Normal psi for standard water hose?

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bshattuck87

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Hey everyone, after we buy our enclosed trailer we are wanting to do mobile detailing out of it. Right now we have a Troy Built TB3000 XP pressure washer (don't hate. lol) to do dealership spray off's. However, once we start mobile detailing, I want to very rarely use the pressure washer and only use it when needed. We will have a 250 gallon tank with a standard garden hose size hose coming off of it. But the tank is basically gravity fed, so if I were to put a nozzle on the end of it, no pressure would come out the nozzle and the water will just drip out the nozzle. I was at Lowes last night and came across this. Say's that it boost's water pressure to 40psi. It would basically be gravity fed on one side and then after the pump it would have pressure. However, is the pressure too much for a garden nozzle? Any thoughts or opinions? There will also be a generator on board for the pump to plug into and I'm sorry if this is the incorrect placing of this question on the forum! Thanks in advance!

Shop Utilitech 1.5-HP Cast-Iron 24 GPM Transfer Pump at Lowes.com

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40 psi should be fine. FYI, normal house pressure is around 40-70 psi.
 
When you have a garden hose nozzle on the end of regular garden hose, does the nozzle regulate the pressure when not in use and the water turned on? Do you think the pump will regulate itself and not burn up?
 
Nozzle regulate the pressure...wha? That looks like a centrifugal pump, so it should be alright deadheaded for short durations.
 
Setec Astronomy said:
Nozzle regulate the pressure...wha? That looks like a centrifugal pump, so it should be alright deadheaded for short durations.
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I'm sorry, but I don't understand your statement, I'll try to reword it since it seems all kinds of confusing.

When you are at home with your garden hose turned on and a nozzle on the end of it, when you're not using it, what keeps the nozzle from blowing off the end of the hose? Would this be ideal to use to wash cars on a daily basis, or is there an alternative solution?
 
The static pressure is what in the water line when the hose is shutoff, this is usually between 40-70 psi in a residential setting. Depending on the supply pipe size when you open the hose and let it flow the pressure will drop and this is known as the residual pressure. The more restrictive the hose (ie smaller diameter, long lenghts...) the more the pressure drop will be. At the very minimum a residual pressure of 20psi is desired. I think what you are asking is that if it would be ok to have the pump on with the hose shutoff. This should be ok for short periods of time but i would not let it run continuosly like that for extended periods. If it's just a matter of one minute on, two off that should be ok. If you're not going to use it for say 5 minutes then I would kill the power. A lot of times the water flowing thru the pump will cool it, so if water is not flowing the pump could overheat.

BTW looking at the specs of that pump it should be fricken awesome. 24gpm is a hella lot of flow. Most hosebibbs are only around 5gpm. disclaimer...they don't state the TDH (total dynamic head) of the pump so that rating of 24gpm could only be at the outlet port of the pump and not what you will be getting at the end of the hose.
 
Deadheading is gonna be a problem. With no way for water in the pump to escape the water will just churn & churn heating up very quickly. Like in seconds. Steam then will at least blow the hose or the seals if not melt the pump.

The ideal way to deal with this is with a pressure tank like on a well. They come in small sizes. Or laking that, some type of flow sensor on the outlet of the pump that will shut the pump off when flow stops.
 
When I was looking at the Lowes website, they also had small pressure tanks for sale.

What is the pressure tanks purpose and how would it attach to that pump?
 
DHCrocks said:
The static pressure is what in the water line when the hose is shutoff, this is usually between 40-70 psi in a residential setting. Depending on the supply pipe size when you open the hose and let it flow the pressure will drop and this is known as the residual pressure. The more restrictive the hose (ie smaller diameter, long lenghts...) the more the pressure drop will be. At the very minimum a residual pressure of 20psi is desired. I think what you are asking is that if it would be ok to have the pump on with the hose shutoff. This should be ok for short periods of time but i would not let it run continuosly like that for extended periods. If it's just a matter of one minute on, two off that should be ok. If you're not going to use it for say 5 minutes then I would kill the power. A lot of times the water flowing thru the pump will cool it, so if water is not flowing the pump could overheat.

