Build Your Own Helium Leak Tester | 10-7 Flow Spec

[dingpud]

Has anyone out there built any type of "bench top" helium leak detectors? I am just getting into this, and thought I would start a thread that I could post some information to. The spec seems to reference a flow of no more that 10^-7.

And of course, I will post the wiki site...
http://en.wikipedia.org/wiki/Helium_mass_spectrometer

This should be interesting...

 

[mgb_phys]

If you doing this yourself there are easier leak detectors to build.
The 'string and sticky tape solution' is to use a Pirani gauge and some sort of large hydrocarbon gas.
The pirani gauge relies on a hot wire in vacuum to measure air pressure, so spraying some nasty (probably now banned) can of hydrocarbon around the leaks get sucked into the vacuum and hits the wire causing a change in reading.

It's not as sensitive as Helium because it doesn't get through such small holes, and irt leaves you with a headache but it is cheap and easy - especially if you already have a pirani gauge on the system.

 

[dingpud]

That's all new to me...thanks for the suggestion. Some sort of hybrid will come out of this...

 

[mgb_phys]

I think it's the mass-spectrometer that's the tricky bit.

 

[f95toli]

And you need a good pump. Most modern leak-detectors use turbo-pumps, older models like the one on the picture use diffusion pumps (with a liquid nitrogen cryotrap).

You probably need to spend at least about $10 000 on the pumps alone.

 

[dingpud]

You probably need to spend at least about $10 000 on the pumps alone.

Holy crap...

 

[mgb_phys]

sorry -not clear, are you intending to build an entire leak detector as a project or are you working on vacuum systems and need some way of finding a leak?

As f95toli said - leak detectors only work in high vac (>10^-6) so you need a good pumping system. You might be abe to pick up an old diffusion pump cheap since most people stopped using them 10-20 years ago.

 

[dingpud]

Yeah, I am looking for 10^-7 so I am probably not going to be able to make this thing...

 

[andy taylor]

hi all, there area vast array of helium mass specs on the market these days..main players in these are alcatel varian leybold and pffeifer...they are all ballpark 10 k ish in price...the alcohol and pirani gauge is a good technique if yiou have little cash...itf your workingon large vac furnace or sucha beast some guys hire systems too... if you were going to get a system i would go for the leybold or alcatel they havea gross hold range ie..tye are subsensitive and will pick the helium up from 10-3 millibar l/sec..regards andy can let you have more info if you wanted

 

[ahmadi zabidi]

hi,
have no idea u wanted to test helium leak to atmosphere or in some sort of system in which helium flow. I do fabricate pneumatic weld leak detector. It works this way...In shipbuilding vessel plates are welded & those fillet needed to go NDT for leakage .one way of doing it is to cover specific welded fillet (test area) with an equipment (vacuum box) that isolate this fillet fr atmosphere pressure. Working prrinciple- pump air out & look for bubbles coming fr those fillet. easy aah! One of major shipbuilder in south east asia have use my equipment successfully (test certified by Bureau Veritas & Shell) we sold bout 50 unit in 2010. size & shape - customised to our client requirement.








QUOTE=dingpud;1947528]Has anyone out there built any type of "bench top" helium leak detectors? I am just getting into this, and thought I would start a thread that I could post some information to. The spec seems to reference a flow of no more that 10^-7.

And of course, I will post the wiki site...
http://en.wikipedia.org/wiki/Helium_mass_spectrometer

This should be interesting...[/QUOTE]