What distance from object does pressure drop off?

[mikew 14]

HI Everyone,

I am cleaning my sidewalk and patio around my house for practice. I don't have a surface cleaner yet so I am using the wand. My machine is rated for 2500 PSI / 3.6 GPM.

What distance would you hold the wand from the surface to obtain 2500 PSI? I'm looking for a range here.... like less than 6 inches or so. At what distance does the pressure begin to drop?? If I hold the wand 12 inches from the surface do I still obtain 2500 PSI at the surface?

Thanks!

Mike

[Pams Pressure & Clean 64]

The pressure begins to drop the instant it leaves the tip.

The amount and rate of drop is in direct proportion to the degree of spray being used. I would venture to say that water volume may also play a role there based on the initial water mass and velocity. That is to say that a zero degree nozzle will lose pressure more slowly than a 40 degree nozzle, all else being equal. (It stands to reason that a higher GPM would retain velocity longer, based on what my somewhat foggy memory tells me about physics class)

To calculate the amount and rate of pressure decrease of a given nozzle over a given distance would require some pretty nifty equipment and also would require an incredibly steady hand during normal operation.

Much easier to take a ride over to Pete and Tracy at Sun Brite Supply in Lawrenceville (right around the corner from you) and pick up a few different size nozzles to keep in the tacklebox.

Cujo

[mikew 14]

The pressure begins to drop the instant it leaves the tip.

The amount and rate of drop is in direct proportion to the degree of spray being used. I would venture to say that water volume may also play a role there based on the initial water mass and velocity. That is to say that a zero degree nozzle will lose pressure more slowly than a 40 degree nozzle, all else being equal. (It stands to reason that a higher GPM would retain velocity longer, based on what my somewhat foggy memory tells me about physics class)

To calculate the amount and rate of pressure decrease of a given nozzle over a given distance would require some pretty nifty equipment and also would require an incredibly steady hand during normal operation.

Much easier to take a ride over to Pete and Tracy at Sun Brite Supply in Lawrenceville (right around the corner from you) and pick up a few different size nozzles to keep in the tacklebox.

Cujo

Hi Cujo,

Thanks for the reply. Makes sense what you are saying. In my testing I can tell a noticable difference once I am maybe 8+ inches off the surface. I was really just wondering if there was a way to know that at 6 inches off the surface my machine is putting out "x" amount of pressure and at 12 inches the pressure drops to "x" .... You would need some pretty nifty equipment to accomplish this.

I've been over to Sunbrite several times. They are really nice and helpful. I purchased several spares nozzles and nozzles to drop pressure for wood cleaning as well.

Thanks!

Mike

[Pams Pressure & Clean 64]

Mike,

It is going to be pretty hard to get true numbers without the test equipment.

One thing you could do is experiment with an inline pressure guage and different nozzles to know what the machine is doing right at the nozzle and then atttempt to extrapolate pressure ranges from there...