help with mystical problem

[wendy's wash]

I have 6 bays. In the last couple of weeks my tire cleaner just stops working in all bays. System set up as follows. Water and tire cleaner enter mixing tank. Then runs down to a pump and ends up in a bladder tank that pressures it up to 50 psi.Line goes out to first selenoid and t's off to next one. All selenoids have pressure at all times. Each bay is seperate from all others. Each bay has 24v supply. When tire cleaner does not work, every thing else still works at that bay. Bay soap, wax, foambrush, timer has power. There is no power at selenoid. Pressure is fine. Nothing comes out at bays. All of a sudden it starts working. I don't know where to look now. If I call a tech and it works when he comes out, the response will be pay me and I need it to not work when I come out. I am between a rock and a hard spot now. I dont think the odds of all 6 rotary switches going bad and then fixing them selves at the same time is impossable. If it was a bad ground then nothing would work. What would be the common denominator for each bay. Is there something I am missing besides logic. Any suggestions.

 

[MEP001]

Start with this: Disconnect the tire cleaner pump and bleed off all the pressure. Make sure the gauge reads zero once everything's unhooked from the inlet to the solenoids. If the gauge isn't sitting at zero, replace it, then reconnect everything and watch it for a while.

You may have a problem, maybe a check valve in a bay that's letting pressure back through on tire cleaner or a bad regulator or pressure switch on your bladder tank/pump system, that's creating too much pressure behind the solenoids. All solenoids have a MOPD rating, which is the maximum pressure difference between the inlet and outlet against which the solenoid can open. If something allows the pressure to exceed that MOPD, the solenoids can't open. A lot of older systems I've seen that used a bladder tank have solenoids rated only to 50 PSI.

 

[bmills]

You didn't mention if you blended air with the tire cleaner mix for a foaming application. If you are blending air perhaps your air pressure has exceeded your fluid pressure and is winning the blending battle and therefore no solution is coming out. Usually when this happens the air will purge itself temporarily and the fluid will come out during this lapse in air pressure and then the cycle will start over again with no fluid.

Check the balance between air and fluid pressures. Zeroing out both systems, as in the prior post, and resetting the proper application pressures will get you going again. A rule of thumb would be air at 2/3 fluid pressure. I.e. 50 psi fluid, 33psi air. That should get you in the ballpark with consistent delivery to all bays assuming your lines are suffiecient diameter. You can fine tune from there.

Good Luck

 

[MEP001]

You didn't mention if you blended air with the tire cleaner mix for a foaming application. If you are blending air perhaps your air pressure has exceeded your fluid pressure and is winning the blending battle and therefore no solution is coming out.

In my experience, too-high air pressure won't cause an intermittent problem where no bays get tire cleaner.

 

[wired]

If all the bays are stopping at the same time check if your mix tank has a screen on the output that may be getting clogged or gelled up.

 

[MEP001]

If all the bays are stopping at the same time check if your mix tank has a screen on the output that may be getting clogged or gelled up.

That would likely not cause an intermittent problem. The pump would starve for water and fail.

 

[jbcarwash]

Most likely all solenoids share a common 24v neutral wire. Check all connections from all TC solenoids all the way back to the transformer. If all else fails, run a new 24v neutral to the solenoids. Always use stranded wire, as solid wire can break inside the insulation and thus be hard to see. Solid wire is cheaper, but causes these kinds of problems after some flexing.

 

[wendy's wash]

Up and Running!

I want to thank everybody for their input to our problem. Yes, we have a winner. MEP001 was totally correct in the diagnosis. When the chemical stopped flowing again, my wife was outside in the bay and I was in the storeroom. I broke the first line loose at the seloniod and releaved pressure.
She hollared the bay is working now. As I was checking it before, I would break the line loose and check other things too like like loose ground, power and then go to bay and check it. That is why I couldn't tell what it took to get it working again. It took 2 of us. Pressure guage stuck at 50 psi.
Once again Thanks for help.