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MEMORANDUM 

TO: Melanie King, Environmental Protection Agency 

DATE: January 27, 2010 

RE: Management Practices for SI RICE Area Sources < 500 hp 

PROPOSED MANAGEMENT PRACTICES AT AREA SOURCES

On March 5, 2009 EPA issued Proposed Revisions to Code of Federal Regulations Title 40, Part 63, 

Subpart ZZZZ ("Proposed Rule") for certain Spark Ignited Reciprocating Internal Combustion Engines 

("SI RICE"). The Proposed Rule included management practices such as oil changes and spark plug 

replacements for certain SI RICE area sources. The Clean Air Act allows EPA to establish management 

practices based on Generally Available Control Technology (GACT) rather than MACT for area sources. 

EPA's proposed SI RICE management practices for existing area sources, however, far exceeded any 

standard maintenance practice requirements and in fact may increase the environmental impact of the 

industry by increasing waste and air emissions. Each excessive oil change could generate up to 30 gallons 

of waste used oil. For example, the Proposed Rule's used oil change frequency could generate 430 

gallons of additional waste oil from one Ajax 2SLB engine in one year. When considered across all 

affected engines, unnecessary oil changes could result in considerable additional waste. 

In response to the Proposed Rule, Exterran, JW Power Company and CSI (EJC) submit the following oil 

and spark plug inspection, analysis, and change management practice recommendations. Based upon 

extensive industry preventive maintenance experience and current best practices developed and improved

upon over many years, this document presents recommended oil and spark plug inspection intervals; 

parameters for changing the oil or replacing the sparkplugs; and recordkeeping requirements. These 

recommendations have been prepared to ensure the optimal maintenance of existing SI RICE without 

creating unnecessary waste due to excess oil changes and vehicle miles traveled to remote facilities. For 

example, with the advent and application of synthetic oils and synthetic oil blends, oil change intervals 

have been increased based on observed product performance. Improved lubricants combined with 

increased reservoir and pump capacities also allow for expanded oil change intervals. This proposal 

requires owners/operators to inspect engines at set intervals to determine whether an oil change or spark 

plug replacement is needed based upon the inspection parameters detailed below. 

Although these recommendations are based upon applying management practices to SI RICE less than 

500 hp, EPA should also consider expanding the application of management practices to all SI area source 

RICE, particularly those in rural locations. Should engines > 500 hp be included within the scope of 

management practices, the associated time intervals for these engines should be extended to account for 

the additional capabilities (e.g., oil reservoir volume) for these engines. 
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Recommended Inspection Intervals and Analysis Parameters

Recommendations for inspection intervals and analysis parameters are discussed in this section, followed 

by tables that summarize the recommendations. These tables use a tabular format similar to Subpart 

ZZZZ tables and provide recommendations for rule revisions. In addition to defined action levels, the

proposed approach includes flexibility to adapt to evolving performance metrics or metrics applicable to a 

particular engine and lube oil. For example, additional advances in lubrication could result in 

performance metrics that are not consistent with specification defined below. In this case, the operator 

could rely on an alternative action level based on the oil manufacturer's specified action level, or 

alternative monitoring techniques. 

4SRB/4SLB <500 hp

4SRB/4SLB Spark Plug Inspection and Replacement. Industry best practices provide that 

owners/operators inspect the spark plugs or analyze spark performance at least every 1,440 hours of 

engine operation. This inspection ensures that the spark plug is able to continue to provide the necessary 

spark required to ignite the air/fuel mixture. This assessment consists of a visual inspection of the plugs, 

or analysis of spark performance using standard diagnostic instrumentation. 

The spark plug is the most accessible power cylinder component and can be the most relevant diagnostic

utility available to detail conclusions regarding engine operating conditions. Should a spark plug 

electrode be worn or damaged, the air/fuel mixture may not be optimally combusted, potentially resulting 

in increased emissions, reduced engine power, and reduced efficiency. Visual inspection of the firing

ends of each cylinder's spark plug can suggest a variety of possible engine conditions. For example, a 

visual inspection of a spark-plug firing end may identify oil or carbon fouling which indicates an engine 

component is experiencing high temperature or excessive wear. If the spark plug is fouled it can be 

cleaned, regapped and returned to service. If the spark plug is worn, cracked or otherwise damaged then 

replacement is necessary. 

Depending upon engine size and configuration, spark voltage/performance may be best measured using a 

non-invasive diagnostic tool, in which case the spark plug does not have to be removed, to assess spark 

plug performance. One tool that may be used for such an analysis is a piece of equipment capable of 

measuring whether the spark plug, spark plug wiring, spark plug coils and voltage have enough energy for 

the spark plug to properly fire. Results of testing can trigger the need to clean or replace plugs.

