Check this link. It is from the makers of Sequence pumps.
http://www.mdminc.com/Friction_Loss_Chart.htm

"~ jan" wrote in message
...
This was originally posted by Rob Farlee in RP:

The links do longer work, perhaps someone knows of a good one we could
use?
----start--
Simplest way is to follow the guidelines he
website no longer active
1-1/2 inch pipe for up to 1800 gph
2 inch pipe for up to 3600 gph.

More complicated way is to iteratively estimate the total head, which
is the sum of static head plus dynamic head.

Here's a table of dynamic head (pipe friction back pressure):
website below no longer active
http://www.flash.net/~blhill/pages.a....html#friction

2400 gph through 70 feet of 1-1/2 inch pipe = 6 foot dynamic head.
2400 gph though 3 feet of 1 inch hose = 2.4 foot dynamic head
Total head = 3 + 2.4 + 6 = 11.4 feet.

Now refer to the performance table on the pump's box. Guess the
flow rate at 11 foot head would be 1200 gph. Use that for the next
iteration.
1200 gph, 70' 1.5" pipe = 2 foot head
1200 gph, 3' 1" hose = 1 foot head
Total head = 3 + 2 + 1 = 6 feet.

Again referring to the pump's table, 1700 gph at 6 feet.
1700 gph, 70' 1.5" pipe = 4 foot
1700 gph, 3' 1" hose = 1 foot
Total head = 8 feet.

Pump table: 1500 gph at 8 feet.
1500 gph, 70' 1.5" pipe = 2.8 feet
1500 gph, 3' 1" hose = 1 foot
Total head = 7 feet.

Pump table: 1600 gph at 7 feet.
Iterate again, we'd get 1550 gph. Close enough.

If you go to 2 inch pipe, head will be 3 feet less, flow will increase
by about 300 gph. If you get rid of the 1 inch hose, head will be 1 foot
less, flow will increase by about 100 gph. Both together, 2 inch pipe,
dynamic head would be 1.5 foot, total head 4.5 feet, flow 1850 gph.
That's a 15 to 20 percent increase in flow. Not clear if it's worth it;
depends on how much trouble it'd be to replace the pipe.

For all these Danner pumps, as head increases, both water flow
and electric power drawn decrease. The Danner 2400 gph pump has 1 inch
fittings. I think these act as nozzles to limit the maximum flow if no
plumbing were attached. This keeps a load on the motor, limiting the
maximum electric current and heat the motor must dissipate. That's just a
guess, though. - Rod
----end--
~ jan
------------
Zone 7a, SE Washington State
Ponds: www.jjspond.us