About Backflow-Prevention Valves
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Vacuum-Breaking Valves
Also known as vacuum breakers, these valves have vents that open when pressure drops to relieve vacuum conditions and prevent backward suction from drawing liquid into upstream piping.
Chrome-plated bronze valves are more corrosion resistant than brass valves.
303 stainless steel valves have the best corrosion resistance.
Elbows are designed for intermittent flow. They discharge liquid directly and should not be installed in areas where spillage could cause damage.
Straights are often used with steam coils, heat exchangers, and space heaters.
For technical drawings and 3-D models, click on a part number.
- For Use With: Water
- Seal Material: Silicone Rubber
Brass Body | Chrome-Plated Bronze Body | ||||||
|---|---|---|---|---|---|---|---|
Pipe Size | Max. Pressure | Temperature Range, °F | Port-to-Port Lg. | Each | Each | ||
NPT Female Inlet × NPT Female Outlet | |||||||
| 1/4 | 125 psi @ 70° F | 35° to 180° | 1" | 000000 | 00 | 0000000 | 000000 |
| 3/8 | 125 psi @ 70° F | 35° to 180° | 1" | 000000 | 00 | 0000000 | 00000 |
| 1/2 | 125 psi @ 70° F | 35° to 180° | 1 1/4" | 000000 | 00 | 0000000 | 00000 |
| 1/2 | 125 psi @ 70° F | 35° to 180° | 1 5/16" | 00000000 | 000000 | 000000 | 00 |
| 3/4 | 125 psi @ 70° F | 35° to 180° | 1 1/2" | 00000000 | 00000 | 0000000 | 00000 |
| 1 | 125 psi @ 70° F | 35° to 180° | 1 5/8" | 00000000 | 00000 | 000000 | 00 |
| 1 1/4 | 125 psi @ 70° F | 35° to 180° | 2" | 00000000 | 000000 | 000000 | 00 |
| 1 1/2 | 125 psi @ 70° F | 35° to 180° | 2 1/4" | 00000000 | 000000 | 000000 | 00 |
| 2 | 125 psi @ 70° F | 35° to 180° | 2 3/4" | 00000000 | 000000 | 000000 | 00 |
- For Use With: Air, Argon, Helium, Krypton, Neon, Steam, Water, Xenon
- Seal Material: EPR Rubber
| Inlet Pipe Size | Outlet Pipe Size | Max. Pressure | Temperature Range, °F | End-to-End Lg. | Body Material | Each | |
Brass Body | |||||||
|---|---|---|---|---|---|---|---|
NPT Male Inlet × NPT Female Outlet | |||||||
| 1/2 | 3/8 | 300 psi @ 70° F | -20° to 365° | 1 3/4" | Brass | 0000000 | 0000000 |
| 3/4 | 1/2 | 300 psi @ 70° F | -20° to 365° | 2 1/8" | Brass | 0000000 | 000000 |
| 1 | 3/4 | 300 psi @ 70° F | -20° to 365° | 2 3/8" | Brass | 0000000 | 000000 |
303 Stainless Steel Body | |||||||
NPT Male Inlet × NPT Female Outlet | |||||||
| 1/2 | 3/8 | 300 psi @ 70° F | -20° to 365° | 1 3/4" | 303 Stainless Steel | 0000000 | 000000 |
| 3/4 | 1/2 | 300 psi @ 70° F | -20° to 365° | 2 1/8" | 303 Stainless Steel | 0000000 | 000000 |
| 1 | 3/4 | 300 psi @ 70° F | -20° to 365° | 2 3/8" | 303 Stainless Steel | 0000000 | 000000 |
Vacuum-Breaking Valves with Garden-Hose Fittings
- For Use With: Air, Water
- Seal Material: Rubber
Prevent dirty, contaminated water from backing up into your garden hose line—install these valves between a faucet and a garden hose. Also known as vacuum breakers, these valves have a built-in check valve that blocks backflow, so you can leave your hose in a utility sink full of dirty water without the water going back into the line.
When the check valve is closed, it has vents that open to release the water. This reduces pressure in the line and confirms the valve is working. Because these valves vent water, use them in environments where spilled water won’t cause a problem. This design adheres to ASSE Standard 1011 for valves with a vent.
Mount valves to faucet outlets with a set screw, and easily thread or unthread a hose while the valves stay in place.
