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MEMORANDUM 

TO: Melanie King, Environmental Protection Agency 

DATE: April 9, 2010 

RE: Extended Intervals and Consistency for Spark Ignited RICE 

Management Practices 

SPARK IGNITED ENGINE EXTENDED AND CONSISTENT INTERVAL JUSTIFICATION

This memorandum was prepared to support the collective comments of Exterran, JW Power and 

CSI ("EJC Coalition") previously submitted on June 3, 2009 and advocates for longer intervals and 

consistency when applying management practices to Spark Ignited Reciprocating Internal 

Combustion Engines ("SI RICE") at area sources. On March 3, 2010, EPA issued the National 

Emission Standards for Hazardous Air Pollutants for Reciprocating Internal Combustion Engines; 

Final Rule (“diesel rule”), for diesel-fueled Compression Ignited ("CI") RICE. EPA included 

bifurcated management practices for diesel engines located at area sources of hazardous air 

pollutant (“HAP”) emissions. An interval period of 1,000 hours was established to inspect the 

oil and air filter. A second interval period of 500 hours was established to inspect the belts and 

hoses. Based upon the cleaner-burning combustion properties of SI RICE and the practicalities 

of inspecting rural, unmanned engines, EPA should establish a single, consistent management 

practice intervals for all SI RICE management practices based up engine type, e.g., 1,440 hour 

interval period for rich burn SI RICE and 4,320 hours for lean burn SI RICE. 

 Further information supporting the longer, consistent intervals is provided below. For 

the sake of efficiency, this addendum supplements but does no repeat the SI RICE management 

practice recommendations submitted to EPA on January 27, 2010. 

SI RICE Extended Intervals 

 The longer inspection intervals for SI RICE are justified because of the cleaner-burning 

characteristics of natural gas. For example, liquid fuels such as diesel and gasoline contain 

significant proportions of carbon, sulphur, and nitrogen. When diesel enters the combustion 

chamber the liquid fuels wash the lubricant from the cylinder walls causing dilution and carbon 

particles or soot is formed. The carbon deposits/particles deplete the engine oil additives thus 

shortening the oil life. The combination and accumulation of these oil contaminants (unburned 
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fuel, ash, and acids) accounts for the potential breakdown of the lubricant thus potentially 

accelerating the engine oil contamination and decreasing the effectiveness of the oil 

lubrication. 

 Natural gas is a cleaner-burning gaseous fuel free from the liquid hydrocarbons that can 

potentially cause the accelerated oil contamination discussed above. Due to the cleaner 

burning, gaseous nature of natural gas, the by-products of combustion (carbon particulates and 

ash) are significantly reduced which slows the rate in which contaminants are released into the 

engine oil. As a result, it is reasonable to expect an increased oil change/analysis interval of 

1,440 hours for rich-burn SI RICE located at area sources of HAP emissions. 

 As discussed in the January 27th Management Practice submittal, the engine 

configuration of the Ajax 2-stroke lean burn (2SLB) RICE allows for an even greater extended 

inspection interval for both spark plugs and oil inspections. Ajax 2SLB RICE 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. Ajax 2SLB are also 

slow speed, lower combustion engines, which means that the spark plug fires less than and at a 

lower temperature than a typical 4SRB or 4SLB engine, thus allowing extended intervals for the 

spark plugs. 

Interval Consistency

 Finally, we request that any SI RICE Management Practice intervals be consistent across 

all inspections. Bifurcated inspection intervals will create excessive trips to remote area 

sources which increase costs and vehicle emissions but do not provide a corresponding 

environmental benefit. Creating a consistent inspection interval for all management practices 

eliminates the unnecessary trips. 

In lieu of belts and hose inspection, the SI RICE Management Practice recommendations 

submitted on January 29, 2010 included proposed intervals for spark plug inspections and 

replacements. 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. 

 Although preventative maintenance standards require that belts and hoses be 

inspected, current maintenance and operating practices do not indicate that an increased 

frequency of belt or hose inspections reduce emissions. In fact, should a faulty belt or hose fail, 
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the engine will shut down, therefore preventing increased emissions. 

 Any inspection interval for spark plugs (or belts and hoses) should be consistent with 

other inspection interval periods on SI RICE. As submitted in the June 8, 2009 comments to EPA 

on the SI RICE, a majority of the SI RICE are located at rural, remote, unmanned locations. This 

is particularly true for area sources. Management practice intervals should be consistent to 

prevent excessive staffing, vehicle trips, and costs which do not improve engine performance or 

reduce emissions.