Model 31 flowmeter allows for the low controlled flow of nitrogen gas through the copper tube to prevent oxidation. Nitrogen purging prevents contamination. The flowmeter is compensated to 50 psig. It features a brass body, sensitive needle valve for fingertip control and durable, easy-to-read, flow tube and cover. It has 1/4 in SAE flare inlet and outlet connections. Must mount the flowmeter vertically for accurate reading. Conveniently vacuum-packed for point-of-purchase display.