In-line pressure and vacuum relief valve - F 31.1 N | KITO Armaturen

KITO F31.1N Pressure and Vacuum Line Valve

The KITO VD/TG-1, F31.1N series, is a self-actuated line valve designed for simultaneous pressure relief and vacuum protection in tanks or vessels. It is primarily intended for installation on breathing lines in the vapor phase of process systems.

Operating Range

The F31.1N is selected when required pressure settings exceed those of the F31N. The pressure pallet is spring-loaded, while the vacuum pallet is weight-loaded. No external pneumatic or electric actuator is required.

• DN 25–40: PN 40
• DN 50–150: PN 16
• ASME: 1" to 6"
• Vacuum: approx. 6 to 158 mbar, depending on DN
• Pressure: >200 to 350 mbar for DN 25–100
• Pressure: >150 mbar for DN 125–150
• Face-to-face length C adaptable to installation

Materials and Sealing

Standard version features a carbon steel body/cover, with optional stainless steel 1.4571. Seat, shaft, 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 Flow Calculation

Flanged connection per EN 1092-1 type A, optional ASME B16.5 Class 150 RF. Flow curves are based on air at ρ=1.29 kg/m³, 273 K, atmospheric pressure. Stated flows are achieved with 40% accumulation above setpoint, per DIN 4119.

Typical Applications

• Tank breathing lines with elevated opening pressure
• Solvent, chemical, or fuel tanks in vapor phase
• Blanketing systems with nitrogen or inert gas
• Vapor collection for treatment or safe disposal
• Vacuum protection during tank unloading

FAQ

When is F31.1N selected over F31N?
When the required pressure setting exceeds the F31N range. For lower settings, use F31N.

CE Marking?
The technical datasheet specifies versions without EC certificate and without CE marking.