The new cutoff switch came in for my compressor. Just like the old one, it has 1/8" NPT threads and an o-ring. That alone doesn't quite make sense to me, as I thought NPT threads were self-sealing.
There is possible residue of a sealant on the old switch, but I can't be sure.
Should I use Teflon tape here?
Is there a locknut above the O ring? If so the threads are not NPT. Take it by a hardware store and check it on a new fitting.
If it really is NPT than the O-ring isn't doing anything.
If it is a straight ORB it will not have the locknut/adjusting nut above the o-ring, if it is an ORB elbow it will.
Can't really hurt to use a sealant on it.
If they really are NPT threads you should use teflon tape on them. They rely on this for a seal:
Thanks, folks.
This is what I got:
So there's obviously no nut above the threads, and I think the o-ring is superfluous. I lack the means to verify that the threads on the original were NPT, but all the replacement switches were advertised as NPT, and AFAIK, most compressor fittings are NPT.
I'll use the Teflon tape.
See if there is a recess for the o ring, and if it bottoms when you thread it in. If it does, you don't need the tape.
That looks like a straight thread. Teflon tape is not necessary. There won't necessarily be a recess for the o-ring, likely just a flat surface.
That looks like a straight thread to me. I work with 1/8-27 threads daily, never seen one with an o-ring.
looks like straight thread to me too. Compare it to the threads on the old one, you don't want to screw straight threads into pipe.
The hive mind was once again correct. They were straight threads, no sealant necessary. The o-ring seated, no leaks, and my el cheapo compressor works again!
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