Entire carwash looses prime

[Ghetto Wash]

I've got a 7 bay SS that on busy days, all 7 bays act like they loose prime all at the same time. The only thing I can figure is that there is not enough suction capacity to handle all 7 bays at a time. If I shut down a couple of bays, everything is fine. I have one rinse tank with one outlet on the bottom, gravity fed. It is 1/2" and from there it tees off to the seven pump stands. 2506 tips at 1000 psi is 3 gpm times 7 bays is 21 gpm.

I guess my questions are:

Is one 1/2" outlet large enough to handle 21 gpm or do I need to find a way to make it bigger?

How large is your outlet on your tank if it handles more than one pump?

 

[washnvac]

All mine are 1.25 or 1.5 inches for 5 bays or less. I have a 9-bay that has a 2 inch feed. On that one the two inch runs by each pump, then it is t'd with a 3/4" feed to the pump. I am quite sure if all 7 bays are sucking from that 1/2" line, you are starving the pumps. I can not believe they would run only 1/2".

 

[Ghetto Wash]

Sorry, I double checked and it is 3/4", not 1/2". Still a lot smaller than your 1-1/4" to 2" suction.

I agree, I think I'm way undersized (no smart comments needed )

 

[I.B. Washincars]

Is one 1/2" outlet large enough to handle 21 gpm or do I need to find a way to make it bigger?

How large is your outlet on your tank if it handles more than one pump?

Wow, I can't imagine how even a couple of bays can gravity feed from a line that small. My Mark VII equipment feeds from a 2" diameter manifold connected to a 2" outlet in the tank.

 

[Whale of a Wash]

If you can make the tank bigger, or two tanks each feeding half the bays you should be able to solve the problem.

 

[MEP001]

If the outlet to the bays is too small, a bigger tank will make no difference.

 

[Whale of a Wash]

Your right a bigger tank won't make a difference if the 7 bays were on forever.
I have 3 bays and a touchfree on a 1" line. When we put in the IBA it would starve the bays if all were running. By doubling the storage tank it allowed us enough time to pass that One bay would stop running and the system would slightly keep up. I would also suggest new spray tips on all the bays to save a little water. We had looked into a pump that would suck the water out of the water supply, but our city didn't like that option. On the last car wash I built we put in a 4" line 6 bays a IBA and lawn sprinklers running, and lots of pressure.

 

[MEP001]

Your right a bigger tank won't make a difference if the 7 bays were on forever.

The issue here isn't the city feed to the tank, it's the size of the hole in the bottom of the tank that feeds the bays that's too small. I've seen the exact same issue on a 5-bay fed with one single 1/2" port out the bottom, any time more than three bays were in use and trying to draw hot water they would all cavitate and lose pressure. It has nothing to do with "forever," the pressure loss and pulsation was instantaneous when that 4th bay comes on, and was instantly worse with the 5th.

 

[I.B. Washincars]

MEP is right on this. Your trying to feed 7 pumps through a drinking straw. The larger tank would help if you were feeding the tank with a 1/2" line, but drawing out of a 1/2" line to the pumps ain't gonna cut it on a gravity feed system.

 

[Ghetto Wash]

I havn't been diligent about keeping my tips new. Changing them out should help and I plan on doing so before cutting the tank and adding a larger fitting. In the meantime I lowered my pressure on all bays by 50 psi hoping that that buys me some time.

 

[JMMUSTANG]

Check your water main line coming into the equipment room.
What is the pressure going in before your pressure regulator or backflow preventor and what is it after the device?
If it is lower after the device you will need to open it up to get more water flow to your equipment.
I had to open up the valve more after the device to get rid of the problem.
Problem solved but lately I haven't had enough business to have the problem anyway.

 

[MEP001]

Changing them out should help and I plan on doing so before cutting the tank and adding a larger fitting.

