Some of the most commonly used hydraulic fluids include mineral oil based fluids, with additives, as well as water and synthetic fire resistant fluids. It is important to know what type of hydraulic fluid you are using when specifying a hydraulic filter element. 

Mineral Oil

HL: Oil with no active additives

HL: Oil with additives to protect against corrosion and aging (HLP)

HM: Oil with increased protection against corrosion, aging, wear

HV: Mineral Oil (Class HM) with a higher Viscosity-Temperature Index (HVLP)

HG: Oil (Class HM) with shock resistant features

Fire Resistant Fluids - Water Based

HFA: Oil in Water emulsion (water>80%)

HFB: Water in Oil emulsion (water>40%)

HFC: Water Glycol (polymer in water)

Fire Resistant Fluids - Synthetic (water free)

HFDR: Phosphate ester

HFDS: Chlorinated hydrocarbons

HFDT: HFDR and HFDS

HFDU: Synthetic anhydrous liquids other than phosphate ester

Need help with a Hydac, Pall or other hydraulic filter application? Contact Filter Element Store for your hydraulic filter element needs.