High velocity pressure vacuum valves provides automatic control of pressure differentials during cargo loading/unloading, ballasting, or thermal variations and gas freeing purpose on tanks. General Description IMO MSC/Circ. 677/1009, IMO.MSC.1/Circ.1324 ISO 15364:2000 STRONG STABILITY NON-HAMMERING NON-OSCILLATING N.D50mm ~ 250mm JIS, ANSI, DIN etc FLANGE WEIGHT LOADED TYPE The purpose of High velocity pressure vacuum valves is designed to prevent the flame passage into cargo tanks and to relieve excessive over pressure or under vacuum of cargo tanks during cargo loading, discharging, ballasting and thermal variations. Also, our valve could be used to device for gas freeing of cargo tanks and for preventing penetration of sea water into water ballast tanks during valve and deck are submerged under seawater level due to vessels rolling, pitching and stranding in case of installation on ballast tank.