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  • The Water Supply (Water Fitting) Regulations 1999 provides five backflow prevention categories dependant on the risk level of the water use. The regulations require back-flow prevention devices to prevent the water on the premises being drawn backward into the public drinking water supply. Backflow may occur in a number of situations, including burst pipes in the street or cross connection of the mains water supply with pressurised supplies on the premises. An assessment needs to be made of the potential dangers to health of the backflow – if the backflow water comes from a butcher’s shop it is more likely to be contaminated than a newsagent. In the legislation, fluid risk category 5 covers the following areas: Fluid which represents a serious health hazard because of the concentration of pathogenic organisms, radioactive or very toxic substances, including any fluid which contains –  faecal material or other human waste: butchery or other animal waste: or pathogens from any other source.   A non-exhaustive list of examples of this include: General: Industrial cisterns Non-domestic hose union taps Permeable pipe other than domestic gardens, laid below or at ground level, with or without chemical additives Medical: Mortuary and embalming equipment Commercial clothes washing plant in health care premises Food processing: Butchery and meat trades Slaughterhouse equipment Vegetable washing To provide category 5 compliance, Access Irrigation produce a Cat 5 break tank and pump set. The break tank has a category ‘AB’ air-gap and the pump re-pressurises the water. An auto start device on the pump brings the pump on when there is a water demand and will stop the pump when the demand ceases. The pump set is available with a range of Lowara pumps which can be matched to the flow and pressure requirements of the project. The storage tank holds 91 litres of water and has a 1/2” BSP inlet thread and will handle an inflow of up to 1,200 l/h into the tank.

  • One of the neatest ways of installing an irrigation system is to locate all of the control valves in underground chambers. Not only does this hide away all of the messy control valves, but it prevents unauthorised tampering with the control equipment. The only problem with this solution is when you do want to change the watering times, you have to grovel in the underground chamber. To solve this problem, a fully waterproof Bluetooth irrigation controller is now available in the UK. The controller itself is IP68 rated, so it is designed to be fully immersed in water and will control up to 4 solenoid valves, plus a master vale and a rain sensor. The app itself will store the details of up to 200 controllers, as well as manually start, stop or suspend the controller from up to 10m away. For extra security a passcode can be added. To make installation simple, Access Irrigation also produce valve box kits which include a valve box and also 2 or 4 irrigation valves. These are designed to be buried in the garden, with an underground supply pipe bringing water to the valve box and then undergroung pipes going from the control valves to the variour areas to be watered. In 'Home Gardens' a DB valve kit is available to comply with the Water Regulations; this connects via the master valve of the controller. For very simple systems, Access also produce a Bluetooth tap timer, which can be operated from an app.

  • Hunter MP rotator sprinklers provide flexible watering for small lawns. One of the problems with rotor sprinklers is that if the arc is halved, the mpecipitation rate is effectively doubled. This leads to very uneven watering. In contrast the MP (matched precipitation) nozzles ensure that if the arc is reduced, so is the flow of water. Hunter Industries have launced a new short radius nozzle and also a longer range nozzle which will cover up to 10.7m radius. The short radius 800 series are designed for lawn coverage of between 2.6m and 3.0m, making them ideal of UK sized domestic gardens. There are two nozzles in the MP800 range, the Orange/Grey nozzle will cover arcs from 90 degrees to 210 degrees, and the Lime Green will cover a full circle. Both nozzles will operate at pressures between 1.7 bar and 3.8 bar. At the top end of the range the MP3500 sprinkler will cover a radius between 9.4m and 10.7m. At present only one colour is available, the Light Brown option which will cover an arc between 90 degrees and 270 degrees. With an output of 900 l/h a very good mains pressure and flow are needed, or the sprinkler needs to operate from a pump and storage tank. As well as new nozzles, Hunter are also offering a new 'Pro' body. This features a heavier duty spring and a 5 year warranty. It also features a check valve, which is ideal for sites with changes in elevation. With the Pro body, the sprinkler output is regulated to 2.8 bar.

