[PSUBS-MAILIST] over pressure valve

Fri Jun 19 16:52:05 EDT 2015

Jim,
Thank you, that is my point exactly.  
Hank--------------------------------------------
On Fri, 6/19/15, via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 Subject: Re: [PSUBS-MAILIST] over pressure valve
 To: personal_submersibles at psubs.org
 Received: Friday, June 19, 2015, 4:41 PM

 When you are a half foot below
 your OP depth, the automatic 
 OPV knows it and stays shut; when you rise to a half foot
 above your OP depth, 
 the OPV valve knows that and opens just long enough to
 re-equalize the 
 pressure.  It continues to do this as you ascend. 
 Don't latch on to 
 "half foot" as a standard.  I only mean that as
 an example; it depends on 
 the cracking pressure chosen.  In reality, once the
 cracking differential 
 is reached and the valve opens, you'll probably be
 ascending faster than the OPV 
 is releasing internal pressure.  That is, since the
 external water pressure 
 is decreasing as you rise, the differential tends to
 increase unless the OPV can 
 keep up with it.

 Hank, you're making a good point for
 having an adequately 
 sized OPV.

 Guys, we have two different threads
 going on the same 
 topic.  Can we merge them?

 Jim

 In a message dated 6/19/2015 3:16:34 P.M. Central
 Daylight Time, 
 personal_submersibles at psubs.org writes:

   I don't get the "in the
 hands" part... its completely 
   automatic.

   On Fri, Jun 19, 2015
 at 4:09 PM, hank pronk via 
   Personal_Submersibles <personal_submersibles at psubs.org>
 wrote:

 Agreed,
 In 
     the hands of an experienced submarine operator an over
 pressure valve is 
     safe, providing it is large enough.  I have not seen an
 example of a 
     large enough OPV.  A simple valve in the hatch will do
 the same job, 
     just need an umbrella :-)
 The noise of a
 compressor is a welcome sound if 
     it means keeping the dome on the sub 
     :-)
 Hank--------------------------------------------
 On Fri, 6/19/15, 
     Carsten Standfuß" via Personal_Submersibles <personal_submersibles at psubs.org>

     wrote:

  Subject: Re:
 [PSUBS-MAILIST] over pressure 
     valve
  To: "Personal Submersibles
 General Discussion" <personal_submersibles at psubs.org>
  Received: 
     Friday, June 19, 2015, 2:47 PM

  But a
 overpressure vale works
  full auto. A 
     compressor
  not.  

  A OPV needs
  no 
     energy - but a compressor did.

  A OPV needs no room - 
     but
  a compressor did.

  And a
  compressor 
     is
  a noisy 
     solution..

  vbr
  Carsten

  "hank
  pronk 
     via Personal_Submersibles" <personal_submersibles at psubs.org>
  schrieb:
  > 
     Personally I think an onboard
  compressor is a much safer option 
     than an over pressure
  valve.  There
 are multiple safety 
     benefits to an onboard
  compressor,
 over pressure being the 
     biggy.  With a
  compressor you can get
 rid of the pressure 
     without surfacing
  and trying to
 control a perfect ascent.  
     With the OPV you
  have to surface a bit
 and let air out and wait 
     then surface
  more and wait and so on.
 You can't just surface and 
     hope
  the valve keeps up with the
 demand. This is more 
     important
  for subs with large
 domes.
  > The 
     next
  benefit to a compressor is, if
 you lost all your air, 
     you
  surface by dropping your weight. 
 In my case the weight 
     is
  small and I would also drop the
 thruster and tail 
     assembly.
  Still, not much sub out of
 the water.  With the 
     compressor,
  I can open my vent valve
 in the hatch and use the 
     compressor
  to fill the ballast
 tanks.
  > 
     Hank
  >
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