What Is HV, HS Hydraulic Oil?
In China national standard GB/T 11118.1-1994, other than HL, HM types of hydraulic oils, there are also HV and HS types.
HV and HS are two types of low temperature hydraulic oils. HV is for cold regions, and HS is for extreme cold regions. These two types of oil both have low pour point, with HV pour point -36℃ and HS pour point -45℃. HV and HS hydraulic oils are required to work under the normal range of temperatures, therefore they need to have excellent temperature-viscosity performances, which is to have a stable range of viscosity values when working at different temperatures; viscosity index is higher than 130, with other indicators of normal hydraulic oil are met. HV and HS hydraulics oil usually use poly-α-olefin (PAO) or group III base oil with low pour points and high temperature-viscosity performances as the base stock, added with viscosity index improvers with good shear stability. Others additives are equivalent to those added into normal hydraulic oils.