BTW looking at the specs of that pump it should be fricken awesome. 24gpm is a hella lot of flow. Most hosebibbs are only around 5gpm. disclaimer...they don't state the TDH (total dynamic head) of the pump so that rating of 24gpm could only be at the outlet port of the pump and not what you will be getting at the end of the hose.
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DHCrocks very good explination. The only thing I would add is the friction loss for the hose is not figured in or listed so I would also say it's at the discharge side of the pump as you said.

bshattuck87, don't confuse GPM's and PSI. Most power washers only run at 2GPM or less so you should have plenty of water supply. If you use a good quality hose and nozzle it's not going to blow off. You may want to rethink the size of the supply hose feeding the pump though. You should use the largest supply hose you can and the reduce it down at the pump. The pump can only put out what you put in so don't restrict it with a small supply line. As others have already said dont run the pump any longer than you have to without water flowing.
 
Hmmm... This doesn't sound like an ideal way to make it work. Any other suggestions to be able to use a garden hose and nozzle with a mobile business?
 
bshattuck87 said:
When I was looking at the Lowes website, they also had small pressure tanks for sale.

What is the pressure tanks purpose and how would it attach to that pump?
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In simple terms, when flow through the hose ceases, the pump builds pressure in the tank. Once the presure in the tank reaches a certain point it causes a relay to open shutting off the pump.

You'd need a pump tank tee'd to the output of the pump. One side of the tee going to the pump the other side going to the hose. You'll also have to find a way to tap into the pressure side of the pump for the 1/8" line going to the pressure switch. Of course, all the pump electrics are wired through the pressure switch. Most pumps that are meant to do this usually have a dedicated port for the pressure switch.
 
Allen Anderson said:
Why would you not want to use your pressure washer?
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I don't want to run the risk of burning up the pump. Since I'm just getting into this, I need to make sure I have a back up (pressure washer) and I would much rather use just a garden hose set-up.

Plan b Detail said:
You need to get the Surflo Extreme™ ProBlaster™ Washdown Pump.
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Thanks for that link! I don't know why I didn't think about that, since it's a rather commen part on a boat!
 
Why don't you get a 12volt on demand pump from sureflo? this way it is independent from any generator so you don't need to run the generator while you wash the car, it runs off your car battery. That is the way I have it set up and it works awesome!


http://www.autogeekonline.net/forum...ailer-lots-pics.html?highlight=detail+trailer

Here is a link to my trailer set up with the 12v pump to the water tank so you can get an idea of how mine is done
 
WindyCity said:
Why don't you get a 12volt on demand pump from sureflo? this way it is independent from any generator so you don't need to run the generator while you wash the car, it runs off your car battery. That is the way I have it set up and it works awesome!


http://www.autogeekonline.net/forum...ailer-lots-pics.html?highlight=detail+trailer

Here is a link to my trailer set up with the 12v pump to the water tank so you can get an idea of how mine is done
Click to expand...

Wow, that looks awesome. The only thing I would be worried about with the 12v set-up, would be killing the battery. BUT, I could wire up a dual battery set-up with a selector switch, and just switch to battery #2 only while the truck is sitting and just run the pump off of that. Then when I go to start the truck, switch it back to battery #1, start the truck, then switch to both batteries so the truck will charge both of them.

GREAT idea though!
 
A little late to the conversation here, but what about a t after the pump, and an adjustable cracking pressure check valve on one of the t sides with a second hose rerouting water back to the water tank?

You can find adjustable pressure check valves with cracking pressures from 2 or 3 psi to much higher than the 40psi of the pump in question.

I have not tried it myself, but I am fairly sure that it would work like this.
When the water is flowing out of the spray nozzle, you would have a lower pressure inside the hose than the cracking pressure of the check valve. Therefore, no or very little water would return to the holding tank.

When the water is not flowing out of the spray nozzle, there would be a higher pressure inside the hose, than the cracking pressure of the check valve. Therefor, water should flow past the check valve and back into the holding tank.

This would lower the deadhead pressure inside the hose to what is chosen for the check valve's cracking pressure.

You will just have to find how much cracking pressure is needed.
This can be done by placing a pressure checking gauge where you intend on placing the check valve and observing how much pressure is inside the hose when the spray nozzle is fully open.

Choose a check valve that has a cracking pressure that is a few psi above what the water pressure is inside the hose, while the spray nozzle is fully open.

Your local plumbing supply house should be able to provide everything you need (a check valve with a proper cracking pressure and proper size connectors, an extra length of hose, and a t with the proper size connectors.)
 
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