Valves comply with Uniform Plumbing Code (UPC) and are CSA certified, so they're safe to use in sanitary plumbing systems because they prevent contamination from flowing backward into your line.
These valves are designed to be used intermittently. They've been tested under ASME A112.1.3, which assumes the valves will not be used for more than 12 hours at a time.
Chrome-plated brass valves are more corrosion resistant than plain brass valves.
Valves with tamper-resistant set screws have a head that breaks off after tightening to prevent valve removal after installation.
Valves that meet NSF/ANSI Standard 372 are certified lead free.
Brass Body | Chrome-Plated Brass Body | |||||||
|---|---|---|---|---|---|---|---|---|
| Hose Size | Max. Pressure | Temperature Range, °F | End-to-End Lg. | Specifications Met | Each | Each | ||
GHT Female × GHT Male | ||||||||
With Set Screw | ||||||||
| 3/4 | 125 psi @ 70° F | 30° to 180° | 1 1/2" | ASSE Standard 1011, CSA Certified, CAN/CSA B64.2, NSF/ANSI 372, UPC Compliant, ASME A112.1.3, ASSE 1001 | 00000000 | 000000 | 00000000 | 000000 |
| 3/4 | 125 psi @ 70° F | 30° to 180° | 1 1/2" | ASSE Standard 1011, CSA Certified, CAN/CSA B64.2, UPC Compliant, ASME A112.1.3, ASSE 1001 | 00000000 | 00000 | 00000000 | 00000 |
With Tamper-Resistant Set Screw | ||||||||
| 3/4 | 125 psi @ 70° F | 30° to 180° | 1 1/2" | ASSE Standard 1011, CSA Certified, CAN/CSA B64.2, NSF/ANSI 372, UPC Compliant, ASME A112.1.3, ASSE 1001 | 00000000 | 00000 | 00000000 | 00000 |
| 3/4 | 125 psi @ 70° F | 30° to 180° | 1 1/2" | ASSE Standard 1011, CSA Certified, CAN/CSA B64.2, UPC Compliant, ASME A112.1.3, ASSE 1001 | 00000000 | 00000 | 00000000 | 00000 |
High-Pressure Vacuum-Breaking Valves
- For Use With: Air, Argon, Helium, Krypton, Neon, Oil, Water, Xenon
- Seal Material: Fluoroelastomer Rubber
Rated for 12 times the pressure of standard vacuum-breaking valves, these can handle up to 1,500 psi. Also known as vacuum breakers, they have vents that open when pressure drops to relieve vacuum conditions and prevent backward suction from drawing liquid into upstream piping. Body is 316 stainless steel for excellent corrosion resistance.
Flow coefficient (Cv) is the amount of water (in gallons per minute) at 60° F that will flow through a fully open valve with a difference of 1 psi between the inlet and the outlet.
For technical drawings and 3-D models, click on a part number.
Vacuum-Breaking Valves for Chemicals
A plastic body withstands pH neutralizing, cleaning, and plating solutions containing sodium hydroxide, methyl ethyl ketone, and other harsh chemicals. Also known as vacuum breakers, these valves have vents that open when pressure drops to relieve vacuum conditions and prevent backward suction from drawing liquid into upstream piping.
For technical drawings and 3-D models, click on a part number.
