The TK-DL can test pressure vacuum breakers, reduced pressure backflow preventers or double check valve assemblies. TK-DL可以檢測壓力真空斷路閥，減壓防回流閥或雙止回閥總成。
Pre-installation required to double-check valve, and clear the valve internal transport, storage process of the damage caused. 安裝前需仔細檢查閥門，并清除閥門內在運輸、存放過程中造成的損害。
Double Check Valve Assembly shall be installed at referenced cross-connections to prevent the backflow of polluted water into the potable water supply. 在相關的交叉連接處應該安裝一個雙止回閥總成，以防止受到污染的水回流到飲用水系統(tǒng)中。