US2620090A - Safety device - Google Patents

Description

R. H. HILL SAFETY DEVICE Dec. 2, 1952 Filed Jan. 27, 1951 INI'EN'I'OR.

ROBERT H. HILL Patented Dec. 2, 1952 SAFETY DEVICE Rober'tH. Hill, El'gin, 111., assignorto The Marison. Company, Elgin llt, a corporation of. Illinois Application January 2'7, 1951, Serial No. $38,179

5 Claims. (01. 220-80) This invention relates to a safety device and more particularly to a device adapted for use with a metallic cylinder of the kind, in which a fluid under pressure may be transported and stored.

The safety device which has been used heretoforewith a cylinder of the aforesaid character has either been afforded by a frangible disc or by a fusible plug, theuse of the latter-being for the most part confined to cylinders in which a permanent gas such as oxygen is transported and stored. Each of these types of safety devices has inherent objections and neither has proven to be entirely satisfactory.

Thus, the frangible discs that have been em-- ployed heretofore usually have been machined to very clcse limits which, of course, is relatively expensive, but the principal objection to discs of this character has been that they are: subject to fatigueand eventual breakage, especially in those circumstances where a cylinder with which such adisc is used may from time to time be subjected to heat as for example by being. exposed to the sun during the day so that the cylinder may cool during the night. Such alternate heating and cooling (which may be effected in "other Ways) "resultsin a building up and a reduction of pressure in the cylinder, and, while the pressure may not reach that degree of pressure for which the discis set to release, it nevertheless subjects the disc to such pressure that fatigue and eventual breakage of the disc results.

Fusible plugs of the aforesaid character of course afford protection only in instances where the cylinder with which such a plug is used is subjected to heat since such a plug has been arranged to give way when the portion of the cylinder in which the plug is mounted has been subject to at least a predetermined temperature. This, therefore, does not afford protection in an instance Where excessive pressure is built up in the cylinder under circumstances such that the cylinder is not subjected to such a temperature as would cause the fusible plug to give way.

Experience has also shown that it is quite difficult to arrange either of the aforesaidtypes of safety devices in such a Way that the degree of pressure or temperature under which such a device is to let go may be accurately controlled and it has been observed that when a plurality of cylinders each including a safety disc of the frangible type, or a safety plug of the fusible type, have been subjected to identical circumstances of such a nature that release of the devices should beeffected, the safety devices associated with the respective cylinders; usually donot'release simpl taneously but rather that the devices release one at a time over a relatively prolonged period; It is, ofcourse, desirable that a safety device employed with thecylinder of the aforesaid character be of such nature that it will release under predetermined accurately ascertained circurn stances.

It is known that the moment of resistance or bending moment (hereinafterreferred to as, bending moment) of a column or strut (hereinafter referred to as a strut) maybe quite accurately determined and the primary object of this invention is to afforda safety device foruse with a cylinder of the aforesaid character and wherein thebending moment of astrut is the determinative factor for thereleased the safety device.

Other objects of the invention are to utilize, as a strut, a relatively short rod to maintain closed a pressure reliefvalve; to so mount such a rod that one of the supports therefor will be subjected to pressure within a fluid containing cylinder on which my novel safetydevice is mounted; to employ frangible sealing means in association with the strut embodying portions of my novel safety device so as to insure against seepage or other undesirable loss of fluid from within the tank; to so, arrange the elements or my novel safety device that in the event ofarelease thereof, the device may be quickly arranged for reuse by inserting a new strut therein; and to provide a safety device ofthe aforesaid cha acter that will be efiicient and accurate "use and which will be of simple and eeoho-m-icalconstruction.

Other and further'obj ects of the present inven tion will be apparent from the following desc-r-ip tion and claims and "are illustrated in the accompanying drawing which. by way of illustration, shows a preferred embodiment of the present vention andthe principles thereof and what I now consider to be the best mode in which have contemplated applying these principles. Otherembod-iments of the invention embodying the "same or equivalent principles may be used and structural changesmay be made as desired by those skilled inthe artwithout departing from the present invention and the purview cf the appended claims.

Fig. 1 is a view, partly inelevatic andpart'ly in section, showing a portion of a f containing cylinder and the usual outlet fixture associated therewith and on which outlet fixture my novel safetydevice is mounted; l

Fig. 2 is a longitudinal sectional view-of "my safety device as illustrated in Fig. 1, Fig. 2 being drawn to a larger scale than Fig. 1 and showing my safety device in the unreleased position thereof Fig. 3 is a fragmentary view similar to Fig. 2 showing my safety device in the released position thereof; and

Figs. 4, 5 and 6 are transverse sectional detail views taken substantially and respectively on the line 4-4, 5-5 and 66 of Fig. 2.

