This document specifies methods and special requirements for measuring the maximum tolerable pressure difference, effective compression ratio, compression ratio with zero throughput and overflow valve pressure difference of mechanical booster vacuum pumps.It applies to mechanical booster vacuum pumps employed for medium vacuum or rough vacuum applications including gas-cooled mechanical booster vacuum pump and multiple mechanical booster vacuum pump systems.It covers particular characteristics of mechanical boosters that are different from those of the usual positive displacement vacuum pumps. Maximum tolerable pressure difference Δpmax, effective compression ratio Keff, compression ratio with zero throughput K0 and overflow valve pressure difference Δp1 are special characteristics of the performance of mechanical booster vacuum pumps.