[PSUBS-MAILIST] High Pressure Port Dimensions

[Sean T. Stevenson via Personal_Submersibles]

If you are using a SCUBA regulator, keep in mind that the bodies of most of these are chromium plated brass (ergo the female threads have only the associated strength), and the expected supply pressures no greater than 3500 psi or so.

Sean


On November 5, 2016 3:42:25 PM MDT, Hugh Fulton via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>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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