4SRB/4SLB Oil Inspection and Changing. The recommended management practices include changing the 

engine oil at least every 1,440 hours of engine operation. As an alternative to changing the oil, the

operator may conduct an oil analysis at least every 1,440 hours of engine operation and document the 

findings and any actions required by the oil analysis. If any identified oil parameter in the oil analysis, as 

described below, falls outside the designed “Change Level”, the operator should change the oil within 30 

days of receiving the analysis. The 30 day period is necessitated by potential delays in accessing remote 

sites. 
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The oil analysis and Change Levels recommended below identify parameters that indicate whether the oil

is beginning to degrade beyond its useful life. Nitration and oxidation are typical primary reactions that 

occur in the lubricants of natural gas-fired RICE. As these reactions occur, the additives that were 

originally blended with the oil to counteract this process are depleted and engine performance may 

decline, thereby increasing the possibility of engine malfunction or increased emissions. Key markers of 

oil depletion include: 

 TAN - Total Acid Number (TAN) of the engine indicates that the acidity levels have increased 

beyond an acceptable threshold. This is typically caused by exhaust gases permeating from the 

combustion chamber and mixing with the lube oil, resulting in nitration. 

 Viscosity – Viscosity indicates the typical oil life degradation (increasing viscosity) or oil 

contaminants such as water (decreasing viscosity). A decrease in viscosity is a secondary 

indicator of oil contamination (% relative humidity is the primary indicator). 

 Water (% relative humidity) - relative humidity is the primary indicator of water contamination 

in the oil. 

If the oil analysis indicates that an oil attribute falls outside of any acceptable Change Level, as described 

on the table below, the owner or operator will change the oil within 30 days of receiving the analysis

results. Alternatively, the owner or operator may follow the oil manufacturer's recommended parameters 

and action levels. If the oil manufacturer's levels are followed the owner/operator must document the oil 

manufacturer's recommended change levels and whether the oil analysis results fall outside of such levels 

at each inspection interval. 

Natural Gas RICE Oil Change Levels 

Oil Parameter Change Level A Oil Degradation Indicated by 

Parameter 

TAN (mg/KOH/g) > 3.0 above new oil TAN Acidic content indicator 

Vis @ 100C, (cSt) -20%/+30% change from new Oil viscosity 

Water (%) > 0.5 Water contaminant indicator 

A Owners and operators may follow the oil manufacturer's recommended change levels. If the oil manufacturer's 

levels are followed the owner/operator must document the oil manufacturer's recommended change levels and 

whether the oil analysis results fall outside of such levels at each inspection interval. 

2SLB <500 hp

The engine configuration of the Ajax 2SLB RICE allows for an extended inspection interval for both 

spark plugs and oil inspections. Ajax 2SLB have an extended inspection interval because the power 

cylinder is separated from the crankcase and uses a sealed piston rod for the mechanical connection. Due 

to this engine configuration, no combustion blow by products get into the crank case to contaminate the 

oil. The Ajax lubrication process is described further in Appendix A. Ajax 2SLB are also slow speed,

lower combustion engines, which means that the spark plug fires less than and at a lower temperature than 
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a typical 4SRB or 4SLB engine, thus allowing extended intervals for the spark plugs. 

2SLB Spark Plug Inspection and Replacement. Industry best practices provide that spark plugs for 2SLB 

should be changed or inspected at least every 4,320 hours of engine operation. Visual inspection of the 

firing ends of each cylinder's spark plug can suggest a variety of possible engine conditions. For example, 

a visual inspection of a spark-plug firing end may identify oil or carbon fouling which indicates an engine 

component is experiencing high temperature or excessive wear. If the spark plug is fouled it can be 

cleaned, regapped and returned to service. If the spark plug is worn, cracked or otherwise damaged then 

replacement is necessary. 

Depending upon engine size and configuration, spark voltage/performance may be best measured using a 

non-invasive diagnostic tool, in which case the spark plug does not have to be removed, to assess spark 

plug performance. One tool that may be used for such an analysis is a piece of equipment capable of 

measuring whether the spark plug, spark plug wiring, spark plug coils and voltage have enough energy for 

the spark plug to properly fire. Results of testing can trigger the need to clean or replace plugs.

2SLB Oil Inspection and Change. The recommended management practices include changing the 

crankcase engine oil at least every 4,320 hours of engine operation. (See Appendix A for a description of 

the unique lubrication system associated with 2SLB engines.) As an alternative to changing the crankcase 

oil, the operator may conduct an oil analysis at least every 4,320 hours of engine operation and document 

these findings. If the oil analysis indicates that any listed parameter exceeds or falls below the designated 

Change Level, the operator will change the oil within 30 days of receiving the analysis results. The 

recommended Change Levels for the 2SLB are the same as the 4SRB and 4SLB Change Levels described 

above. 