- For Use With: Air, Ammonia, Argon, Beverage, Carbon Dioxide, Chlorinated Water, Diesel Fuel, Drinking Water, Ethylene Glycol, Food, Helium, Hydrochloric Acid, Kerosene, Krypton, Liquid Carbon Dioxide, Methanol, Methyl Ethyl Ketone, Mineral Spirits, Natural Gas, Neon, Nitric Acid, Nitrogen, Oil, Oxygen, Soap Solutions, Sodium Hydroxide, Sodium Hypochlorite, Water, Xenon
- Diaphragm Material: Fluoroelastomer Rubber
- Seal Material: Fluoroelastomer Rubber
| Pipe Size | For Pipe Schedule | Max. Pressure | Min. Opening Pressure, psi | End-to-End Lg. | Color | Temperature Range, °F | Each | |
PVC Plastic Body | ||||||||
|---|---|---|---|---|---|---|---|---|
NPT Female × NPT Female | ||||||||
| 1/2 | 80 | 100 psi @ 75° F | 1 | 4 5/16" | Gray | 40° to 140° | 000000 | 0000000 |
| 3/4 | 80 | 100 psi @ 75° F | 1 | 4 5/8" | Gray | 40° to 140° | 0000000 | 000000 |
| 1 | 80 | 100 psi @ 75° F | 1 | 5 1/8" | Gray | 40° to 140° | 0000000 | 000000 |
CPVC Plastic Body | ||||||||
NPT Female × NPT Female | ||||||||
| 1/2 | 80 | 100 psi @ 75° F | 1 | 4 5/16" | Light Gray | 40° to 180° | 0000000 | 000000 |
| 3/4 | 80 | 100 psi @ 75° F | 1 | 4 5/8" | Light Gray | 40° to 180° | 0000000 | 000000 |
| 1 | 80 | 100 psi @ 75° F | 1 | 5 1/8" | Light Gray | 40° to 180° | 0000000 | 000000 |
- For Use With: Air, Ammonia, Argon, Beverage, Carbon Dioxide, Chlorinated Water, Diesel Fuel, Drinking Water, Ethylene Glycol, Food, Helium, Hydrochloric Acid, Kerosene, Krypton, Liquid Carbon Dioxide, Methanol, Methyl Ethyl Ketone, Mineral Spirits, Natural Gas, Neon, Nitric Acid, Nitrogen, Oil, Oxygen, Soap Solutions, Sodium Hydroxide, Sodium Hypochlorite, Water, Xenon
- Piston Material:
PVC Plastic Body: PVC Plastic
CPVC Plastic Body: CPVC Plastic - Spring Material: Plastic Polymer
- Seal Material: Fluoroelastomer Rubber
| Pipe Size | For Pipe Schedule | Max. Pressure | Min. Opening Pressure, psi | End-to-End Lg. | Color | Temperature Range, °F | Each | |
PVC Plastic Body | ||||||||
|---|---|---|---|---|---|---|---|---|
NPT Female × NPT Female | ||||||||
| 2 | 80 | 100 psi @ 75° F | 1 | 8 1/2" | Gray | 40° to 140° | 0000000 | 0000000 |
CPVC Plastic Body | ||||||||
NPT Female × NPT Female | ||||||||
| 1 1/2 | 80 | 100 psi @ 75° F | 1 | 7 15/16" | Light Gray | 40° to 180° | 0000000 | 000000 |
Threaded Two-Stage Backflow-Prevention Valves for Drinking Water
- For Use With: Drinking Water
- Seal Material: EPDM Rubber
Keep backflow from contaminating your drinking water supply—these valves meet NSF/ANSI 61 for use with drinking water. They consist of a primary check valve and a secondary check valve. If the primary check fails to close when flow stops or reverses, the secondary check valve engages to prevent backflow.
Single-union valves have a union fitting on one end.
Double-union valves have a union fitting on both ends.
For technical drawings and 3-D models, click on a part number.
| Pipe Size | Max. Pressure | Min. Opening Pressure, psi | Temperature Range, °F | End-to-End Lg. | Each | |
Brass Body—Single Union | ||||||
|---|---|---|---|---|---|---|
NPT Female Inlet × NPT Female Outlet | ||||||
| 3/4 | 175 psi @ 180° F | 5 | 35° to 180° | 3 3/4" | 00000000 | 000000 |
| 1 | 175 psi @ 180° F | 5 | 35° to 180° | 3 3/4" | 00000000 | 000000 |
NPT Male Inlet × NPT Female Outlet | ||||||
| 3/4 | 175 psi @ 180° F | 5 | 35° to 180° | 3 3/4" | 00000000 | 000000 |
Brass Body—Double Union | ||||||
NPT Female Inlet × NPT Female Outlet | ||||||
| 1/2 | 175 psi @ 180° F | 5 | 35° to 180° | 3 3/4" | 0000000 | 000000 |
| 3/4 | 175 psi @ 180° F | 5 | 35° to 180° | 3 3/4" | 0000000 | 000000 |
| 1 | 175 psi @ 180° F | 5 | 35° to 180° | 4" | 0000000 | 000000 |
Easy-Maintenance Threaded Two-Stage
Backflow-Prevention Valves for Drinking Water
- For Use With: Drinking Water
- Seal Material: Buna-N Rubber
Integral shutoff valves isolate flow for inline maintenance, and a top-entry cover provides easy access to internal components. These valves meet NSF/ANSI 61 for use with drinking water. For maximum protection from system contamination, they consist of a primary check valve and a secondary check valve. If the first check fails to close when flow stops or reverses, the secondary check valve engages to prevent backflow. A strainer prevents debris from blocking the check valves.
