gpm from watertanks

Clean County

New Member
I have a 465gallon water tank in the bed of my dodge dually which has a water line running into a 100 gal water tank in my enclosed trailer which is then hooked up to my landa hw pw which uses 5 gpm. The water line here is a 1.25" i.d. which has no problem generating 5gpm via gravity. I also have 2 other hook ups off this tank to use for my cold water pw which I use to clean wood.On those hookups I use 3/4" garden hose with water gravity fed to my cold water units which are placed outside of the trailer because they are not vented.This hose line is aprox 15' long. Everything is set up with quick connects so it only takes about 2 minutes to set up the cold water units. The 15' hose line generates only 2.5 gpm and my cold water pw's need 4 gpm. These pw's can suck water out of a bucket. Everything is working fine but my question is this: Will this set up eventually ruin the pumps on my cold water pw because of limited flow of gpm's? p/s-Dan this bb is great for the powerwasher contractor
 

Greg Cross

New Member
John, whether or not your cold water pumps will be damaged depends mainly on your pump specs & the inlet water supply.

Pump inlet supply is rated a few ways:

1) Negative pressure feed (measured in
-psi). For example a pump may be rated for max -5 psi inlet pressure. -5 would be the greatest amount of vacuum the pump should be subjected to. Your pumps are probably subjected to some vacuum. If you want to verify this, buy an automotive type vacuum gauge & connect it to the pump inlet port opposite the port for the water feed.

Start the machine (holding the gauge at the same level as the pump head) and pull the trigger. It is fine to have some vacuum as long as you do not exceed the specified negitave inlet pressure. Often times excessive vacuum will cause a pressure loss, starvation and failed inlet seals.

2) Flooded: When the water supply hose is removed from the pump, water will free flow from it at the GPM rating of the pump or greater.

3) Pressure fed: Although a great percentage of pumps are rated from -PSI to positive pressure, you don't want to exceed the max inlet pressure rating.

If you are not sure of the inlet specs of your pump, post the make & model here and I will look them up for you. Otherwise feel free to call me at work 1-800-274-9376.


Hope this helps,

Greg Cross
 

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