The basic parts of a drip system

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this is a summary of a the basic parts for a drip irrigation system.

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The basic parts of a drip system

  1. 1. The Basic Parts of a Drip SystemTo return to the main page of the Drip Irrigation Design GuidelinesIllustration of a very simple drip system.Valves:Valves turn on or off the water flow through a pipe.Isolation valves are manually operated valves used for infrequent shut-off of the water. Typically an isolation valve islocated at the water source so the water can be shut off for repairs or shut off during the non-irrigation season. Isolationvalves may also be installed anywhere on the irrigation system to allow the shut down of sections for repair, this is commonon large systems where shutting down the whole system for a repair would be inconvenient.Control valves are the valves that turn on and off the water to individual "circuits" or areas of the yard that are irrigatedseparate from one another. The control valves can be automatic (usually electric-powered using a solenoid) or manuallyoperated (hand-powered, ie; turn, turn, turn!) There may be just one control valve or there may be several control valves on adrip irrigation system. For example one control valve may turn on and off the water to emitters/drippers in a vegetablegarden. Another control valve might turn on and off the water to emitters for some hanging pots on a patio. Another controlvalve might turn on and off the water for the emitters at shrubs around the house. Another could even turn on and off waterfor sprinklers in the lawn, or water for filling the swimming pool or pond. For more information on valves for drip systems,Backflow Preventer:The backflow preventer is a device that prevents dirt, salmonella, dog pee, etc. from being sucked back into your drinkingwater from the drip system. You need to use a backflow preventer on ALL drip systems. No exceptions! For moreinformation on backflow preventers, why you need one, and a simple guide to which type to use, see the page on backflowpreventers.
  2. 2. Pressure Regulators and Pressure Reducing Valves:A pressure regulator reduces the water pressure and keeps it at a constant level. A pressure reducing valve is another namesometimes used for a pressure regulator, both are the same thing.Most drip systems operate best at lower water pressures than are common in a typical water supply system. A pressureregulator is used to lower the pressure and then keep it at that pressure, even if the incoming water pressure varies up anddown. You probably will need to install a pressure regulator on your drip system if your water pressure is higher than 2,8bars (40 PSI). Keep in mind that a pressure regulator only reduces the water pressure. It will never increase the waterpressure, so if you dont have enough water pressure a pressure regulator will cause you to have even less!While the name sounds similar, a "back-pressure valve" is not a pressure regulator and has a different purpose.There are two general types of pressure regulators used, non-adjustable ones (with a factory pre-set outlet pressure) and oneswith user adjustable pressure settings. Either type may be used for a drip system. As a general rule the non-adjustable typeare used for small homeowner drip systems that utilize less than 3 control valves. Those people who want the best ofeverything, regardless of cost, would want to use the adjustable-type pressure regulators, as they allow more flexibility andare usually more accurate.Inexpensive, non-adjustable-type pressure regulators (see photo below) are most often used for simple home drip systems.They are typically made of plastic and have a pre-set outlet pressure. They often have very specific flow ranges and will notwork if used at flows higher or lower than the listed range. Since they are not adjustable, be sure to buy the correct one forthe flow and pressure your drip system needs. The non-adjustable-type regulators must be installed AFTER the control valve,so if you have more than one control valve you will also need one regulator for each of the control valves. If a valve isinstalled after a non-adjustable-type pressure regulator it can result in a pressure surge that can damage your drip system. Ithas been my experience that when used on systems where very high water pressures are present some of the non-adjustable-type regulators may allow a quick pressure surge to pass through just after the valve is opened. If you experience problemswith drip tubing blowing out of the fittings right after the control valve is opened you may be experiencing this problem. Tryswitching to an adjustable-type pressure regulator.Non-adjustable-type pressure regulator.(Install after control valve) The classic adjustable-type pressure regulator can go before or after the control valve. This type of regulator is most oftenmade of brass or bronze, (some plastic versions are made) and has a large screw on it that is used to adjust the outletpressure. The adjustable-type pressure regulator you use needs to be the correct size as rated by the manufacturer for the flowrange. Unfortunately the sizing formulas they provide are somewhat difficult to understand. As a general rule a 50mm (3/4")adjustable-type pressure regulator will work acceptably for drip systems designed using the Drip Irrigation Guidelines on thiswebsite, provided the regulator is set to reduce the pressure by at least 1,4 bars (15 PSI). It is common for the pressureregulator to be a smaller size than the pipe it is installed on. Adjustable-type pressure regulators are often found in theplumbing department of hardware stores rather than with the irrigation supplies.The adjustable-type pressure regulators may be installed either before or after the control valves, whichever you prefer. Onlarger drip systems, with multiple control valves, the valves are often grouped together in one or more locations and a single
