Machine threaded thermocouple in NPT system

[neo82087]

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]

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.

 

[Bobby_M]

Yeah I was gonna say that too. A 1/4"-20 tap is cheap enough.

 

[mr x]

Where exactly do you plan to put the thermocouple?

 

[neo82087]

http://zamonski.com/herms/mashtun.htm

Similar to this, I'm putting the thermocouple on the end as it enters the mash tun.

 

[mr x]

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]

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

 

[Bobby_M]

This tap: 26035A121
and this brass plug: 50785K24

I do have to agree with MrX though, it might not pick up the temp so well.

 

[HenryHill]

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...