How To Install A Sprinkler System Backflow

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by C.Swift and Yard. Higgins^* (6/xx)
Revised by Kurt Jones^**

Quick Facts….

• Backflow prevention devices must be installed on all sprinkler systems (including sprinklers attached to hoses) using drinkable (fit for drinking) water.
• Backflow prevention devices are designed to preclude contagion of the potable water arrangement from pesticides, feces and other hazardous materials.
• Hose connection backflow prevention devices may provide protection for the arrangement when insecticides, other pesticides or fertilizers are applied by means of a hose-end spray zipper.

Introduction

Backflow prevention devices protect the drinking water system from contamination due to backflow of not-potable (contaminated) water into the potable (fit for drinking) water supply. Backflow is of two types, back-siphonage and backpressure.

Whatever drop in pressure in the chief city water line can result in back-siphonage backflow of fertilizers, pesticides, manures and other contaminants through sprinkler heads and the irrigation pipe arrangement into the potable water supply. This same contamination may occur through a hose-attached sprinkler, spray nozzle or pesticide sprayer. This presents a serious threat to public health. This drop in pressure level can event from a break in the line or by lowered mainline pressure level due to loftier h2o withdrawal, as may occur during fire fighting operations.

Improper installation of a lawn sprinkler pump or injector system may forcefulness contaminants back into the potable water supply. In this case, the pressure exerted past the pump is greater than the pressure level in the potable water arrangement. This is known as back-force per unit area backflow.

If properly installed, an canonical backflow prevention device will forbid back-siphonage and/or dorsum-pressure backflow. Not all devices are designed to handle both types of backflow.

Backflow prevention devices are designed for installation on sprinkler systems connected to beverage (drinking) h2o supplies just. Sprinkler systems only continued to irrigation h2o (ditch systems) do non require backflow protection. Some parts of the state of Colorado accept dual irrigation systems that apply irrigation and potable h2o through the same irrigation system. These systems require a reduced pressure principle assembly to protect the domestic water supply.

Figure one: Atmospheric vacuum breaker.

Effigy 2: Plastic and contumely comination AVB units are bachelor.

The device selected must be the proper device for the degree of hazard and take been canonical past the Foundation of Cantankerous Connectedness Control. Contact your county health, planning or building department for a listing of approved devices. These devices must be certified upon installation and at least annually to insure continued backflow prevention. Testing must be done by a contract backflow technician whose backflow certification is electric current. Contact your community water purveyor for the backflow testing companies and individuals in your area. If your water purveyor does not provide you a list of testers, it is up to you as the water consumer to select i. The Colorado list of contract backflow technicians tin be found at http://www.backflow.org/.

Permits unremarkably are required for systems that crave backflow prevention devices prior to the installation of a sprinkler system. The installation blueprint, to include the type and placement of backflow prevention devices volition be canonical during the allow review process. Permits are available from city/county building departments.

Types of Backflow Prevention Devices:

A mechanical backflow prevention device allows h2o to period in only 1 management. Pressure level vacuum breakers (PVB), and the reduced pressure principle device (RP), are the ones unremarkably used in residential sprinkler systems. The RP device must exist used for more hazardous back-pressure situations.

Vacuum Breakers: These are effective simply confronting back-siphonage. These mechanical backflow preventers are not to exist used when back-force per unit area bug may exist. There are two types, the atmospheric vacuum breaker (AVB) and the pressure vacuum breaker (PVB).

The atmospheric vacuum breaker (AVB) is gravity operated and must be installed in a vertical position. The disc float associates tends to stick in the closed position if under continuous water pressure for long periods of time. It must exist installed on the downstream side of all close-off valves on each sprinkler zone valve. Ane AVB device is needed in each zone. Check with the water district, planning/building or health department in your county before installing AVBs to ensure they are legal in your area.

Combination AVB and sprinkler valves are bachelor. In these units, a single-valve body combines both a control valve and an atmospheric vacuum breaker. When used, these combination devices must exist installed in a vertical position on each zone, with the AVB side downstream of the command side of the unit. This device must always be installed at least half-dozen (half-dozen) inches (check local codes) above all downstream pipage and outlets.

Pressure Devices:

The force per unit area vacuum billow (PVB) is designed to open up afterward long periods of continuous water pressure. This type of device may be installed under a constant pressure level upstream of all control valves. This device must exist installed in a vertical position and at to the lowest degree twelve (12) inches above all downstream piping.

Figure 3: Pressure level Vacuum Breaker

Figure four: Reduced Pressure Device

Effigy 5: Hose connection vacuum breaker.

While more expensive than the AVB or combination device, merely one PVB is needed for an entire sprinkler organisation. The PVB is equipped with test cocks and must be tested yearly by a backflow technician.

The reduced pressure (RP) backflow device is the highest level of protection bachelor. This device protects from backflow and dorsum pressure level. When installing the device, a minimum of 12 inches of access and clearance between the lowest portion of the device and grade, floor or platform must be provided. At that place must exist adequate clearance around the assembly so that testing and repairs tin can exist accomplished. Reduced pressure level backflow devices are often used when pressure vacuum breakers cannot be used (i.e. when downstream pipage is higher than the 12 inch clearance mentioned above).

Hose Connections

Sprinkler attachments, spray nozzles and other items attached to a hose continued to the potable h2o supply must be protected by the use of an approved hose connection vacuum breaker. These devices are designed for hose threaded outlets (sill cocks, hose bibs).

Backflow prevention is disquisitional when using a hose-end sprayer connected to the potable water supply. Backflow tin can easily suck an insecticide or other chemical back into the domestic water system. A hose connection vacuum breaker should be used as minimum protection when fertilizers, insecticides or other pesticides are applied with a hose-cease sprayer.

Additional Notes

Backflow prevention devices are designed with the caste of health hazard in heed. Unless prohibited in your area, lawn sprinkler systems using potable h2o tin can be used with either an AVB or PVB device unless a higher caste of risk exists. The injection of fertilizers, pesticides or other contaminants through the irrigation system represents a higher caste of hazard and requires the use of a device such as the reduced pressure level principle backflow associates (RP device) to ensure rubber.

Winterizing Systems

Backflow prevention devices will be damaged by freezing during the wintertime unless drained of all water. Encounter 4.719, Domicile Sprinkler Systems: Preparing your Sprinkler System for Winter for details.

Hose connection vacuum breakers are best removed, drained and stored for the winter.

^*C.E. Swift, former Colorado Country University Extension, Horticulture Amanuensis, Tri River Area. M. Higgins, Grand Junction Pipe and Supply, M Junction, Colo. ^**Kurt Jones, Colorado State University Extension amanuensis, natural resrouces and agronomics, Chaffee Canton.4/03. Revised vi/20.

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Source: https://extension.colostate.edu/topic-areas/yard-garden/home-sprinkler-systems-backflow-prevention-devices-4-714/

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