Designing a sprinkler system to put water on house during brush fire

[dschag]

Hello. I live in the Los Angeles area, in the mountains with a lot of thick, dry chaparral. I've put in a watering system on top of the ground until I can decide if it is the best I can do. It doesn't throw as much water as I had hoped, where I would like it, and would like to identify the elements and see anyone can suggest improvements. Here's what I have:

1. Roughly 300' perimeter
2. 10,000 gallon water tank running off a well
3. The water pump is a vertical type that was designed to accommodate remote fire hydrants (as I understand it, the pumps ramps up speed as water is demanded)
4. I have a 2 1/2" water line out of pump that goes to the house (where, of course, the pressure is regulated to about 65 lbs)
5. Before split to house, I have a 2" line (then stepping down to 1 1/2" then to 1") going into two in ground water cabinets that use 3/4" rainbird electric valves
6. OK, so off of 3 separate valves, I have run 3 lines of 3/4" pvc:

• 75' with 4 rainbird impact sprinklers mounted on 1/2" risers that are 3' tall and aimed at my roofs
• 150' with 7 sprinklers (as above)
• 125' with 5 sprinklers (as above)

The reason different lengths and number of heads is due to trying to maximize desired water effect and just adjusted lengths and heads based on performance. For some reason the 150' section performs better, thus has more heads. I'm just wondering if my design is pretty solid and whether I could pick up some through flow performance (more volume, more distance, etc.) through a different configuration. Are the valves restricting the flow? Should I be taping into the 2 1/2" main directly? Are the rainbird impact sprinklers the best for throwing a distance, moving back and forth, and scattering water high and low?


Or, maybe I don't even know the question I really should be asking? Thanks for any comments or ideas.

 

[dschag]

Hello. I live in the Los Angeles area, in the mountains with a lot of thick, dry chaparral. I've put in a watering system on top of the ground until I can decide if it is the best I can do. It doesn't throw as much water as I had hoped, where I would like it, and would like to identify the elements and see anyone can suggest improvements. Here's what I have:

1. Roughly 300' perimeter
2. 10,000 gallon water tank running off a well
3. The water pump is a vertical type that was designed to accommodate remote fire hydrants (as I understand it, the pumps ramps up speed as water is demanded)
4. I have a 2 1/2" water line out of pump that goes to the house (where, of course, the pressure is regulated to about 65 lbs)
5. Before split to house, I have a 2" line (then stepping down to 1 1/2" then to 1") going into two in ground water cabinets that use 3/4" rainbird electric valves
6. OK, so off of 3 separate valves, I have run 3 lines of 3/4" pvc:

• 75' with 4 rainbird impact sprinklers mounted on 1/2" risers that are 3' tall and aimed at my roofs
• 150' with 7 sprinklers (as above)
• 125' with 5 sprinklers (as above)

The reason different lengths and number of heads is due to trying to maximize desired water effect and just adjusted lengths and heads based on performance. For some reason the 150' section performs better, thus has more heads. I'm just wondering if my design is pretty solid and whether I could pick up some through flow performance (more volume, more distance, etc.) through a different configuration. Are the valves restricting the flow? Should I be taping into the 2 1/2" main directly? Are the rainbird impact sprinklers the best for throwing a distance, moving back and forth, and scattering water high and low?


Or, maybe I don't even know the question I really should be asking? Thanks for any comments or ideas.

 

[Sponsor]

 

[dschag]

I could add that the rainbirds are throwing the water about 25'.

 

[Valveman]

If you have one of those variable speed pumps that is supposed to ramp up speed as you use more water, you should not need to regulate the pressure down to 65 PSI with a regulator. The pressure coming out of the pump determines how far the sprinklers will throw water. Of course the 3/4 pipe will lose some pressure along the way. You can push a lot of water through a 3/4" pipe if you put enough pressure behind it. But it take more pressure from the pump than if you had larger pipe.

Those variable speed type pumps are not very dependable even when power and everything is good. So I certainly would not want to count on one during a fire. I would probably hook up a gasoline powered pump to run the fire sprinklers. However, these are made for high volume low pressure, so you would want as large of pipe to the sprinklers as needed. And you would probably need sprinklers with larger outlets to get the flow you need at the lower pressure.

 

[dschag]

I could add that the rainbirds are throwing the water about 25'.

 

[dschag]

Sorry valveman, I think I confused you. I connected the sprinkler lines BEFORE house regulator. The pressure gauge at my house pump reads about 75 pounds. I already have a back up generator (Generac, on propane, comes on automatically, and I have the sprinklers spraying the well pump, the house pump, the propane tank and the Generac--but of course does not guaranty that something won't happen). Can you see any other improvements on the system I am testing out? Thank you.