The sprinkler pipe size from the water supply source to a sprinkler shall be not less than 3/4 of an inch (20 mm) in diameter.
Although 1/2” tubing is great for small and medium gardens, those with more irrigation demands will likely want something bigger. That's where 3/4” Poly Tubing comes in. This size is ideal for large gardens and small-scale farming.
If you choose to use PVC pipe for your irrigation laterals, make sure to use pipe that is at least 3/4" thick. 1/2" inch laterals clog very easily. If you choose to use fittings, most common PVC fitting types work fine.
While the most common, traditional domestic service line is size ¾-inch with a ⅝-inch water meter, the most common piping sizes in RFSS applications for one- and two-family dwellings are 1-inch, 1½- inch, and 2-inch.
A common rule that is followed for obstructions within 18 inches of the sprinkler deflector is the “three times rule”. This requires sprinklers to be positioned away from obstructions a minimum or three times the maximum dimension of the obstruction.
Nothing should be in that area between the bottom of the sprinkler heads and the imaginary horizontal plane parallel to the ceiling that is 18 inches below. This is done to allow an even and unobstructed spray pattern from the sprinklers when triggered to extinguish the fire.
My recommendation is to bury sprinkler lines 8-12 inches. I usually try to keep a standard depth of 10" because it provides more safety if I need to do some type of ground work so I don't have to worry about hitting lines. A walk-behind rototiller generally won't go deeper than 8".
The trenches will be relatively shallow, usually 6 to 12 inches deep, depending on your area's freeze cycles and frost severity. The trench must also be deep enough to allow the sprinklers to retract underground to prevent breakage from lawn machines. Dig the trench by hand or rent a trencher (a real timesaver).
You can operate 2 or 3 sprinklers at one time with 'Y's and extra hoses, depending on your water pressure. To run more than one sprinkler off the same faucet, attach a 'Y' to your faucet and run a hose to each sprinkler.
In a water flowing pipeline, water pressure and pipe size are dependent on each other. If the diameter of a pipe decreases, the pressure in the pipe will automatically rise. As per the scientific approach, pressure can be reduced by reducing the area of conveyance.
At different pressures, the sprinkler head and nozzle will consume different amounts of water. For example, at 35 pounds per square inch (PSI) the 5000 Series Rotor using the 3.0 nozzle will use 3.11 gallons per minute (GPM). If your home's water capacity was 10 GPM, you could place 3 heads per zone.
Home fire sprinkler systems use CPVC (chloro-polyvinyl chloride) or PEX plastic piping. Special glue secures the CPVC pipe connections, reducing the problems of sweating copper joints or threading steel pipe. NFPA 13D is referenced in many building and fire codes.
Having a pipe too big can cause a whole new set of problems. Too big is always better than too small but only if it's a little too big, not a lot. An efficient design will usually use three or four sizes of pipe.
For spray heads, it is 30 psi, with an operating range of 15 to 30 psi. For drip lines, this is about 20 psi, with an operating range of 15 to 30 psi. Remember, flow rate and pressure are directly related to one another. If pressure is not well-controlled, irrigation efficiency will suffer.
All standard sprinkler heads—pendent, upright, and sidewall—have the same minimum sprinkler distance from walls: four inches. For sidewall heads, that's the distance from an end wall (10.3. 4.3.
Polyethylene is the ideal choice for those environments that require flexible tube. Rocky soil or cold climates where the soil will likely freeze are where this type of tube works best. Due to their high pressure ratings, this type of tubing is becoming more commonly used in home sprinkler systems than ever before.
Pipe slope is a critical element in reducing water collection following a sprinkler system drain. Water removal is important in that the largest detriment to sprinkler system life, corrosion, occurs across interfaces between air and water.
However, bonding and grounding are two different things, with different purposes. In regard to fire sprinkler systems, while bonding of the sprinkler system piping is acceptable, using the sprinkler system piping as a grounding electrode is prohibited per NFPA 13 and NFPA 24.
Irrigation lines are typically installed at a depth of 10” (to the top of the pipe) to prevent a standard 8\" shovel blade from reaching the lines. A 12” depth would be best. This is for residential installations, not commercial. The mainline (pressurized line) should be between 12” to 18” deep.
Check your system's design.
Keep the spray at least 2 feet away from the house.
The “Four Times Rule” is really just an extension of the “three times rule” however it covers extended coverage sprinklers and the maximum clearance is 36 inches (0.9144 m).
Sprinkler heads must be a maximum of 12-15 feet apart, depending on the hazard rating of the space (it ranges from Light Hazard to Extra Hazard 1&2), and at least half that distance from the nearest walls (typically 7.5 feet away).