GB353107A - Improvements in safety valves - Google Patents

Abstract

353,107. Safety valves. COCKBURNS, Ltd. and MAcNICOLL, D., Clydesdale Engineering Works, Cardonald, near Glasgow. May 2, 1930, No. 13538. Addition to 313,751, [Class 135, Valves &c.]. [Class 135.] A safety-valve of the kind actuated by a leaky piston under the control of an auxiliary exhaust valve has the control pressure for the auxiliary valve taken from a point outside the zone of pressure-velocity transformation in the boiler. In the form shown in Fig. 2, the main valve 1 is coupled by a spindle 2 to a piston 8 working in a cylinder 4 formed in a cover 5, which also carries the auxiliary valve. The auxiliary valve 13 is loaded by a spring 19 and actuated by a piston 15 subject to boiler pressure admitted either through an external pipe connection 24 or through a passage 22 in the inlet branch extended to a remote point by a pipe 23. The main valve is loaded by a, spring 2<1> and is provided with an easing gear 20. In a modification the auxiliary valve is situated at a remote point, in which case a pipe connection replaces the passage 21. In a further modification the main valve member is formed directly on the actuating piston which works in a cylinder inserted. into the main casing. In the form shown in Fig. 6. the actuating piston 32 for the auxiliary valve 13 works in a chamber 33 formed in the main valve. The chamber 33 is connected by passages 34 with an annular chamber 35 fed with steam pressure through the control pipe 24. When the main valve is closed the chamber 35 is also connected to the main inlet 9 through an annular passage 35<1>, which passage is restricted by a lip 1<1> as the main valve opens. Specifications 122,581 and 132,811, [both in Class 135, Valves &o.], are referred to.