  3. 3. adjustable-type pressure regulator is installed on the mainline before all of the valves in a group. This cost-saving measureallows a single pressure regulator to be used for several valves.To operate accurately the adjustable-type pressure regulators require a pressure drop between the inlet and outlet of theregulator. The amount of pressure drop varies depending on flow, at low flows less drop is required. As a general rule mostregulators will work well if you set the pressure at least 1,4 bars (15 PSI) lower than the inlet pressure. If the pressure drop isless than required, the regulator tends to not work as accurately, and may allow the pressure to vary up and downconsiderably.Brass adjustable-type pressure regulator. The large silver bolt on top is turned to change the outlet pressure.Using a Valve as a Pressure Regulator:Can I reduce the pressure by partially opening the control valve and not use a pressure regulator? This is a common question,and the answer is yes, you can. If the water pressure from your water source does not fluctuate, and the temperature of thevalve does not change, a partially closed valve will work just fine. A pressure regulator is nothing more than a valve with apressure sensor attached to it. The sensor opens and closes an internal valve in the pressure regulator to keep the pressure atthe outlet constant. So yes, you can use a partially closed valve to reduce the pressure, however you need to be aware of theproblems this can cause. Sometimes the vibration of the water passing through the valve will cause the valve to open or closea little over time. The biggest problem occurs when the water is warmer or colder than the valve. The valve will changetemperature as the water goes through it and expand or contract, this results in a change in how much water goes through thevalve, and that changes the water pressure. If the valve closes due to vibration or temperature change the pressure may bereduced to the point the drip system stops working correctly and the plants dont get watered. If the valve opens too far thewater pressure will be too high. This results in emitters popping out of the tubes and tubing sections blowing apart at thefittings where they connect together. Often when the tubes blow apart they whip around, spraying water all over the place.The worst situation is when there is an open window nearby and the water sprays into the house through the window! So ifyou are willing to live with those risks, you can use a standard valve in place of a pressure regulator. All you do is open thevalve slowly until the pressure desired is obtained downstream of the valve, then leave it at that setting. I suggest periodicallychecking the valve and water pressure to make sure it has not changed.Filter:The filter cleans the water. You should use a filter. Some companies tell you their products dont need a filter when used withcity water, or that it is optional. Optional at the expense of your future time and money! Save yourself dead plants and lots ofgrief and just install a filter. Drip emitters have very small openings that are easily clogged. Water piped to your house is notfree from stuff that will clog your emitters! It contains small grains of sand, bits of rust and scale from pipes, even very smallsnails (the size of a grain of sand) are very common in city water systems.I suggest that you use a filter with a 150 mesh screen or one with a higher mesh number like 200 mesh. A good quality filtermay be installed before the valve or pressure regulator, but the inexpensive filters often sold for drip systems should beinstalled after the pressure regulator. A good filter will have a maximum pressure rating of 10,3 bars (150 PSI) or higher. Ifthe package does not list the pressure rating it is probably an inexpensive low-pressure model.I like to use a top quality filter and install it right at the water source so it protects the control valves and the pressureregulator too. Most valve failures result from sand or rust particles clogging the tiny passages inside the control valves! As
  4. 4. long as you need to use a filter, why not get a good one and have it protect the valves too? It will probably pay for itselfwithin 5 years by preventing a valve failure! Use a filter that is the same size as, or larger than, the valve. For moreinformation there is a separate, free, tutorial on filters.Emitters:The emitters are what controls how fast the water drips out onto the soil. Most emitters are small plastic devices that eitherscrew or snap onto a drip tube or pipe. Some models are preassembled as part of a tube. The most common emitters sold emit4 liters/hour (4,0 l/hr) of water. Thats about 1 gallon per hour (1 gph). There are many different types and brands available,they each have advantages and disadvantages listed in the detailed page on Drip Emitters. Click here for detailed informationon what type of emitter is best for your drip system.Directrices de Diseño de Riego por GoteoIndex to the Guidelines: Índice de las Directrices: • Drip Irrigation Design Guidelines (this page) Pautas de Diseño de Riego por Goteo (esta página) • The Basic Parts of a Drip System Las partes básicas de un sistema de goteo • Drip Irrigation Emitters Emisores de Riego por Goteo • Drip Emitter Spacing Emisor de goteo espaciado • Drip Irrigation Valves Válvulas de Riego por Goteo • Irrigation Backflow Preventers Riego Reflujo preventores • How to Find the Size of a Pipe ¿Cómo encontrar el tamaño de una pipa • Drip Systems for Slopes and Hillsides Los sistemas de goteo para pendientes y laderas • Gravity Flow Drip Systems Gravity Flow sistemas de goteo • Drip System Sample Detail Drawings Por goteo sistema de muestreo Detalle Dibujos Basics - What is Drip?Drip irrigation has its roots in agriculture, where in many parts of the world it was the only option available forharsh climates with limited water supplies. Its development depended on advancements in polyethylene tubing,and its growth was most rapid in arid and drought-plagued regions. Beginning in the late 1960s farmersdiscovered that by using drip irrigation they could increase yields while lowering water use. The 80s saw dripirrigation making the transition into commercial landscape with mixed success. In todays market, drip irrigationis well-trusted and used extensively in agriculture, and is actively utilized in commercial landscaping andresidential gardening. Drip Irrigation is the slow application of water directly to the plants root zone using"drippers", which are also referred to as "emitters". Maintaining an optimum moisture level in the soil at all timesresults in less water lost to the sun and the wind. No water is wasted on non-growth areas, and the root zone ismaintained at its ideal moisture level, combining the proper balance of water and air for a very efficient irrigationsystem. Unlike drippers, "microsprinklers" throw the water over a wide area, and are designed to be used inareas where drippers are not practical, such as large areas of ground cover or flowerbeds. Like drippers,microsprinklers have many of the same benefits, resulting in abundant foliage and less water use. Low volumeirrigation offers some key advantages and benefits to both contractors and homeowners. • We now know that drip irrigation is the precise and slow delivery water to plants roots.
