Telstar Vacuum Pump

[KiwiBob]

I have been offered a Telstar 2F-3 Vacuum pump.
This is the type refrigeration engineers use to recharge cooling systems.
Has anyone tried using one of these on their vacuum chambers.
They are supposed to be able to pump to 2 microns which I think is about -2bar.

 

[magpens]

Vacuum is vacuum ... and 2 microns is right next to nothing ... like almost 0 bar. . So from that perspective you are OK.

Next question is how long does it take to pull that vacuum ?

You are probably going to be evacuating a paint pot ... something like a cubic foot. . If you can get down to 0 in a minute or so, I would say you are good to go.

Will be interested in other replies.

Just did a search ... here is the result: http://www.techeiscatel.ru/media/datasheet/AVS_Telstar_2F3-2F6-2F10.pdf

Base pressure for that pump is 25 microns, and pump rate is about 3 cubic meters per hour. . As I interpret, you are very much OK.
Wish I had that pump. . Sounds every bit as good as the pumps I used for evacuating similar chambers in experimental physics.

 

[KiwiBob]

I have just picked it up and it pulls my 4lt chamber down to -30psi in less than 30 seconds. Being a commercial design I don't think it will over heat on long jobs. I will be doing a batch tomorrow so will repost on how it copes

 

[magpens]

Please let us know how it goes.
It will be useful information for me when I come to buy my own vacuum system for casting.

If your chamber is well sealed and if you have a valve between the pump and the chamber, you might be able to get away with switching the pump off after you have pulled the vacuum. . You should, of course, have a gauge on the chamber itself to determine if you have to restart pumping.
I think things will be OK as long as the chamber pressure does not rise above about 10-20 Torr. (mm of Hg). Atmospheric is 760 Torr.

Thanks. . And, good luck ! . Time for me to hit the sack. . Goodnight, or good evening !

 

[Dehn0045]

I use a generic version that is similar. Mine overheats after a couple hours, my understanding is that this style is not meant as "continuous duty". Since it is pulling such a low vacuum there is not much flow going through the pump, so there is nothing to carry the heat away. I put an external fan on it and it will usually run without tripping on high temperature. If you had a full-time stabilizing operation then a belt driven continuous duty version would probably be the right choice, for hobbyists a cheap rotary vane like this seems to be the right choice (you could buy about 30 of them for the same price)

 

[KiwiBob]

Ok guys it works perfectly. I ran it continuously for four hours at -30psi and I could still hold my hand on the pump. I use it for stabilising spalted wood so need some long periods depending on the timber. Next time I will measure the actual temp. My pump was a used unit being sold by a refrigeration engineer. He told me it was four years old. I paid $80NZ and he has more available but I guess freight to the US would be a killer.