Reduced Pressure Principle Backflow Prevention Device Assembly Relief Valve Drainage Quality

A 4 to 10 inch RPZ with a zone pressure of 50 PSI will discharge 500 gallons per minute during a catastrophic event such as the first check vale not holding tight when the RPZ in a no flow or static state. At this rate, a 1,200 cubic foot building would be filled with water in 19 minutes.

Water discharging from an RPZ relief valve is not only a volume issue (amount of water discharging) but it can also be a water quality issue and should be taken into consideration as well. If the first check valve is leaking and the RPZ is in a no flow state, the water discarding form the relief valve is most likely potable water that has chlorine residual. Depending on where the discharge pipe terminates, the discharge of chlorinated water may require a NPDES permit. Also another issue relating to the relief valve discharge is that if the second check valve is fouled and backpressure exists, non-potable water possible harmful and a health hazard is now being introduced into the environment. The potential hazardous from the water discharging from the relief valve should be evaluated prior to installing an RPZ. Certain precautions should be taken into consideration when a discharge occurs. It is important for the facility owner, the public health and code official, fire department and hazmat participants understand the risks involved and to recognize that a discharge from the RPZ relief valve may be considered a hazardous materials release. The discharge coming from the relief valve may be listed by the Federal Environmental Protection Agency as a hazardous waste which states that hazardous waste is waste that is dangerous or potentially harmful to our health or the environment. Hazardous wastes can be liquids, solids, gases, or sludge. They can be discarded commercial products, like cleaning fluids or pesticides, or the by-products of manufacturing processes. This material could be chemical, biological, or radiological in nature. Check with the local and state authorities for assistance regarding this matter.