How To Adjust Water Pressure On Sprinkler System

Managing Pressure in the Home Irrigation Organization

By Kevin Moore, Justin Quetone Moss

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Impact of Pressure on the Operation of an Irrigation System
How does Irrigation System Design Touch Force per unit area?
Addressing Bug Associated with Pressure
How Much Water tin I Save with a High Pressure System?
Toll of a Pressure-regulated Irrigation System

The purpose of an irrigation system is to provide supplemental water to the landscape when rainfall is insufficient. A system that is properly designed, installed and maintained will utilize h2o resource in a sustainable manner. A critical component of irrigation efficiency is pressure level direction. High pressure is ofttimes overlooked during design and installation. Low pressure may bespeak a maintenance consequence or harm to the system. This fact sheet will discuss pressure management as a tool for improving irrigation efficiency.

Pressure is defined as a force per unit area. You have probably checked the air pressure in a tire and noticed that the gauge has units of psi, pounds per foursquare inch. Residential water force per unit area is ideally about xl to 60 psi, however, this tin can vary significantly based on location.

Impact of Pressure on the Performance of an Irrigation Arrangement

If an irrigation system has low h2o pressure, it causes a loss in irrigation efficiency. Some of the sprinkler heads may not pop up from the ground during operation. Water leaving a spray head or rotor will non accomplish next heads and the spray pattern volition not be uniform. Brownish areas of the landscape that are not receiving acceptable water may exist evident, leading you to run the irrigation system longer. In some cases, there will be donut-shaped zones of dark-brown grass around a sprinkler caput (Figure 1).

Grass with low irrigation pressure has uneven patterns.

Figure 1. Low irrigation pressure level can pb to uneven irrigation patterns and poor plant health. Photo courtesy of David Gerken.

High h2o force per unit area causes a different set of problems. Commencement is the potential of damage to the arrangement. Only like too much air blown into a balloon, the components of an irrigation organization can intermission if the pressure becomes besides loftier. This is most likely to occur where pipe is joined with a PVC plumbing equipment. The second trouble associated with high pressure is more than common, a loss of irrigation efficiency. When the pressure level at a spray nozzle is too high, the h2o leaves the nozzle every bit a fine mist instead of large droplets. Carried away past the wind, the fine mist evaporates before reaching the landscape. If a mist is seen around spray heads, loftier water pressure is likely (Figures 2a and 2b). High pressure also increases the catamenia rate of irrigation equipment (Figure 3). If the pressure moves exterior of the design range for the device, then the application uniformity can subtract drastically. For example, presume a sprinkler is operating at an optimum pressure level of thirty pounds per square inch (psi). The spray is evenly distributed inside the arc and the flowrate is 3.three gallons per minute (GPM) (Figure 4a). Now, presume the pressure of that same sprinkler is increased to 50 psi, which is above the recommended operating range. The spray is no longer a uniform pattern and the catamenia rate has increased to 4.8 GPM (Figure 4b).

Healthy green is being watered by a high pressure irrigation system.

Figures 2a and 2b. High pressure in an irrigation system leads to misting and a reduction in irrigation efficiency. Photos courtesy of Oklahoma City Utilities Department.

Typical relationship of pressure versus flow rate.

Figure three. Typical human relationship of pressure versus menstruation charge per unit. As pressure increases, the period of water from a single irrigation head besides increases.

An optimum pressure of 30 psi the spray pattern is evenly distributed.

Water pressure bing increased to 50 psi and the spray pattern degrades while the flow rate increases.

Figures 4a and 4b. At an optimum force per unit area of thirty psi (elevation) the spray pattern is evenly distributed. When the force per unit area is increased to 50 psi (lesser) the spray blueprint degrades while the flow rate increases. Photos courtesy of Brent Mecham, Irrigation Association.

How does Irrigation Arrangement Design Impact Force per unit area?

