check valves

[Bubbles Galore]

I haven't had to change out any check valves at my wash yet (purchased last Nov) and was wondering if I am missing something. How long do the check valves last for? How can you tell if one isn't working? I rinse most of my bays down each day and haven't noticed anything out of the ordinary. Am I missing something?

 

[MEP001]

You won't see a check valve problem just by rinsing bays, unless one has failed catastrophically and is letting full flow through the wrong way. At least once a week I run all cycles on all bays and look for things like a blast of tire cleaner when I go from rinse to spot-free.

I prefer to have one check valve for tire cleaner/presoak/air combined, with a Speedaire regulator inside that will exhaust excess pressure through a hole. That way if a check valve fails, the liquid will just vent without doing any damage and I'll see a problem right away. Clear lines on the spot free tubing will let you see if tire cleaner is backing up into that system.

Good check valves will last many years. Parker used to, but I quit using them when their reliability went in the hole. I use the stainless steel Fluid Controls with the Teflon seat and haven't had one fail yet.

 

[Twodose]

I prefer to have one check valve for tire cleaner/presoak/air combined, with a Speedaire regulator inside that will exhaust excess pressure through a hole. That way if a check valve fails, the liquid will just vent without doing any damage and I'll see a problem right away. Clear lines on the spot free tubing will let you see if tire cleaner is backing up into that system.

Are you talking about back pressure if a cv fails? Can you explain more in detail what you are talking about here?

 

[MEP001]

More about backflow of high-pressure into the low-pressure lines. When I was a tech, we had a customer with a new wash that got a bad batch of check valves. About once a week one would stick open temporarily and would blow a line off a low-pressure pump or at the tank feeding it (There was a check valve at the tank), or would crater the pump. The reason there was so much damage was because there was a separate check valve for each line rather than combining all the LP functions on one check valve. Another "tech's" solution was to add a check valve to the bottom of each stack of solenoids. This only changed the problem - now it would either blow the tubing or it would trap too much pressure in the manifold and none of the solenoids could open. The customer was no help to diagnose because besides being a 70-year-old woman, the gauges were pegged on the high side of the stop, and all she could tell anyone was that it wasn't working and the gauge "read zero." She finally called me directly, almost in tears out of frustration, and I replaced the three check valves with one of a different brand, which solved the problem.