February 22, 201115 yr Hi all, I have been looking at hi-lo (two stage) pumps and have become confused of what size motor they require. Do you calculate motor by adding both sides of the pump together or only one side doing the most work? Looking at Batson he is giving lower HP compared to supply houses? Yours in confusion. To give you some idea of my dilema, a 8 gpm two stage pump stated as requiring a 5 hp motor to run. By Batson calculations the high pressure side runs at 1.6 gpm @ 3000psi needs 3hp the low pressure runs 4.6 gpm @ 900 psi needs 2.5hp. Batson has examples of 8gpm needing 3hp while the supply houses state that the larger (16gpm) need 13+ hp to run. I am restricted to using electric and 4KW (5hp)phase conveter. Thanks Andrew
February 23, 201115 yr Most pump manufactures rate ther 2 stage log spliter type pumps for gasoline horsepower. I think it takes 2.5 gas hp to equal 1 elecric hp. I have ran my 13 gpm pump with a 5 hp 3400 rpm electric for years with no problems. 2500 psi.
February 23, 201115 yr Author Thanks all, Makes sense running the higher hp only. Also thought HP was a standard value, not different between petrol/gasoline and electric? Andrew
March 2, 201115 yr Most pump manufactures rate ther 2 stage log spliter type pumps for gasoline horsepower. I think it takes 2.5 gas hp to equal 1 elecric hp. I have ran my 13 gpm pump with a 5 hp 3400 rpm electric for years with no problems. 2500 psi. I think you are underpowered....you have verified the psi and gallon flow how? Ric
March 2, 201115 yr There is a lot more that meets the eye when figuring this stuff out.. If you are thinking of using a "log splitter" pump they are designed to run at 4000rpm attached to a gas engine... With a electric motor you can get by with a smaller motor but also understand that because the electric motor runs slower you will be getting less out of the pump.. A better measurement is how many cubic inches (or Cubic Centimeters) per revolution the pump moves... Also go to the manufactures web site and look at the actual spec's listed for you pump. The GPM and PSI listed when they are trying to sell it to you are not very realistic, but they do give the actual numbers on the cut sheets
March 3, 201115 yr Based on calculated volume of the cylinder and speed of ram the 1st stage is getting 10.8 gpm at 475 to 600 psi on the gauge, 2nd stage 2.7 gpm at 2500 psi
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