Method and apparatus for preventing hazardous explosion of ammonium nitrate

摘要

A one-shot thermal fuse mounted directly on the casing of a centrifugal pump to prevent overheating and concentration of ammonium nitrate. The thermal fuse is screwed into a standard pipe coupling welded to a designated location on the pump casing. The thermal fuse has an electrical contact connected in the pump control circuit. A compressed spring is prevented from urging the electrical contact into an open position by a pellet of fusible material which is designed to melt at a desired threshold temperature below the temperature at which ammonium nitrate explodes. If the heat produced by the pump melts the pellet of fusible material, the spring is released, thereby opening the electrical contact and shutting off the pump. Alternatively, the temperature-sensitive element mounted on the pump casing can be a thermocouple or a temperature switch having a bimetallic element.