Vacuum Breaker 3/4" Hose Thead Anti Siphon Backflow Preventer

Product Description

Use a vacuum breaker to prevent water from flowing back from your drip irrigation system into your household water. This prevents contamination of your water supply. Most municipalities require backflow prevention devices at the beginning of any irrigation system.

Product Details

• Should not be installed under static (constant) water pressure
• Install after manual or electric control valve
• Inlet: 3/4" FHT (Female Hose Thread)
• Outlet: 3/4" MHT (Male Hose Thread)
• Hose Washer Included

Product Details

• Should not be installed under static (constant) water pressure
• Install after manual or electric control valve
• Inlet: 3/4" FHT (Female Hose Thread)
• Outlet: 3/4" MHT (Male Hose Thread)
• Hose Washer Included

Replacement for

Acu-Drip A110, Ag Products PASV77H, Aquarius Brands PASV77H, Drip Depot 1023, DripKing BP, Dripworks FAVBH Jain Irrigation PASV77H, MrDrip 106, Orbit DripMaster 61256D 67750, Pepco PASV77H, Raindrip R622CT R622CB 62200UB R620CT R620CB A620CT A620CB 62000UB, Sprinkler Warehouse D45, The Drip Store A015, Raindrip Hose Anti Syphon

Related Tutorials

• Connecting to the Water Source
    Hose Bibb vs. Electric Solenoid Valve
• Drip Irrigation System Design and Installation Guidelines
    Everything you need to know about Drip Irrigation

Tips & Tricks

Use Teflon tape on pipe threads

For a water-tight seal

Always use Teflon tape with pipe-threaded fittings. Wrap Teflon tape clockwise 4 - 5 times around pipe threads. Hose-thread fittings use a hose washer to make a water-tight seal.

Back Flow

An unintended reverse flow of water from an irrigation system into the main water supply. It is caused by backpressure or a back siphon. Irrigation systems come in contact with many potentially harmful materials including fertilizers, pesticides, bacteria, insects, and animal waste. These contaminates will pollute household water supplies if sucked back in via backflow. 

 

Backpressure can be created by a pump in the system or when pipe/sprinklers in the zone are at a higher elevation than the point of connection to the water source. 

 

Back siphoning can occur if there is a break in the supply pipe and/or a drop in pressure of the supply line. Backflow most commonly occurs when there is a temporary sudden loss of pressure from the main water supply. 

 

A properly installed backflow preventer will prevent backpressure or back siphonage from impacting the main water supply. 

Backflow Preventer

A device installed on an irrigation system to prevent water in the irrigation pipes from flowing back into the main (household) water supply. Irrigation systems come in contact with many potentially harmful materials including fertilizers, pesticides, bacteria, insects, and animal waste. These contaminates will pollute household water supplies if sucked back in via backflow.

Types of Backflow Preventers

Air Gap

An Air Gap is a backflow prevention system that prevents water from being sucked, or siphoned, back into the water supply. There is a physical space (vertically) between a discharge pipe and the flood-level rim of receiving vessel. The receiving vessel is open and not under pressure.

The air gap must be at least double the diameter of the supply pipe measured vertically above the overflow rim of the receiving vessel. The Air Gap must be 1 inch or greater.

While not always practical, an Air Gap provides the maximum protection available against backflow (and potential contamination of water supply).

Atomospheric Vacuum Breaker (AVB)

An Atmospheric Vacuum Breaker is a backflow preventer that is installed above the highest point in an irrigation system. It contains a float (air inlet valve) which closes when water is moving in the normal direction, keeping air out of the system. If a siphon begins to form, the float drops to allow air into the system, breaking any potential backflow into the main water supply. Atmospheric Vacuum Breakers should be installed at a minimum of 6" above the highest pipe or outlet in the system.

Double Check Valve Assembly (DC)

A Double Check Valve (or double check assembly) is a backflow preventer containing two positive-seating check valves assembled in series.  A ball valve or gate valve is installed at each end for isolation and testing of each check valve. Small ball valves, called testcocks, provide locations for attatchment of testing equipment.

The benefit of the double check valve is that it does not need to be installed abouvr the highets head or pipe in the irrigation system. It can be installed underground in a valve box.

Pressure Vacuum Breaker (PVB)

A Pressure Vacuum Breaker (PVB) is a backflow device containing a spring loaded check valve and an independently operating air inlet valve. Since the PVB is not designed to protect aginast backpressure, it must be installed at least 12" above the highest head or pipe in the irrigation system. It provides a better solution against backsiphonage than an atmospheric vacuum breaker as the spring-loaded valve dows not rely on gravity as does the AVB. 

Reduced Pressure Principle Assembly (RP, RPA, RPZ)

A Reduced Pressure Principle Assembly is a backflow device consisting of of two two independently acting check valves and a mechanically independent, hydraulically dependent automatic pressure differential relief valve located between the two check valves. The relief valve maintains a reduced pressure zone between the two check valves that is lower than the supply pressure. A ball valve or gate valve is installed at each end for isolation and testing of each check valve. Four small ball valves, called testcocks, provide locations for attatchment of testing equipment. The RP must be installed 12" above the highest head or pipe in the irrigation system.

Hose Thread

Officially called "Garden Hose Thread" (GHT), hose threads are found on garden hoses and many irrigation parts and adapter fittings. Generally referred to as "3/4" hose threads" the outer diameter is 1.0625 inches and has a pitch of 11.5 tpi (threads per inch). Hose threads are NOT the same as pipe threads and should never be screwed into pipe threaded fittings.   

Male hose threads are found on the outside of a fitting and thread into female hose threads.

Female hose threads are found on the inside of a fitting and accept male hose threads.

Hose threads do not require Teflon tape or pipe dope (like pipe threads), just a hose washer. If you find a water leak with hose threads, it is most likely a worn hose washer. It may be time to replace it. Hose washers are found inside fittings with female hose threads. See also Pipe Thread, Adapter, Swivel, Hose Washer, Teflon Tape

Pipe Thread

The common term for National Pipe Thread (NPT). Pipe threads require Teflon tape or pipe dope to create a water-tight seal. Do not thread together pipe threads and hose threads. See also Teflon Tape, Pipe Dope, Hose Thread.

Teflon Tape

A non-adhesive tape (made of Teflon non-stick material) that is used to create a water-tight seal with pipe threaded fittings. It is tightly wrapped in a clockwise motion 3-4 times around the male pipe threads. Male and female fittings are then threaded together.

Hose Washer

Rubber gasket found inside fittings with female hose threads that makes a water-tight seal. See also Hose Thread.

View our complete glossary of irrigation terms.