - 30 low throttling SER 

Bristol Babcock Series 5455 Model 

624-III 20 2 20 - 30 low throttling SER 

 35 3 20 - 30 low throttling SER 

Bristol Babcock Series 502 A/D 

(recording controller) 20 <6 N/A low throttling SER 

 35 <6 N/A low throttling SER 

Fisher 4100 Series (large orfice) 20 50 47 low throttling Replace 4195 

 35 50 54 low throttling Replace 4195 

Fisher 4150 and 4160 20 10-35 11 - 35 high throttling SER/Mizer 4195 

 35 10-42 24 - 65 high throttling SER/Mizer 4195 

Fisher 4194 (differential pressure) 20 3.5 12 - 14 moderate throttling SER 

 35 5 13-18 moderate throttling SER 

Fisher 4195 20 3.5 13-18 moderate throttling SER 

 35 5 12-115 moderate throttling SER 

Foxboro 43AP 20 18 N/A moderate throttling SER 4195 

 35 18 N/A moderate throttling SER 4195 

ITT Barton 338 20 6 20 - 30 moderate throttling SER 

 35 6 20 - 30 moderate throttling SER 

ITT Barton 335P 20 6 18 - 30 low throttling SER 4194 

 35 6 20 - 30 low throttling SER 4194 

Natco CT 20 35 N/A low throttling Mizer 

 35 35 N/A low throttling Mizer 

 

TRANSDUCERS 

Bristol Babcock Series 9110-00A 20 0.42 N/A 

 35 0.42 N/A 

Fisher 546 20 15 - 40 high throttling SER 646 

 35 30 35 - 60 high throttling SER 646 

Fisher 646 20 <1 N/A 

 35 <1 N/A 

Fisher 846 20 <1 N/A 

 35 <1 N/A 

 

LEVEL CONTROLLERS 

Fisher 2900 20 23 22-51 moderate throttling LBC/2901 2001NB/1001A 

 20 23 18-127 moderate snap LBC/2902 2001NB/1001A 

 Fisher 2900 (Continued) 35 23 28-51 moderate throttling LBC/2903 2001NB/1001A 

 35 23 27-153 moderate snap LBC/2904 2001NB/1001A 

Fisher 2500 Series 20 42 N/A moderate throttling SER 

LEVEL CONTROLLERS (Continued) 

 35 42 44-72 moderate throttling SER 
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Controller Model 

Signal 

Pressure (psi) 

Manufacturer 

Data (scfh) 

Field Data 

(scfh) 

Number 

in Field 

Throttling 

or snap 

Retrofit 

choices 

Low Bleed 

Alternatives 

 

Fisher 2660 Series 20 1 N/A moderate 

 35 1 N/A moderate 

Fisher 2100 Series 20 <1 N/A low 

 35 <1 N/A low 

Fisher 2680 20 <1 N/A moderate 

 35 <1 N/A moderate 

Fisher L2 

 

Invalco CT Series 20 N/A low throttling Mizer 

 35 40 34-88 low throttling Mizer 

Norriseal 1001 20 N/A N/A moderate 1001A/2001NB 

 35 N/A N/A moderate 1001A/2001NB 

Norriseal 1001 (A) 20 0.007 N/A high throttling 

 20 0.2 N/A high snap 

 35 0.007 N/A high throttling 

 35 0.2 N/A high snap 

Wellmark 2001 20 0.007 N/A low throttling 

 20 0.2 N/A low snap 

 35 0.007 N/A low throttling 

 35 0.2 N/A low snap 

 

POSITIONERS 

Fisher 3582 20 14 22 high throttling 

 35 18 24 high throttling 

Fisher 3661 20 8.8 N/A moderate throttling 

 35 12.1 N/A moderate throttling 

Fisher 3590 (electro-pneumatic) 20 24 N/A high throttling 

 35 36 N/A high throttling 

Fisher 3582i (electro-pneumatic) 20 17.2 N/A moderate throttling 

 35 24 N/A moderate throttling 

Fisher 3620J (electro-pneumatic) 20 18.2 N/A moderate throttling 

 35 35 N/A moderate throttling 

Fisher 3660 20 6 N/A moderate throttling 

 35 8 N/A moderate throttling 

Fisher Fieldvue Digital 20 14 N/A moderate throttling 

 35 49 N/A moderate throttling 

Masoneilan 4600B Series 20 N/A low throttling 

 35 18-30 N/A low throttling 

Masoneilan 4700B Series 20 N/A low throttling 

 35 18-30 N/A low throttling 

Masoneilan SVI Digital 20 <1 N/A low throttling 

Masoneilan SVI Digital (Continued) 35 <1 N/A low throttling 

Masoneilan 7400 Series 20 24-50 N/A low throttling 

 35 24-50 N/A low throttling 

POSITIONERS (Continued) 

