Pressure testing and recovery pumps

[NorCalHawaii]

Hola Amigos! We have been having a helluva time with our pre run pressure tests on our new rack mounted system, specifically with pumps holding pressure. The system it's self holds pressure/vac just fine over 24 hrs @ 90 psi. Our first CMEP OL didnt fare so well...it failed before we ever used it, never held pressure...so, we got a CPS TR600 as a back-up. It held up to our first pressure/vac test over 24 hrs and made two runs before failing a 90 lb./10 min pressure test for round 3, days later. System is solid, holds pressure/vac over 24 hrs, but when pump is in the loop, no go. Is it the pumps or ME? Are recovery pumps supposed to hold 90 lbs of pressure over time? The TR600 is rated to 500 psi. Why on earth wouldn't it be able to hold 90 lbs of pressure? The second CMEP is on its way and we replaced the tr600 but i want to be sure that we're not missing something basic with the pressure testing protocol. The guy/business who sold us the tr600 asked us why we pressure test. I was dumbfounded. Should i have been? Is a 10 min 90#, then a 60 min 90# then a 6 hr 90# and then 12 and finally 24 hours of integrity overkill? underkill? thoughts, ideas, options? All help greatly appreciated.

 

[NorCalHawaii]

pressure testing with nitrogen if it matters....

 

[jswick93]

The only way I could imagine the CMEP-OL not holding pressure is due to a bad ball valve, loose fittings/bolts or inproperly seated gaskets on most likely the cylinders. The things seal up pretty well.

 

[Rickys bong]

How much drop are you seeing? Most recovery pumps will leak across the piston seals after they've been used a bit.

Test the pump on its own. I use a set of refrigeration gauges so I have a gauge on the inlet and outlet. Plug/valve off the port attached to the outlet, Pressurize with air to 60-90psi and valve off the inlet.
You'll generally see a slow drop on the inlet side and none on the outlet. If the inlet drops quickly the piston seals are tired. If both drop, you have bad exhaust valves and piston seals or an internal leak.

RB

 

[Gray Wolf]

How much drop are you seeing? Most recovery pumps will leak across the piston seals after they've been used a bit.

Test the pump on its own. I use a set of refrigeration gauges so I have a gauge on the inlet and outlet. Plug/valve off the port attached to the outlet, Pressurize with air to 60-90psi and valve off the inlet.
You'll generally see a slow drop on the inlet side and none on the outlet. If the inlet drops quickly the piston seals are tired. If both drop, you have bad exhaust valves and piston seals or an internal leak.

RB

What RB said.

Neither the piston seals, nor the poppet valves are high integrity seals, so don't expect them to hold pressure over time.

Because in a closed system, they don't leak to atmosphere, slow leakage shouldn't present a problem beyond flooding the crankcase with vapor and leaching bearing grease.

If you have both liquid and vapor valves closed on your tank when you pull the initial vacuum with other valves open so as to purge the entire system, the piston seal and valve leaks won't be an issue.

If the flood manifold is full of liquid, simply close the vapor valve on the tank and leave column flood valve closed as well during evacuation.

 

[NorCalHawaii]

What RB said.

Neither the piston seals, nor the poppet valves are high integrity seals, so don't expect them to hold pressure over time.

Because in a closed system, they don't leak to atmosphere, slow leakage shouldn't present a problem beyond flooding the crankcase with vapor and leaching bearing grease.

If you have both liquid and vapor valves closed on your tank when you pull the initial vacuum with other valves open so as to purge the entire system, the piston seal and valve leaks won't be an issue.

If the flood manifold is full of liquid, simply close the vapor valve on the tank and leave column flood valve closed as well during evacuation.

Grey and Ricky thank you for the reply. The pressure drop was minimal but noticeable and i refuse to let it go at "it's just leaking a little..." What you are saying makes sense and gives me warm fuzzys. Thanks again!

 

[Pvnuts]

Will pay upfront for advice

Will pay upfront for advice

Hi Everyone,

I have a CMEP-Ol Gen 3 that just came in. What is an acceptable slow leak on the input. Mine will show a small drop after 20 minutes or so under vacuum and a faster drop under small pressure by adding butane vapor at the input.

I am willing to pay upfront for someone who is in the know about these pumps to get me up and running asap. Every day I'm losing money and will start loosing customers soon as it took a long time to get this unit.

Thanks in advance

 

[learningta]

I have a CMEP-Ol Gen 3 that just came in. What is an acceptable slow leak on the input. Mine will show a small drop after 20 minutes or so under vacuum and a faster drop under small pressure by adding butane vapor at the input.

Hard to say without seeing how you are testing. Intake/input won't hold any significant pressure from the intake port side, the valves will pop open and that pressure will go into the cylinders and past the output valves too. The valves in the CMEP aren't like automotive valves that close with any significant valve pressure, they are basically just glorified check valves.

That said I would consider any leakage externally or to atmosphere to be unacceptable. Probably not a bad idea to pull the top cover and spray down with soapy water to see where it's leaking. If pressurizing intake and it's coming out the exhaust side I would run it.

If you're near Denver I can certainly help you out.