Re: [PSUBS-MAILIST] Design depth

[Jon Wallace <jonw@psubs.org>]

Dan,

It sounds like you have some strange plastic.  PVC specs for 14 inch diameter show .437 inch thickness for Sched-40 and .75 inch thickness for Sched-80.  Regardless, PVC of such large diameter just won't suit you well.  Small diameter PVC (up to 3inches) can be used successfully for non-critical components down to depths normally accessed by home-builders (350-500 feet), but only if you can absorb the financial loss to the component if the housing fails prematurely.  For example, I fabricated a cheap 1.5 inch PVC housing for a $79 web cam I want to use underwater.  For serious work with components that would actually hurt you financially if the housing fails it is a good idea to stay away from PVC.

Regarding the UnderPressure program, the results you posted appear almost identical to those provided by the old DOS version.  My biggest beef with the program is that it is not open source.  Therefore, we cannot inspect it to see what formulas they use to get their results nor audit the code to ensure it is bug free.

Jon


On 12/16/2010 5:47 PM, Daniel Kubiak wrote:

Jon,
 
I had a piece of 14" PVC in my garage that I thought I could use.  With a rough guess of 1/4" wall thickness, Under Pressure gave me about 25'.  However, I went out and measured the wall thickness and it is only .187".
 
I'd like to think that when it came down to building my submersible I would have picked up the piece of pvc and thought twice about using it regardless of report from Under Pressure.
 
I attached a copy of the report so you all can see what Under Pressure creates and see what factors it takes into account.  Also, if your new version isn't working, Jon, you probably need to download the free SQL Server Express 2005 from Microsoft.