Natural Gas engines need special attention paid to inlet fuel quality if it is known that the gas is contaminated.  Even clean pipeline grade gas can be somewhat contaminated, this contamination may become concentrated in situations where an engine is a standby unit.  Protection for these units is not very expensive and worth the assurance that if dirt or moisture does exist it will be removed.  A Triton particulate and aerosol removing filter upstream of a gas engine will assure clean fuel.