US95382A - Improvement in safety-valves for steam-generators - Google Patents

Description

N. PETERS. PHGTO-LITHOGHAPMER, WASHINGTDN D C 'ilniid giedre gaat cum,

FERDINAND ROCHOW, NEW YORK, N.Y.

. Letters Patent No. 95,382, (lated lSqJtcmbcr 28', 1869.

IMPROVEMENT IN SAFETY-VALVES FOR STEAM-GENERATORS.

The Schedule referred to in these Letters Patent: and making part of the same.

To all whom it may concern f Be it known that I, FERDINAND RocHow, of the city, county, and State of New York, have invented an Improved Safety-Valve for Steam-Generators; and I do hereby declare that the following is a full, clear, and exact description thereof, which will enable those skilled inthe art to make and use the same, reference being had to the accompanying drawings, in which-v Figure 1 represent-sa vertical section through the centre of the valve, and the several parts connected, therewith. l

Figure 2 represents av plan or top view of a part of the enclosing-chest, showing the manner of attaching the lever It to the outer chest. l

Figure 3 represents a vertical section of the .valve-v box, with the valve and inner cap in elevation, in which is also shown a section of the upper part of a .stcain-generatorand steam dome,1to illustrate theapplication of the safety-valve.

In the accompanying drawings- A represents the valve-box, which consists of two concentric shells.

rlhe outer one, A, forms the valve-seat, and is fitted solid into a flange, M, which is bolted yto the boiler or to the steam-pipe. y

The inner one, A1, forms a hollow cylinder, which is either made to reach directly into the steam-room of the boiler, as shown in the dotted lines A2, or which, where this is not practicable, is closed. by a disk, B, screwed into or bolted to it, and connected by a' small separate pipe, O, with the interior of the steam-room of the boiler.

` Both these shells are connected together by a su'icient number of ribs C C. The outer cylinder A extends above the inner one,

and is so much greater in diameter than the inner one,

.las to leave an open passage, O, between them, as large .,as the area ofthe opening in the valve-seat, and through this passage the steam escapes, as indicated by the arrows, when the valve lifts off its seat.

'lhe valve is formed'cylindn'cal at its lower part D, where it is turned ofI" and furnished with a'sleeve, E, which is bolted tightly to it from underneath, through an annular hoiizontalange, by bolts a. This sleeve. is fitted so as to work easily in the cylindrical part A1 of the valve-box, so that this part of the valve acts like a piston within the inner cylinder A1. A

The connecting-neck D-of the valve is of diminished diameter, and made semi-spherical, so as to present the least possible resistance to the dow of the escaping steam; and is also furnished with three or four wings b b, by which the valve is guided in its seatand case. i

The valve D is kept on its seat by the pressure of the spring G acting on the Washer H', nuts J J, and stem K.

The spring is heid in 4irs place by a cap, L, the 1anter being screwed solid on to the valve-box A by an the cap, near the valveseat, to allow the steam to escape freely beneath the cap L. v

The stem K is guided at its upper end by the downward-projecting boss l, cast within the cap L, being bored out suiciently deep to allow the stem K to rise the desired height therein.

The washer H fits loosely on the stem K, and a feather, c, fastened into the washer, works in a corresponding groove in the stern, so that the stem cannot turn in the washer, while the lower end of said stem passes into a central opening'in thevalve, and is fitted y into a socket in the closed bottom of said valve.

'lhe operation of this valve is as-follows:

As long as the valve closes tight' on' its seat, the steam from the boiler will exert on it the following pressures:

First, in the upper part of the cylinder A1, (which cylinder -is of greater diameter than the opening in the valve-seat,) a downward pressure, due to the difference between the area of cylinder A l and of theopening in the valve-seat.

Second, in the lower part of the cylinder A1, an upward pressure, due to the full area of the cylinder A1. The difference of both, which is simply a pressuredue to the area of the opening in the valveseat, is, therefore, the total pressure on the valve, as long as it is on its seat. When the valve just commences to raise, the pressure of the spring, and of the steam on the valve, are just on anequilibrium. Practically, the spring is adjusted to exert the proper pressure on the valve, by screwing up the nuts VJ J so much that the valve will just commence lifting when the pressure in the boiler, which-is indicated by a steam-gauge, has reached its intended limit.