  • Causes of Water Hammer Like any other moving fluid, flowing water has momentum.  When subjected to a sudden change in flow, shock waves propagate through the system.  This occurrence is referred to as ‘water hammer’.  Flow changes can occur due to the operation of valves, the starting and stopping of pumps, or directional changes caused by pipe fittings.  Other causes may be the rapid exhaustion of all air from the system or the recombination of water after water column separation. When sudden changes in flow occur, the energy associated with the flowing water is suddenly transformed into pressure at that location.  This excess pressure is known as surge pressure and is greater with large changes in velocity. Water hammer is usually caused in high pressure (e.g. mains pressure) water systems either when a tap is turned off quickly, or by fast-acting solenoid valves, which suddenly stop the water moving through the pipes and sets up a shock wave through the water, causing the pipes to vibrate and ‘shudder’. Water hammer will be made worse by having worn valves and pipework inadequately supported. There are five probable areas to look at for the cause of water hammer and a number of possible cures - the appropriate cure will depend upon the actual cause and the installation.  If the water hammer only started after some work was done on the plumbing system, start by looking at those areas; however, any change to a plumbing system may start water hammer in another area. Probable Sources of Water Hammer Inadequately secured pipework – more likely to cause water hammer after new work has been done; if water hammer first occurs without new work having been done, check the other possible cures first. Ball and float valves. Fast acting valves. Worn stop valves. Trapped air. Unsecured Pipework Ensure that pipework is clipped, secured and supported at regular intervals using pipe clips of the appropriate size. Ball /Float Valves Water hammer can result from ripples inside open water tanks where the water level is controlled by a ball/float valve – the ripples being caused by the inflow of water with the result that the valve float ‘bobs’ up and down thus repeatedly opening and closing the valve.  This repeated opening and closing of the valve sets up shock waves which reverberate along the pipework causing the water hammer effect. If the water tank is plastic, a metal reinforcing plate fitted on the side of the tank where the float valve is installed will reduce the flexing of the tank. Other than the above, ripples in the water will usually only cause problems if the ball/float valve is worn or if the valve has a low pressure valve nozzle fitted when the water supply is high pressure.  Ensure that the washers and diaphragms in ball/float valves are not worn and that the appropriate valve nozzle is fitted.  The latter should not be the problem if the water hammer started some time after the valve was fitted. On small tanks, fitting a Torbeck cistern valve is another possible cure as it will prevent ripples on the water surface, so the valve will close cleanly. Solenoid Valves Some electrically operated solenoid valves stop the flow of water instantaneously, so possibly setting up the shock wave through the pipework to cause the water hammer.  Flexible hose attaching the valve to the water supply may be enough to absorb any shock in the pipework. Stop Valve Stop valves (stopcocks) and taps can cause water hammer if they have loose gland packing and/or worn washer jumpers.  Stop valves will generally be open when the water hammer shock wave travels through the pipework and the shock wave could well ‘rattle’ the valve handle and a loose jumper. While it is possible to tighten the gland packing and replace a loose jumper, the easiest way to cure the problem is to replace the stop valve. Trapped Air Problems associated with air entrapment can be minimized by preventing air from accumulating in the system.  This can be accomplished by using air-relief valves positioned at the high points of the piping system.  In areas of relatively flat terrain these should also be used in the vicinity of the pump discharge, near the middle of the line, and at the downstream end of the line. Empty pipelines should be filled as slowly as possible to allow entrapped air to escape. Other Considerations All pipework should be sized so that the flow velocity is not more than 1.5m/s. Surge arrestors (relatively simple devices such as small pressure tanks or buffer vessels, which can absorb shock waves) can be installed at strategic positions in the pipeline to minimize the effects of water hammer in the system.  Surge arrestors should be installed as close to the source of the problem as possible.

