[PSUBS-MAILIST] High Pressure Port Dimensions

Sat Nov 5 17:42:25 EDT 2016

Alan,  The thread lengths and specs are SAE J-1926-1.  Ports on the regs are generally 3/8”  .  Female thread lengths for  3/8”, 7/16” ½” 9/16” are 10mm, 11.5, 11.5, 12.7  resp.  The male threads are shorter.  All in parker or Swagelok literature.  Those ports are fine in the small sizes up to about 1-1/16”.  Smaller sizes are good for over 6,000 psi  and up to approx. 9,000 psi. in SS.  Brass is not so good  Think of it as a ratio of area to circumference.  We don’t like doing burst tests on Threads of 1-5/16” as the thread stretches and then the o-ring pops out at around 20,000 psi, which negates the test.  Generally 6 threads on most sizes is sufficient. 

Hugh  

From: Personal_Submersibles [mailto:personal_submersibles-bounces at psubs.org] On Behalf Of hank pronk via Personal_Submersibles
Sent: Sunday, 6 November 2016 1:17 AM
To: Personal Submersibles General Discussion
Subject: Re: [PSUBS-MAILIST] High Pressure Port Dimensions

Alan,

There must be a how many threads per mm to how much psi chart out there.  You would think if the plug is 7.16 mm long, then that should be your bench mark.

Hank

On Friday, November 4, 2016 10:23 PM, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

I am still in the process of ordering some pressure transmitters that
will screw in to the high pressure port of a scuba tank. Have had a 
number of quotes, & it looks like some manufacturers will do a limited
run with the non standard 7/16 UNF thread. I am not sure what to 
specify with regard to thread length. Have measured 3 hp ports &
they are around 11.5mm deep. The depth gauge thread that screws 
in to it is about 8.76mm long & the blank / plug that fits in the port is 7.16mm long.
Any transmitter thread length over the port depth will bottom out & not 
be able to compress the  o-ring which is on the pressure transmitter.
I was thinking of specifying 10mm but wondered if there was an industry 
standard length. 
Am nit picking a bit here but want to get it right, as others may want to
order the same product if it works well.
Regards Alan

Sent from my iPad
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