Moore Products – Model 750P 20 N/A moderate throttling 

Controller Model 

Signal 

Pressure (psi) 

Manufacturer 

Data (scfh) 

Field Data 

(scfh) 

Number 

in Field 

Throttling 

or snap 

Retrofit 

choices 

Low Bleed 

Alternatives 

 
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Moore Products – Model 750P 35 42 N/A moderate throttling 

Moore Products 73N-B PtoP 20 36 N/A low throttling 

 35 N/A low throttling 

PMV D5 Digital 20 <1 N/A low throttling 

 35 <1 N/A low throttling 

Sampson 3780 Digital 20 <1 N/A low throttling 

 35 <1 N/A low throttling 

VRC Model VP700 PtoP 20 <1 N/A low 

 35 <1 N/A low 
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Retrofit 

Gas 

Type Condition 

 

Throttle or Snap 

Supply 

Pressure 

 

Output 

Range Model Manufacturer 

 

Facility 

Description 

 

Location 

LSD 

 
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Appendix D

Pneumatic Instruments Optimization Flowchart 
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Appendix E 

Case Study 

Setting 

Compressor Station - Dehydration/Compression 

Initiated 

September 2004 

Situation 

The client, an oil and gas producer, wished to reduce its greenhouse gas 

emissions as part of its corporate environmental stewardship objectives and to 

realize fuel gas cost savings. It was decided that a low-bleed retrofit kit for 

minimizing methane emissions from constant venting pneumatic controllers 

would be implemented. 

 

Low-bleed technology was installed on two pressure controllers. One controller 

was located in the TEG dehydration skid and the other was located in the 

compressor skid. Initial readings on the controllers indicated a vent rate of 10 scf 

per hour for the dehydration location and 47 scf per hour for the compressor 

location, giving a combined venting rate of 55 scf per hour from these pneumatic 

devices. 

Solution 

The low bleed technology was installed in September 2004. The installation took 

approximately 4 hours with no loss of production for the field. The installation 

allowed for full valve stroke. Vent rates from the controllers after this procedure 

were as follows: 

• dehydration location 3 scfh, and 

• compressor location 12 scfh. 

Conclusion 

The combined net reduction in methane emissions to the atmosphere was 40 

scfh or 73%. In addition, the client was able to prevent 130 tonnes per year CO2

equivalent combined from being vented to the atmosphere unnecessarily. 

Payout of the units is achieved in 12 months using $5 per mcf gas. 
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Economics 

Consumption 1,368 scf/day 

Savings (73%) 960 scf/day 

Price of gas $5 Cdn/mcf 

SER Cost $ 1,770 (885/ea x 2) 

Annual Savings $ 1,752 

Payout 12 months 

Environmental Benefits 

Methane Reduction* 73% 

Methane Volume Reduction* 350 mcf/year 

CO2 Equivalent Reduction* 130 tonnes/year 

*All figures refer to net reduction in emissions to the atmosphere. 
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Appendix F 

References 

1. Estimate of Methane Emissions From the US Natural Gas Industry, David 

Kirchgessner, Robert Lott, Michael Cowgill, Matthew Harrison, Theresa 

Shires 

2. Lessons Learned from Natural Gas STAR Partners: Options for Reducing 

Methane Emissions from Pneumatic Devices in the Natural Gas Industry, 

United States Environmental Protection Agency, , July 2003 

3. Methane Emissions from the Natural Gas Industry, Volume 12 Pneumatic 

Devices, Theresa M. Shires, Matthew R. Harrison, 1996 

4. Technology demonstration Report “Sirius Emission Reducer”, CETACWest, Clearstone Engineering, 2005 

5. Success Points to Global Opportunities to Cut Methane Emissions, US 

Natural Gas STAR Program, Fernandez, R. Lieberman, and Robinson, D. 

Oil and Gas Journal, July 12, 2004. 

6. www.epa.gov/gasstar/ Lessons Learned, Converting Gas Pneumatics to 

Instrument Air, Options for Reducing Methane Emissions from Pneumatic 

Devices in the Natural Gas Industry, Convert Pneumatics to Mechanical 

Controls.