Method for operating a vacuum pump and vacuum pump

Vacuum pump 10 and method for operating a vacuum pump wherein first the humidity in the vacuum pump, or humidity in the environment of the pump, is determined and if the determined humidity is above a pre-set threshold a control signal is generated to control condensation reduction means for reduction of humidity within the vacuum pump or to generate a warn signal. Preferably the humidity is determined by a humidity sensor 20, or an environmental humidity sensor 22. The pump may be a scroll pump and the reduction of condensation may be achieved by controlling, with control unit 12, an inlet valve 24, outlet valve 26, gas ballast system 18, 19, and the vacuum pump itself in addition to a cooling system and/or a heating system. When the pump is shutdown the control unit may close the inlet valve and/or close the outlet valve and may continue to run the pump for a pre-set time until the humidity falls below a second threshold. The warning signal can alert a user to condensation in the pump. Benefit: prevents corrosion particularly of cast iron dry vacuum pumps.