What is a double check valve assembly?
The Double Check Valve Assembly (DCVA) is essentially two single check valves assembled within one body and furnished with four test cocks and two shut-off valves. Double check valve assemblies are commonly used to protect against medium hazard installations such as lawn sprinkler systems.
When should a double check valve be used?
A double check valve is used for fluid category 3 protection, where there is a risk of substances of low toxicity such as common disinfectants.
What is the difference between a double check valve and a backflow preventer?
Double check valves are used for non-health hazard cross connections in continuous pressure applications. RPZ backflow preventers include two check valves like a double check backflow preventer, but they also have an intermediate relief valve that opens to atmosphere if both check valves should fail.
Where do you install a dual check valve?
Place the Double Check Valve within 2 feet of the meter box, (See note 5.1 below). 2.2. A tee with a ball valve is required before you install your double check valve. This is to ensure a continuous water supply to the residence during a leak or mechanical breakdown of the sprinkler system.
Does outside tap need double check valve?
The check valve is used to prevent a back flow of water re entering the mains system (as per Water Regs), not to prevent freezing. As long as you’ve got a double check valve on the pipe work leading from the mains supply to the outside tap, you’re fine.
Can a double check valve be installed underground?
The Double Check Valve Assembly: May be installed either above ground or inline (underground)
What is the purpose of the double check valve in the park brake system?
Double check valves are used in an air brake system to direct a flow of air into a common line from either of two sources, whichever is at the higher pressure. They may be used for directing air flow for specific functions or to select the higher pressure of either of two sources of air as a supply source.
What is the difference between a check valve and a dual check valve?
Type EA (verifiable) and type EB (non-verifiable) single check valves are used to protect against backflow in fluid category 2 applications. Double check valves are typically two single check valves linked together, providing failsafe backup if one of the check valves fail for any reason.
How long does a double check valve last?
Dual Check Valve – This is the most common method of protection. The backflow devices are considered “non-testable” and the only required maintenance is rebuild or replacement of the device once every five years.
Can a double check valve be installed vertically?
If installed in a vertical configuration, it must be a minimum of 6 inches from floor, and no higher than 5 feet to the centerline of the #2 shut-off valve. All assemblies must maintain a sufficient clearance from any wall, and 24 inches in front of assembly to ensure accessibility for maintenance and testing.
Can you bury a double check valve?
The Double Check Valve Assembly shall not be buried in earth but may be installed below ground in a meter box or pit provided that ball valve test cocks fitted with brass plugs are used.
What is the screw for on a double check valve?
Most outside taps have an integral double check valve, look for the small drain screw on the underside, that allows the space between the two check valve to be drained.
What is a dual plate check valve?
A Dual Plate Wafer Check Valve is defined as a mechanical device that allows a one directional fluid’s flow. Dual Plate Wafer Check Valves work through a disc with a spring that opens when the fluid flows in regular direction; and, when the fluid returns, the spring closes the disc to avoid the passage of the fluid.
What is a double valve replacement?
A double valve replacement is a replacement of both the mitral and the aortic valve, or the entire left side of the heart. This type of surgery is not as common as the others and the mortality rate is slightly higher.
What is a duck bill check valve?
Duckbill Check Valves. Duck-bill check valves are commonly used for river outfalls at wastewater treatment plants, as well as for stormwater outlets where one-way service is required.
What is a well water check valve?
Check valves used on well water system piping are used to hold pressure in the system when the pump stops. Check valves on well piping also prevent backspin of the well pump, water hammer and upthrust inside the pump.