Patent ID: 8915265

Claim:
A double-walled above-ground storage tank comprising: (a) a tank roof, a tank floor, a primary tank and a secondary tank, which together define a tank interstitial space therebetween, wherein the primary tank and the tank floor together define a tank interior volume; (b) a main containment chamber formed by a chamber wall; (c) an ancillary containment chamber formed by an ancillary chamber wall, wherein the ancillary containment chamber is above and contains the main containment chamber, and both the main and ancillary containment chambers are disposed within the tank interior volume; (d) a high level shutdown pipe which extends between a freeboard portion of the tank interior volume and the main containment chamber, passing through the ancillary containment chamber, and comprising a high level shutdown valve disposed within the main containment chamber, wherein the high level shutdown valve comprises a fluid sensor and a switch operative to stop inflow into the tank, or signal an alarm or both.