How shoud one switch off a rotary vane pump?

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Jukka Salminen

If you use a water pump it's safer to open the shutter first, otherwise the water could flow back from the pump.

Phil Denby

Hi Ekaterina, You should ideally valve the vacuum port side of the pump off, switch the pump off and then let in air to the vacuum side once the pump has come to rest. This ensures there is no residual vacuum left in the pump which would potentially allow the diffusion of pump oil out of it towards your vacuum system. Many pumps do now actually have automatic valves inside them to prevent this, but it is always a good precaution to take.