How to Use a Diffusion Pump

The system must be in a vacuum state before the diffusion pump can work. 

Let the mechanical pumps evacuate the traps before they are placed in liquid nitrogen to prevent freezing oxygen within the traps. 

The diffusion pump should be bypassed in the early stages of the system s pump-down, the cooling water for the diffusion pump must be turned on early, and the diffusion pump must be in a vacuum before the diffusion pump heaters are turned on. If your air-cooled diffusion pump has a fan, turn it on now. Some diffusion pumps are wired so that turning on the heater also turns on the cooling fans. If you have this setup, verify that the fan is working when the heater is turned on. Be sure that the diffusion pump is open to a pump before turning on the heater. Otherwise the heated pump oil s expansion could cause the diffusion pump to explode. 

Metal diffusion pumps require no adjustment because they are factory-set to provide the right temperature. The important thing is to make sure they are filled with the proper amount of oil. After attaching to a vacuum system, simply plug the outlet of the metal diffusion pump into an appropriate (110-120 V or 220-240 V) outlet. If the pump is water-cooled, connect a relay to shut off power to the pump in the event of a water pressure loss. 

When shutting down the system, isolate the diffusion pump and the system from the mechanical pump(s). Vent the mechanical pump(s) after shutting them off. 

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