  • The use of mains water in England and Wales is regulated by the Water Supply (Water Fittings) Regulations 1999, an Act of Parliament which lays down what can and cannot be done with drinking (potable) water supplied by the water companies. The Act contains two important principles: water should not be wasted and water should not be contaminated. In order to comply with the first principle, it is important that the water provider is contacted before an irrigation system is installed, with information on what system is being proposed. To comply with the second principle, all irrigation systems must have some means of back-flow prevention. Depending on how the water is used, the law assigns a risk category from 1-5. Category 3 allows use of fixed head sprinkler systems with the sprinkler heads no less than 150mm above the ground level. When using hoses, or any other irrigation nozzle located below 150mm, then the risk category is category 5. For irrigation systems which fall into category 3, a ‘Type EC’ verifiable double check valve or ‘Type ED’ non-verifiable double check valve is sufficient protection. This needs to be fitted into the pipework and protected from frost. For irrigation system in category 5, such as dripline and sprinklers below 150mm, a ‘Type A’ airgap is normally required. Most domestic cold water tanks have a ‘Type B’ arrangement, so it is important to ensure the break tank is designed for irrigation. ‘Type A’ airgaps consist of an inlet valve which is positioned above the highest possible water level of the tank. This eliminates any possibility of the inlet valve being submerged, and water from the tank being drawn back into the mains water supply. With a ‘Type AA’ airgap, the rim of the tank forms an overflow and the inlet valve is positioned above the tank rim. With a ‘Type AB’, a large overflow weir is cut into the side of the tank to prevent the water level reaching the inlet valve. As ‘Type A’ airgaps result in the mains water pressure being lost, a pump is then needed to re-pressurise the water supply. Vertical or horizontal electric pumps are normally used for this purpose, normally under the control of an irrigation timer or an auto-start device. Access Irrigation can supply compliant water storage tanks, and also produce a range of pressure booster units which combine a break tank with a pressure booster set. Note: If the irrigation system is to be installed in a private, single occupancy dwelling (referred to as a ‘Domestic’ or ‘House Garden’ in the regulations) then there are slightly less stringent rules apply – see blog post ‘Water Regulations for Domestic Gardens’.

  • Drip irrigation systems are designed for use in large scale horticulture and agriculture, where the cost of water; or the scarcity of water precludes sprinkler systems. In landscape projects, drip irrigation systems are normally designed where the project requires very unobtrusive watering, such as public spaces, or the planting is incorporated in hard-to-reach planters or troughs. A drip irrigation system designed for field scale crops will generally use either a buried drip tape with a relatively thin wall disposable drip tape under crops of 1-3 seasons duration; or a thicker walled drip pipe either on the surface or sub-surface for longer duration crops such as vines or orchards. Sub surface drip systems are more economical in terms of water efficiency, but can be more prone to accidental damage. The design of the drip irrigation system needs to take into account the pressure losses in the pipework on long runs and also the topography of the field - sloping or undulating sites may need non-leakage design drippers to prevent water from leaking from the low points once the system has been turned off. For landscape drip irrigation designs, thick walled drip lines would generally be used to water border areas - either pegged to the surface of buried under a mulch. Drip lines in a landscape setting are more prone to damage from maintenance staff, so a thick walled pipe is essential. Drip lines on larger beds would be spaced at approximately 0.5m apart across the bed. For smaller planters the drip irrigation system will need to be designed to bring water to each individual planter - generally using micro-bore drip pipe and drippers. Ideally on landscape projects the supply pipes for the drip irrigation system would be installed during the initial build process to ensure all of the supply pipework is hidden away. To design a drip irrigation system a plan of the site is required along with information on the available water supply. For agricultural projects water can be taken from rivers, storage ponds or rainwater catchment areas such as farm buildings. For landscape projects mains water is generally used but water regulations generally require break tanks for back-flow prevention. The drip irrigation system can then be designed and pipe work sizes and quantities calculated.

  • Most people are unaware that there are legal requirements to take into consideration when connecting an irrigation system to a domestic garden tap. This simple guide provides you with the information you need to make sure you stay on the right side of the law!  What you can connect to the mains water supply is regulated by an Act of Parliament - the Water Supply (Water Fittings) Regulations 1999; these regulations superceed the old water bylaws in England and Wales.  If you are a domestic house then you must have a double check valve on all 'hose union' taps - outside taps to you and I. The double check valve is designed to prevent water and contamination flowing backwards from the garden and into the water main.  With a double check valve fitted, then you can run border sprinkler systems which have their sprinklers more than 150mm above ground level. You can also use a hand-held hose.  If you want to run a drip system (either for borders or hanging baskets) then you also need a DB Valve. This is a special valve which fits onto the tap or after a timer which again prevents back-flow. You still need the double check valve as well, but the DB Valve provides a 'belt and braces' solution. The DB Valve has to be fitted higher than the highest dripper and has to be fitted after the tap or timer, as it will not stand full mains pressure for prolonged periods of time.  One of the sad things about many of the 'consumer' irrigation companies is they never tell the customer that a DB Valve is necessary to comply with the law.