Alternative Monitoring 

In the event that alternative products or technologies are utilized or become available that could extend 

the inspection intervals or change levels currently proposed, requests shall be submitted to the Director of 

the Office of Air Quality Planning and Standards, or the Director's delegee, for approval of the alternative 

inspection intervals and/or change levels. Examples of such alternative products or analytical tools could 

include improved lubricants, high energy ignition systems, or premium precious metal tipped spark plugs. 

Draft language for petitioning the Director for alternative inspection intervals or change levels, based 

upon alternative provisions in 40 C.F.R. § 63.6620, is provided below in the "Summary of Management 

Practices" section. 

Skip or Extended Period Monitoring

As referred to under current leak detection and repair regulations such as NSPS Subpart VV (40 C.F.R. 

§60.483-2a), “skip period” monitoring could prove effective in dealing with premium oils and spark plugs 

that are capable of further extending expected change intervals. This also provides rule flexibility to 

adapt to technology advances. EPA could consider a form of skip or extended period monitoring that 

would allow for an affected facility to skip a required interval or extend the intervals based upon 
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successful checks of the previous two intervals. For example, if the change levels were not exceeded after 

two inspection periods, then inspection intervals could be extended by 1,440 hours after the next oil 

change. This would also reduce the amount of alternative monitoring requests submitted to the agency 

due to technology advances, such as the use of premium oils and plugs. Draft language for allowing skip 

period monitoring, based upon 40 C.F.R. § 60.483-2a, is provided below in the "Summary of 

Recommended Management Practices" section. 

/Continued on the Next Page/ 
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Summary of Recommended Management Practices

Based upon the foregoing, for engines 500 hp and smaller, the following are recommended changes to 

proposed Table 2d of Subpart ZZZZ in Part 63 – Requirements for Existing Stationary RICE Located at 

an Area Source of HAP Emissions. This document focuses on smaller units but EJC supports similar 

Management Practices for engines larger than 500 hp at area sources. 

Table 2d

For each 

You must meet the following emission 

or operating limitation at all times, 

except during periods of startup or 

malfunction 

You must meet the following emission or 

operating limitation during periods of 

startup or malfunction 

1. NonEmergency 

2SLB <500 HP 

a. Change or inspect oil via oil 

analysis program* every 4,320 

hours of engine operation.+

b. Change or inspect spark plugs 

every 4,320 hours of engine 

operation** 

a. Change or inspect oil via oil 

analysis program* every 4,320 

hours of engine operation.+

b. Change or inspect spark plugs 

every 4,320 hours of engine 

operation** 

2. Non-Emergency 

4SLB <500 HP 

a. Change or inspect oil via oil 

analysis program* every 1,440 

hours of engine operation. 

b. Change or inspect spark plugs 

every 1,440 hours of engine 

operation.** 

a. Change or inspect oil via oil 

analysis program* every 1,440 

hours of engine operation. 

b. Change or inspect spark plugs 

every 1,440 hours of engine 

operation.** 

3. Non-Emergency 

4SRB <500 HP 

a. Change or inspect oil via oil 

analysis program* every 1,440 

hours of engine operation. 

b. Change or inspect spark plugs 

every 1,440 hours of engine 

operation. ** 

a. Change or inspect oil via oil 

analysis program* every 1,440 

hours of engine operation. 

b. Change or inspect spark plugs 

every 1,440 hours of engine 

operation. ** 

* The following are recommended parameters for the oil analysis. If analysis indicates that any of these parameters 

fall outside of the Change Level as indicated, the oil should be changed within 30 days of receiving the analysis. 

Each analysis shall be documented with the actions taken as a result of the analysis.

Natural Gas RICE Oil Change Levels 

Oil Parameter Change Level A Oil Degradation Indicated 

by Parameter 

TAN (mg/KOH/g) > 3.0 above new oil TAN Acidic content indicator 

Vis @ 100C, (cSt) -20%/+30% change from new Oil viscosity 

Water (%) > 0.5 Water contaminant indicator 

A Owners and operators may follow the oil manufacturer's recommended change levels. If the oil manufacturer's 

levels are followed the owner/operator must document the oil manufacturer's recommended change levels and 

whether the oil analysis results fall outside such levels at each inspection interval. 
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+

 The oil analysis intervals is for the crankcase oil on 2SLB engines 

** During the inspection of the spark plug, a visual inspection of a spark-plug firing end may identify oil or carbon 

fouling which indicates an engine component is experiencing high temperature or excessive wear. If the spark plug 

is fouled it can be cleaned, regapped and returned to service. If the spark plug is worn, cracked or otherwise 

damaged then replacement is necessary. Depending upon engine size and configuration, spark voltage/performance 

may be best measured using a non-invasive diagnostic tool, in which case the spark plug does not have to be 

removed, to assess spark plug performance. 

