On Jul 5, 9:38*pm, Gil wrote:
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.

To determine the pump's capacity you need to take a few things into
consideration. For example, the 30 psi you mention - was it taken from
the discharge side of the pump? If so, it would be the pump's 'residual
pressure' with a flow of 10 gpm. If this is the case, then the pump is
still capable of a higher gpm flow. You could try using two discharge
points of the same size and note the residual pressure while flowing. As
the pump reaches its gpm capacity the residual pressure will start
decreasing and the water being discharged will be considerably more.

*From what you described I would think your pump is capable of pumping
considerably more than 10 gpm. All you have done so far is determine
that the pump is capable of pumping 10 gpm through a 3/4" outlet with a
residual pressure of 30 psi.

Keep in mind that the 'residual' 30 psi pressure is not the flow
pressure. There are other factors such as the depth the pump has to draw
the water up from, the distance from the pump discharge to the outlets,
the number of elbows or right angle turns that may be in the line
feeding the outlets, etc.

All measurements were taken on the discharge side (see arrow on pic).
I have an existing sprinkler system that is about 10 years old and
failing (poor coverage from original design). I'm filling out a design
sheet from Rain Bird and calculated PSI and GPM per their
instructions. I currently have 4 zones setup, but I think my yard
should have 5 (125' X 80' lot). At the end of the day, I may need an
new system installed so I'm trying to work this out before I send in
the paperwork to Rain Bird. I don't want to end up with a band-aid - I
want a nice functional system.

[img src="http://www.jaymartinreptiles.com/misc/pump2.jpg" /img]