pulley size for vacuum pump???

[roybar maple]

wondering if anyone can help me out. I have a surge pump that was run with a 5 hp motor it had a 5" pulley on it and the pump had a 10" pulley.I bought a 13 hp gas engine and wondered what size pulley i need on it. any help would be greatly appreated

[davey]

the first thing you need to determine is what rpm the pump is supposed to be run at. After that just determine a speed slightly above an idle for your engine, do the math to figure the ratio from engine rpm to pump rpm and that is your pulley size. I have a surge that needs to run at about 425, my engine is running at about 2200 rpm. 425 goes into 2200 5.17 times. my pump has a 14 inch pulley. 14 divided by 5.17 = 2.7. therefore I am using a 2.75 inch pulley. This also allows the motor to run very low, I used about 5 gallons of gas in a 26 hour run.

[roybar maple]

thanks for the help davey!!!

[maple connection]

I had a 13hp Honda on a surge alamo 60 I used a 2.5 inch pulley on the engine with a 10" pulley on the pump. I ran it just over Idle. One tank of gas lasted 7 hours pulling 18.5 inches.

[roybar maple]

thanks for the info maple connection! i put a 3" on the motor and 10" on the pump.let ya know what i get out of it when we fire it up today

[roybar maple]

well i got the pump running and at just over a idle i ampulling 23" thanks to everyone for the help.

[maple flats]

A surge dealer can give you the rpm rating even at higher vacuum levels. My dealer gave me the pump RPM for pulling 19". Mine is an Alamo rotary vane, he said my 75 cfm pump would run at 900 rpm at 15" for 75 cfm, for me to get 10 cfm at 19" he told me to run at 700 rpm. He used a chart and calculated the number from there. As I have been going it works good. So far I have worked up to 18" I will crank the controller to 19" later today. That will be my max because I am using a Zero vacuum tank that could collapse at higher vac.

[NH Maplemaker]

Check out this site for pulley calculation. http://blocklayer.mobi/pulley-belteng.aspx Great tool to save! JimL.

[maple connection]

Roybar Maple
I hope you can hold 23" threw out the season. You should be fine with the 3" pulley. My only concern is keep an eye on the pump so it doesn't over heat. Use the spit and sizzle method. If you spit on the pump and it sizzles its to hot open the regulator. Kind of crazy but, it works great.Good Luck, and hope you have a great season.