Small 2.75" flange diffusion pump!

[Robert Dwyer]

So today my new diffusion pump came in the mail and I am very excited! It comes with what appears to be a copper cold trap, which aligns perfectly with the flange of my pneumatic valve i have set up to go to the vacuum a chamber. It also comes with a controller attached to the side.

A few questions though:

1. I do not have the type of pump needed to pump LN2 through the cold trap, so do I need to remove it from the pump or can I leave it?
2. What is the tubing near the bottom of the pump for? I know around the neck water is supposed to pumped through to cool the system, but I do not know why it would be needed at the bottom.

Below are the pictures of the new pump:

Top of the Controller

Controller Text

Tubing at the Bottom of the Pump

[Richard Hull]

The bottom cooling loop is a boiler cooler. Most often this is to allow a very rapid cool-down of the boiler at shut down. Allows the system to be shut down and let up to air quickly. Special valving is often used here. In the early days, a small amount of boiler cooling was often used in normal operation before thermostatic controls and proper design and matching of the heater to thermal metal mass limited the high end boiler temp.

Richard Hull

[Robert Dwyer]

Thank you for the reply Richard, that is good to know! Now, with regards to the cold trap mounted on top, I was thinking of possibly mounting a container of something like styrofoam around it and using a dry ice/acetone bath to cool it. Would that work, or am i better off just using LN2 or removing it?

[Jerry Biehler]

Thats not an LN2 trap, that is a water cooled trap.