Hello everyone,
I want to install an automatic garden irrigation system. For this, I plan to use a pump that provides a maximum pressure of 4.4 bar. At 3.5 bar, the pump delivers a water flow rate of 3.1 m³/h (3.4 yd³/h). Since my largest zone only requires 1.6 m³/h (1.8 yd³/h), this is more than enough.
I will be using Hunter or Rainbird nozzles. The question I have is which pop-up sprinklers I need. There are models with pressure regulation that reduce the pressure to, for example, 3.1 or 2.8 bar. However, they cost about 10 euros each. With 30 sprinklers, that adds up.
I have researched this topic a lot but keep reading conflicting opinions. Some say the entire irrigation system only works properly if I use pressure-regulated pop-up bodies everywhere. Others say to save the money and use 32 mm (1 1/4 inch) polyethylene pipes with standard pop-up bodies without pressure regulation.
Does anyone here have experience with this and can tell me if the system works just as well with pop-up bodies without pressure regulation?
I want to install an automatic garden irrigation system. For this, I plan to use a pump that provides a maximum pressure of 4.4 bar. At 3.5 bar, the pump delivers a water flow rate of 3.1 m³/h (3.4 yd³/h). Since my largest zone only requires 1.6 m³/h (1.8 yd³/h), this is more than enough.
I will be using Hunter or Rainbird nozzles. The question I have is which pop-up sprinklers I need. There are models with pressure regulation that reduce the pressure to, for example, 3.1 or 2.8 bar. However, they cost about 10 euros each. With 30 sprinklers, that adds up.
I have researched this topic a lot but keep reading conflicting opinions. Some say the entire irrigation system only works properly if I use pressure-regulated pop-up bodies everywhere. Others say to save the money and use 32 mm (1 1/4 inch) polyethylene pipes with standard pop-up bodies without pressure regulation.
Does anyone here have experience with this and can tell me if the system works just as well with pop-up bodies without pressure regulation?
W
wiltshire25 Aug 2025 11:00BoPaDi24 schrieb:
Do I understand correctly that if the pump curve shows the pump delivering 1.6 m³/h (about 7 gpm) of water at 4.4 bar (64 psi) and I run only one zone where all the sprinklers together consume exactly 1.6 m³/h, the pump will automatically adjust to 4.4 bar? No, unfortunately that is not the case. The diagram shows a characteristic curve under standard conditions.
The number of sprinklers, their flow rate/pressure regulation, the pipe length, pipe diameter, and elevation profile—all of these affect the actual amount of water delivered.
Use pressure regulators and you won’t need to do much calculation. You can make a rough estimate and then adjust practically at the sprinkler by means of the pressure regulator.
From the pump curve, choose a realistic operating range that provides a “buffer for practical implementation.” For an operating point of 1.6 m³/h (about 7 gpm), I would, for example, base calculations on 20 l/min (1.2 m³/h) (about 5 gpm). Divide the number of sprinklers by the flow rate at the target pressure; this gives you the number of sprinklers that can reasonably operate simultaneously—the target pressure is adjustable.
From the sprinkler curve, you get the throw distance. Now you can adjust a few parameters until you find the right positions. Thanks to the buffer and the pressure regulator, minor calculation errors can be compensated in practice. A rough estimate is sufficient.
If you do not want pressure regulation because it costs about €300 extra, you have to accept variable pressure. Here are some incomplete parameters to discourage you:
1. Length, pipe diameter, and material matter: pressure loss relative to pipe diameter is significant. For example, in a 1/2" PE pipe, you lose about 0.35 bar (5 psi) pressure over 10 m (33 feet) at 1.2 m³/h (about 5 gpm); in a 1" pipe, it is only about one-tenth of that.
2. Elevation changes count. 1 m (3 feet) corresponds to about 0.1 bar (1.5 psi) pressure gain downhill or loss uphill.
3. Simple sprinkler formula (good approximation): Water flow = sprinkler constant multiplied by the square root of nozzle pressure, which corresponds to the pipe pressure.
Each nozzle will have a different throw distance. Happy planning!
Thank you for the detailed explanation.
Could I use a pressure reducer directly at the valve of each circuit instead of pressure-regulated housings? That way, I would feel more flexible.
So, I would set the pressure reducer at the valve to 3.2 bar (46 psi) and then lay everything behind it with a 32 mm (1.25 inch) pipe. That would give me the same result as with the pressure-regulated housings, right?
Could I use a pressure reducer directly at the valve of each circuit instead of pressure-regulated housings? That way, I would feel more flexible.
So, I would set the pressure reducer at the valve to 3.2 bar (46 psi) and then lay everything behind it with a 32 mm (1.25 inch) pipe. That would give me the same result as with the pressure-regulated housings, right?
W
wiltshire25 Aug 2025 15:45BoPaDi24 schrieb:
Could I use just a pressure reducer directly at the valve of each circuit instead of the pressure-regulated housings? That would feel more flexible to me. Of course, you can do that. However, I don’t see the flexibility advantage compared to an adjustable pressure regulator—rather the opposite. I would install a premium system as it was designed. Often, years of experience and details are behind these considerations, which only become apparent when taking a detour.
The sprinkler is not adjustable. The pressure-regulated housings are all preset to a specific pressure – 2.1 bar, 3.1 bar, or 2.8 bar in the case of Hunter. Unfortunately, this preset cannot be changed. The MP Rotators operate optimally at a pressure of 2.8 bar (40.6 psi). The R-VAN by Rainbird, on the other hand, works best at 3.1 bar (44.9 psi). With a pressure reducer installed at the beginning, I would have the flexibility to adjust the pressure. That is what I meant by more flexibility.
W
wiltshire25 Aug 2025 17:13I did not express myself well, or rather I expressed it incorrectly. On the sprinkler, you adjust the throwing range with a small screw, not the pressure. So everything is fine with the constant pressure.
BoPaDi24 schrieb:
The MP rotators operate optimally at a pressure of 2.8 bar (40.6 psi).Yes, but only for one season. I installed about 40 of them. After each winter, 20-40% of the nozzles had to be replaced because they stopped rotating (even after cleaning and ultrasonic baths). The internal mechanism is very delicate and therefore sensitive to even the smallest amounts of dirt or lime deposits over the winter. I have since replaced almost all of them with JPG and I20 gear-driven sprinklers and have had very good results. It is just more difficult to implement this where very short throw distances or replacement of strip sprinkler nozzles are involved.