BSPP thread size on Neptune FS50

John71 · Aug 19, 2020

This may be an odd question, but does anyone know what the actual BSPP thread size is on the FS50? I want to use them inline on 1/2" RODI tubing with John Guest fittings that go from BSPP to RODI tube and I want to make sure I can get the correct adapter before I try it out. I have contacted Neptune, but so far they are taking forever to respond.

SuncrestReef · Aug 19, 2020

Measuring threads is never easy, but according to my micrometer the male threads on the flow sensor are 0.782" OD, 0.733" ID, and 14 threads per inch. I looked up a standard BSPP thread chart and it states a 1/2" BSPP male fitting is 0.82" OD at 14 threads per inch, so I'm not sure if my micrometer is slightly off.

Outer diameter:

Inner diameter:

John71 · Aug 19, 2020

SuncrestReef said:
Measuring threads is never easy, but according to my micrometer the male threads on the flow sensor are 0.782" OD, 0.733" ID, and 14 threads per inch. I looked up a standard BSPP thread chart and it states a 1/2" BSPP male fitting is 0.82" OD at 14 threads per inch, so I'm not sure if my micrometer is slightly off.

Outer diameter:

Inner diameter:

Thanks...pretty much tells me what I need to know. Are the openings chamfered around the inside at all? It almost looks like they are slightly from the picture, but hard to tell.

SuncrestReef · Aug 19, 2020

John71 said:
Thanks...pretty much tells me what I need to know. Are the openings chamfered around the inside at all? It almost looks like they are slightly from the picture, but hard to tell.

I'm not sure if you're asking about the ends of the threads, or the interior opening. Here are a couple more photos, so hopefully this answers your question.

John71 · Aug 20, 2020

SuncrestReef said:
I'm not sure if you're asking about the ends of the threads, or the interior opening. Here are a couple more photos, so hopefully this answers your question.

Was looking at the interior opening. Can you give me a shot of what the inside of the threaded end of the PVC adapter looks like that comes with it? AFAIK it is supposed to seal against the "flat" although I hear that you typically use teflon tape with it too. Wanted to see if the inside of the adapter is just flat or if it is slightly conical shaped where it seats.

SuncrestReef · Aug 20, 2020

John71 said:
Was looking at the interior opening. Can you give me a shot of what the inside of the threaded end of the PVC adapter looks like that comes with it? AFAIK it is supposed to seal against the "flat" although I hear that you typically use teflon tape with it too. Wanted to see if the inside of the adapter is just flat or if it is slightly conical shaped where it seats.

Not sure if these photos will show what you’re looking for. It’s not easy getting an interior shot.