In the accompanying drawing I have shown a fragment of a fluid containing cylinder C of a conventional construction and having the conventional fitting F mounted in the outlet opening thereof. The fitting F includes a discharge passage H] which leads to the usual outlet ll, discharge through the outlet ll being controlled by a valve including the stem l2. An outlet passage [3 leads from the discharge passage I through a threaded boss I4 provided on the fitting F inwardly of the outlet ll. My novel safety device is adapted to be mounted on this threaded boss.

My safety device includes a body l5 having a tapped opening l6 extending inwardly from the larger end thereof and terminating in a shoulder IT. The tapped opening [6 is adapted to be securely fitted onto the threaded boss M, as best shown in Figs. 2 and 3, and a gasket la is interposed between an imperforate disc is, engaged with the shoulder l1, and the inner end of the boss I4 when the body I5 is properly mounted on the threaded boss l4, this gasket and disc affording a fluid tight seal to prevent undesirable escape of fluid from cylinder C through the passages I0 and I3. The disc I9 is frangible and may be made of a wide variety of materials. For example, the disc may be of lead or other frangible metal or may be made of a plastic material or even of paper of suitable thickness. The gasket is may also be lead or other suitable and somewhat yieldable material.

Rupture or shear of the disc [9 is prevented by the apparatus mounted in the head portion of the body [5. Thus a bore 2|, that communicates with passage l3, leads inwardly from the shoulder l1 and a recess 22 of reduced diameter is provided at the inner end of the bore whereby the shoulder 23 is afforded at the inner end of the bore. A piston 24 is mounted in the bore 2| to be reciprocal therein and normally, as shown in Fig. 2, the inner end of the piston 24 rests against the adjacent surface of the disc l9 to thereby reinforce the same and prevent rupture thereof so long as the pressure in the cylinder C does not exceed a predetermined degree. In order to maintain the piston in engagement with the disc IS a strut member 25 is provided which, in the present instance, is cylindrical in form and which has one end thereof mounted in a socket 26 in the inner face of the piston 24 while the other thereof is mounted in a socket 21 provided at the bottom of the recess 22. When the piston is disposed in engagement withthe disc l9 it closes off flow through the discharge passages 28 which lead from the bore 2| to the exterior of the body [5.

It is the strut 25 that is effective to maintain the piston 24 in engagement with the disc l9 and thereby prevent rupture or shear of the disc until a predetermined pressure has been built up in the cylinder C. When, however, the pressure in the cylinder attains a predetermined degree, then the force exerted through the disc 19 onto the piston 24 will be sufiicient to cause buckling or bending of the strut 25 and when the strut 25 so bends, the piston 24 moves away from the disc I9 which therefore shears and the piston is driven into engagement with the shoulder 23. This discloses the discharge passages 28 and thereupon fluid flowing from the cylinder 0 through the discharge passage [0 and outlet passage [3 enables pressure within the cylinder C to be relieved. Thus it will be seen that it is the bending moment of the strut 25 that controls the release of my novel safety device.

In the present instance the strut C is of cylindrical configuration and desirably the length of the strut is from four to ten times the diameter thereof. The strut as such is made from a metal such as copper or silver that is substantially free of impurities. In the present instance the strut 25 is formed of copper and is substantially .080 inch in diameter and substantially .625 inch in length. The diameter of the piston 24 is .3125 inch. Under such circumstances the bending moment of the strut 25 is such that release of my safety device will be effected when a pressure of 1800 pounds per square inch is attained in the cylinder C.

Once my safety device has released and the parts have assumed substantially the position shown in Fig. 3, my safety device may be removed from the threaded boss I4 and thereupon the bent strut 25 may be removed by first removing the piston 24. Thereafter a new strut 25 is arranged in the position of the strut 25 shown in the drawings and the body I5 is again fitted upon the threaded boss [4 with a gasket 58 and the disc 19 in the positions shown in Fig. .2 and, when the parts are properly positioned, the adjacent end of the piston 24 will be in contact with the disc I9.

It will be manifest from the foregoing description that I have provided a safety device which enables the hereinabove set forth and kindred objects of this invention to be realized and while I have illustrated and described a preferred embodiment of my invention, it is to be understood that this is capable of variation and modification, and I therefore do not wish to be limited to the precise details set forth, but desire to avail myself of such changes and alterations as fall within the purview of the following claims.

