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Engine air filters are designed to actually increase their efficiency by using this initial layer of dust as an added filter layer. Initial filter efficiency is usually approximately 98% but increases to more than 99% by the end of the service life of the filter.Therefore, changing an air filter before the useful service life is achieved can result in premature engine wearFinal pressure drop = initial clean pressure drop + 2.5 kPa (Thumb Rule)Diesel Engine Vs SI Engine Fuel Economy based on Intake Air Restricition:While the level of restriction on a closed-loop, feedback, throttled, spark-ignition (SI) engine would not be expected to affect fuel economy (as described above), the additional pumping loss might be expected to affect the fuel economy of the un-throttled diesel engine.ISO 5011 dust test for Air CleanersOil-bath air cleaners, while sometimes required to meet customer specifications, are not recommended by Caterpillar. At best their efficiency is 95% as compared to 99.5% for dry-type filters. Their relative ease of service and insensitivity to water are advantages easily outweighed by disadvantages, such as: Lower efficiency Low ambient temperature limits, low oil level, high restriction at low air flow (such as at low idle), and installed tilt angle may lessen efficiency further. Oil carry-over, which is the oil becoming airborne in the air intake system whether resulting from overfilling or increased air flow, can seriously affect turbocharger and engine life, and may actually become an engine fuel.Queries:Dual Element Air Cleaners Vs Double element or Dry Type with Safety elementISO 5011 to be downloaded. Not available on Web?

Air filters replacement periodicity:The average efficiency of air filters is99.8 % for passenger vehicles and 99.95 for commercial vehicles [3]. Efficiency remains constantthroughout the engine speed range [1]. As the air filter builds a dust film, the holes in the mediabecome smaller, and the filter becomes more efficient at trapping dirt. As the filter traps dirt, it is moredifficult for the air to pass through the filter, and restriction increases in the air induction system. Mostdiesel engines operate at a maximum 4.98 to 6.22 kPa vacuum under full load

Too frequent servicing of the air filter, especially within the first 30 % ofits service life can significantly increase engine wear

Conclusions on air filter clogging influence on power.1. The main criterion of engine air cleaner filter replacement is the value of air flow restriction.2. Variations of air flow restriction within the recommended range do not have significant influenceon the engine power and fuel consumption3. Premature replacement of the engine air cleaner filter may increase engine wear and reduce itsservice life.4. Periodicity of replacement of engine air cleaner filter cartridges on the tested vehicles types doesnot ensure complete utilization of the filter capacity and resource.