Description of an Improved Safety Valve for Steam Boilers

Abstract

Mr. Nasmyth gave a description of an improved safety valve for steam boilers, and referred to the calamitous boiler explosions which had been so frequent of late, and observed that, as a means of prevention, none was more efficient than a good safety valve. He proceeded to inquire what were the causes of the failure of the ordinary safety valve—wherein was it deficient? The function of a safety valve was to have some part of the boiler which would open and allow the steam to escape on a certain pressure being reached. This object was very simply attained by a valve of the ordinary construction, loaded either by a weight attached directly to the valve, or by a small weight increased in its efficiency by a system of levers. The ordinary safety valve (of which a model was shown) was liable to stick fast, owing to the muddy sediment of the water collecting round the spindle of the valve. In the common construction of valves the conical form was generally adopted. It was thus important that the internal and external cones should exactly coincide, and it was necessary to guide the spindle very correctly into the centre. This arrangement was subject to the inconvenience of the spindle sticking fast on the one hand, or if it were too slack, it would fail to perform its functions. It was highly probable that many accidents had arisen from the safety valve not having acted efficiently. His improved safety valve consisted in ...