Replies

1. 
   caseyr | Sep 01, 2006 01:45am | #1

   The graphic in the first site below does a better job of explaining than I can:

   http://www.coleparmer.com/techinfo/techinfo.asp?htmlfile=PumpInstallation.htm
   http://www.hondapowerequipment.com/pumter.asp

2. 
   HammerHarry | Sep 01, 2006 02:17am | #2

   Head is pressure, put in terms of a column of water.  And suction lift is the height you have to lift the water from where it is to where the pump is.  Discharge head is the height from the pump to where you're putting the water. And for every 1 psi you want at the end, you need 2.3 more feet of head. Total head is these all combined.

   So if you're lifting the water up 10 ft to the pump, and putting it 20 ft up in the air, you need 10 +20 = 30 ft total head.  Except that, if you want the water to be at 20 psig once it reaches that 20 ft up in the air, you need 20 x 2.31 = 46 more feet, for a grand total of 76 ft head.  Plus, ya gotta account for the friction in your pipe.

    

1. 
   brownbagg | Sep 01, 2006 04:54am | #3

   there is a point where a pump will not suck no more. I do not remember I think its like 60 feet but dont quote me on that. that why some wells have injection pumps,

1. 
   DanH | Sep 01, 2006 06:30am | #5

   Actually, the height of concern for "suction" is where the pressure of the atmosphere will no longer push water up the pipe. This is the nominal height of water in a water barometer -- about 34 feet.

   If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison

1. 
   HammerHarry | Sep 01, 2006 01:24pm | #6

   34 feet if the pump requires no NPSH...as a rule of thumb, for practical purposes, 25 ft is the limit.

1. 
   DanH | Sep 01, 2006 01:50pm | #7

   Right. 34 is the absolute limit -- what you'd be able to do with very slow flow. Any friction in the suction pipe subtracts from that, as does cavitation in the pump itself. And of course the limit is lower at higher altitudes.
   If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison

2. 
   webby | Sep 01, 2006 02:41pm | #8

   Thanks for the site, and the clear explanation. I have been looking at getting a used  2 or 3 inch pump for storm water situations.

   Webby

3. 
   brownbagg | Sep 01, 2006 05:17pm | #9

   make sure it has a Honda motor on it.

2. 
   riverman | Sep 01, 2006 05:02am | #4

   Thanks for the explanation in simple terms. I'm getting ready to buy a trash pump to pump goose crap out of a pond as was wondering what all the numbers meant.