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.

Abstract: A pressure difference relief valve, viz. a pressure relief valve or a vacuum relief valve, for a liquid container has a valve body which opens or closes a valve opening of a valve housing in response to the pressure difference between the interior of the valve housing and the ambient atmosphere. The valve body is connected to a slidably mounted stem. The valve is constructed with spring elements which are clamped against the stem from opposite sides thereof at a controlled force to create a frictional resistance to sliding movement of the stem. Hereby any tendency of the valve to vacillate between the closed position and a fully open position under the influence of fluctuations of the gas or air flow, e.g. caused by turbulence, is eliminated or reduced.