  • Specifying a pump on an irrigation system will boost available pressures and water flows, allowing larger zones and enabling more thirsty items such as pop up sprinklers to be used, however the pump also needs fittings on the inlet and the outlet to connect it to the water source and ensure that it will run reliably. In this video, Mike Briley from Access Irrigation talks through the options for surface mounted pumps and also submersible irrigation pumps. All pumps and fittings are available from Access Irrigation, along with friendly and helpful advice.    

  • Small irrigation systems such as drippers can generally be run off the mains water supply without problems, but as water flows get larger there is the danger that the water supply will not be large enough. In addition, sprinkler systems require a certain pressure to operate. If there is too little flow or pressure then the irrigation system will not work properly. To ensure the irrigation system will work as planned it is vital to have some flow and pressure information from the water source. With this information available we can then ensure that the system is designed around the available supply - if the pressure is too low a pump can be specified. If the flow is too low the irrigation system can be divided into zones to ensure there is always enough water to operate the irrigation system. Although it may seem like extra work to obtain the pressure and flow data, it will save embarrassment later on when the irrigation does not work properly, and the cost of relaying pipes and adding extra valves to remedy the situation at a later date. Measuring the flow and pressure This video explains the equipment needed and the process of measuring the water flow. You will need a pressure gauge and a bucket with litre graduations. The process is briefly outlined below: 1. Obtain a static pressure - with the outlet valve closed measure the static pressure on the gauge. In the video this was just under 4 bar, which is very good for a domestic supply. 2. Obtain flows at set pressures - as the outlet tap is opened the pressure will drop - the more flow the lower the pressure. We wish to obtain flow readings at 3.0, 2.0 and 1.0 bar. To do this we shall slowly open the tap until the dial on the pressure gauge is reading 3.0 bar. If you are using a smaller container, time how long it takes to fill the container at this pressure and note it down. If you are using a large container as in the video, time how long it takes to fill from one marked capacity to the next mark. Note the flow and the volume you have filled. Open the tap slowly until the pressure gauge reads 2.0 bar and repeat. Repeat for 1.0 bar. 3. Once you have the data you need to translate the flow into litres per hour. To do this divide the capacity by the time it took. For example when the flow was measured at 3.0 bar, if the bucket had 5 litre graduation marks and it took 20 seconds, divide 5 (litres) by 20 (seconds). Then multiply the result by 3,600 (the number of seconds in an hour). Eg. 5 divided by 20 times 3,600 = 900 litres per hour. Pressure and Flow: 3.0 bar 900 l/h 2.0 bar 1,240 l/h You will notice that as the pressure falls the flow increases 1.0 bar 1,450 l/h 4. Once you have calculated the flow for each of the pressure points, either send the information to us along with the plan of the garden, or plot a graph of the data to help you design the system yourself. Note: A simpler, but less accurate, method is to measure the flow and pressure with the tap 3/4 open and 1/4 open.  

  • This extraordinary vertical forest is being constructed in Milan as part of two residential towers. The towers house of 730 trees, 5,000 shrubs and 10,000 plants. These drawings of the building were produced by Stefano Boeri, Gianandrea Barreca, and Giovanni La Varra, the architects who designed the project for the firm Boeri Studio. The architects state that in addition to being pleasant to behold, the two towers will help purify the city air, increase bio-diversity and protect residents from the sun and noise pollution. By bringing the plants into the city, they also aim to reduce the effects of 'urban sprawl'. For wildlife, especially birds and insects a haven in the middle of one of Italy's largest cities will be of enormous benefit. Tree-planting recently began on the structures, but not before the architects spent some two years working with botanists to determine which varieties and sizes would best suit their purpose. Once the project is finished later this year, they will be watered mainly with grey water produced by residents, and tree care will be managed by building staff at the towers. With so many plants to water, the design of the irrigation system must have been right at the heart of the project. Although we do not know the details, drip watering systems will have inevitably been used to bring water to the root zones of each plant. The irrigation system has been designed to use grey water from the showers and sinks in the building. This will have then been stored and filtered before being pumped into the irrigation system. One of the challenges of using grey water is the soap content, as this will clog conventional drip nozzles if the levels are too high. Companies such as Netafim have pioneered drip lines able to cope with grey-water systems, as well as filtration systems.  

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