Know the thread size ?

[davecole]

Want to replace the gauge. Before I order one, I need the thread pitch/size. I’ve already got a good guess. But do you KNOW? 

thanks in advance.

 

[Eaglebeak]

There's no way to tell for sure unless you remove it. If it's an American-made valve I would put my money on it being 1/8 NPT. It is sealed with thread tape so which also points to it being a tapered (NPT) type.

 

[Gerry52]

1/8 npt

 

[cwcarrera]

I have used a couple of these, they work very well and the 2 I have used are very accurate.

https://www.ebay.com/itm/LIQUID-FILLED-PRESSURE-GAUGE-0-5000-PSI-1-5-FACE-1-8-NPT-BACK-MOUNT/192831726337?hash=item2ce5aaa301:g:yxkAAOSwW0tcbC~F

Chip

 

[davecole]

Chip, you’re the best. That’s the way I’ll go ! 

 

[cwcarrera]

 

[Chickenthief]

1/8" NPT (US National Pipe Thread which is conical!) is something like 9.7mm~.381"

1/4" NPT is roughly 13.1mm~.515"



So a dial caliper will sort you out in a jiffy!



To add to the confusion you can encounter BSP (British Standard Pipe which is cylindrical) and BSPP (British Pipe Thread Tapered which is comparable to NPT). The main difference between US and UK standards is that US is 55deg thread angle and BSP is Whitworth thus 60deg.

So a male US thread can go fully into a UK female but not the opposite.

 

[cwcarrera]

To add to the confusion you can encounter BSP (British Standard Pipe which is cylindrical) and BSPP (British Pipe Thread Tapered which is comparable to NPT). The main difference between US and UK standards is that US is 55deg thread angle and BSP is Whitworth thus 60deg.

I think you got the two British threads backwards...

BSPP is British Standard Parallel Pipe, thus being parallel and not tapered.

BSP also known as BSPT is British Standard Pipe Tapered, thus being tapered thread.

Here is a link to an article that explains all the differences very well;

https://www.indanc.com/Additional-Departments/Header-Content/TECH-ZONE/USEFUL-ARTICLES/The-Difference-Between-BSPP-BSPT-and-NPT-Fittings#:~:text=BSPT%20fittings%20require%20sealants%20whereas,and%20do%20not%20require%20sealants

 

[Chickenthief]

Yup!

Got those ancient bass ackwards standards mixed. Sorry.



But the NPT 55deg thread angle and the BSP 60deg angle thing still holds.

US goes into UK but no UK into US threads.