An irrigation system is made upwards of several components, and nearly all of these tin can bear on the system pressure. Consider a typical residential irrigation system and its components (Effigy v). There are 5 main parts in a system that movement h2o throughout the mural: water meter, backflow preventer, command valves, mainline and lateral lines. Each of these has a force per unit area loss due to the friction associated with flowing water. An easy way to remember these pressure losses is past using the 5-4-three-2-i rule of thumb, which indicates the pressure loss in psi from each of these five main irrigation system components (Table 1). Based on this information, expect a total pressure driblet of nigh xv psi (5 + 4 + iii + 2 + 1) from the utility supply line to 1 of the sprinkler heads. If the utility is delivering water to your house at a pressure of 60 psi, so expect a pressure of about 45 psi at each head. However, the pattern of each specific irrigation organization can crusade this pressure to be higher or lower.

Figure 5. Typical components in an irrigation system. Illustration courtesy of Hunter Industries.

Different types of irrigation equipment have different ideal operating pressures for maximum efficiency. For rotors, this is about 45 psi, with an operating range of 25 to 65 psi. For spray heads, information technology is 30 psi, with an operating range of 15 to 30 psi. For drip lines, this is about 20 psi, with an operating range of 15 to 30 psi. Remember, flow rate and pressure are directly related to one another. If pressure level is not well-controlled, irrigation efficiency volition suffer.

Addressing Problems Associated with Pressure

If you suspect irrigation issues are associated with pressure, so a good first step is to measure the water pressure at 1 of the hose bibs on your house. This does not account for force per unit area losses within the irrigation system itself, only it tin provide a rough idea of how much pressure is being delivered to the organization. Measure the pressure at the aforementioned fourth dimension of 24-hour interval the irrigation system runs, equally pressure can vary throughout the day. A pressure level judge can be purchased for $10 to $20 online or at a local hardware shop. Some of these will thread directly to the hose bib, while others will require an adapter. If a pressure level of less than 25 psi or greater than 125 psi is measured, contact the utility department for further investigation.

If home pressure appears to be acceptable, merely the irrigation pressure seems low, check the post-obit items.

Verify the isolation valve for your irrigation system is completely open up. This should be located in a green valve box somewhere between the h2o meter and backflow prevention device (Figures 6a and 6b). Sometimes the valve box can become covered with grass. Probing the grass with a screwdriver may help locate the chapeau.

Figures 6a and 6b. The isolation valve is typically located in a pocket-sized green valve box well-nigh the h2o meter or backflow preventer. This valve is in the airtight position. Photos courtesy of Kevin Moore.
Verify the valves are completely open on the backflow device. At that place are several different styles available, just the pressure vacuum breaker (PVB) and reduced pressure principle assembly (RPA) are common in Oklahoma (Figures 7a and 7b). Backflow devices are typically located outside, simply may be found in the garage in newer homes.

Figures 7a and 7b. Backflow preventers are designed to keep irrigation water from flowing back into the pipes used for drinking water. A pressure vacuum breaker (pinnacle) and a reduced force per unit area principle assembly (bottom) are 2 common backflow devices in Oklahoma. Note that both of the greenish- or bluish-handled valves are aligned with the pipage. This is the fully open up position. Photos courtesy of Robert Reaves
Inspect the backyard for any obvious water leaks. Since the pipe is buried underground, await for soggy locations that never seem to dry out, or lush patches of grass in an otherwise dry location.
Turn on the irrigation system and look for broken heads. This could be an obvious fountain of water coming from one of the heads or a stream of water coming from the base near the ground. Make repairs as needed.
It is possible that the system was installed with undersized pipe and also many sprinkler heads on a zone. Low pressure level can be addressed past irresolute to lower menstruum nozzles or decreasing the number of heads in the zone. Contact an irrigation contractor for assistance in evaluating your system.

The force per unit area associated with a fluid at rest is referred to as static pressure. When a fluid is in motility – like when it flows through a pipage – the pressure volition drop along the length of the pipe due to friction. The force per unit area of a moving fluid is referred to as dynamic force per unit area.

If the irrigation force per unit area is high, there are several ways to solve the problem.

