Pipe Threads need help

Post by **PJ.zook** » Sat Mar 21, 2009 4:43 pm

Im in need of quick outers wisdom. Im fitting an electrical Speco water temp gauge in my zook, and need to tap a thread into my thermostat housing for the supplied sensor.
The supplied sensor has a 1/8 NPT thread which is tapered (i think you automatically assume that with NPT), now i have a tap here that is 1/8 BSPT28. When measuring with verniers, the tap is not tapered, but can i still use it, are they the same?

Post by **SIMMO84** » Sat Mar 21, 2009 4:48 pm

Yeah itll work its not supposed to be tapered. that is what is supposed to seal th ejoint.

Post by **ricky1970** » Sat Mar 21, 2009 4:57 pm

NPT and BSPT are not the same, from memory 1/8 BSPT is 28tpi and 1/8 NPT is 27tpi. Thread form is also a little differant.

Post by **awill4x4** » Sat Mar 21, 2009 5:19 pm

You'll have no problems, we use our 1/8" NPT tap to cut threads and fit 1/8" BSPT brass fittings all the time, mainly because our 1/8" BSPT tap is rooted.
Regards Andrew.

Post by **nastytroll** » Sat Mar 21, 2009 7:14 pm

NPT = National Pipe Tapered thread, american.

BSPT = British Standard Pipe Taper thread.

BSPT and NPT taps should be tapered. A BSPP is parraelle as is NPF.

NPT is also a bigger diameter than BSPT.

You can get away with mixing NPT and BSPT in your application as its low preasure but they are 2 different threads.

Pipe and hydraulic thread details here.
http://www.ryco.com.au/TechInfo.aspx?WebPageId=71

Post by **GRPABT1** » Sat Mar 21, 2009 7:35 pm

On another note supercheapy sell in hose spacers with threads that fit specifically for this.

Post by **PJ.zook** » Sat Mar 21, 2009 7:38 pm

Thanks for the replys. I will drill and tap some scrap aluminium and test fit the sensor, see if there will be any problems. My thermo housing has a perfect space to fit the extra sensor, so i dont need the spacer thanks anyway.

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