The 350S double check is designed for installation on potable water lines to protect against back-siphonage and back-pressure of polluted water into the potable water supply. It is intended for applications where a potential health hazard does not exist. For high hazard applications see the 375 RPZ backflow preventer.
The 350S's unique and compact design allows the entire flow housing to be removed for cleaning or repair without having to remove the valve from service. For installations outdoors in cold climates, this design feature makes it easy to winterize by removing all wetted components between the shutoff valves. An optional blow out flush kit includes a replacement housing cover with two 3/4" female NPT connections for attaching air or water hose couplings or plugs (customer supplied) for use during winter shutdowns. Test cocks are all on top for easy access.
The main valve body is cast bronze with a reinforced Nylon housing. Fasteners and springs are 300 series stainless steel, elastomers are silicone and Buna-N (FDA approved) and internals are Delrin (NSF Listed). Full flow ball valves and strainer housings are cast bronze and the strainer screen is stainless steel. Maximum working pressure is 175 psi and the maximum working temperature is 180° F.
Standards compliance, vertical or horizontal: ASSE Listed 1015, IAPMO Listed, CSA Certified B64.5, Approved by the Foundation for Cross Connection Control and Hydraulic Research at the University of Southern California. Overall length below is with the strainer included.