Tradition Precision Innovation


Venting a tank truck compartment requires the highest precision and reliability. That's why you need Alfons Haar fittings!

Vapour transfer valve (vent valve PKV, PKVF), according to EN 13082 and ADR, ensures together with the pneumatic control, that the compartment is vented to the atmosphere before opening a foot valve (PBV). After closing a foot valve (PBV), the vapour transfer valve closes with delay so that there can never be over-pressure or a vacuum in the compartment.

The prescribed pressure and vacuum breather vent according to EN 14595 and ADR is integrated in the vapour transfer valve...

  • If there is a thermally-related increase in pressure, this will rule out impermissible over-pressure.
  • if there is a thermally-related drop in pressure, or if the pneumatic forced control fails, an impermissible vacuum is prevented.
  • If the tank truck turns over (on its side or upside down) the pressure control valve opens taking the static fluid column above the valve into account when pressure increases, so that the fluid cannot escape.

The vapour transfer valves are available with and without automatic sequence control in a nominal size of 65.

 Flame arresters according to EN 12874

The flame arresters according to EN 12874 are mounted on the vapour transfer valve. This enables the vapour collection manifold to be connected as well as preventing flame transmission into the tank.

Depending on what is required, the flame arresters can be designed as end-of-line flame arrester (connection DN 75) or as a deflagration, detonation and endurance burning flame arrester (connection DN 50).


 Please find here our brochures for more detailed information:

and also