DE/S-MK VI - IIB3

Function and Description

The deflagration proof and endurance burning proof PROTEGO^® DE/S -MK VI type device is a state of the art high velocity vent valve working on the principle of a dynamic flame arrester. It is primarily used as a device for flame transmission proof venting of cargo spaces and loading systems of tankships during the loading process and on the journey. The valve offers reliable protection against excess pressure, prevents product losses almost up to the set pressure and provides protection against atmospheric deflagrations as well as endurance burning if stabilized burning occurs. The PROTEGO^® DE/S-MK VI high velocity vent valve is available for substances of Explosion groups IIB3 and IIC (NEC group C MESG ≥ 0,65 mm and B MESG < 0,50 mm). 

The valve cone (1) is kept in a closed position by a corrosion resistant permanent magnet (2). The set pressure is adjusted by the distance of the permanent magnet to its counterpart (3). Upon reaching the set pressure, the valve opens directly to a full lift with only a minor pressure rise (jump characteristic). The set pressure is therefore very close to the maximum allowable working pressure (MAWP) of the cargo space.

The tank pressure is maintained up to the set pressure with a tightness that is far superior to the conventional standard due to our state of the art manufacturing technology. This feature is ensured by valve seats made of high-quality stainless steel with an individually lapped valve cone. After the excess pressure is discharged, the valve reseats and provides a tight seal. The design of the valve cone and valve seat produces a vertical, free jet that transports the gases far away from the discharge opening. This keeps the deck free of gas. The shape of the valve cone and valve seat promotes the drainage of rainwater when closed. A function check of the valve is easily performed with a manual lift gear (4) which Returns to its initial position after actuation. A lateral flange connection, DN2, is standard for a vacuum valve (such as the PROTEGO^® SV/E-S see volume 7).

If the set pressure is exceeded, explosive gas/product-vapour air mixtures are released to the atmosphere. When reaching the adjusted set pressure, the velocity at which the mixtures Exit the valve cone gap (5) (the gap between the valve seat and the valve cone) is much higher than the flame velocity. If this mixture ignites, flashback into the tank is prevented. If the mixture flow continues and stabilized burning occurs, the dynamic flame arresting feature prevents flashback ignition even in the case of endurance burning. As the system pressure decreases, the discharge velocity at the valve cone gap decreases also. The design ensures, that even in the closing pressure range, the valve cone closes in a timely manner keeping the discharge velocity far above the flame velocity and thereby preventing flashback.

The PROTEGO^® DE/S-MK VI high velocity pressure relief valve is also approved for oscillating flow. If a very long pipe is installed between the cargo space and valve, chattering can occur due to the resistance in the pipe or resonance phenomena. This can especially occur during partial load operation. This so called „hammering“ does not occur when a sufficient flow passes through the valve and the flow in the upstream line does not stop. The design is therefore a function of the required flow capacity. Accordingly, there are two different designs: one with a lift of 10 mm and one with 50 mm.

The valve can be used at an operating temperature up to +60°C / 140°F; since the valve is approved for group IIB3 (NEC Group C) vapours, it also meets the requirements of European Marine Equipment Directive 96/98/EC (MED).

Type-approved according to ATEX Directive and EN ISO 16852; approved according to IMO MSC/Circular 677, 1009 by GL (the C version), and other international standards.