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Tuesday, June 27th 2017, 10:14pm

Main line question

Main line question

I am getting ready to install a sprinkler system and have gone back and forth on the main line. I am thinking either 1& 1/4in schd. 40 pvc or 1" cl 200 and 1" laterals.
My furtherest head will be aprox. 260 ft from where I will tie into. I have a 5/8 meter and will install 1" double check backflow. For 11/4 in your psi los is .63 psi per 100 foot and for 1" class 200 its 1.30. I have ran the calculations and I should be good with either mathematically. I live in East texas- we get some cold but not much.

I would like to run the 1" and save money and have read conflicting reports regarding sch. 40 vs class 200 for main lines....




Posts: 2,272

Location: USA


Wednesday, June 28th 2017, 2:50am

Pretend that class 200 doesn't exist. Spend the extra money. I worked on 200 just today. Of course I put my shovel right through it. It broke like a potato chip doubling the difficulty of the job.


Supreme Member

Posts: 5,269

Location: Metro NYC


Wednesday, June 28th 2017, 6:52am

Your numbers have to work, for the system to work, so your supply pressure has to be enough to overcome whatever losses are in the system plumbing.

One thought about systems going into Texas lawns. For the present moment, a lot of those systems are using Double Check Valve Assembly backflow protection, which is conveniently installed in a valve box near the curbside water meter. This is subject to change, since Texas has been getting into sprinkler system regulations in a big way, and they could decide that they want the same toxic-rated backflow preventers that other states require as a matter of law.

It would be looking ahead to plan your present installation to allow for the plumbing to change over to using one of the toxic-rated backflow preventers, neither of which is conveniently installed in an underground valve box. One of them, the RPZ (like your DCVA, but on steroids) has a pressure loss almost 10 psi greater than what you are working with today. Allow for the extra pressure loss in the future, and a regulation change won't paint you into a corner.

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