Fusor Forums

Have a new vacuum chamber, but two of the seals have an unknown type.

And I think I need to replace them.
It's all full-metal, and the seal seems to be a long fine circular spring with aluminium. It looks like a re-usable type of wire seal, but I don't know if it's re-usable.
The chamber is Leybold Heraus.

The thickness of the "wire" is about 4mm, and the inside diameter is 453mm.

One side of the flange is completely flat, the other side has a 3mm deep groove for the seal.

I believe that's called a C Ring seal. They come spring energized (like yours) and without the spring.

helicoflex

I too think that it's a helicoflex.

Yes that was the correct answer, question is a few weeks old.

Chamber is operational now, but there are still some leaks.

Since helium leak detectors are very expensive, I will try with 5%H2-95%N2 and a hydrogen sensor to find the leak.

I ordered a TGS821 sensor, which can detect 50ppm H2, but I'm a bit in doubt about how to proceed with it. It's made for atmospheric pressure air, so it seems to be logical to place the sensor at the exhaust of the fore vacuum pump.
But, the oil from the pump might contaminate the sensor, maybe... I do have a mist filter.

I can also place it between the turbo and the fore vacuum pump, but would it work at E-1 mbar? The sensor is an alumina substrate with sintered SnO2 (semiconducting), the resistance of the SnO2 drops in the presence of H2, but the absolute H2 pressure is much lower at E-1 mbar. Would it work? we will see.

50ppm is a partial pressure in the order of 5 E-2 mbar if I'm correct, very low for leak detection. How big is your leak?