Abstract: A pressure relief valve includes a valve housing and a drop-shaped body with a conical valve surface that cooperates with a conical valve seat at an upwardly directed blow-off opening of the valve housing. The drop-shaped body is connected to a lifting disc in the housing. The inner configuration of the housing provides an annular passage around the lifting disc which is smaller in area when the lifting disc (and drop-shaped body) is in its uppermost, fully open positioning as compared to its lowermost, closed positioning.

Abstract: In a safety equipment for a tank having a system for collecting the gas expelled from the tank during loading, a pressure relief valve is connected in parallel to the gas collecting system of the tank. The pressure relief valve is constructed with a front chamber. The front chamber communicates with the blow off outlet of the pressure relief valve and is closed by means of a rupture disc and is connected to the interior of the pressure relief valve through a by-pass. The rupture disc is designed to burst at the maximum permissible tank pressure, thereby to protect the tank against explosion in case loading of the tank is accidentally started before connection has been properly established from the gas collection system of the tank either back to the storage tank of the loading station or to an authorized system for otherwise disposing of the gas.