Canadian engineer . arged per Minute Fig. 5.—Results of Tests on Inspector Type of PopSafety Valve. steam is forced to impinge directly upon it before beingdeflected downward toward the bottom of the chamber whereit reacts. The effect of the impact upon the lip of thevalve is increased by the expansive force of the steam actingin the lip chamber on account of the partial and momentary 594 THE CANADIAN ENGINEER Volume 22. confinement before it passes into the open air. Some-times openings are made through the lip or in the floor ofthe chamber, through which the steam escapes and so re-duces the
Canadian engineer . arged per Minute Fig. 5.—Results of Tests on Inspector Type of PopSafety Valve. steam is forced to impinge directly upon it before beingdeflected downward toward the bottom of the chamber whereit reacts. The effect of the impact upon the lip of thevalve is increased by the expansive force of the steam actingin the lip chamber on account of the partial and momentary 594 THE CANADIAN ENGINEER Volume 22. confinement before it passes into the open air. Some-times openings are made through the lip or in the floor ofthe chamber, through which the steam escapes and so re-duces the pressure within the lip chamber that the valvedisk will not lift too high. Annular valves have the additional area located at thecentre of the disk and within the outer seat. This area isexcluded from the action of the steam when the valve isclosed, by means of an inner seat, but is acted upon directlyby the steam when the valve opens. The disk is simply afiat cover for the valve base and has two concentric seats. Fig. 6.—Muffled Locomotive Pop Safety Valve asNow Made. in the same horizontal plane. The central area of the disk,which is not exposed to the steam when the valve is closed,covers a well which communicates to the outer air throughfour hollow arms radiating from itout through the sides ofthe valve body. When the valve opens, the steam is discharged directlyacross the outer flat seat, and there is also a separate addi-tional flow over the inner seat into the central well and outthrough the four hollow arms. The openings through thesearms are controlled by a sleeve, threaded on the valve body,so that it may be turned upward or downward as it should close the open ends of the hollow arms, pre-venting the escape of the steam through the central well,the reactionary eftect upon the disk to lift it against thespring would be greater than if the openings from the wellwere unobstructed; and by locating the sleeve at intermedi-ate points the lift of the valve c
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