Proper order of irrigation components

[gonif]

I'm putting in a drip irrigation system with several zones, automatic valves, and PVC delivery to each zone -- so more involved than just hooking up the drip tube to a hose bib. I'm uncertain where to place the pressure regulator and screen filter, though. Should they go before the pressure vacuum breaker or after (or does it matter)? Can the pressure regulator handle constant pressure, or should I install a "master" valve so the pressure regulator is sandwiched between it and the valve manifold?

The order I was thinking of is:

1) water supply (duh)
2) Pressure vacuum breaker
3) screen filter
4) pressure regulator (this drops pressure to 30 PSI)
5) valve manifold

Or maybe

1) water supply
2) screen filter (to help protect the expensive PVB downstream)
3) pressure regulator (to 30 PSI)
4) pressure vacuum breaker
5) valve manifold

Any thoughts? Thank you!

[hj]

Normally the drip system has a filter and pressure/flow regulator on each zone AFTER the solenoid valve. The pressure backflow preventer goes at the connection to the water supply. Then the valve manifold, valves, and finally the drip zone with the filter and regulator.

[gonif]

You're right, that's how it's usually done. But I think it's done that way because people usually already have a multi-zone sprinkler system, and then later they convert maybe one zone to drip. Since I have a four zone system and it's 100% drip irrigation, it seemed silly to install four filters and four pressure regulators, all inside the crowded valve box. If I only operate one valve at a time, then placing a single filter+pressure regulator ahead of the valve manifold should operate similarly to placing them after each valve, shouldn't it?

[Mr_Pike]

I would do a bit of research into the pressure required for the valves. Its pretty early in the morning to be thinking this hard, but I recall a problem a few years back with a homeowner designed and installed system like this for his greenhouse. The valves would not close correctly because the pressure regulator was in front of them. They had a constant weep.

I saw in my Green industries magazine this weekend, that someone is now making an all in 1 system - valve, filter, regulator. Looked like a cool idea.

You could add a whole system filter in front of the PVB with a 140 mesh screen. I would think that would do the trick for your drip. But if you plan on using only 1 regulator, you should look into a low pressure valve, or at least make sure the ones you plan on using will operate at 30 lbs.

Regulator should go after the PVB. Screen can go before.