Pressure Washer GPM

Posted by on November 1, 2008, 12:42 pm

I understand that GPM can be as important or more important than PSI
for "getting work done". So, I'd like as high a GPM as possible,
obviously. I'd be using the pressure washer for occasional home use
and occasional semi-pro use for handyman/odd jobs.

But I'm concerned about source water flow. I'm on city water, but I
just checked an inside line and an outside hose, and I'm getting 4 GPM
max, maybe 3.5 GPM. Does that definitely rule out a 4 GPM machine?
I'm concerned about cavitation in the pump.

Posted by on November 1, 2008, 8:12 pm

On Nov 1, 12:42=A0pm, nos...@nospam.com wrote:

> I understand that GPM can be as important or more important than PSI
> for "getting work done". =A0So, I'd like as high a GPM as possible,
> obviously. =A0I'd be using the pressure washer for occasional home use
> and occasional semi-pro use for handyman/odd jobs.
> But I'm concerned about source water flow. =A0I'm on city water, but I
> just checked an inside line and an outside hose, and I'm getting 4 GPM
> max, maybe 3.5 GPM. =A0Does that definitely rule out a 4 GPM machine?
> I'm concerned about cavitation in the pump.

I doubt if you will have a problem. First the numbers listed are
usually .... shall we say optimistic. Second the power washer will
be able to "pull" some additional water than the water flow you
measured. In theory it can pull a 32 foot column of water before it
quits, in practice it is less, but still significant.

Posted by on November 2, 2008, 1:37 am

On Sat, 1 Nov 2008 17:12:34 -0700 (PDT), jmeehan@columbus.rr.com
wrote:

> I doubt if you will have a problem. First the numbers listed are
>usually .... shall we say optimistic. Second the power washer will
>be able to "pull" some additional water than the water flow you
>measured. In theory it can pull a 32 foot column of water before it
>quits, in practice it is less, but still significant.

I understand your point, but most of the ones with high GPM are fairly
expensive with quality pumps, so I'd tend to accept their numbers
more. Did not know about "pulling" water though. What does a 32 foot
column of water mean exactly?

Posted by on November 2, 2008, 9:36 am

On Sat, 1 Nov 2008 17:12:34 -0700 (PDT), jmeehan@columbus.rr.com
wrote:

>On Nov 1, 12:42 pm, nos...@nospam.com wrote:

>> I understand that GPM can be as important or more important than PSI
>> for "getting work done". So, I'd like as high a GPM as possible,
>> obviously. I'd be using the pressure washer for occasional home use
>> and occasional semi-pro use for handyman/odd jobs.
>> But I'm concerned about source water flow. I'm on city water, but I
>> just checked an inside line and an outside hose, and I'm getting 4 GPM
>> max, maybe 3.5 GPM. Does that definitely rule out a 4 GPM machine?
>> I'm concerned about cavitation in the pump.

Although power washer may be able to pull some vacuum they are
designed to be force fed. Any restriction of the supply is not a good
thing.

Posted by on November 2, 2008, 9:02 pm

On Nov 2, 9:36=A0am, t...@mucks.net wrote:

> On Sat, 1 Nov 2008 17:12:34 -0700 (PDT), jmee...@columbus.rr.com
> wrote:

> >On Nov 1, 12:42=A0pm, nos...@nospam.com wrote:

> >> I understand that GPM can be as important or more important than PSI
> >> for "getting work done". =A0So, I'd like as high a GPM as possible,
> >> obviously. =A0I'd be using the pressure washer for occasional home use
> >> and occasional semi-pro use for handyman/odd jobs.
> >> But I'm concerned about source water flow. =A0I'm on city water, but I
> >> just checked an inside line and an outside hose, and I'm getting 4 GPM
> >> max, maybe 3.5 GPM. =A0Does that definitely rule out a 4 GPM machine?
> >> I'm concerned about cavitation in the pump.

> > =A0 I doubt if you will have a problem. =A0First the numbers listed are
> >usually .... =A0shall we say optimistic. =A0Second the power washer will
> >be able to "pull" some additional water than the water flow you
> >measured. =A0 In theory it can pull a 32 foot column of water before it
> >quits, in practice it is less, but still significant.

> Although power washer may be able to pull some vacuum they are
> designed to be force fed. Any restriction of the supply is not a good
> thing.- Hide quoted text -
> - Show quoted text -

I agree, but the better models handle it a bit better.

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