Alternative Monitoring Program 

(a) An owner or operator may petition the Director of the Office of Air Quality Planning and Standards, 

or the Director's delegee, for alternative Change Levels or inspection intervals. If the Director, or 

delegee, does not respond to the request within 60 days then the Alternative Monitoring Program is 

deemed approved. 

(b) If you petition the Director for an alternative monitoring program, you must include the information 

described in paragraphs (b)(1) through (5) of this section. 

(1) Identification of the specific parameters you proposed to use as operating limitations; 

(2) A discussion of how you will establish the upper and/or lower values for these parameters which will 

establish the limits on these parameters in the operating limitations; 

(3) A discussion of how you will establish the alternative inspection intervals; 

(4) A discussion identifying the methods you will use to measure and the instruments you will use to 

monitor any alternative parameters, as well as the relative accuracy and precision of these methods and 

instruments; and 

(5) A discussion of the relationship between the proposed alternative parameters and HAP emissions as 

well as how the proposed parameters compare to the operating limitations in Table 2d. 

Skip Period Monitoring

(a) (1)An owner or operator may elect to comply with one of the alternative monitoring periods specified 

in paragraph (b) of this section. 

(2) An owner or operator must retain records of all alternative monitoring periods. 

(b)(1) An owner or operator shall comply initially with the requirements for oil and spark plug inspections 

and changes or replacements as described in Table 2d. 

(2) After two consecutive inspection intervals listed in Table 2d where the oil analysis does not fall outside 

the Change Levels and/or the spark plugs do not require replacement, an owner or operator may skip the

first inspection interval after the next oil change and/or spark plug replacement, as applicable. 
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(3) After three consecutive inspection intervals listed in Table 2d where the oil analysis does not fall outside 

the Change Levels and/or the spark plugs do not require replacement, an owner or operator may begin to

skip two inspection intervals after the next oil change and/or spark plug replacement, as applicable. 

(4) Notwithstanding anything in this section, in no event shall an inspection interval exceed 8,760 

operating hours. 
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APPENDIX A

AJAX 2SLB LUBRICATION SYSTEM

The recommended manufacturer practice for an Ajax 2SLB requires an oil change on an annual basis for 

the crankcase lubrication system. Ajax 2SLB engines have such an extended oil change interval because

the power cylinder is separated from the crankcase and uses a sealed piston rod for the mechanical 

connection. Due to this engine configuration, no combustion blow by products get into the crank case to 

contaminate the oil. The lubrication process is described further below. 

The AJAX integral compressor uses 3 types of lubrication: force feed, splash and flooded. The force feed 

system is used to provide lubrication to the power and compression cylinders, and pressure packings. The 

cylinder lubrication is typically a major source in the contamination of the oil. In the AJAX the cylinder 

lubrication is part of the force feed system and the oil is consumable, meaning a small amount is 

consumed per day. As a result of the force feed system, the contaminated oil from the combustion is not 

brought into the main crankcase lubrication system to contaminate bearings. 

The splash method is used in the crankcase for the crank pins, main bearings, crossheads, crosshead pins, 

and other major internals. The splash system is consists of a large volume of oil filling the crankcase and 

using the engines crankshaft and rods to distribute the oil to crossheads. Since this system is sealed from 

the combustion gasses the manufacturer rates the crankcase oil change at 10,000 hours. In a conventional 

combustion engine the crankcase oil is contaminated by the combustion gasses blowing by on rings and 

the oil used to lubricate the cylinder walls being recirculated through the oiling system. The AJAX 

eliminates this problem by a crosshead between the connecting rod and the piston rod, this allows for a 

seal to be placed around the piston rod, as you can see in figure 1. Another process which degrades the 

oil in a conventional gas engine is the oil’s exposure to the high combustion heat. Many engine models 

use the oil as a heat sink to reduce the operating temperature of vital engine components; however, the 

AJAX’s crankcase oil is not exposed to any high temperatures. Unlike a conventional natural gas engine 

(Caterpillar, Waukesha, etc) the AJAX is a two stroke design, as you can see in figures 2-4. With this 

design all of the high pressure combustion gasses are on the “outboard” side of the piston, meaning no

high pressure gas is ever exposed to the piston rod and thereby contaminating the oil. 

Finally, the flood system is used primarily in the control box for gears, and is not a major source of

degradation for the oil. 
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Figure 1: Combustion End 

 

 Figure 2: Compression Stroke Figure 3: Power Stroke Figure 4: Scavenging 
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