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Checking Check Valves

B

Bubbles Galore

Active member
I am redoing the manifolds for my self serve bays and want to check the existing check valves I have to ensure they are working "correctly".

I open to suggestions, does anyone have a quick and simple way to verify they are functioning correctly?
 
I just blow on them with my mouth. My experience is that the bad ones are pretty obvious.

You could hook them to an air line as well.
 
There is a very simple way to tell. If one is leaking back the low pressure line will rupture. A rupture causes the line to swell and blister and the leak will be a line parallel to the line. If dry rot causes a line to fail, the failure is a crack perpendictular to the line. If the product for the line is coming out the gun, the valve is OK. Although I've been accused of blowing much hot air, I can not blow hard enough to "crack" a high pressure check valve.
 
Mac is right on what goes wrong, but i would add that as long as you are redoing everything replace those few checkvalves under PM and save a future problem by many years.
 
Etowah
I've seen a lot of operators change out a bunch of stuff and reuse old check valves. They usually end up having all sorts of troubles with valves sticking open and blowing lines, probably because of debris getting knocked loose and getting into the seals. My advice would be to replace them and not worry about the old ones.

I plumb low-pressure systems with tire/presoak and air on a common check valve at the boom and use a Speedaire mini regulator on the air solenoids. If that check valve fails, the liquid gets pushed back through the regulator without harming anything, and I see it on top of the tank and know there's a problem. The air line tubing is clear so I can tell which bay needs a check valve. There's also no check valve anywhere on the RO delivery except at the boom - if that valve fails it's harder to catch, but there's no way for any equipment damage to happen.
 
I can't argue with the logic, 4 check valves times 6 bays times $15 each = a lot of cash...but its sage advice, I wonder if I have a bag of quarters laying around...
 
If you do decide to reuse them, I'd recommend taking them apart if they do so, inspecting/replacing any seals that are worn at all and flushing them thoroughly before you reinstall them.
 
Got the manifolds tonight after a small shipping snafu on National Prides part...they look good and should work well, now I'm on the hunt for fittings! I will try and post some before and after pictures of the setup as well.
 
I installed a pop-off valve on the manifolds of my low pressure functions. That way no lines or equipment gets damaged when a check valve fails to close. I can tell when I have a check valve malfunctioning because the pop-off valve will release and there will be chemical sprayed on the floor.
 
I put pop-offs on them too, worked great the first time a check valve failed, then I switched to a check valve that doesn't fail. Now they're all corroded shut.
 
MEP001 said:
http://www.kleen-ritecorp.com/p-23214-14-fxf-teflon-check-valve-by-fluid-controls.aspx

The description is wrong - these have a Teflon seal. I suppose they'll go bad eventually, but I haven't have one fail yet.
Click to expand...

I use those check valves as well. Their older ones were better. The new ones WILL fail eventually. The piece that holds their poppet in the check valve is now made out of plastic to save money. That piece will either break or the screw will come loose and let the poppet blow downstream. Don't get me wrong, they're still good check valves just not as bullet proof as they used to be.

FWIW...when I put them in something as important as our automatic, I special order the stainless internals and locktite the retainer screw.
 
GoBuckeyes said:
The piece that holds their poppet in the check valve is now made out of plastic to save money. That piece will either break or the screw will come loose and let the poppet blow downstream.
Click to expand...
I had that happen on a spot-free check valve where I'd used a 1/4" on a high-volume RO line instead of a 3/8". As far as I can tell the volume just pushed the poppet too hard open and broke it and it ended up wedged in the nipple.

On other check valves it's usually the o-ring that fails when they go bad, or the brass seat erodes and lets the o-ring fail. With Teflon against stainless it shouldn't have either of those problems.
 
FWIW, I replace the spring inside every rebuildable check valve, in the fall, before the car wash season begins. I got tired of having to go up on the roof when it's 15 degrees outside on a "killer" car wash day in the middle of winter.

Not one failure since. It takes a couple of hours, but it's worth it.
 
GoBuckeyes said:
I use those check valves as well. Their older ones were better. The new ones WILL fail eventually. The piece that holds their poppet in the check valve is now made out of plastic to save money. That piece will either break or the screw will come loose and let the poppet blow downstream. Don't get me wrong, they're still good check valves just not as bullet proof as they used to be.

FWIW...when I put them in something as important as our automatic, I special order the stainless internals and locktite the retainer screw.
Click to expand...

Good call...I thought I was doing something wrong. I have used those check valves for many years and have noticed they don't hold up the way they used to. Still my choice of check valve, but they used to be more reliable.
 
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