Self serve pressure difference from soap/wax and rinse

[DrewB]

i have 4 ss bays. I have noticed in 2 bays there is considerable difference in pressure when I go from high pressure rinse to soap or wax. The high pressure soap and wax is much higher (500lbs) than the rinse when it should all be the same. Any idea what to check or what can cause this

 

[JGinther]

Sounds like the pump is starving for water to me.

 

[MEP001]

What is your equipment? Are the pumps louder on soap and wax? I've seen two washes with the same GinSan equipment, they were set up with Cat 5CP6120 pumps running 1700 RPM, then everything is plumbed through 1/2" manifolds including the bypass. The pumps are always starved for water except on rinse.

 

[DrewB]

Without looking ( not at wash now) have cat 310 pumps . Hydrospray . Only happens on 2/4 and all hooked up the same from what I can tell but rinse runs about 1000 psi and soap/ wax at 1500

 

[MEP001]

I misread, soap and wax are higher? Hydrospray has systems with a VF drive to control the pressure by varying the speed of the motor. If yours is of that type, the VF drive is programmed differently on those bays.

 

[stampedecarwash]

I would start from changing the check valve under the hot water tank for those two bays. I had an issue with one my bays pretty much stopping when switching to high pressure (either wax, soap or rinse) sometimes, not all the time ( i hate intermittent problems). The issue was a bad check valve not opening sometimes. Yes who would have thought a check valve can shut down completely. I always thought when a check valve fails it acts like an open pipe.

 

[MEP001]

I always thought when a check valve fails it acts like an open pipe.

That's one reason why I don't like the SMC check valves. The spring that holds the valve closed can uncoil itself off the plunger and it will seat against the nipple on the outlet and stop flow.