US2098399A

US2098399A - Chemical manufacture

Info

Publication number: US2098399A
Application number: US52783A
Authority: US
Inventors: Horace D Munson
Original assignee: Mathieson Alkali Works Inc
Current assignee: Mathieson Alkali Works Inc
Priority date: 1935-12-04
Filing date: 1935-12-04
Publication date: 1937-11-09
Anticipated expiration: 1954-11-09

Description

Nov. 9, 1937. H. D. MUNSON CHEMICAL MANUFACTURE Filed Dec. 4, 1935 NTOR m9, Zm-ZM ATTORNEY @atented Nov. 9, i937 STATE earner entice Application December 4, N35, Serial No. 52,7188

8 Claims.

This invention relates to safety valves, such as are commonly employed in connection with vessels containing fluids under pressure, and is concerned more particularly with a device to be used in association with such a Valve to protect the working parts thereof against the action of corrosive fluids, which results in the sticking of the valve. The new protective device may be employed advantageously with safety valves of various kinds, and it is especially useful for the protection of valves employed on containers for corrosive fluidssuch as liquid chlorine. For pur- I poses of explanation, therefore, a form of the new protective device. suitable for use with a. safety 15 valve of the type employed on chlorine tank cars will be described in detail, but it is to be understood that the utility of the invention is not limited to its-use with the specific safety valve described, nor to the protection of such a'valve against the action of chlorine.

- a selected pressure, such as 225 pounds per square inch. There are a numberof dilferent commercial valves employed for the purpose; and in all these valves, the valve seat is exposed to the action of the chlorine, with the result that the 30 valve seat and disc become corroded and stick together and the valve does not release until pressures are generated much higher thanthose for which the valve has been set to operate.

For the purpose of overcoming these. diflicul- 35 ties, it has been proposed to seal the working parts of t e valve from the fluid, as by means of a diaphr gm backed up by a piston which is held in ace by a frangible copper disc. With such a c nstruction, the development of an excessive pressure in the vessel acts through the diaphragm and piston to shear or puncture the disc with the result that the fluid is then admitted to the valve and causes the latter to 45 open. This proposed expedient solves the dimfiuid upon the valve, but it has the objection that the pressure at which the valve opens is determined by the frangibility of the copper disc, and 50 it is dimcult to obtain discs which fracture uniformly and at the same desired pressure.

The present invention is, accordingly, directed to the provision of a safety valve protective device which overcomes the difllculties above re- 55 ferred to, this device keeping the corrosive fluid cuities resulting from the corrosive action of the (@i. geees) from contact with the valve until a predetermined pressure is generated, and then fracturing within a small variation from a selected pressure to per-- unit the valve to become effective to release the fluid. The device includes .a rupturable closure 5 for the passage through which the fluid is admitted to the working parts of the valve, and this closure, which may be a diaphragm of soft metal,

is exposed on one face to the fluid and is supported against rupture by means which include 10 a frangible member normally under tension. Upon the development in the vessel of the selected pressure, the strain placed upon the diaphragm is transmitted to the frangible member and causes the latter to break, whereupon the dlaphragm is ruptured and the fluid is admitted through the passage to, the disc of the safety valve.

For a better understanding of the invention, reference may be made to the accompanying drawing, in which:

Fig. 1 is a view in longitudinal section of a safety valve with the protective device in place; and

Fig. 2 is a sectional view on the line 2-2 of Fig. 1.

in the drawing, the device is illustrated in connection with a safety valve of large discharge capacity, this valve forming no part of the present invention. The valve includes a base it) with a flange it by which it may be mounted in registry with a suitable aperture in the vessel, and the base carries a housing l2 with a perforated cap 53 threaded thereon. Mounted at the upper end of the base is a cylindrical member is formed at its upper end to provide a valve seat i5 with which cooperates a valve disc to mounted in a member il sliding in a guide housing iia. Themember H is forced downward by a spring i8 acting through a headed rod E9, the head of which bears upon a plate 20, mounted in the member i'i. The pressure at which the valve opens depends on the compression of the spring l8, which can be adjusted as desired, and when a pressure in excess of the predetermined pressure is generated below the valve disc 86, the latter is forced upward from the seat in the usual way to permit escape of the fluid.

In order to protect the valve disc and seat fromthe action of the corrosive fluid, the passage. we in the base of the valve, through which the fluid passes from the vessel to the valve disc, is closed by a rupturable closure which is normally supported against rupture by means of 55 a flangible member under tension. When the pressure within the vessel exceeds a predetermined value, the ,flangible member breaks, permitting rupture of the closure, and the fluid thereupon enters the valve to bereleased by the latter. The means by which the passage for the admission of fluid to the valve is normally closed. include a plug 2| threaded into the base II at the end of the passage Illa. This plug has an Ope ing through it which is closed by a rupturable closure, preferably in the form of a lead disc clamped against a seat formed in the inner wall.

of the plug by a washer 23 held in place by a member 24 threaded into the plug against the seat. The member '24 is cup-shaped and it is of decreasing diameter from its lower open end to its upper closed end. The disc 22 is reinforced by a plate 25, the edge of which is turned to the same taper as that of the member 24-, the top of the plate being of substantially the same diameter as the inner diameter of'member 24 adjacent its upper end. The plate 25 is connected by a plurality of rods 26, passing through the upper. end of the cupshaped member 24 to a yoke 21. The yoke 21 is connected to the upper end of the cup-shaped member 24 by a frangible pin 28, which is of reduced diameter between its ends. This Din may be made of different materials, such as steel, copper, and the like, and it is so formed both with respect to material and dimensions that it will fracture when subjected to a selected tensile force.

