The VQ-SUB is a automatic Pipe-Away Pressure valve / integrated Vacuum valve for protection of cargo tanks in order to avoid excessive over/under pressure during loading, unloading, sloshing and thermal variations.

In case of an undesired tank pressure situation, the VQ-SUB emits the over pressure through a pipe-away system and to a controlled termination. Likewise, if an under pressure occurs, the vacuum valve opens and draws ambient air, through a flame arrester, equalizing the pressure inside the cargo tank.

Attention should be paid to fact that the pressure valve on VQ-SUB is not to be regarded as a dynamic flame arrester, as it only protects the internal over pressure on the connected cargo tank. For sufficient flame protection on the pressure side, a flame arrester, intended for the operation, must be added.