[PSUBS-MAILIST] over pressure valve

[John Kammerer via Personal_Submersibles]

Hi Keith:

765 is my project, I will be giving a update on the build at the convention next week. 

You can reach me off list at subvet596 at optonline.net

John K.
(203) 414-1000

Sent from my iPhone

> On Jun 19, 2015, at 6:31 PM, via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> I never thought of running the compressor to relieve OP, but it makes a lot of sence (can't believe I missed that one). On a large "boat" the snort is a great OP valve.
> 
> John, is 765 your project? If so, I'd love to chat with you off post as I have interest in how that project is progressing along with many, many questions.
> 
> Keith T
> 
> Private via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
>> No, it's the other way around - my issue was caused by the motors getting cold. I put the oil in on a hot VA day, it was 90-95 degrees. At depth the water was at 42 degrees, so about a 50 degree difference. Contraction of the oil at depth was greater than the puny 10ml hose volume, and we were beyond the pressure rating of the lip seals so the motor sucked in water. Then upon return to the surface, the air bubble in the motor stored the pressure and pushed oil back out.
>> 
>> Of course you could also have the issue if you fill the motor cold and it gets hot, such as from running it out of the water or something. 
>> 
>> 
>> 
>>> On Jun 19, 2015, at 5:28 PM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>> 
>>> 
>>> Alec,
>>> At first I resisted the notion of thermal expansion, but I was thinking in terms of heat generated from motor use.  I didn't consider the temperature change from the sun on a black motor until the light went on :-)
>>> I have changed my p trap ss tube to a larger hose so there is more air volume to work with.  I am ready to test that part.  Now I have to fix my bent up rudder :-(
>>> Hank--------------------------------------------
>>> On Fri, 6/19/15, Alec Smyth 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, 5:03 PM
>>> 
>>> Oh! Well I
>>> suppose it just depends on the volume the valve can handle.
>>> This is an interesting calculation, which I have not done
>>> but should. In general, these valves should handle pretty
>>> huge flow rates. But you're right, its basic to surface
>>> very slowly when there's any over-pressure - normally we
>>> dive with under-pressure. For a K-boat sized hatch, an
>>> over-pressure