Watts 994HMB fire hydrant backflow preventer meter construction consists of: meter housing, measuring element, permanently sealed register, and reduced pressure backflow preventer in unitized assembly.

• 美国瓦茨994HMB消防栓防回流阀仪表结构包括：仪表壳，测量元件，永久性密封记录器，和在成套总成内的减压防回流阀。