USRE2675E - Henry watekman - Google Patents

Description

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IMPROVEMENT IN- SAFIITYrVALVES.

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TO ALL WIIOM IT MAY CNCERN: n,

le it known that I, HENRY WATERMAN', of Hudson, in the county of Columbia, in the State of. New York,

vhave invented a new and useful Improvement on the SafetyfValve for Steam-Generators; and I do` hereby declare that the following is asfull, clear, and exact description of the construction and operation of the same, reference being had to the annexed drawings, making a part of this specification, in whichi A represents a vertical section of part of the boiler.- y l' B represents a vertical section of the valve.

C, the ordinary lever.

D, thc weight.

E, the rod upon which the weight is suspended.

F, the piston attachcd'to the rod E.'v

G, the cylinder in which the piston F moves freely.

H is a stand, by means of which the cylinder is attached to the 'boiler or other permanent support.

I I I I represent the Huid in .the cylinder Griwhich covers the piston F. I

k k represent thc overhanging part of the valve, which increases its urea outside of and Abeyond the ground joint. p Y ll l represent a concentric rixn or ledge that directs the steam upwards against the overhanging part k k, by means of which the valve is assisted in rising. v

In the ordinary safety-valve of steam-generators, it has long been known that there existed a strong inclination or attraction between the valve and the-seat, other than that produced by the super-incumbent weight or force; or, in other words, when the valve is loaded, so that steam shall commence to escupe from the generator at a given density or pressure of the steam, it requires a greatly increased forcel against the valve to raise it to a distance from the seat that will allow any-'near approach vto the full capacity of the valve for effecting 'the escape of steam. Thisis true when the superincumbent force is constant, as in the case when .a weight is used; it is still more forcibly felt when the super-incumbent force is aspx-ing, as is the case in all locomotive engines, furthe reason that the force -ot' the spring increases as it is moved. I construct the safty-valve of steam-generators so that the aforementioned disposition shallbecounteracted, and its evil effects entirely. prevented, I desirctc use a weight, whenever it is possible, for 'the1 reason thatthe force duel to its gravity is constant. The weight is generally .used'wth the generatorsoi' stationary and steamboat engines. In the ca se of locomotive engines, however, their jolting, when in motion,vcauses the valve (when a. weight is used) to jump up from its seat before the steam has attained suiieient density or prcssurevto raise it. To counteract this Iolting, jumping tendency, I attach'to the weight a piston, working in a liquid dash-pot. This will only prevent thejolting tendency, however. Another contrivanee is necessary to counteract the disposition of the valve to stick or be attracted to the seat. For this purpose I construct the valve and seat so that the escaping steam shall act upon an increased arca of the valve after it has raised from its seat, or, in other words, so that, when thevalvehas raised from itsseat, the escaping steam is so directed that its force strikes an overhangingv or projecting annular surface on the top of thc valve, and outside of and beyond the ground-joint. Thus, in the drawing, 'c k-indicatcs this overhangingor projecting annular surface, while l l indicates a concentric rim or ledgel so constructed as to turn the force of the escaping steam against c Ic. This force may be moditied by a. proper modification of the ovcrhanging or projecting annular surface; thus, if thc overhanging surface be large, the .force of thc-steam will suddenly open 'alle valve and discharge s`o much steam that the pressure inthe generator will be considerably reduced beforc the valve closes. This overhanging surface 7c k may, however, be made so small `that but little more than the surplus steam actually generated will escape. In either case,

besides overcoming the sticking or attraction of the valvcfto the scat, this most desirable 'object will be attained, v

to wit: the steam pressure in the generator will not risc a particle abovethe initial point of escaping. The peculiarity of this form of valve is this, that while it prevents the steam from rising above the initial point of blowing, the valve will romain open until the pressure is reduced below the initial point of blowing before it will be allow-ed to close, the success or etiieiency of it must 'depend upon a proper proportion of the parts c k and l l; thus, if'thosc parts arc of large proportion and -the steam allowed a. free discharge between them, it

will not at all assist the valve iii-rising. Agai'm'if they are made'too large and the escape between `them be too small, it will cause the valve to `rise too y,easily and remain' open too long, so that the steam will be so much reduced in pressure as seriously to impair their economical and eilcient condition. It has been found, in practice, for instance,'that in :caseef a safety-valve, such as is usually used in the locomotive engines, of ab :india half inches indiameter, with' a pressure of steam about onehundred and thirty pounds per square' inch, if the 4ove'rhanging part kvk is made of a diameterof about one-sixth of an inch, on each side, larger than the valve'proper, and thepledge or rim ZZ is-made of' a diameter about one-sixteenth, on each side, larger`- than out two tnk, so as to leave an opening ofabout onensixteenth of an inchin space between the parts c L" and ZZ, and the part-'k c is made to sink down into the cavity formed by the parts ZZ about one-sixteen`th of an inch, the valve will rise, and willdischarge the steam lfreely, until `the pressure isrednced` about three pounds perinch below the initial point of blowing,lwhich I consider a most desirableand eliicient operation g-these being the'proportions when the pressure is used of .different density, until a small margin of difference is obtained between' the opening point of pres-sure and the closing. Thus it will be seen that when it is ascertained that the generator, has sullicient strength to bear with perfect safety a given load or pressure, the use of this-valve will not allow the pressure to exceed that point, when the valve has been gauged to said point. Boiler explosions, caused by excessive pressure, will therefore be entirely prevented, and boiler leakage, caused by great variations of pressure and temperature, will also be prevented. v Y

The-operation of this `contri-Vance is as follows: Asbefore stated, I prefer, in order to attain a most perfect actionrto use as a superincumbent force a weight which will put upon the valve a steady, uniform force, which'will not increase as it is raised; and tocounteract any'jolting tendency, I use the piston I", working in the cylinder G, immersed in theI I I I. It is evident that the piston cannot move in the cylinder without i r'e uirin the iiuid to ass from one side of the iston to the other. I make the iiston suicientl small so q g P P l .Y 1

that it will not only move without touching the'l sides of` the cylinder, `but will allow the fluid to pass slowly, yet freely; Thus it will be seenthat the Apiston will move slowly to its proper position, avoiding any sudden Amotioncaused .by jar orjolting. Then when the steam has been raised yto a point that, by its-pressure upon the the parts Z Z must also besuch, as to form a suiicient retardment of the escaping steam, or

lower side of that portieri of the valve within the area of the opening through the seat, it is enabled to raise the superincumbent weight, it will allow thesteam to escape.' This escaping steam is then, by the concentric rim or ledge Z l, directed upward-'against the enlarged area of the valve made by the over-hanging part 7c, the comparative sizeof which must be such, and the size of' the orifice made by the approach of the parts 7c c and just suiciently to raise the valve and counteract the sticking tendency of the valve before mentioned, for, as before mentioned,

when the'valve is assisted too much by the improper proportion of. these parts, the valve will stay open too i long, the steam will escape until it will be too much reduced in pressurel This action will defeat the object I- have'in view, which is to keep the pressure of the steam aspnear as possible the initialpoint ot' blowin not allow it to goabove that, point, andnot to escape materially below it.

What I claim as my invention, and desire to secure by Letters Patent, is-

1. The piston F, attached to the weighted end of the valvc-lever, within the cylinder G, and immersed in the liquid in the cylindem-combined and operating in the manner and for the purpose hereindeseribed.

' 2. I also claim the concentric rim or ledge l Z and the overhanging part of" valvole k, constructed, com,- bined, and operating in the manner and for thepurpose herein settorth.

g, and

HEN RY WATE lili/l AN.

Witnesses:

Gnd W. RICHARDSON,

W. Poort.

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