Question
Hi--
I'm trying to determine whether my commercial system will work. I have a city source to a 2" meter giving me 35PSI minimum (which I guess I need to use). I will be running about 1500 LF of main line and using a 2" RPBP. The system will all be drip irrigation, but will probably include about 6 quick couplers. It seems that I am losing too much pressure in the RPBP and the main line alone. I'm not left with any pressure at the end. What am I doing wrong? It seems like the drip system should work easily with this setup.
Thanks!
Jim

Answer
Hi Jim

I have to little information to give you an good advice, but I'll try:
You says a 2" PVC pipe running 1500'??

Lets roll,
To run a drip system you need at least 30PSI


A 2" water meter delivers a Maximum Available GPM (Maximum Safe GPM)of 51GPM and a PSI lost of 2PSI.   

Reduced Pressure Backflow Preventer.(RPBP) You will need to obtain the manufacturer's pressure loss information for the reduced pressure backflow preventer you plan to use. As a general rule pressure losses for reduced pressure backflow preventers range from 8 and 12 PSI. So using 12 PSI would be a fairly safe figure.

1500' 2" PVC pipe (You need to know the GPM you get from the meter}. If we take the Maximum Safe GPM of 51 gpm we have a PSI loss factor of 1.99, so in a 1500' run you loss 29.85 PSI.

The total PSI loss will be 2+12+29.85=43.85PSI. YOUR SYSTEM WILL NOT WORK!

You have to do several zones in order to get it work.

My best advice is hire an irrigation company in your area to help you. But if you want do it in your own please check this web site: http://www.irrigationtutorials.com/dripguide.htm it will be useful.

Regards
Guillermo