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Help Identifying this Vacuum Fitting

Posted: Thu Nov 06, 2014 11:43 pm
by Dave Xanatos
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?

Thanks,

Dave
DSC01302.JPG

Re: Help Identifying this Vacuum Fitting

Posted: Fri Nov 07, 2014 12:26 am
by Doug Browning
Looks like the usual pipe thread for a thermocouple gauge.

Re: Help Identifying this Vacuum Fitting

Posted: Fri Nov 07, 2014 12:44 am
by Dave Xanatos
OK... I'm assuming that's different from NPT even... yet another new fitting to try to recognize :)

Thanks,

Dvae

Re: Help Identifying this Vacuum Fitting

Posted: Fri Nov 07, 2014 12:48 am
by Carl Willis
The TC gauge thread is 1/8" NPT.

Re: Help Identifying this Vacuum Fitting

Posted: Fri Nov 07, 2014 12:56 am
by Dave Xanatos
Now THAT's a familiar thread! :) Thanks.

Dave

Re: Help Identifying this Vacuum Fitting

Posted: Fri Nov 07, 2014 4:13 am
by Jerry Biehler
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.

Re: Help Identifying this Vacuum Fitting

Posted: Sat Nov 08, 2014 8:19 pm
by Chris Bradley
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.

Re: Help Identifying this Vacuum Fitting

Posted: Fri Nov 21, 2014 8:36 am
by Jerry Biehler
BSP does show up mostly on Japanese stuff, that is what they use on most fittings.