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Machine threaded thermocouple in NPT system

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neo82087

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I've got a 1/4x20 .5 inch thermocouple that I need to get into my system
somehow. I want to put it on a 1/2 female pipe thread outlet, but I'm not sure
how to incorporate it. I thought about using a 1/2 x 1/8 bushing, but I'm not
sure if that would work since the 1/8 pipe thread is 27 threads/inch. Anyone
know of another way to incorporate a machine threaded screw into a system that
uses all pipe thread? Thanks
 

fifelee

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neo82087 said:
I've got a 1/4x20 .5 inch thermocouple that I need to get into my system
somehow. I want to put it on a 1/2 female pipe thread outlet, but I'm not sure
how to incorporate it. I thought about using a 1/2 x 1/8 bushing, but I'm not
sure if that would work since the 1/8 pipe thread is 27 threads/inch. Anyone
know of another way to incorporate a machine threaded screw into a system that
uses all pipe thread? Thanks
Buy a plug for the 1/2NPT then drill and tap a hole in the plug for the 1/4-20.
 

mr x

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You may want to cut that thermocouple and throw the bolt away. The wires are just twisted at the end. What I like to do is to run the wire down 1/4"ss tubing (although any inert standard size tubing will do)and seal the end with silicone, with the bare sensing connection just sticking out. Now you can drill out a compression fitting and you have a watertight seal to slide the tubing through.

The problem I see with your situation is that a drilled out plug in that area could screw with your readings. If you have to do it, try to get a hollow cast plug so the thermocouple will sit in the wort better.
 

raceskier

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You could try an AS4861 (formerly AN912 and can be found under that part number)-06 Pipe Bushing. It is a 1/2-14NPT outer thread witha 1/4-18NPT inner thread. The 1/4-20 machine thread is close enough to the 1/4 -18 pipe thread that you could probably get a few threads to engage. Use teflon tape and it won't leak. Kinda "ghetto" but I think it will work.

Mc Master-Carr: http://www.mcmaster.com/
Part No. 44705K394
 

HenryHill

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My experience with electronics and liquids is that you 'pot' the wires into what ever you are planning to seal.

'Potting' is pouring a two part epoxy around the wires-MUCH better than silicone.
This is the industrial method and not exactly more expensive if you have any type of two part epoxy.

Silicon is 'ghetto', and asking for a failure-sorry, just saying...:eek:
 
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