[PSUBS-MAILIST] (no subject)

[Cliff Redus via Personal_Submersibles]

 Hank,
I would use a direct acting cartridge style proportional pressures reducing valve, something like a Hydraforce EHPR08-33X Hydraforce | Pressure Rising with Current - EHPR08-33.  These are installed in a small aluminum manifold in which you connect hydraulic tubing with Swagelok fittings.  These valves let you specify a control signal, usually 4-20mA.  They then can be used to automatically hold the pressure and any level between zero and the maximum your pressure supply can make.  You then use a small inexpensive PLC like the Automation Direct Click PLC CLICK (Stackable Micro Brick PLC) | AutomationDirect along with pressure transducer and an inexpensive small touch screen display.   Again, you can get these from Automationdirect. You would also need to install in the PLC an analog current output that will would be connected to the proportional pressure regulator. You then program the PLC with your laptop with some simple ladder logic that sends the control current to the proportional pressure regulator to step through the pressures you want the test chamber to see over time.  Most of these small PLC's have data logging capability so you can log test chamber pressure as a function of time.  If you also installed a contactor on the power to the pressure supply, the PLC could be programed to shut down the system if the viewport failed based on the measured test chamber pressure dropping to zero.  

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CLICK (Stackable Micro Brick PLC) | AutomationDirect

Save on CLICK Series Programmable Logic Controllers at AutomationDirect, your source for Click PLCs at low price...
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These proportional pressures reducing valve could also be run with a microprocessor like Jon uses and setup in a similar way.
Best 

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Hydraforce | Pressure Rising with Current - EHPR08-33

PROPORTIONAL PRESSURE REDUCING / RELIEVING CARTRIDGE VALVE
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    On Sunday, November 13, 2022 at 09:45:39 AM CST, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  
 
 Hi submarine friends.  I just completed a pressure test to failure on our Cast Epoxy port.  The port was 1 inch by 8 inches OD.  An acrylic port this size is rated to fail at 2,100 feet sea water.  My Epoxy port failed at 1,225 psi or 2,744 feet fresh water.  
  Any ideas on how to make a hydraulic apparatus to cycle the port  from zero to operating depth in my chamber?  
Hank
Sent from my iPhone

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