Monthly Archives: December 2016

Pressure Compensated Drip Pipe

Pressure Compensated Leaky Hose The Professionals Choice Of Drip Pipe

This is a pressure compensated leaky hose and offers a very even and reliable coverage compared to other makes of leaky hose.  For more information concerning pressure compensated leaky hose please click the link below

Example of a header

If you would like to watch a brief video about Netafim please click here
Please click here to watch a brief video explaining how to use a push fit fitting

The diagram below should give you a visual ideal how drip pipe works

Pressure compensated drip pipe has a dripper inside the pipe at either 30 or 50 cm spacing.  The drippers are pressure compensated which means that the same amount of water will drip from the first to last dripper ( 1.6 LPH) even if the pipe is running up or down hill.  This is achieved using a filter.  When water is dripped on to the soil water spreads between 50 and 60 cm in diameter.  The surface stays quite dry however under the soil as per the side profile we can see the water spreading.  Providing the drip pipe is operated for 30 minutes per day, every day the soil will stay damp and plant will thrive.  On top of this because the soil surface is dry there is reduced germination of annual weeds and less evaporation that is associated with spray irrigation as much of the water is used to cool the soil. Added to this benefit the foliage and flowers of the plants do not become damage as the water is applied to the soil surface

Watering A Border Using A Header Pipe

Below is an example of how Netafim should be laid out so that wider borders can be watered.  The example below would water the complete border 1.5 meters in width by the length of the pipe.  So if we assume the border below is 10 meters in length then 30 meters will water 15 square meters

Use drip irrigation every day for 30 minutes

Drip irrigation should be used for 30 minutes every day.  The reason is because the soil is being used like a sponge.  If you take a dry sponge and pop it under running water you will see that most of the water runs off.  Now get the same sponge soak it with water and ring it out.  Pop the sponge back under the flowing water and you will see that most of the water is absorbed by the sponge

Although it may seem very satisfying to water by hand, if you dig into the soil when you’re finished you will find only the top inch or so is wet. Most of us don’t have the patience or time to water properly by hand. Giving a 20×3-foot vegetable bed the inch or more of water it needs during the heat of summer would leave you holding the hose for almost a half an hour (assuming your hose can deliver 2 gallons per minute). Even if you had the patience required, the water flows so fast, much of it runs off along the soil’s surface rather than sinking in.

Using a sprinkler also has several disadvantages compared to drip irrigation. Sprinkling increases the spread of plant diseases, especially if you water in the evening when leaves have less chance to dry off quickly. Sprinkler irrigation also uses more water than drip irrigation, wastes water on weeds in the rows and creates muddy paths. Your best bet is drip irrigation. —Steve Reiners, Ph.D., associate professor of horticultural sciences, Cornell University.

How Many Pop Ups Will I need And What Location Should I put Them In

The correct way to layout a pop up lawn watering system is to arrange the pop ups so that they throw the water in to the middle of the lawn rather than running them down the centre of the lawn throwing water out at 360 degrees.  In other words pop ups should be if possible located on the edge of the lawn as per the diagram below.


Pop ups installed in this way water the lawn more efficiently as the area that we want to water receives the water and little or no water is wasted with over spray.  This is even more important with paths and patios as when you spray water repeatedly on to a smooth stone surface  a clear bacteria can develop that forms almost like a think jelly like film which is very slippery.  Over longer periods of time the stone could develop algae or moss and this again would look messy.


In the simple examples above we can see that the picture on the left is throwing water in to the centre of the lawn while the picture on the right is an example of central 360 degree rotors that will water the same area.  On the right hand picture we have assumed the patio is at the bottom end and used a 180 degree nozzle as I am sure that at the very least patio furniture etc should stay dry

When watering near a drive  we again want to throw the water away from the drive as water sprayed on to a tarmac drive will encourage moss or if cars are parked on the drive we would soon see streaks for on the cars unless we were using recycled rainwater.

How Close together should we put a pop up

Some companies suggest the 3 or point rules however this put a huge amount of water on per square metre and ultimately adds more zones.  What we think is the best alternative is to use a pop up that applies water evenly to start with like the MP Rotator in a pro spray body and space the bodies at intervals equivalent of the radius of the spray as per the example below.  The pop up in the example has a radius of 5 metres ( the central pop up has a radius of 5 metres and a diameter of 10 metres.  So the pop up bodies are spaced 5 metres apart starting and finishing in the corners at 90 degrees


Pop Up Lawn Watering For Large Lawns

Pumps and Tanks For Large Lawns

A large lawn will need to be watered using a pump with a tank.  The reason for this is so that we can have a reliable higher pressure and a higher reliable flow.  The reason for the higher flow and pressure is so that we can run more pop ups from one zone and cover the area that needs watering efficiently.

There are a lot of thing to consider prior to buying a tank and a pump and this will be covered in more detail later however here is a basic example to give you an idea.

