making a connection without admitting gas
Posted: Tue Mar 26, 2019 9:46 pm
Ok, Here is a tricky problem I have. I'm working on a 1985 vintage maser prototype that has NO documentation.
It is a completely sealed (welded) system.
It has a small external ion pump as well as an internal gettering system.
I have powered up the ion pump and it appears that the system has held its vacuum.
There is also a TC gauge tube welded onto the vacuum side and it also shows a good vacuum.
Now the problem.
There is a Hydrogen source capsule that utilized metal hydrides.
It looks as if there is no Hydrogen left!
What happens inside the source is that Hydrogen (at some pressure) is input to a (probably Nickel) thin walled tube.
The tube is heated by passing current through it and causes Hydrogen to diffuse thru the wall onto the vacuum side.
I can see the output line of the Hydrogen source and it does directly access the vacuum system.
There is a 3/8" copper pinch off on the other side of the Hydrogen source, which "I think" is on the Hydrogen side.
There is another bigger pinch off on the main cylinder which is on the Vacuum side.
So if I put a hole into the 3/8" pinch off it should not vent into the Vacuum side.
Such a hole could be connected to a new Hydrogen source from a small compressed gas tank and regulator.
I'd like to avoid getting any air into the pinchoff.
Is there a saddle tap/vampire tap/self tapping valve or some other method to make the hole and at the same time seal around it to prevent contamination? Maybe with low pressure Hydrogen flowing while the puncture is made?
ANY suggestions welcome!
Cheers,
Corby
It is a completely sealed (welded) system.
It has a small external ion pump as well as an internal gettering system.
I have powered up the ion pump and it appears that the system has held its vacuum.
There is also a TC gauge tube welded onto the vacuum side and it also shows a good vacuum.
Now the problem.
There is a Hydrogen source capsule that utilized metal hydrides.
It looks as if there is no Hydrogen left!
What happens inside the source is that Hydrogen (at some pressure) is input to a (probably Nickel) thin walled tube.
The tube is heated by passing current through it and causes Hydrogen to diffuse thru the wall onto the vacuum side.
I can see the output line of the Hydrogen source and it does directly access the vacuum system.
There is a 3/8" copper pinch off on the other side of the Hydrogen source, which "I think" is on the Hydrogen side.
There is another bigger pinch off on the main cylinder which is on the Vacuum side.
So if I put a hole into the 3/8" pinch off it should not vent into the Vacuum side.
Such a hole could be connected to a new Hydrogen source from a small compressed gas tank and regulator.
I'd like to avoid getting any air into the pinchoff.
Is there a saddle tap/vampire tap/self tapping valve or some other method to make the hole and at the same time seal around it to prevent contamination? Maybe with low pressure Hydrogen flowing while the puncture is made?
ANY suggestions welcome!
Cheers,
Corby