Air pressure must not exceed 50 pounds per square inch (psi) during the blow out procedure. A pressure-regulating valve must be used to avoid over pressurization of the system. Air volume should be high and air pressure low.
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.
Under 40 is considered low, so you may need to boost pressure if installing an irrigation system. Over 80 is high, and many household water appliances may be at risk of damage over this range. A pressure reducing valve may be necessary. Static pressure is affected by elevation.
For many sprinklers, the recommended operating water pressure ranges between 30-40 pounds PSI. A pressure regulator ensures that water pressure consistently stays within this recommended PSI range, regardless of the water pressure before it reaches the sprinkler.
Drip irrigation systems are designed to work at an even lower pressure than is set for the house, with the optimal pressure for a drip system between 15 and 30 PSI.
Most spray sprinklers have recommended operating pressures between 30 pounds per square inch (psi) and 45 psi. Operating a sprinkler system at a pressure higher than recommended can cause significant water waste, due to excessive flow rates, misting, fogging, overspray, and uneven coverage.
A drip system that operates at high pressure (above 40 psi) may appear to be operating adequately, however it is more likely to develop problems over time.
Normal psi for a home pipe system is between 30 and 80 psi. While you don't want the psi to be too low, it violates code to be above 80. Instead, you should aim for a psi that's between 60 and 70.
Most residential plumbing systems are designed to handle 40 to 60 PSI of pressure, with 80 PSI being the typical maximum and anything over 100 PSI being possibly detrimental to plumbing components.
The minimum volume an air compressor must be able to provide to properly blowout an irrigation system is 20 cubic feet per meter (CFM).
Understanding Cubic Feet Per Minute (CFM)
CFM is measures at a given PSI and increases in direct proportion to the horsepower (HP) that is applied. While small, mobile at-home air compressors may deliver around 2 CFM, industrial air compressors with 200 HP can achieve air flow of around 1,000 CFM at 100 PSI.
Generally, the larger a pipe is, the higher the water flow. The water pressure level always has to be taken into consideration, however. Even the biggest, smoothest pipes will not have effective water flow if the water pressure is low, because there is not enough strength to defeat the force of friction.
If your home's water capacity was 10 GPM, you could place 3 heads per zone. Consult the Performance Charts on or inside the box your sprinkler head came in for your head's exact performance data, or locate the performance data in the Support area of this website.
You need pressure regulators to achieve the intended distribution pattern and application rate. If you do not control the system pressure, it can negatively affect the sprinkler performance. Without regulators, the throw radius can alter, fitting, and emitters could even take damage or blow out of the tubing.
The ideal water pressure for a house will be somewhere in the range of about 45 to 65 psi. Anything higher than 80 psi can cause damage, and anything much lower than 45 psi may result in issues when you use your shower, toilet, dishwasher and other water-consuming appliances.
When the water pressure is too high, the hoses and internal components of your appliances are exposed to conditions that can lead to excessive wear or a complete failure. Not only does this increase the risk that the appliance may fail prematurely it may also void the warranty.
Normal water pressure is generally between 40 and 60 PSI. Most homeowners prefer something right in the middle around 50 PSI. Once you measure the water pressure in your house, you can adjust it to a setting that is ideal for all family members and household uses.
Although there is a 30/30 rule (30 foot max length, 30 gph max flow rate), others recommend keeping runs of 1/4" tubing under 20 feet. Keeping these runs short should be fairly easy, since 1/4" tubing typically comes off the main 1/2" line only far enough to reach nearby plants or trees.
So, in most cases, a pressure regulator will be necessary to protect a drip system and help it work properly. That will ensure optimal results with your plants. Of course, if your water source can be delivered at a very low pressure, a regulator probably will not be necessary.
Pressure Regulator: Most drip systems operate at low pressure, usually less than 20 psi. Pressure regulators reduce incoming water pressure to the ideal pressure for the drip system. Water companies are required to deliver water at a minimum of 30 psi, although pressures can exceed 80 psi.
Keep in mind that while all drip irrigation systems are designed for low pressure, most operate on 12 - 20 PSI (pounds per square inch).
Typical sprinkler flow rates may vary from 4 gallons per minute (gpm) from a 5/32-inch nozzle at 30 pounds pressure to over 11 gpm from a 7/32-inch nozzle at 70 pounds pressure. The nozzle size is usually stamped on the nozzle. Wheelmove systems typically have 3/16-inch nozzles.