The present invention relates to a temperature-sensitive safely valve assembly (10). The assembly (10) comprising a first region (16) for a first pressurised fluid, a second region (20) for a second pressurised fluid, a valve (26, 28, 27, 26a and 26b) between the first and second regions (16, 20) designed to be actuated by the pressure of a first pressurised fluid in the first region against biasing means (58) to open an outlet (54), for a first pressurised gas, from the first region, and heat-sensitive sealing means (34) on the second region (20), being de-scalable at high temperature to de-pressurize the second region, thereby actuating the valve (26, 28, 27, 26a, 26b) to close the outlet and seal the first region (16).