Jensen Pumpjack motor/prime mover

Re: Jensen Pumpjack motor/prime mover

You might need to contact Jensen pump for help.

I am not sure why the 3 hp motor failed... The power needed to move just the water (500', 5 GPM, 100% efficiency) is only 0.6 HP

Is there a lot of friction/losses? Are you moving more than 5 GPM (i.e., pump is designed for 1,750 RPM motor and you installed a 3,500 RPM motor and are really pumping 10 GPM)? Perhaps the motor design was an 860 RPM version...

Is the counter weight improper for in-well hardware?

Placing a current meter on the motor and measuring water flow (GPM) may tell you a lot (is the motor drawing more current than it is rated for 100% of the cycle, just part of the cycle, is the voltage drop too much at the pump motor, etc.)...

Also, measure the water pressure at the pump outlet--For centrifugal pumps, placing a restricting valve at the outlet reduces HP requirements. For a Jack Pump (positive displacement) adding a restricting valve at the outlet will increase HP requirements.

About at the limits of my knowledge.... (or even a bit past... :roll:)

-Bill

Re: Jensen Pumpjack motor/prime mover

According the to rough numbers you have supplied (0.61 "raw horse power" for water lift--I would guess that a 1 HP minimum motor would be required to meet your specifications (500' head, 5 GPM). Personally, I probably would tend towards 1.5-2 HP if the electrical drop supports that amount of current (and verify with an AC current meter that the rated current is not exceeded).

Assuming 4" pump bore and 20" stroke...

H*PI*R^2/231cu" per gallon = 20"*3.1416*2"^2/231 cu" per gallon = 1.09 gallons per stroke

5 GPM = ~5 strokes per minute

5 strokes per minute * 29.6 input:output = 148 RPM

Assuming two widely available motor RPM's ... 1,760 vs 860 RPM

1,760 RPM / 148 RPM = 11.9:1 belt reduction ratio
860 RPM / 148 RPM = 5.8:1 belt reduction ratio

The above are just guesses--but seem self consistent.

Regarding the direction to turn the gear box... Depending on the way the links are set up--you will frequently find that something like 220 degrees (made up number) of the crank rotation moves the 20 inches, and the other 140 degrees moves the 20 inches back... So there can be an additional "leverage" (220 degrees is more shaft rotation than 140 degrees)--So, I would probably set direction to "lift" the water during the 220 degrees as there is less strain on the motor and "slower" motion (less stress due to momentum changes). You can also look at the "leverage" of the belt drive so that the "tension side" is closest to the mounting bases of the motor and gear box.

If, there is no obvious mechanical advantage for either direction--then I would not worry--or use an amp meter and see if you can find which direction produces lower average current draw (if you really are worried).

You can also look at the direction of any bolts that hold pulleys/rotating hardware on... Things that turn clockwise (when facing the bolt head) should have right hand threads. Things that have left hand threads should turn counter clockwise. Following this rule the bolts tend to self tighten--rather than to self loosen). (i.e., car wheels on the right side have right hand nuts to hold them on--older trucks and vehicles would put left hand nuts on the left side of the vehicle).

You also asked about prime movers... Are you looking for gas/diesel power as an option for this guy?

I also see you have been asking around other places regarding this pump--any useful information yet (I guess that would include me too :roll:)?

-Bill

PS: Doing an engineering design dump here--many of these issues are secondary effects and normally most "sane" people would probably not worry about them.

Re: Jensen Pumpjack motor/prime mover

If you can find a good source for 800-900 RPM motors--they seem to be getting rare... The older motors (decades old) are so power-inefficient that it is worth converting to a modern motor--even if you have to play with the ratios more.

You could try getting a 1 belt adjustable pulley--and play with it until you get the right flow/pump speed/motor current--then get a fixed multi-belt pulley once you know the size (if you need it).

If the driving pulley diameter is too small--you will probably have belt slippage and flex-heating/wearing (2.65 inch diameter was the minimum I saw in Grainger's with just a quick look through my old catalog).

-Bill

PS: Obviously, playing with the final pump speed (strokes per minute) will give you the ability to reduce motor loads too... Sort of depends on how much water you need... 5 GPM is not a lot--if you need direct flow... However, since you have storage tanks--5GPM x 24 hours per day is 7,200 Gallons per Day--perhaps way more than you normally need.