Plumbing 101: unraveling the appearance of backflow preventers
What To Know
- RPZs have a relief valve that opens if the pressure in the zone between the check valves exceeds a certain level.
- Signs of a failing backflow preventer include water leaking from the test cocks, difficulty opening or closing the test cocks, or a drop in water pressure.
- The relief valve on an RPZ opens if the pressure in the zone between the check valves exceeds a certain level.
Backflow preventers are essential devices installed in plumbing systems to prevent contaminated water from flowing back into clean water lines. These devices come in various shapes and sizes, but they all share certain common features that make them easily identifiable.
Types of Backflow Preventers
There are two main types of backflow preventers:
- Double Check Valve (DCV): DCVs have two check valves that close automatically when water pressure drops, preventing backflow. They are suitable for low-hazard applications.
- Reduced Pressure Zone (RPZ): RPZs have three check valves and a pressure-reducing diaphragm. They maintain a lower pressure in the zone between the check valves, which prevents backflow even if one check valve fails. RPZs are used in high-hazard applications.
Visual Characteristics
Body
The body of a backflow preventer is typically made of brass or bronze. It is usually cylindrical or rectangular in shape and has threaded connections on both ends.
Inlet and Outlet Ports
Backflow preventers have two ports labeled “inlet” and “outlet.” The inlet port is where water enters the device, and the outlet port is where water exits.
Check Valves
Check valves are one-way valves that allow water to flow in only one direction. They are located inside the backflow preventer‘s body.
Pressure-Reducing Diaphragm (RPZ Only)
RPZs have a pressure-reducing diaphragm that separates the inlet and outlet check valves. This diaphragm maintains a lower pressure in the zone between the check valves, preventing backflow.
Test Cocks
Backflow preventers have two test cocks, one upstream and one downstream of the check valves. These test cocks allow for testing the functionality of the check valves.
Relief Valve (RPZ Only)
RPZs have a relief valve that opens if the pressure in the zone between the check valves exceeds a certain level. This prevents damage to the diaphragm and other components.
Bypass Valve (Optional)
Some backflow preventers have a bypass valve that allows water to flow around the check valves in case of an emergency.
Size and Shape Variations
Backflow preventers come in a range of sizes and shapes to accommodate different plumbing applications. Small backflow preventers may be only a few inches long, while larger ones can be over a foot long. The shape of the backflow preventer can also vary, from cylindrical to rectangular to triangular.
Installation
Backflow preventers should be installed by a licensed plumber. They are typically installed on the water supply line, upstream of any potential sources of contamination.
Maintenance
Backflow preventers require regular maintenance to ensure they are functioning properly. This maintenance typically includes testing the check valves and replacing any worn or damaged components.
Recommendations: Ensuring Safe Water Supply
Backflow preventers are essential devices that protect our water supply from contamination. By understanding what a backflow preventer looks like, you can help ensure that your plumbing system is safe and functioning properly.
Frequently Asked Questions
1. What is the difference between a DCV and an RPZ?
A DCV has two check valves, while an RPZ has three check valves and a pressure-reducing diaphragm. RPZs are used in high-hazard applications where backflow prevention is critical.
2. How often should backflow preventers be tested?
Backflow preventers should be tested annually by a licensed plumber.
3. What are the signs of a failing backflow preventer?
Signs of a failing backflow preventer include water leaking from the test cocks, difficulty opening or closing the test cocks, or a drop in water pressure.
4. Can I install a backflow preventer myself?
It is not recommended to install a backflow preventer yourself. Backflow preventers should be installed by a licensed plumber to ensure proper installation and functionality.
5. What is the purpose of the relief valve on an RPZ?
The relief valve on an RPZ opens if the pressure in the zone between the check valves exceeds a certain level. This prevents damage to the diaphragm and other components.
