Pop up watering systems for lawns can be a very cost effective way to keep your lawn in tip top condition. However before you start there are a few essential point that you must consider.
How does a pop up work
Almost all pop ups are water powered. The body of the pop up stays in the ground and when the water flows the central riser is pushed up by water pressure. When the riser reaches the top a wiper seal is forced out and prevents any water passing between the riser and the body. The wiper seal needs a minimum water pressure in order to be forced out and make the seal between the riser and the body. On most pop ups this is about 1.85 bar pressure.
What happens to water pressure as we use water
Water pressure in a mains supply is normally measured as static pressure. What this means is that when you read the water pressure you should make sure that every thing is off and that no water is being used. This is called static water pressure. For most houses in the UK you static water pressure would be about 3.5 bar however pressures can be as high as 10 bar and as low as 1.5 bar depending on your location and the condition of the water pipes running to your house. As we turn on taps etc and the water starts to flow we will see the water pressure drop. The more water we use the lower the pressure will fall. A typical house in the UK will have a flow from the water main of about 1200 litres per hour however this can vary down to as low as 600 litres per hour and up to 2000 litres per hour or more. Below is a chart which will give you an idea of how the amount of water we use reduces water pressure. We would normally produce readings at various flows in order to make the graph more accurate however in this example we have used a straight line
We can clearly see from the graph below that our pressure will drop based on the amount of water we use. In other words the amount of water spraying out of the nozzle. On top of this the range of the spray from the pop up will vary depending on the pressure at the nozzle. All pop ups have what we call a sweet spot. In other words an ideal working pressure and this will be explained later on 