开云体育

?

I am an experimentalist retired but have some part time contract work to help pay for my toys on a beer budget. I have some personal experiments that I want to try out with my vacuum systems. I am assuming there are others in this group in my situation; decided to provide information that might help others. I have tried finding information regarding repairing Welch vacuum pumps in order to try fixing those bought very cheep on Ebay. Recently I purchased a Welch 1402 pump, with ballast, at a relatively cheep price from Ebay. The pump was very dirty with sludge; it required extensive cleaning; I was forced to take the pump completely apart, including the ballast valve, and wash and clean it throughly. I am not claiming the following procedure is correct; but that it has worked for me.

First of all I wish to thank the following link for giving me guidance in fixing my pump:

I decided to try out making my own gaskets using the sheets given in : ; I used an Xacto knife to cut out the form for both gaskets required.

To reseal the ballast valve I use the information given in: ; from there I purchased the suggested Loctite 592 Thread Sealant 50ml ~ 59231 from:



I can't count the number of times I assembled / disassembled the 1402; in reassembling I partially tightened the bolts to allow the vanes to clear the stator without sticking. Finally I tightened them after the vanes seemed properly seated. My pump still wasn't working properly. I noticed bubbles occurring ; fixed it by adjusting and cleaning the valves. Afterward the pump seemed still weak pumping. I decided to flip the vanes each 180 degrees. I was lucky, this fixed my pump; it now pumps very fast; and seems to achieve , with moderately used oil, about 2 Microns as read by my TC gauge ( I zeroed it using a diffusion pump). I am very happy with my pump now.

I am hopping this information helps someone in this group