GPM vs PSI for distance

[Clear Shine]

Looking to add a pump to a 13hp motor. A 5.5GPM pump should put me at about 2200 +/- PSI. I will be using this for a softwash housewash rig. Here is the question. Which one makes the difference (PSI vs GPM) for throw with my Downstreamer? I am looking to get the same amount of distance out of this new rig as I am out of my current 5.5/3500.

 

[bears]

well look at it this way. You can buy a karcher electric pressure washer that will put out 1500psi at 2gpm and be able to shoot maybe 50 feet tops or you could have the local fire department show up with a 700gpm @ 200psi pump. What do you think is going to shoot further???

 

[Clear Shine]

I don't think you get what I am asking.....same General 5.5GPM pump on both rigs....will the distance be the same since they both will be carrying the same GPM or does the PSI come into play for strictly distance when pulling through my downstreamer......

 

[Christopher]

With the same 0040 or 0050 nozzle on the gun and using the 5.6gpm vs 8gpm machine, the 8gpm machine shoots further.

The nozzle will reduce the pressure so your machines will probably shoot about the same distance.

I am planning on basically the same thing, honda clone 13hp with gear box and General 2021 pump for house washing or for fleet washing.

 

[bears]

Sorry I guess I didn't understand the question.

 

[Paul Kassander]

They will shoot the same you will be down streaming at the same psi with the same gpm. For rinsing the lower gpm would be a much better choice for siding than the 3500 psi.

 

[Clear Shine]

They will shoot the same you will be down streaming at the same psi with the same gpm. For rinsing the lower gpm would be a much better choice for siding than the 3500 psi.

Paul, maybe I am misunderstanding what you are saying but they will have the same GPM, not the same PSI

 

[Christopher]

Here is what you do. If you have a gauge between the pump and the unloader, turn the pressure down to about 2500psi (I have seen some of these 13hp 5.5gpm machines make around 2500psi) and put the 0040 or 0050 nozzle on your gun and pull the trigger and see how far it shoots. Mark that spot with a cone/brick/employee, whatever.

Next put the pressure back to where it should be and spray beside where you sprayed before and mark the spot and see how far apart they are, might not be more than 10' or so with the pressure difference.

If you are using this for house washing, you will probably be using the fan mostly except for the soffits and eaves. This rig should be able to hit the soffits and eaves of most 2 story houses. If it does not spray that high then you need a bigger engine for that pump. The gpm and psi is what gives it distance.

Like in my example earlier with the 5.6 and 8gpm machines, the 8gpm will shoot higher and further than the 5.6gpm machine. I can hit the soffits and eaves of a 3 story building with either machine but on a windy day I will use the 8gpm machine as the wind will not affect the spray as much as the 5.6 machine.

 

[Paul Kassander]

Paul, maybe I am misunderstanding what you are saying but they will have the same GPM, not the same PSI

When you downstream yes. They are both 5.6 gpm pumps and when you are down streaming you will only be at like 100psi with a #40 nozzle.

The only time the PSI will be different is when you rinse with the higher psi nozzle ie 5.5 or 6.5 or what ever.

If flow is different and pressure the same the higher volume unit will shoot farther, but the original question was about two units with the same gpm.