Install a pressure regulation device for the entire firm. If the pressure is more than eighty psi to the house, then consider this option to protect the plumbing and appliances inside your home. Contact a licensed plumber for this project.
Install a pressure regulation device at the irrigation organization betoken of connexion. This is the same type of device used for the entire business firm, but there may exist circumstances when yous would only need pressure regulation for the irrigation system. Contact a licensed plumber for this project.
Regulate the pressure at the control valve for each zone. If you take a newer irrigation system, so you can probably install a pressure level-reducing device directly on the control valve. A pressure reduction of at least 15 psi is required for these devices to function properly. One of these will be required for each zone in the system. A local irrigation parts supplier should be able to help make up one's mind if pressure regulation tin be added to your existing control valves. These are typically located in a rectangular valve box with a greenish lid (Figures 8a and 8b). Remove the lid and try to identify the brand and model of valve that is installed in your organisation. If this is hard due to the age or position of the valve, accept a picture with you to the parts supplier. They may be able to identify the valve based on the photo. An irrigation contractor also tin can help to place the type of equipment currently installed.
Regulate pressure at the head. About irrigation equipment manufacturers sell pressure-reducing spray heads and rotors that will reduce the force per unit area at each device to the optimum operating pressure. This is a relatively straightforward modification that can be made past the homeowner, but requires the replacement of the spray torso internals for every head in the system. Some homeowners will make this modification over fourth dimension on a zone-past-zone basis.

Green rectangular valve box that says control valve.

Zone control valves inside the a green valve box.
Figures 8a and 8b: Zone control valves
are typically located inside a green, rectangular valve box. There tin exist several of these depending on the size of your organization. Photos courtesy of Kevin Moore.

How Much Water can I Salve with a Loftier Pressure System?

It is fairly common to find high irrigation organization pressures throughout Oklahoma communities. Oklahoma State University partnered with the Metropolis of Oklahoma City, Oklahoma Urban center Cute and Urban Lawn and Mural to retrofit the equipment in several median strips to demonstrate potential water savings associated with pressure regulation (Figure 9). In one case, the boilerplate pressure at the spray head prior to the retrofit was 60 psi. A total of 157 spray heads were replaced with pressure-regulated spray heads, designed to reduce the pressure level at the nozzle to 30 psi. Based on manufacturer data, the full output of the system at 60 psi was 215 gallons per minute (GPM). At xxx psi, the output was reduced to 153 GPM. This is a difference of 62 GPM (Figure 10). The irrigation organisation was operated on an odd- or even-day schedule for 18 minutes each run. For a typical summer month, this pressure reduction should provide a savings of 16,740 gallons of water! This is the equivalent of 973 showers for a typical American. In addition to the water savings, less mist was generated during functioning. This means that more of the water made it to the soil, where it could be used by the grass and landscape plants, and less water was carried into the street by the current of air. A typical residential system contains about xl spray heads and h2o savings are probably closer to 4,000 to 5,000 gallons per month. This is a good example of how a little work can get a long way toward improving the efficiency of an irrigation organisation and conserving a valuable resources.

Construction workers working on Oklahoma City median retrofit project on North Classen Boulevard.

Effigy 9. Oklahoma Urban center median retrofit projection on Due north Classen Boulevard. Photograph courtesy of Joshua Campbell.

Bar chart comparing the water usage and system pressure for retrofit projects in Oklahoma City.

Figure x. Based on manufacturer data, the installation of pressure-reducing spray heads reduced h2o consumption by nearly 30 per centum during one of the median retrofit projects in Oklahoma Urban center.

Cost of a Pressure-regulated Irrigation System

The toll departure between standard sprays and rotors and their pressure-regulated counterparts is only a few dollars. Labor cost from the installation of pressure-regulated heads is identical to installation of standard heads. If y'all have high h2o pressure, then pressure-regulated heads or devices should always exist used. The return on investment (ROI) when water force per unit area and h2o rates are high is typically one year or less. From then on, the homeowner has an irrigation system operating at optimum pressure, both saving money and applying water more uniformly to the landscape.

For additional information about maintaining the functioning of an irrigation system, delight refer to the post-obit fact sheets.