When the valve commences to liften its seat, and steamto blow on, the steam-pressure inthe upper part of Acylinder A1 will gradually diminish as the steam escapes more rapidly. There will also be a greater pressure against the arch d2, in the upward4 direction,

against which the escaping steam strikes, than againstn total increase of pressure of steam against the valve,-

in an upward direction from the point whenthe valve commenced to rise, as the pressure in the-lower part of the cylinder A1 is from that point constantly the same, whatever distance the valve may lift off its seat, viz, the pressure inside of the steam-boiler, itV not being, affected by the flow of the escaping steam.

The above-described increasing surplus of 4pressure in lifting the valve, has therefore to overcome the increased tension of the spring. But this surplus of pressure can be increased by giving the cylinder' A1 the proper diameter, because the additional annular area thus added to the cylinder A1 and piston D by means of the sleeve E, is always acted upon with the full boiler-pressure from below, while the pressure on top of it is decreasing with the rapidity of the escaping steam, or with the distance which the valve rises from its seat. i 4

Vhen the valve has been raised so high that the escaping steam has reached its maximum speed (which ought to be the height of lift of a perfect safety-valve) in the upper part of the inner cylinder A1, then the action of the steam in this part would remain unaltered on the valve, whether. it raised more cr not, and if there were any surplus of upward pressure left, the valve would not commence to come down on its seat again before there had blown offso much pressure in the boiler, that this surplus of pressure were reduced to nothing.

Thus, by giving the diameters of the inner cylinder A1, and the opening in the valve-seat of the outer cylinder A, the proper proportion, the valve lmay, first, be enabled to raise the required height, even against the increasing tension of a spring, relieving the boiler of an Vundue pressure in the shortest possible time; and, second, it may be enabled to keep open until the pressure of the boiler has fallen Vany desired amount below the pressure at which it commenced to raise.

A cylindrical lock-up chest, I), is screwed on to the right-augled flange M, in such manner that an inner rim, p, bears hard on to the valve-box A, and securely holds it in its place. This lock-up case covers the whole mechanism, and is furnished with a nozzle, Q, for the escape of the steam, opposite to which there is a partition, d, in the interior, cast across the opening, so that no meddling with the valve is possible through this nozzle.

There is, further, an opening in the lock-up case left between two eyes eve, cast on the outside of the chest P, and the latter is fitted with a screw-thread, so that when it is screwed down hard upon the fiange M, this opening is opposite one of the connecting-legs f on the cap L.

A forked lever, R, by which the valve may be raised from outside, in order to blow off steam, reaches through this opening into the chest, under the washer H, on each side of the nuts J J, the connecting-leg j' being made narrow enough to allow the fork of the lever 1t to embrace it.

A bolt, S, passing through the eyes e e and the lever R, makes its fulcrum, and connects it to the chest 1?, while a lip, h, is cast on the inside of the chest, under this lever, to support it and prevent its moving downward and bearing on the valve.

The cap L is screwed on to the valve-box Awth a left hand thread, V, and the chest I on to the flange M with right-hand 0r reverse thread W, so that when the lever It is secured in its place, it is impossible to nnscrew the chest P, as an effort to do so would cause the lever fitting over the leg f to screw the cap L harder on to the valve-box A, and thus the outer case and the inner cap are completely locked together.

An eye-splint, i, is put through the end of the bolt S, which extends outside of the eye c, and a lock put into the eye of this splint, so as to prevent the bolt from being withdrawn.

The application of the safety-valve to a boiler is represented in lig. 3 of the drawings, and it will be secu that a steam-pipe extends from the valve-box into the steam-dome. i

To this steam-pipe, I prefer to attach an umbrellalike shield or disk, somewhat below the opening in the dome, for the escape of the steam, so as to break or interrupt anycurrent of water which may be drawn up by the force of the escaping steam, when this should blow off too suddenly, and cause the water to fall back again into thc boiler. The arrows in this figure show the direction of the escaping steam when the valve lifts.

