US47869A - Improvement in safety-valves - Google Patents

Description

UNITED STATES PATENT OEEICE.

JOHN Y. SMITH, OF ALEXANDRIA, VIRGINIA.

IMPROVEMENT IN SAFETY VALVES.

Specification forming part of Letters Patent No. 47,869, dated May 2li, 1865.

To all whom, t may concern.-

Be it known that I, JOHN Y. SMITH, of Alexandria, in the county of Alexandria and State of Virginia, have invented certainnew and useful Improvements in Safety-Valves for SteanIGeiierators 5 and I hereby declare that the following, taken in connection with the accompanying drawings, is such full, clear, and

exact description as will enable others skilled in the art to make and use the same.

On locomotive-boilers and other steamgen erators the safety-valve mostly used consists of a cap fitting an opening` in the top of the boiler, which cap is' held down by means of a lever weighted or spring-balanced to the proper degree of pressure. The dangers attending the use of this safety-valve arise, first, from the fact, well known to engineers, that the cap becomes fast or, as it were, cemented into its seat as soon as the vibration attending the operation ofthe en gine ceases; second, from the fact that the safety-valve is under the control of engineers, who very frequently recklessly tamper with the valve so as to prevent it from blowing off steam when its pressure exceeds the calculated resistance of the boiler.

To obviate these evils is the object of my invention, and I have accomplished the same by construct-ing a safetyvalve in the following manner:

The principle which underlies my invention consists in the employment, in lieu of the cap, of a disk made of sheet metal or composition struck off or punched out by suitable dies or machinery. i. rIhis disk is of a resistance to pressure upon its surface equal to that which is calculated to be thelimit of pressure to which the boiler may be with safety exposed. The disk is inserted in the boiler, so as to be inaccessible to the engineer, by means of a skeleton valve, of which the disk forms apart, and which, together with the disk, operates like anordinary safety-valve. When 'the pressure in the boiler exceeds the limit of safety, then the disk will burst, allowing steam to escape through the skeletoirvalvc. v

The valve-case may be provided with a stopcock to shut oft' the steam after the bursting of the disk; but in order to prevent tampering on the part of the engineer I propose to com' bine with the disk a pendent rod which traverses the way in the cock, preventing it from or outsidethe valvecase, the rod abuttingV against the skeleton-valve or the outside lever to lift the valve when the temperature increases and exceeds that corresponding to the pressure of safety.

In the accompanying drawings, A is the valve-case, which may be screwed in or bolted over the opening of the boiler or steam-dome. It is here shown provided with a stop-cock, 13, for the purpose before mentioned. The upper end of the valve-case is formed into a conical seat, against which is fitted the valve composed of three parts, viz., first, a skeleton valve C, which consists of a valve-ring whose outer and lower face is made to fit the valve-seat, with downward-projecting wings fw, whereby the valve in its up-and-down play is securely guided, and an internal annular shoulder, a. Upon this shoulder rests secondly, a metal disk, D. This is composed of brass, iron, or

other suitable material, such as will break or l tear under a pressure exceeding that of calculated resistance. This metal disk is held in place by, thirdly, a skeleton cap, E--zZ c., a ring directly opposite the shoulder a, from which ring spring ribs terminating into the seat F of the pintle or fulcrum pin ofthe weighted or spring-balanced lever.

The operation of this contrivance, it will be understood, is precisely like that of any othercombine With the disk the rod It, which, traversing the aperture in the cock, prevents it from being shut off, which would defeat the object of my safety contrivance.

In Figure 2 I have shown the expansion device before referred to. It consists of a steel cage having in itscenter a brass rod,`s,

traversing a disk, L, which is properly screwedunder a pressure exceedingthat of safety.

2. The construction of the valve' of three parts, substantially as herein described7 and for the purposes set forth.

8. In combination with a safety-valve constructed and operating as described, the stopcock7 for the purpose set forth.

4. In combination with avvalve and valvecase provided with a stop-cock, as described, v

the pendent rod fast to the disk, substantially as set forth.

In testimony whereof I have signed my name to this specification before two subscribing Witnesses.

` J. Y. SMITH.

Witnesses A. POLLAK, Jos. L. CooMBs.

Images