Under normal working conditions, the diaphragm 22 closes the' lower end of the base of the safety valve, and thus prevents contact of the fluid under pressure with the working parts of the valve. Corrosion of the valve parts is thus prevented, and since the fluid does not enter the valve, minor leaks, resulting inthe case of tank cars from vibration, are avoided. Whenever a pressure develops within the tank or vessel in excess of the force at which the pinv 28 will break, the transmission of this pressure through the ductile diaphragm '22, the rods 26',

and the yoke 21 causes thepin 28 topart at the portion of reduced diameter. As soon as this occurs, the diaphragm ruptures and the central portion thereof with theplate 25 is forced upwardly and becomes wedged in the upper end of the cup 24 above the discharge openings 22. The compressed fluid now enters the base of the valve, contacts with the valve disc it, opens the valve, and escapes in the usual way. Because of the relative sizes of the plate 25 and the bore of the member 24, the escaping fluid can act to wedge the plate tightly in position above the.

openings 29, so that the plate will not obstruct the openings. Preferably, the breaking .pin 28 is selected so as to break at a pressure slightly less than that at which the safety valve releases,

device has the additional advantage of being relatively sensitive and uniform in operation, this advantage being obtained by the 'use of the breaking pin as the frangible element. Such .yoke to cause the frangible pins can be made so that the device will release within a variation of five (5) percent plus or minus of a selected pressure, and thus are not only much more sensitive and uniform in operation than the frangible discs heretofore proposed, but also cheaper.

I claim:-

1. A protective device for closing a passage against the flow of a fluid under pressure which comprises a rupturable diaphragm closing said passage and exposed on one face to said fluid,

and means normally out of contact with said ,sure to be released by said valve, comprising a rupturable diaphragm closing said passage and exposed on one face to said "fluid, and means for supporting said diaphragm against rupture including a plate contacting with the other face of said diaphragm, a hollow frame with a tapering inner bore, said plate beingmovable into said frame upon rupture of said diaphragm and having a tapering edge corresponding to the taper of said bore, and a frangible element operatively connected to said plate and frame, said element being normally under tension and preventing movement of said plate which would permit said diaphragm to be ruptured.

3. A protective device for closing a passage against the flow of a fluid under pressure which comprises a rupturable diaphragm closing said p s e and exposed on one face to said fluid, and means on the other side of said diaphragm and normally out of contact with said fluid for supporting said diaphragm, said means including a frame, a plate contacting with the face of the diaphragm not exposed to the fluid, a yoke; a frangible element connecting said frame and yoke, and means connecting said plate and yoke to cause the frangible element to be subjected to tension.

4. A protective device for closing a passage against the flow of a fluid under pressure which comprises a rupturable diaphragm closing said passage and exposed on one face to said fluid, and means on the other side of said diaphragm and normally out of contact with said fluid for supporting said diaphragm, said means including a frame mounted in said passage beyond the diaphragm and havingopenings through it, a

plate contacting with the face of the diaphragm not exposed to the fluid, a yoke beyond said frame, a frangible member connecting said yoke and frame, and means connecting said plate and element to be subjected to tension.

5. A protective device for closing a passage against the flow of'a fluid under pressure which comprises an annular seat extending circumferentiaily of said passage, 9, rupturable diaphragm having its periphery resting on said seat, said,

diaphragm closing said passage and being exposed on one face to said fluid, a frame engaging the other face of said diaphragm and holding normally out of contact with said fluid forsupporting said diaph agm, said means including a frame, a plate within the frame contacting with the face of the diaphragm not exposed to the fluid, a yoke beyond the end of the frame, a frangible element connecting the yoke and frame, and a member extending through said frame and connecting said plate and yoke to cause the frangible member to be subjected to tension.

7. A protective device for closing a eagainst the flow of a fluid under pressure which comprises a plug mounted 'in the wall of the passage and having an opening through it, a

rupturable diaphragm mounted in the opening through, said plug and closing said passage, said diaphragm being exposed on one face to said fluid, and means on the other side of said diaphragm and normally out of contact with said 5 fluid for supporting said-diaphra m, said means including a frame mounted in said plug, a plate contacting with the face of the diaphragmnot exposed to the fluid, a yoke, a frangible element connecting said yoke and frame, and means con- 10 necting said plate and yoke and causing the frangible member to be subjected to tension.

8. A protective device for closing a passage against the flow of a fluid under pressure which comprises a rupturable closure for said passage 15 having a face in contact with the fluid, and means normally out of contact with the fluid for supporting the closure against rupture, said means including a frangible member subjected to a pulling strain by thepressure of the fluid act- 20' ing through said closure.

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