What is required protection for a closed loop system containing glycol?

In a closed loop system containing glycol, a Reduced Pressure Zone (RPZ) backflow preventer is required to ensure proper protection against potential backflow. Closed loop systems are typically used for heating and cooling applications where glycol serves as a heat transfer fluid. The RPZ device is specifically designed to handle situations where there is a risk of contaminant backflow into the potable water supply.

One of the main features of an RPZ is its ability to maintain a pressure differential, which prevents the reverse flow of unapproved fluids, such as glycol, into the drinking water system. This is particularly important in systems where the fluid may be toxic or harmful if it enters the public water supply. The RPZ consists of two check valves with a pressure-sensing mechanism that opens the valve to drain any backflow incident, ensuring that contaminants are not able to enter the potable water supply.

Other options, while they serve valuable purposes in certain applications, do not provide the same level of protection as an RPZ in handling the specific risks associated with closed loop systems containing glycol. For instance, dual check valves are generally less effective against backsiphonage than an RPZ, and air gaps, while providing effective separation, may not be practical in many system configurations