AirSept's A/C Charge Guard filter allows technicians to charge refrigerant into hybrid vehicles while eliminating the risk of lubricant contamination. Introducing even a small amount of PAG oil (the lubricant commonly used in belt-driven compressors) can damage the high voltage insulation in an electric compressor. A single A/C Charge Guard unit allows no more than 240 ppm of liquid (including PAG) into the A/C system, less than 1/4 of the 1,000 ppm limit proposed by SAE J2788H. J2788H also recommends technicians change or flush hoses before charging a hybrid vehicle with equipment that also used to service non-hybrids. Charge Guard traps lubricant coming out of the service hoses and saves the tech from having to flush or change hoses.