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.