In-line pressure and vacuum relief valve - F 33.1 N | KITO Armaturen

Pressure and Vacuum Line Valve KITO F33.1N

The KITO VD/T-1, series F33.1N, is a self-actuated line breather valve designed for tanks and vessels. Overpressure is vented via piping, while vacuum relief is supplied from the atmosphere. This valve is primarily intended for installation on gas-phase piping systems.

Operating Range

The F33.1N covers higher pressure setpoints than the F33N. The pressure pallet is spring-loaded; the vacuum pallet is weight-loaded. Valve actuation is by differential pressure, with no external actuator required.

• DN 25–40: PN 40
• DN 50–150: PN 16
• ASME equivalents: 1" to 6"
• Vacuum setting: approx. 6 to 158 mbar
• Pressure setting: >200 to 350 mbar for smaller DN
• For DN 125–150: pressure range from >150 mbar
• Lower setpoints: see F33N series
• Higher setpoints: subject to technical review

Materials and Sealing

Body and cover are available in carbon steel or stainless steel 1.4571. Seat, shaft, loading weights, and spring components are stainless steel 1.4571. Valve sealing is metallic. Gasket options: HD 3822 or PTFE. Seat O-ring options: VMQ-FEP, Viton, NBR, or VMQ-PFA.

Connections and Standards

Standard connection: flanged 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. Supplied without EC certificate and without CE marking.

Typical Applications

• Storage tanks with vent piping
• Storage of solvents, fuels, or volatile chemicals
• Lines to scrubbers, activated carbon filters, or VRUs
• Overpressure protection during filling
• Vacuum protection during emptying

FAQ

When is F33.1N selected over F33N?
When higher pressure setpoints are required than those covered by the F33N range.

How does it differ from F32.1N?
F33.1N admits air from the atmosphere for vacuum relief. F32.1N uses piping for both venting and vacuum replenishment.