Testing Low Pressure Oil Service Switches

[Jamey]

I was wondering if anyone had a good way to pump up switches that have a low setpoint in an oil service. The hydrolic pumps we are currently using dont function well down around the 5-10 psi range. I was told I could use a pneumatic pump but had to keep it up above the switch when using it. Tried it and got oil back in the pump, needless to say, I had to tear it down and clean it up again. Another fella at the last ISA show in Houston said they were in the process of making a pneumatic that had a reservoir on it to catch the oil returning to the pump during bleed down, sounds good, but I know there has to be a way you guys have doing it over the years.

Any help is appreciated.
:confused:

[jcbvh]

Using a hydraulic pump on that low of pressure might be your problem, but what about putting a swag valve after your pump to a tee to your switch. At the tee put another swage valve going to a bucket or some sort of catch pan. When your pumping up to the switch have the valve at the tee to the bucket closed. Pump it up normally. When you goto bleed it off, close the valve by your pump, and open the bleed valve at the tee to the bucket. Then open your valve by the pump. Hope that helps

[landshark]

We use a pneumatic filter housing in line. That way when you vent it out at the pump the suction pulls the oil and it runs to the bottom of the filter housing while the air stays on top and out the pump without gettin back in the hand pump. We use a hand pump on switches from around 30 psi all the way down to 3psi with this method and have not had problems with the hand pump getting oil in it.

[50ae]

Why not just use a Mansfield Green with oil in it? It has both low and high pressure settings and a venier.

[NavyNuke]

Keep it simple. Use a Hydraulic system that uses a type of fluid that the one under test has. I don't mean to fill the resevoir with #6 oil either. If you have a few hydraulic hand pumps then dedicate one to the type of fluid under test. Some I&C shops don't do this because of the purchase price. A couple of tips: Keep the tap point/hose on the resevoir above the system under test but always apply pressure with it at the same level-every time. Lastly, don't fill the resevoir more than half way. In the event of excessive back-flow you won't lock up the tester.