Spring time of 2020 force us to stay at home due to Coronavirus and many people got into garden jobs wich normally were left behind by other social activities. My project was to develop automated irigation for my yard. I got the info from friends that they’re using Hunter system and that’s was my choice. Afterwards, I noticed also other suppliers like RainBird and Toro component compatible with Hunter. Gardena can be other variant for all kind of home watering and Irritriol for drip system.
As online retailer I used gardenium.ro as they have complete offer for accessories, good prices and phone support in case you do not know some details. They can make the design also but I didn’t check this service. As local supplier I used dedeman as they have some guys which give you indications even if sometimes the products at are bit expensive. Low cost variant for dedeman is Leroy Merlin and premium quality is Romstal.
As first step I planned 2 grass areas to be watered. A 460 m2 area on right side of my house and a 80 m2 in front. Both areas have rectangular shape with approx 540 m2.
As supply I have a well and I used a sumersible pump to pull out the water from ~20m deep. The 4″ pump Wasserkonig PS4-150 1.8kW pump (alternative is Sterwins pump or Wasserkonig WK2400-80) has specification in the datasheet a flow rate of 33 l/min at 19m height. This information is important when starting to plan the number of sprinklers per zone and then the number of zone for total area as a 100e to 200e pump will not be able to provide enough pressure for the flow rate requested by all sprinklers.
Theoretical performance of the pump can be derived using following simple rules. For each 10m height the pump loss is 1 bar. For 100m horizontal the pump lose 1bar. For the table above we can assume that for 33l/min the pressure given by the pump is 1.9 bars and for 16 l/mim we have 5.9 bars (59 meter divided by 10 bars per meter).
More precise data from table below shows my example for 25mm PEHD and 33l/min flow rate a 1.8 bars losses for 100 meters. As the the real length of the pipe is about 50m, the calculation shows at 33l/min an overall pressure drop of 3 bars. At lower flow 16 l/min, the pump pressure will be higher, in this case 5.9 bars.
Hunter recommends the MP Rotator nozzle grass irigation for slow absorption of water to increases efficiency. For the lateral rectangle area of 460 square meters I used 4 zones, each zone having sprinklers at aprox 7m x 8m covered by 4x MP3000 sprinkles. In the front area of 89 square meters I used 6x MP2000 rotator sprinklers. Both areas are shown below.
- Zone 1 – 6x sprinklers MP2000
- Zone 2 – 4x sprinklers MP3000
- Zone 3 – 4x sprinklers MP3000
- Zone 4 – 4x sprinklers MP3000
- Zone 5 – 4x sprinklers MP3000
By using 4xMP Rotator 3000 for each zone the flow request is calculated using Hunter table below.
- 1x MP3000 90 deg – 3 l/min (corner)
- 2x MP3000 180 deg – 14 l/min (laterals)
- 1x MP3000 360 deg – 13 l/min (center)
- Requested flow per zone: ~30 l/min
- Recomended pressure: 2.8 bars