Pressure STD for use with TEST CELL and AGATES

[airbud]

Does any one have an idea for a STD to use during onsite calibration of TEST CELL's or AGATES? We are currently using our PPC2AF with purge function hoping that we dont get oil in our transducers and damage the unit, this has already happened once before and was very costly.

-Bud

[mdbuike]

You could use the fluid seperator.

Mike

[OlDave]

Blinded by the obvious.

[USMCPMEL]

Maybe he does not have a fluid seperator? Or maybe he has one but does not know what it is?

[OlDave]

OK Bud, sorry for the flip response.

It's been over 10 years since I did a test cell but I'm guessing nothing much has changed. I also tested one of the prototype PPC2's and I believe we had contamination problems also. I think the little fluid separator was a direct result of some of the testing I performed and was an accessory provided with the production units. I always was of the opinion that the capacity of the separator was a little small and did not adequately address the problems associated with aerosolization of the oil/fuel, but that's how it all ended up.

All that being said, I started to make a practice of purging the system a couple of times with compressed air before hooking the PPC2 up to calibrate. I would attach the long hose of the TC trailer to the test port on the TC and apply about half scale pressure. Send my helper out to crack the fitting on the TC to bleed the air/oil/fuel off at the downstream end. Do that a couple of times and then do a blow through with the hose open. That cleaned as much crud out of the lines as I could get. Only then would I attach the PPC2 and apply the calibration pressures.

Personally I always thought of the PPC2 as somewhat fragile for Test Cell work. It seemed to perform adequately in the lab for the most part, but the dirty, nasty, far from ideal environment of on-site work seemed to be a bit hard on it.

[Velasco]

I know this is an old post, but very easy to answer, I use PPC on test cells a lot. I have never had a problem with this method and have cal'd test cells for almost 10 years. You need a shut off valve on the PPC2's test port. After you reach your pressure and have finished with your reading, shut off the the valve (should be right on the PPC test port) hit ESCAPE key on ppc2 ( this will stop it trying to control) and bleed the pressure in the line off at the test cell port ( either just crack the AN fitting or put a 2nd valve on a T inline closer to the test cell port to vent pressure ). Once all the nitrogen/air/fuel/oil is bled out of the line then very slowly open the shut off valve at the PPC2 test port, this will blow all the pressure left over from the PPC outward from it eliminating any chance of contamination coming into PPC2. Don't use the VENT button at all on the PPC2. No contamination from the test cell will ever make its way back to the PPC this way. The fluid separator is not neccesary when done this way, and the fluid separator is not very good at keeping lots of oil out of PPC2 like with a test cell. The fluid separator is more of a safety device to prevent damage from people accidentally using an oil gage on the PPC2, not really meant to use as an oil gage calibrator.

Also when doing test cells usually you have a long line going from the PPC2 to the test port, make a nice U shape with it, have the PPC up higher than the lowest point of the line so any oil/fuel that gets into line won't drip down into PPC2 but get trapped in the U part of line.

Relying on the fluid separator to prevent oil and fuel from entering the PPC2 will lead to a dead PPC2 eventually, the stuff gets past and jams the valves, DHi charges about $3,000 to repair them after this.