In-line pressure and vacuum relief valve - F 31 N | KITO Armaturen

Pressure and Vacuum Line Valve KITO F31N

The KITO VD/TG, series F31N, is a line-mounted valve designed for simultaneous overpressure and vacuum relief in tanks or vessels. It is intended for installation in breathing lines where controlled venting and vessel protection against vacuum are required.

Operation

This is a self-actuated valve. The pressure pallet opens when internal pressure exceeds the setpoint, while the vacuum pallet opens if vessel pressure drops below the allowable vacuum. Both functions are integrated within a single body, with a defined tank side.

Dimensions and Setpoints

• DN 25–40: PN 40
• DN 50–150: PN 16
• ASME equivalents: 1" to 6"
• Vacuum setpoints: approx. 1.7 to 148 mbar, depending on DN
• Pressure setpoints: approx. 1.7 to 200 mbar, depending on DN and configuration
• For higher setpoints, use type F31.1N

Face-to-face length C can be adapted to existing piping, facilitating replacement of legacy valves or installation in confined spaces.

Materials and Sealing

Body and cover are available in carbon steel or optional stainless steel 1.4571. Seat, shaft, and weights are stainless steel 1.4571. Sealing options: NBR, Viton, PTFE, EPDM, or metal. For setpoints ≥100 mbar, only PTFE or metal sealing is permitted.

Connections and Flow Calculation

Standard flange: EN 1092-1 Type A. Optional: ASME B16.5 Class 150 RF. Flow rates refer to air at ρ=1.29 kg/m³, 273 K, with 40% accumulation above setpoint, per DIN 4119.

Typical Applications

• Tank breathing lines
• Solvent, fuel, or chemical storage tanks
• Inert gas distribution networks
• Vapor collection for treatment
• Vacuum collapse protection

FAQ

Difference from F30N?
The F30N operates as either pressure or vacuum relief depending on installation orientation. The F31N integrates both functions in one unit.

CE Marking?
Technical documentation states the valve is supplied without EC certificate and without CE marking.