I claim:

1. A safety device of the kind described including a body having a piston reciprocally mounted therein and on one face of which the pressure of a confined fluid is adapted to be impressed, a collapsible strut in said body and engaged at right angles with the other face of said piston for preventing movement of the piston until at least a predetermined fluid pressure is impressed on said piston whereby collapse of said strut is eifected, and discharge means including an outlet port in said body disclosed upon movement of said piston after the collapse of said strut and through which discharge means the fluid may be released after the predetermined fluid pressure is impressed on said. piston.

2. A safety device of the kind described including a body having a bottomed bore therein which opens through one end thereof, a piston of a diameter corresponding to said bore mounted in said bore for movement therein and upon which the pressure of a confined fluid may be impressed, a collapsible one-piece strut disposed axially of the bore between the bottom of said bore and said piston for preventing movement of said piston until at least a predetermined fluid pressure is impressed on said piston whereby collapse of said strut is effected, and discharge means including an outlet port in said body disclosed upon movement of said piston after the collapse of said strut and through which discharge means the fluid may be released.

3. A safety device of the kind described including a body having a tapped opening extending thereinto from one end thereof and adapted to be mounted on a threaded boss having a passage therein adapted to communicate with a confined fluid, said body also having a bottomed bore extended thereinto from the inner end of said tapped opening, a piston mounted in said bore and upon which pressure of confined fluid communicated through said passage may be impressed, a collapsible one-piece strut in said body arranged axially of the bore between the bottom of the bore and the inner face of said piston for preventing movement of the piston until at least a predetermined fluid pressure is impressed thereon whereby collapse of said strut is effected, discharge means including an outlet port in said body disclosed upon movement of said piston after the collapse of said strut and through which discharge means the fluid may be released, the piston having a diameter corresponding to the diameter of said bore so as to be slidably engaged with the inner side walls of said bore.

4. A safety device of the kind described including a body having an opening extended thereinto from one end thereof, said body also having a bore extended thereinto from the inner end of said opening, said bore being smaller than said opening whereby a shoulder is afforded at the inner end of the opening and on which an imperforate frangible disc may be disposed to seal off said bore from said opening, a piston in said bore behind the disc and engageable with the disc to reinforce the same and on which the pressure of a confined fluid effective on said disc may be impressed, and a strut in said bore extending axially of and between the closed end of the bore and the inner face of said piston for preventing movement of the piston until at least a predetermined fluid pressure is impressed on said piston whereby collapse of said strut is effected, said body having a discharge port there-in communicating with said bore and adapted to be disclosed upon movement of said piston after the collapse of said strut and through which the confined fluid may escape following a rupture of said disc upon retraction of said piston from engagement with said disc after collapse of said strut, the piston having a diameter corresponding to the diameter of said bore so as to be slidably engaged with the inner side walls of said bore.

5. A safety device of the kind described including a body having a tapped opening extending thereinto from one end thereof, said body also having a bore extended thereinto from the inner end of said opening, said bore having one end closed and being smaller than said opening whereby a shoulder is afforded at the inner end of the opening, a threaded boss having a passage therein adapted to communicate with a confined fluid, said boss being extended into said tapped opening, an imperforate frangible disc disposed between said shoulder and the inner end of said bore when said body is securely mounted on said boss, said disc being eifective to seal off said bore from said passage, a piston in said bore having an outer face engageable with the disc to reinforce the same and on which outer face fluid pressure effective on said disc may be impressed, and a strut positioned axially in said bore and axially of said piston, one end of said strut being engaged with the inner face of the piston for preventing movement thereof until at least a predetermined fluid pressure is impressed on the piston whereby collapse of the strut is effected, said body having a discharge port therein communicating with said bore and disposed to be disclosed upon movement of said piston after collapse of the strut and through which the confined fluid may escape following a rupture of the disc upon retraction of said piston from engagement with the disc after collapse of the strut, the said strut being disposed centrally in said bore by means of sockets at the closed end of the bore and the inner face of the piston, respectively, in which sockets the ends of the strut are inserted, and the piston having a diameter corresponding to the diameter of said bore so as to be slidably engaged with the inner side walls of said bore.

ROBERT H. HILL.

REFERENCES CITED The following references are of record. in the flle of this patent:

UNITED STATES PATENTS Number Name Date 2,079,164 Glab May 4, 1937 2,263,840 Franck Nov. 25, 1941 2,353,254 McCandless July 11, 1944

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