May 14, 2010 03:08 am
Re: Newbie needs help with small solar water pump
The flow reduction is based on a couple of things. The first is the height you are pumping. If the pump is pumping 40gph at 1 foot, it will do less at two, less at 3 and less at 4. In this case 4 feet is the Mfgs upper limit.
The second source of flow reduction is the pressure drop in the pipe or tubing. Every foot adds to it, as do the different fittings. What that drop is, is affected by the length, the diameter, and how much water you are attempting to move through it. You can think of it as being similar to friction.
Trying to move 40gph through the small tubing would be like having to pump the water an extra 15 inches higher. By upsizing the tubing, the extra work is equivalent to about 3.5 inches. So, we are saving almost a foot of pumping.
That one foot may be come important if your heights are slightly off.
If the Mfg is comfortable with the pump working many hours a day at a 4 foot lift, and we stay below that height (real height plus height equivalent losses), I wouldn’t worry about the motor.
The thing that will kill it is if it becomes plugged with debris and cavitates or runs dry for long periods. What are you planning to protect against that in the stream ?