You might consider adding several small bulkheads to the tank instead of paying a welder to come in and weld a large fitting. Stainless steel is a little tough to cut with a hole saw, but if you do it right it should go smoothly. I've done lots of cutting and drilling of stainless, it just takes slow speeds, lubrication and lots of pressure behind the cutting tool. It generates a lot of heat while cutting which is what kills the tool.

Check your water main line coming into the equipment room.

This is clearly NOT a case of water supply from a main. Your post makes very little sense - to what device are you referring? The "device" discussed in this thread is a stainless steel tank with too small a hole to feed seven bay pumps.

 

[JMMUSTANG]

I've got a 7 bay SS that on busy days, all 7 bays act like they loose prime all at the same time. The only thing I can figure is that there is not enough suction capacity to handle all 7 bays at a time. If I shut down a couple of bays, everything is fine. I have one rinse tank with one outlet on the bottom, gravity fed. It is 1/2" and from there it tees off to the seven pump stands. 2506 tips at 1000 psi is 3 gpm times 7 bays is 21 gpm.

I guess my questions are:

Is one 1/2" outlet large enough to handle 21 gpm or do I need to find a way to make it bigger?

How large is your outlet on your tank if it handles more than one pump?

MEP001
Because he stated that when he shut down a couple of bays he did not seem to have the problem. I was only suggesting that maybe the water pressure feeding to the rinse tank was not receiving enough water thereby the tank might not be filling up quick enough to supply all the bays.
As for the "device" on his main it most likely is a backflow preventor.
If it is a matter of water supply flow from his rinse tank and he has enough constant supply to the tank he should increase the outlet size and install a larger tank.

 

[MEP001]

The outlet of the tank is too small for seven bays. That's the problem, not supply TO the tank, and not the size OF the tank.

 

[jprb]

Have you checked the float valve inside the rinse tank? I've had them fail to open completely, allowing the tank to go dry.

JPRB

 

[I.B. Washincars]

Have you checked the float valve inside the rinse tank? I've had them fail to open completely, allowing the tank to go dry.

JPRB

He is not having supply problems to the tank, he can't supply enough water to the pumps (7 of them) to gravity feed through a 1/2" line. This is such a slam-dunk I can't imagine that there is any debate at all as to what the problem is. He either needs a bigger outlet or multiple outlets, nothing else is going to fix this problem.

 

[jprb]

Ghetto Wash,
Is this a problem that has just showed up (at an old wash), or something you've discovered at a new wash?

JPRB

 

[MEP001]

Have you read the posts? A single 3/4" outlet from a tank to feed seven bays and you're looking elsewhere for the problem?

 

[Randy]

All of these guys are right. You’re starving your pumps for water and you’re going to damage your pumps if you don’t correct the problem soon. You can install a screw in type 2” bulkhead fitting and re-plumb the pump water supply to 2” or eliminate the tank all together. We eliminated the water supply tanks years ago. No more pesky flow valves, No more overflowing tanks, No more wet floors. What brand equipment is this?

 

[Ghetto Wash]

The tank stays full, not a problem there. Problem only shows up when all 7 bays are on high pressure, drawing from the tank, no one using foam brush, presoak or tirecleaner. Doesn't happen often, but does happen.

Adding a few bulkhead fittings is a good idea. I can add one or two small ones or one large one and replace the existing suction manifold. I have another multi-compartment tank in storage, but would rather not use it if I don't have to.

jprb, this is an old wash and I haven't had this problem before, although I'm not always there and to have all 7 bays on high pressure at the same time, no low pressure, no one driving in or out is a rarity so I might not have seen it before. I have slightly increased pressure over the years and have not been good at keeping the tips new which I am assuming what put me over the edge in capacity. I think I've been standing at the edge of the cliff for years. Ive got 6 bay washes and 5 bay washes that are built the same, so I am assuming that the increase to 7 bays is part of the problem.

The equipment was manufactured by Advanced Carwash Systems - out of business for 20 yrs or so.