Reduced-pressure-zone valves have a relief valve that discharges backflow if both check valves fail. Valves with an air inlet provide high-capacity relief in emergency conditions. If both check valves fail, the inlet introduces air to quickly displace liquid for faster discharge through the relief valve.
| Pipe Size | Max. Pressure | Min. Opening Pressure, psi | Temperature Range, °F | End-to-End Lg. | Features | Specifications Met | Each | |
Bronze Body—Dual-Check Valve | ||||||||
|---|---|---|---|---|---|---|---|---|
NPT Female × NPT Female | ||||||||
| 1/2 | 175 psi @ 180° F | 30 | 35° to 180° | 12 3/4" | Strainer | ASSE 1015, CSA Certified, NSF/ANSI 61, USC Foundation Approved | 0000000 | 0000000 |
| 3/4 | 175 psi @ 180° F | 30 | 35° to 180° | 14 5/16" | Strainer | ASSE 1015, CSA Certified, NSF/ANSI 61, USC Foundation Approved | 0000000 | 000000 |
| 1 | 175 psi @ 180° F | 30 | 35° to 180° | 17" | Strainer | ASSE 1015, CSA Certified, NSF/ANSI 61, USC Foundation Approved | 0000000 | 000000 |
| 1 1/2 | 175 psi @ 180° F | 30 | 35° to 180° | 21 5/8" | Strainer | ASSE 1015, CSA Certified, NSF/ANSI 61, USC Foundation Approved | 0000000 | 000000 |
| 2 | 175 psi @ 180° F | 30 | 35° to 180° | 24 13/16" | Strainer | ASSE 1015, CSA Certified, NSF/ANSI 61, USC Foundation Approved | 0000000 | 00000000 |
Bronze Body—Reduced-Pressure-Zone Valve | ||||||||
NPT Female × NPT Female | ||||||||
| 1/2 | 175 psi @ 180° F | 30 | 35° to 180° | 12 3/4" | Relief Valve, Strainer | ASSE 1013, NSF/ANSI 61, USC Foundation Approved | 00000000 | 000000 |
| 3/4 | 175 psi @ 140° F | 30 | 35° to 140° | 18 1/16" | Air Inlet, Relief Valve, Strainer | ASSE 1013, NSF/ANSI 61, USC Foundation Approved | 0000000 | 00000000 |
| 3/4 | 175 psi @ 180° F | 30 | 35° to 180° | 16 15/16" | Relief Valve, Strainer | ASSE 1013, NSF/ANSI 61, USC Foundation Approved | 00000000 | 000000 |
| 1 | 175 psi @ 140° F | 30 | 35° to 140° | 19 5/8" | Air Inlet, Relief Valve, Strainer | ASSE 1013, NSF/ANSI 61, USC Foundation Approved | 0000000 | 00000000 |
| 1 | 175 psi @ 180° F | 30 | 35° to 180° | 18 1/4" | Relief Valve, Strainer | ASSE 1013, NSF/ANSI 61, USC Foundation Approved | 00000000 | 000000 |
| 1 1/4 | 175 psi @ 180° F | 30 | 35° to 180° | 21 13/16" | Relief Valve, Strainer | ASSE 1013, NSF/ANSI 61, USC Foundation Approved | 00000000 | 00000000 |
| 1 1/2 | 175 psi @ 180° F | 30 | 35° to 180° | 22 3/4" | Relief Valve, Strainer | ASSE 1013, NSF/ANSI 61, USC Foundation Approved | 00000000 | 00000000 |
| 2 | 175 psi @ 180° F | 30 | 35° to 180° | 26 11/16" | Relief Valve, Strainer | ASSE 1013, NSF/ANSI 61, USC Foundation Approved | 00000000 | 00000000 |
NPT Male × NPT Male | ||||||||
| 1 1/2 | 175 psi @ 140° F | 30 | 35° to 140° | 24 3/8" | Air Inlet, Relief Valve, Strainer | ASSE 1013, NSF/ANSI 61, USC Foundation Approved | 0000000 | 00000000 |
| 2 | 175 psi @ 140° F | 30 | 35° to 140° | 25 15/16" | Air Inlet, Relief Valve, Strainer | ASSE 1013, NSF/ANSI 61, USC Foundation Approved | 0000000 | 00000000 |
Threaded Two-Stage Backflow-Prevention Valves
- For Use With: Air, Water
- Disc Material: EPDM Rubber
- Seal Material: EPDM Rubber
For maximum protection from system contamination, these valves have two integral check valves with a vent between them. If the primary check valve fails to close when flow stops or reverses, overflow is discharged through the vent and the secondary check valve prevents backflow.
