However, it does not have to be complicated at all, what you need to know is the two basic principles of irrigation basic guide, which are the flow rate and the pressure at your water outlet. Knowing the the pressure and flow rate will help you finding the the most efficient sprinkler which will give you the best performance and most importantly preventing you having a costly error in your system.
The First Step: FINDING THE FLOW RATE
For residential and low volume water systems, calculating the flow rate in the system is quite simple. All you need is just a bucket and a timer. Please note that all the water outlets in the house or system have to be turned off before testing for the water flow rate.
We have the flow rate calculator ready for you to use in this link: https://www.irrigationbox.com.au/garden-hose-flow-rate-time-calculators
The process will be as simple as below:
- Open the tap at the full capacity
- Place the bucket underneath the flow`
- Time the amount of time it takes to fill the bucket
For example: 10-litre bucket take 15 seconds to fill
10 litre / 15 seconds x 60 = 40 litre per minute average flow rate
You can also calculate it the other way round, choose a certain amount of time and measure the amount of water in the bucket. For example: Fill the bucket when the water flow from the tap is under full blast for 10 seconds, then measure the amount of water inside the bucket. If in 10 second you are getting 12 litres, it means that: 12 litres / 10 seconds x 60 = 72 litres per minute average flow rate.
Alternatively, you could use a flow meter as well. Especially for bigger water applications, the most accurate way would be to use a flow meter or checking the pump’s performance curve to understand its water delivery capacity.
The Second Step: FINDING THE WATER PRESSURE
Pressure is the measurement of force within a system. This is the force that moves water through pipes, sprinklers and emitters. Static pressure is measured when no water is flowing and it can be easily obtained by a pressure gauge. However, due to the friction loss in the pipe between the sprinkler and water source or pump, the pressure at the sprinkler might be less that the pressure reading at the water source or pump.
Common Pressure measurement units: 1 Bar = 14.5038 psi = 100 kPa
Once you find out the water pressure and the flow rate in your system, you have to also consider the friction loss or pressure loss in between the water source and sprinkler head, which are depending on the diameter and length of your hose or pipe and how much flow rate you have in your system. Using the right size of a pipe or hose is very important to maintain the highest pressure you have got in your system. In order to accommodate the desired flow rate along the distance you need to move the water, right size and type of pipe or hose is required.
Please feel free to use our friction loss calculator to help finding the correct number in this link https://www.irrigationbox.com.au/pipeline-pressure-loss-calculator
The last thing we have to consider is elevation, so it is when your area or land is sloping downhill or uphill from the water outlet. The elevation affects the water pressure in your system.
However, it is simply adding or subtracting 4.5 psi for every 3 meters of elevation. When the area is going uphill, simply subtract 4.5 psi to your water pressure and the same way when it is going downhill, simply add 4.5 psi to your water pressure.
Static water pressure – Friction Loss +/- psi change from the elevation = psi available to sprinkler
- Water Pressure = 50 psi
- Friction Loss = 11 psi
- Elevation = 3 meters downhill = +4.5 psi
- Final psi on the sprinkler = 50 – 11 + 4.5 = 43.5 psi
Once you find out the water pressure and flow rate in your system, then you can determine which sprinkler would be the most suitable according to your requirements.
You have water flow rate of 150 litre per minute and pressure of 30 psi.
Firstly, check our wide range of the impact sprinklers in our website https://irrigationbox.com.au/impact-irrigation-sprinklers and see the tables to check which sprinkler would fit your flow rate and pressure.
In this case, you will see that the DuCaR Atom 28 sprinkler would fit both your pressure and flow rate.
Secondly, click on the DuCaR Atom 28 and see the technical specifications chart below in order to get a more accurate detail.
Values for a single sprinkler
Rainfall per hour
As you can see below on the chart, with 150 l/min and 30 psi, you could use 12mm nozzle and the sprinkler will work at the highest efficiency to irrigate approximately 21-metre radius.
You have a pump running for the irrigation system.
Firstly, check the performance curve of your pump. In this example, we have DuCaR DKT 80 PTO pump. If you go to the pumps technical specifications detail https://irrigationbox.com.au/ducar-dkt-80-pto-irrigation-pump, you will find this performance curve below.
From the performance curve of this pump, you can see that the performance starts to drop significantly on 80m3/hour at 80 m head (8 Bar pressure).
80 m3/h = 1333 l/min
8 Bar = 116 psi pressure
As a result, if you have this DuCaR DKT 80 pump, you have so much flow rate and that you are able to operate few sprinklers at the same time. DuCaR Green 150 or DuCaR Jet 200 would be able to accommodate if you decided to run only one sprinkler.
All our sprinklers head comes with different sizes of nozzles that allow you to have the best match for the flow rate and pressure in your system. In addition, you could also add a skid base or a wheeled cart or a tripod stand that will fit to the sprinkler depending on your purpose and how you would like to run the sprinkler with.
Our website, irrigationBox offers the right sprinklers that suit all your requirements in order to achieve the highest efficiency and give you best performance. With us, it is about providing high quality sprinklers that will work the best for you and not just about the price of the sprinklers. With us, you can buy online with confidence! Or visit our warehouse in 12/49 Jijaws Street Sumner QLD 4074 to find all your agriculture irrigation equipment.