Inline Pressure & Vaccum Relief Valves For Tanks

Inline pressure relief / vacuum relief valves for tanks are used in closed or semi-closed vapor systems, inert gas lines, and tank vent lines where pressure variation is not discharged directly to atmosphere but routed through connected piping. The valve opens in the relieving direction when system pressure exceeds the specified set pressure and opens in the inbreathing direction when vacuum develops, protecting tanks, vapor headers, and connected equipment from mechanical overstress during filling, emptying, or thermal cycling.

This category includes KITO inline pressure / vacuum relief valve types F18N, F30N, F30.1N, F31N, F31.1N, F32N, F32.1N, F33N, F33.1N, F37N, F37.1N, F50N, F61N, F61.1N, F63N, F70N, F71N, F72.3N, and F80N. These series cover combined pressure and vacuum relief configurations, as well as pressure-only or vacuum-only execution. Type F80N is also available with integrated flame arrester protection for applications involving flammable vapors, subject to suitability review for the specific gas group, operating conditions, and applicable explosion protection requirements.

Valve selection should be based on pressure setpoint, vacuum setpoint, required venting or inbreathing capacity, allowable line pressure loss, and the diameter and geometry of the connected piping. Material compatibility with the process medium, operating temperature, condensate formation, and the risk of polymerized or sticky deposits should also be evaluated. Available configurations in this category include pressure classes PN 10, PN 16, and PN 40, with body materials such as 1.0619, 1.4408, 1.4571, and steel.

In vapor recovery systems or common vent headers, the valve should be assessed together with line losses, isolation valves, flame arresters, drain points, and the overall ATEX design basis. Maintenance should include inspection of seats, discs, gaskets, weights or spring-loaded setting components, verification of free mechanical travel, and confirmation that the flow path is clean. Deposits and fouling can shift the opening pressure, increase leakage, or reduce venting capacity.