Emitter Drip tubing

post by Robmoo on Jun 27, 2022

I’m using the rainbird emitter drip tubing for my lawn. The emitters are every 18 inches and put out .9gal/hour. In the settings do I select drip tubing or emitter. How does Rachio know the spacing between emitters? I saw the settings for nozzle output in advanced.

post by spaceman_spiff on Jun 27, 2022

Emitter. I use the same Rainbird emitter tubing for my shrubs.

PR (in/hr) = (231.1 cubic inches / gal * GPH) / A
where GPH = The total GPH of your drip line. In your case, it’s essentially 0.9 * (total length of your drip tubing in inches / 18)
and A = area that you are dripping, in square inches

post by Robmoo on Jun 27, 2022

Frankly the emitter tubing is under the turf and I have no idea exactly how long each run is. Each emitter does .9 gal/hr and has to cover 324 inches squared. That takes 1.4 gallons which will take an emitter 1.55 hours. If I divide .9 inches/hr by 1.55 hours I get .58 inches.

I wonder how long it takes the program to update once one has changed the zones.

post by Robmoo on Jun 27, 2022

I made those changes and the watering schedule times only changed by 2-4 minutes per zone. I expected quite a bit longer runs at the lower flow rate.

I’ll let Rachio do its thing over the next couple of weeks and I’ll adjust if I’m mowing too often or the grass isn’t thriving.

post by spaceman_spiff on Jun 28, 2022

The schedules are updated almost instantaneously once you change zone settings.

For reference, my one drip zone that’s mainly emitter tubing (0.9 gph per) ends up being 0.82 in/hr. I try to double-run my shrubs. Like, one run down one side (say, north), then come back and do the other side (south), so it’s getting dripped by multiple emitters at the same time. I know you mentioned yours are under the turf, but if your runs are similar, your PR looks a touch low. Are you dripping shrubs or grass? You said “turf,” so I’m just curious.

post by Robmoo on Jun 28, 2022

The emitters are 18" apart and the runs are 18" apart. So each emitter is watering approximately an 18" x 18" square or a 324 square inch area. It takes 1.4 gallons to fill a 324 square inch area to 1 inch depth. This will take approximately 1.55 hours at .9 gal/hr. If I divide .9 gal/hour by 1.55 hours, I get .58 gal.

I think that I’ve calculated this correctly. See any flaws?