Brass Orifices & Venturi Meters Vbs-270 Description 3/4" Npt Screwed Venturi Metering Orifice (Vcw) Head Loss 10% Max Operating Pressure: 250 Psi Permits Accurate Setting Of Burner Air And Gas Flow Or Optimum Efficiency. Lower Pressure Loss Than Plate Orifices. +/ - 1% Accuracy Depending On Location. One Piece Machined Brass Connection. Includes Brass Hex-Head Screws To Plug Holes When Measurements Are Not Being Taken. Application Low Cost Metering Device That Provides Accurate Setting Of Air Or Gas For Optimum Efficiency.