Abstract: An open top tank for storing volatile liquids has a circular floating roof buoyantly supported on the surface of the stored liquid within a confining cylindrical shell of the tank. Adjustable sealing means extends between the roof and the top of the shell for sealing the gap between the roof and the surrounding shell. The adjustable sealing means includes a plurality of cylindrical annular sections of different diameters nested one inside another in telescoping relationship, the sections being coaxial with the shell and positioned above the floating roof. Limit means interconnects adjacent ones of the sections for limiting the vertical movement of each section relative to the next adjacent outer section and the outermost section relative to the surrounding shell. The limit means transfers the weight of any section in its lowest position through the limit means to the tank shell.

Abstract: A vapor recovery system for closed volatile liquid storage facilities including loading rack systems for tank trucks, rail cars, ship and barge cargo compartments. These facilities have provision for charging the system with blanketing gas under controlled pressure conditions for admixture with vapor of the volatile liquid. This mixture is processed for recovery of the vapor and gas constituents under the supervision and control of precision oxygen monitoring. Whenever the detected percentage of oxygen exceeds a predetermined safe value, corrective measures are taken immediately and automatically and acknowledging devices are activated and additional blanketing gas may be supplied to decrease the percentage of oxygen in the facility. Vapor and gas mixtures monitored and found safely non-combustible are processed by compression and heat exchange to condense some of the vapor and to elevate the pressure level.