Which two types of check valves are most common in a water system?

The two types of check valves most commonly used in a water system are ball check valves and double check valves. Ball check valves utilize a ball that floats and seals the inlet when flow reverses, preventing backflow and ensuring that water only travels in one direction. This design is effective in a variety of applications, particularly in systems where backflow can cause contamination or other issues.

Double check valves consist of two check mechanisms in one unit, providing a higher level of protection against backflow than a single valve. This type is particularly important in situations where the risk of contamination is high, making it a preferred choice in many public water systems. The dual mechanism adds an extra layer of reliability, ensuring that if one valve fails, the other serves as a safeguard against undesirable backflow.

In contrast, gate and globe valves are more commonly used for regulating flow rather than preventing backflow. Y and angle valves do not specifically function as check valves; instead, they serve different purposes such as directing flow in a plumbing system. PVC and metal valves refer to the materials from which valves are made rather than their function as check valves. Thus, the focus on ball check valves and double check valves is a recognition of their critical role in maintaining water quality and system integrity in