  5. 5. • Conventional irrigation systems rate sprinklers and bubblers in gallons per minute. Drip irrigation flow rates are in gallons per hour not per minute, because of the low flow from each emitter. For example a lawn sprinkler may be rated at 1 to 5 GPM (gallons per minute), or 60 to 300 GPH (gallons per hour).• A drip emitters are usually rated at 1-4 GPH (gallon per hour); a microsprinkler might be rated at 15-45 GPH (gallons per hour).• With conventional watering systems, water is lost through run off or evaporation, or blown away by wind, or wasted on non-growth areas. Using drip irrigation, water is absorbed slowly into the soil, directly into the root zone, and no water is wasted on non-growth areas. By placing water just at the root zone of the plant you can water much less and not as often. This method causes the water to be pushed deeper into the soil and helps to promote the plants roots to grow downward and not just laterally, as they would with shallower watering.• The very low flow of water from outlets on a drip system also enables you to water a much larger area from a single water source. Less water usage equals a larger single watering zone.• Another advantage of using a low flow drip system is that you do not need high pressure to supply the drippers and microsprinklers. Most drip systems are recommended to run at about 15 to 30 PSI (pounds per square inch). For comparison most houses have water pressure of anywhere from 40 PSI to 60 PSI. The benefit is that you do not have to worry about large pressure drops in your household water flow just because the irrigation system has turned on; for example you will not notice if the system goes on when you are in the shower! Because of this low pressure, drip systems can use tubing and other components that do not require glue, clamps or hard-to-connect components. In fact, most components of a drip system can be moved or reused. This is explained in more depth in other sections• There are other details about drip irrigation that make it the only sensible way to water your landscape but here we have provided only a broad overview. To see all the details scroll back up to our main help menu and check out the other sections.
  6. 6. • Conventional irrigation systems rate sprinklers and bubblers in gallons per minute. Drip irrigation flow rates are in gallons per hour not per minute, because of the low flow from each emitter. For example a lawn sprinkler may be rated at 1 to 5 GPM (gallons per minute), or 60 to 300 GPH (gallons per hour).• A drip emitters are usually rated at 1-4 GPH (gallon per hour); a microsprinkler might be rated at 15-45 GPH (gallons per hour).• With conventional watering systems, water is lost through run off or evaporation, or blown away by wind, or wasted on non-growth areas. Using drip irrigation, water is absorbed slowly into the soil, directly into the root zone, and no water is wasted on non-growth areas. By placing water just at the root zone of the plant you can water much less and not as often. This method causes the water to be pushed deeper into the soil and helps to promote the plants roots to grow downward and not just laterally, as they would with shallower watering.• The very low flow of water from outlets on a drip system also enables you to water a much larger area from a single water source. Less water usage equals a larger single watering zone.• Another advantage of using a low flow drip system is that you do not need high pressure to supply the drippers and microsprinklers. Most drip systems are recommended to run at about 15 to 30 PSI (pounds per square inch). For comparison most houses have water pressure of anywhere from 40 PSI to 60 PSI. The benefit is that you do not have to worry about large pressure drops in your household water flow just because the irrigation system has turned on; for example you will not notice if the system goes on when you are in the shower! Because of this low pressure, drip systems can use tubing and other components that do not require glue, clamps or hard-to-connect components. In fact, most components of a drip system can be moved or reused. This is explained in more depth in other sections• There are other details about drip irrigation that make it the only sensible way to water your landscape but here we have provided only a broad overview. To see all the details scroll back up to our main help menu and check out the other sections.

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