The sleeve E is necessary whenever the cylinder A1 is larger than the opening in the valve-seat, be-

canse, if the piston-part Dlof the valve were simply made larger, thevalve could ,not be got in, as it has to be putin from the top, through the opening in the seat, and the sleeve E afterward screwed to it from below. By making the sleeve E larger or smaller, any surplus of pressure can be obtained, as above described.

I have found that a valve may be' set to blow off, say at fifty pounds pressure, and that this pressure` can be increased to one hundred pounds before the valve will open as wide as it ought, the pressure under the valve being only fifty pounds when it is raised so much o its seat. I can proportion my valve so as to raise enough to give the whole area of the openings through all the passages, maintaining no higher pressure than as much as 'when it is started' to blow off'.

This safety-valve may also be weighted by a lever and weight, as represented in fig. 4. In this case the sleeve E is not necessary, as the weight does not iucrease with the height the lever lifts. The cylinder A1 need not, in this case, be made larger than the opening in the valve-seat, the sleeve E, by'which the increased diamctcr of the valve is effected, being only a necessity in combination with a spring-weighted valve. When the valve, therefore, is weighted by a spring, the removable sleeve is necessary, to increase the diameter of the valve.

Figure 4 shows the application of my invention to a safety-valve weighted by a lever, the valve-box A being airauged exactly as in fig. l, with the pistonpart D of valve I) rather smaller than the opening in the valve-seat, at least, not larger, so that there is no sleeve E required to put in from below.

The lever U is hung in a hinge, T, cast on the box A, and it has' sufficient upward movement to allow the valve to raise its intended height, as seen atl the dotted lines a n.

Figure 5 is a modification of fig. 1. Although the piston-part Dl of valve D is larger than the opening in the valve-seat, the disk B is done away with by the arrangement ofthe separate opening A2, which forms the valve-seat proper, and which is secured on box A by the cap L, when screwed down hard. In this, the valve D2 and piston-partD have to be made in two separate pieces, and the annular valve is 'screwed to the neck l) after the seat A2 is placed over the valve, as shown in dotted lines', or the piston-part Dl has to be made small enough'to slip through the valve-seat, and a sleeve secured to it afterward, analogous to sleeve E. By this modification, the valve may be readily withdrawn by. simply nnscrewing the ea'p L.

Having described my invention,

I claim-l- 1. A valve-box of a safety-valve, having an interior cylinder, A1, which is, at its upper end, in direct and unobstructed communication with the opening in the valve-seat D2, and, at its lower end, in permanent free communication with the interior of the boiler only, while the escape-opening, with which its upper end communicates, is also in free and unobstructed coin-y munication with the interior of theboiler, when the valve is made to form a piston, closed at its lower end, constructed and arranged substantially as before 'described.

2. The combination of the annular sleeve E with the cylindrical portion Dl of the valve, and the inner cylinder A1 of the .valve-box, substantially as before described.

3. The inner cap L, constructed with a left-hand screw-thread, V, and the enclosing-chest P with a right-.hand screw-thread, W, in combination with the forked lever R, whereby the said cap and chest are securely lockedtogether, substantiallyas before described.

4. The inner enclosingcap L, constructed with legs f f, and an annular screw-ring, L2, in combination with the lever R, constructed so as to embrace one ofthe said legs, thus constituting the lock, substantially as before described.

5. The inner cap L, for enclosing the spring Gi, and' the outer chest P, for enclosing said cap, constructed and arranged substantially as before described.

6. The inner cap L, for enclosing the spring G, constructed with a cylindrical hollow guide, l, projecting within the spring, so as to form a; guide for the spindle K, substantially as before described.

7 The guard d, arranged above the bottom of the' cap L, and with reference to the exterior of said cap, and the escape-pipe Q, so that, in connection with thc cap, a double protection is afforded to the adjustingdevices of the spring, substantially as before described.

8. The construction and arrangement of the chest P, forked lever R, bolt S, eye-splint fi, and flange M,

with the cap L, valve-box A, and valve D, constructed and arranged substantially as before described.

FERDINAND ROOHOW.

Witnesses:

ADoLrLnvINGnn, H. HEYMANN.

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