[Trochoidal]

Originally Posted by Choda

^^^ UPDATE

This picture is wrong. I reached out to Go Fast Bits about the mac valve. they said the "P" stamped in the side is not a fake indicator, its a thread indicator. This mac valve has what is called parallel thread or BSP thread which is also 1/8. So not sure why the hell they would carry these and not the common 1/8 npt threaded valves but whatever. So another order from amazon and I should be all set.

If and when I have to change this valve, ill be going with a 1/8 npt valve.

Hey Choda, I’ve followed along with your progress. Looks like you’re getting it all together nicely.

BSP comes two ways. BSPP and BSPT. Last letter indicates P for parallel and T for tapered.

Comparing this NPT to BSPP the differences are thread angle, form and pitch. NPT in the 1/8” size is 60° angle with flats at the root and the crest of threads. NPT is 27 TPI.

BSPP in the 1/8” size is 55° angle with radius at the root and crest unless truncated. BSPP is 28 TPI.

We machine BSPP threads at my job because the radius is stronger than the flats of the NPT. Another purpose is BSPP will use a seal washer versus sealing on the threads of the tapered thread (NPT). BSPP is common in higher pressure applications.