On Jul 5, 11:06*pm, Tomas wrote:
I have a Myers 1.5HP well pump for my sprinkler. It's about 10 years
old. Sitting outside in the elements, I cannot read too much on it
anymore. Seems to me that 10GPM is extremely low. Is it and if so,
could it be due to the pump being old? Could it be due to the well -
not supplying enough water. I'm in central Florida if that matters and
no rust from the well water. I have no idea how deep it is. It looks
like it's being fed with a 2" pipe.

Pressure and GPM were measured just after the pump out of a 3/4"
opening. It took 29 seconds to fill a 5 gallon bucket. 30PSI was
measured from the same spot. Although, 4 sprinkler heads were
"spraying" water down at the end of the run if that matters.

On a side note, it ran at least a couple of times for a few hours
without water - lost its prime somehow. It still functions though.

The pump you have is an injector pump. The pump housing contains an
injector, a centrifual pump and a small water store. Water from the
store is circulated at high prseeure by the centrifugal pump through
the injector (a series of venturii), this sucks water up from the
well. If you think the performance is down it will be because sand
from the well has worn away parts. As clearances increase the pump
delivers less water. Most pump manufacturers supply a kit of the
wearing parts; impellor, venturii etc to fix this.

A pump's capacity depends on the total head (or pressure) it has to
work against. This will include the depth of the well, the hieght you
are lifting to above the ground and the resistance of all pipework.
The manufacturers provide a pressure/ volume shifted graph for each
pump.
The relationship is non-linear, you need the graph to work out how
your pump will perform.
There is 0.43psi for every foot head lifted. (plus the pipework
resistance)