What size tank do I need

Tanks come in many shapes and sizes and prior to buying a tank we would need to know how much water we are using and how quickly we can fill the tank while the water is being used. The example below will give you an idea of the maths used however even this can vary as many timers can have delays programmed in which will delay the start between zones in order to allow the tank to refill.  In the example below we will assume we want to keep the tank as small as is possible

In this example we will have 4 zones watering the lawn.  We will assume the tank is filled by the mans water supply and that it is filling at the rate of 500 litres per hour.  We will assume that each zone will run for 30 minutes

Zone 1 uses 3500 litres per hour

Zone 2 uses 2500 litres per hour

Zone 3 uses 3500 litre per hour

Zone 4 uses 2500 litre per hour

Assumed information

1  The tank is filling at 500 litres per hour

2  Each zone will run for 30 minutes

If zone 1 comes on at 5 am and runs for 30 minutes it will require 1750 litres of water.  In that 30 minute period we know that the tank will receive 250 litres from the main.   In order for zone 1 to run completely without running out of water we would need a tank with a minimum volume of 1500 litres.

If zone 2 were to start up straight after zone 1 and our tank was only 1500 litres then it would run out of water straight away.  At this point we could decide to purchase a larger tank or to programme a delay prior to starting zone 2.  To fill the tank the delay would have to be 3 hours in order to completely fill the tank which would make it very awkward  to water all zones at the ideal time of the day which is very early morning.  Because of this we may want to increase the size of the tank in order for us to water zones 1 and 2  this morning one after the other and then  zones 3 and 4 on the follow morning.

If we assume that we will water zones 1 and 2 today and then zones 3 and 4 tomorrow then the calculation for tank sizes is below


Zone 1running for 30 minutes will use 1750 litres and zone 2 will run for 30 minutes and use 1250 litres.  So the total amount of water used in the 1 hour ( 30 mins per zone )  is 3000 litres.  In the 1 hour period the tank fill would have supplied 500 litres so would need a tank with a minimum tank size of 2500 litres

The example above is not a true example and only supplied as a guide as there are many other point to consider prior to buying a tank for watering the lawn.  Please do call or email our experts who will be happy to help or as an alternative please do use our free planning service

What Size Pump Will I need

If we look at the example above we can see that both zones 1 and 3 are using 3500 litres per hour.  As these have the highest volumes we will focus on these as the 2 smaller zones can if required have pressure regulators fitted.  So we know we need 3500 litres per hour and we know from the previous article that we need a minimum pressure at the spray head of 1.85 bar however the ideal pressure is 2.5 bar.  Something that we will not cover in detail here is friction so for this example we will assume a friction loss of .5 bar so we will need a pressure at the pump of 3 bar which will give us a pressure at the spray head of 2.5 bar.

All pumps are supplied with a pump performance curve.  This curve will let you know what the outlet pressure from the pump is at a given flow.

In the example above we can see 4 curves which represent various models of this particular pump supplied by the Italian pump manufacturer Dabs.  The horizontal line along the bottom shows the flow and the vertical line at the side shows pressure.  If we put a mark at the 3500 litre per hour mark and draw a straight line up we can see that the smallest model would be totally unsuitable for our application.  However if we follow the red line across we can see that two models fit our requirements and will deliver 3.5 bar at the pump or if we look at the purple line we can see that the larger pump in this family will deliver 4.5 bar when running with a flow of 3500 litres per hour

In this article we have not covered friction related to pipe sizes, fittings, filters, valves etc.  Soe of these will be to complex on very large systems so please do take advantage of our free planning service

How Many Pop Ups Can I Attach To Each Zone

Fingers crossed you have read the article that explains how pressure and flow effect the operation of a pop up and how pressure reduces as we use water.  If this is the case then read on if not then go back and read the first article.

We need to know how much water each pop up is using per hour and the amount of water pressure we have from our water source.  In the example below will assume we are fitting a pop up system to a small garden and we are going to run it from the mains water supply.  For large gardens we would probably use a tank and a pump.  This will be covered in a later article when we will explain to you how to decide what size tank you would need and the size of pump.  In the example below we will use a Hunter Pro Spray body combined with an Mp rotator nozzle as these are very cost effective, apply water very evenly and apply water slowly over a longer period of time making them ideal for low flow and low pressure applications which mains water supplies generally are.  On top of this the MP Rotator now accounts for about 85% of our pop up sales because of their leading spray pattern that applies water at 11mm per hour very evenly to the lawn .

Let us assume our water pressure is 4 bar and our flow from the tap is 1500 litres per hour.

lets now put this in to a simple graph

From the example above we can see that in order to maintain 2.5bar at the tap the maximum amount of water we can use per zone is about 550 litres per hour.  There are other pressure loses to consider however this goes beyond the scope of this article.  Please do take advantage of our free planning service if a more detailed plan is required.

Now we know what water we can use we can now see how much our MP Rotators are going to use per hour.  In this example we are going to assume we have a 10 metre by 8 metre lawn

We are using Mp 2000 nozzles set at 90 degrees in the four corners and in the middle we will use one MP1000 at 360 degrees.  From our mp rotator chart we can see that the mp 2000 rotator nozzles are using 74 litres per hour and our Mp1000 at 360 degrees is using 161 litres per hour.  This gives us a total of 457 litres per hour and if we pop this on to our chart we will see that our water pressure at the tap will be close to 3 bar.  From this we can assume depending on the pipe layout etc that we will probably be maintaining 2.5 bar at the MP Rotators spray head so it is well within the scope of pop up operation.  To view the mp rotator water usage guide please click here

Before You Start Planning Your Pop Up Watering System

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