N120 Series backpressure valve is installed after the meter, and it holds backpressure on the meter until vapor is forced back to the tank through the vapor eliminator. In this way vapor cannot form within the meter during liquid delivery. Intended for smaller pumps, N120 Series are ideal on such applications as cylinder filling installations. All units have a 1/4-inch FNPT tapped and plugged boss on the inlet side of body and can be used for both LP-Gas and Anhydrous Ammonia (NH3) service.