back pressure from spot free

[stampedecarwash]

Hello, noticed in two of my bays when customer uses sport free, I see almost 100 psi of back pressure on the cat pumps. I don't have a check valve on the high pressure line from the pumps to the bay so it makes to have some back pressure, but why only two bays?

 

[MEP001]

Most likely only those two gauges will read pressure that low. With no check valve on the line as you said, they will all have pressure back to the pump.

 

[stampedecarwash]

Most likely only those two gauges will read pressure that low. With no check valve on the line as you said, they will all have pressure back to the pump.

I checked the gauges and except for one all the other gauges are the same (2000 psi max). However I checked the set up on the boom and they seem to be different. Some have SF as a separate line Teed to the high pressure line, and some SP is Teed to the Tire cleaner and then Teed to the high pressure. So since I have different setting its hard to compare them.

 

[MEP001]

It shouldn't matter either way. It's normal for the spot free pressure to read on the high pressure gauge. They could be different brands or just not accurate anymore. I assume the ones tee'd to the tire cleaner lines are tee'd in after the check valve there, otherwise you'd likely have some issues with spot free backing up into your tire cleaner or vice versa.

 

[APW]

Mep, should there be a HP check valve at the pump or does it matter?

 

[stampedecarwash]

It shouldn't matter either way. It's normal for the spot free pressure to read on the high pressure gauge. They could be different brands or just not accurate anymore. I assume the ones tee'd to the tire cleaner lines are tee'd in after the check valve there, otherwise you'd likely have some issues with spot free backing up into your tire cleaner or vice versa.

Correct, the tire cleaner and spot free have been backing up to each other, so I just added a check valve in front of the spot free. But not having a check valve didn't really create any issues like seeing soap in my spot free tank (I guess it wasn't making its way all the way back to the tank since its low pressure, and it doesn't matter to have spot free in tire cleaner it just makes it a bit watery) . I was seeing a bit of a soap in the beginning of spot free function, which I still see after adding the check valve (all of my bays do that)
But adding a check valve fixed my other problem which I posted a different note. On this bay I had a dripping issue from the gun. Now with the check valve added on spot free, no more dripping, yey.

 

[MEP001]

Mep, should there be a HP check valve at the pump or does it matter?

It shouldn't need one, if the pump's seals and valves are in good condition it won't allow spot free to backflow through it.