The Protectoseal 4276 Pressure Relief Rim Vent is designed
for use on floating roof tanks. They are mounted around the
rim of the tank roof system and provide casual relief for any
pressure accumulations under the pontoon sections of the
roof. The Rim Vents are relatively small in size in that they
accommodate only the vapor area above the pontoons. The
pressure relief is provided by hinged pallets with nominal set
points of 1″ W.C. The pallets hinge open and then reclose
when pressure is relieved. The Rim Vents relieve to
atmosphere are not considered to be primary relief devices
for the storage tank.