Pressure Relief Pop-Off Valve with scavenging outlet. Replaces most older valves which do not have a scavenging outlet for carrying away waste gas overflow. Adjustable from fully open to fully closed with adjustable spring tension to set popoff pressure. Transparent rotatable housing with standard 15mm tapered male outlet connection, allows position and operation of the valve to be observed. Threaded base (3?4"20) fits many anesthesia machines directly, others require an adapter