This part of ISO 21360 specifies methods for measuring the volume flow rate, base pressure, water vapour tolerance, power consumption, and the lowest start-up temperature of positive displacement vacuum pumps, which discharge gas against atmospheric pressure and with a usual base pressure <10 kPa. In this part of ISO 21360, it is necessary to use the determinations of volume flow rate and base pressure specified in ISO 21360-1. This part of ISO 21360 also applies to the testing of other types of pumps which can discharge gas against atmospheric pressure, e.g. drag pumps.