In-line pressure and vacuum relief valve - F 33 N | KITO Armaturen

Pressure and Vacuum Line Valve KITO F33N

The KITO VD/T, F33N series, is a self-actuated line breather valve for tanks and vessels. It is specified where gas venting must be routed via piping, while vacuum relief is achieved by atmospheric air intake.

Tank Operation

The tank side connects to the vapor phase line. Under overpressure, the pressure pallet opens, directing vented gases to a collection or vent line. Under vacuum, the vacuum pallet admits atmospheric air. Operation is by weighted loading, without external actuators.

Sizes and Settings

• DN 25–40: PN 40
• DN 50–150: PN 16
• ASME equivalents: 1" to 6"
• Vacuum setting: approx. 1.7 to 148 mbar
• Pressure setting: approx. 1.7 to 200 mbar, depending on DN and configuration
• Shell extension available for higher pressure settings in certain sizes
• Length C can be adapted to installation requirements

Materials and Sealing

Body and cover in carbon steel, with option for stainless steel 1.4571. Seat, shaft, and weights available in 1.4571. Standard seal is NBR; options include Viton, PTFE, EPDM, or metal-to-metal. For settings ≥100 mbar, only PTFE or metal seals are used.

Connections and Flow Data

Flanged connection per EN 1092-1 type A; ASME B16.5 Class 150 RF optional. Flow rates specified for air at ρ=1.29 kg/m³, 273 K, with 40% accumulation above setpoint, per DIN 4119.

Typical Applications

• Tanks with vent piping
• Storage of solvents, chemicals, or volatile liquids
• Lines to scrubbers, activated carbon filters, or safe venting systems
• Overpressure and vacuum protection during filling/emptying

FAQ

How does it differ from F32N?
The F33N admits air from atmosphere. F32N is used when both venting and air intake are piped.

CE Marking?
Technical datasheet indicates version without EC certificate and without CE marking.