Strainers prevent debris from blocking the check valves.
Chrome-plated brass valve is more corrosion resistant than plain brass valves.
Valve with an unthreaded vent is commonly used on laboratory faucets and other applications with intermittent flow. It discharges overflow directly and should not be installed in areas where spillage could cause water damage.
Valves with a threaded vent can be connected to drain pipes to prevent spillage. They are designed for applications with continuous flow and are often installed on water supply lines to boilers, processing tanks, and other equipment.
For technical drawings and 3-D models, click on a part number.
| Pipe Size | Max. Pressure | Min. Opening Pressure, psi | Temperature Range, °F | End-to-End Lg. | Vent Type | Features | Each | |
Brass Body | ||||||||
|---|---|---|---|---|---|---|---|---|
NPT Female Inlet × NPT Female Outlet | ||||||||
| 1/2 | 175 psi @ 250° F | 25 | 35° to 250° | 4 15/16" | Threaded | Strainer | 0000000 | 0000000 |
| 3/4 | 175 psi @ 250° F | 25 | 35° to 250° | 4 1/2" | Threaded | Strainer | 0000000 | 000000 |
Chrome-Plated Brass Body | ||||||||
NPT Male Inlet × NPT Female Outlet | ||||||||
| 3/8 | 150 psi @ 140° F | 25 | 35° to 140° | 2 3/8" | Unthreaded | __ | 0000000 | 000000 |
Two-Stage Backflow-Prevention Valves with Solder-Connect Fittings
- For Use With: Air, Water
- Disc Material: EPDM Rubber
- Seal Material: EPDM Rubber
Solder these valves to copper tubing for a permanent, leak-tight connection. They have two integral check valves with a vent between them for maximum protection from system contamination. If the primary check valve fails to close when flow stops or reverses, overflow is discharged through the threaded vent and the secondary check valve prevents backflow. Attach the vent to drain pipes to prevent spillage. These valves are designed for applications with continuous flow and are commonly used on water supply lines to boilers, processing tanks, and other equipment. All have an integral strainer to prevent debris from blocking the check valves.
For technical drawings and 3-D models, click on a part number.
Vent Port | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| For Copper Tube Size | For Tube OD | Max. Pressure | Min. Opening Pressure, psi | Temperature Range, °F | End-to-End Lg. | Vent Type | Gender | Pipe Size | Thread Type | Features | Each | |
Brass Body | ||||||||||||
Solder Connect × Solder Connect | ||||||||||||
| 1/2 | 5/8" | 175 psi @ 250° F | 25 | 35° to 250° | 4 3/8" | Threaded | Female | 1/2 | NPT | Strainer | 0000000 | 0000000 |
| 3/4 | 7/8" | 175 psi @ 250° F | 25 | 35° to 250° | 4 13/16" | Threaded | Female | 1/2 | NPT | Strainer | 0000000 | 000000 |
Frostproof Vacuum-Breaking Valves with Garden Hose Threads
Stop backward flow in outdoor faucets with garden hose outlets. This valve drains when closed to prevent freezing. To prevent tampering, tighten the set screw until the head breaks off.
Inlet | Outlet | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Ht. | Hose Size | Thread Type | Gender | Hose Size | Thread Type | Gender | Max. Pressure | Temp. Range, °F | For Use Outdoors | Specifications Met | Each | |
Brass | ||||||||||||
| 2" | 3/4 | GHT | Female | 3/4 | GHT | Male | 125 psi @ 70° F | 35° to 180° | Yes | ASSE 1011, CSA Certified, CAN/CSA B64.2, ASME A112.1.3 | 00000000 | 000000 |