Help Identifying this Vacuum Fitting

Every fusor and fusion system seems to need a vacuum. This area is for detailed discussion of vacuum systems, materials, gauging, etc. related to fusor or fusion research.
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Dave Xanatos
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Help Identifying this Vacuum Fitting

Post by Dave Xanatos » Thu Nov 06, 2014 11:43 pm

I haven't had a lot of hands-on with various fittings yet, just KF/NW & CF... this doesn't look like swagelock, or VCR to me... is it just NPT?

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Dave
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Doug Browning
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Re: Help Identifying this Vacuum Fitting

Post by Doug Browning » Fri Nov 07, 2014 12:26 am

Looks like the usual pipe thread for a thermocouple gauge.

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Dave Xanatos
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Re: Help Identifying this Vacuum Fitting

Post by Dave Xanatos » Fri Nov 07, 2014 12:44 am

OK... I'm assuming that's different from NPT even... yet another new fitting to try to recognize :)

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Dvae
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Carl Willis
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Re: Help Identifying this Vacuum Fitting

Post by Carl Willis » Fri Nov 07, 2014 12:48 am

The TC gauge thread is 1/8" NPT.
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Re: Help Identifying this Vacuum Fitting

Post by Dave Xanatos » Fri Nov 07, 2014 12:56 am

Now THAT's a familiar thread! :) Thanks.

Dave
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Jerry Biehler
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Re: Help Identifying this Vacuum Fitting

Post by Jerry Biehler » Fri Nov 07, 2014 4:13 am

Yep, NPT. Just use generic teflon tape on it, I have some on a fitting on my SEM and it is sitting at 5x10^-6.

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Chris Bradley
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Re: Help Identifying this Vacuum Fitting

Post by Chris Bradley » Sat Nov 08, 2014 8:19 pm

Just to cover bases here, such thread couplings may also come as BSP 1/8".

BSP is 28 threads/inch, NPT is 27, otherwise all apparently the same until you find they only screw up a couple of turns and leave you wondering what's going on!

Perhaps you are unlikely to see BSP in the US, but it exists so is not impossible.

It's trouble here in UK because we get both. Gotta be careful not to scrap a thread putting one with the other!

FWIW, BSP 1/4" is 19 TPI and NPT 1/4" is 18 TPI.

For 1/2" they are both 14/inch and you can sort of use one with the other but BSP is a 55 deg thread and NPT is a 60 deg, so you get a bit of interference though stuffed with some teflon tape they tend to 'work'.

3/4" are also both 14/inch, but the NPT is a shade smaller diameter too so you can fit NPT into BSP with a bit of teflon tape wadding in the gap in an emergency but not necessarily the other way around. Not recommended!

The general note is to be mindful the two standard exist.

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Re: Help Identifying this Vacuum Fitting

Post by Jerry Biehler » Fri Nov 21, 2014 8:36 am

BSP does show up mostly on Japanese stuff, that is what they use on most fittings.

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