US2413490A - Fixed temperature responsive device - Google Patents

Description

Dec.31 ,194 6. EVANS 2,413,490

FIXED TEMPERATURE RESPONSIVE DEVICE Originl Filed April 15, 1939 I FlG.'lg

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INVENTOR E C. EVANS ATTORNEY Patented Dec- ,31, me

mm 0. Evans, Dongan Hills, N. Y... mm a American District Telegraph Company, Jersey City, N. 3., a corporation of New Jersey Original application April 15, 1939, Serial No.

267,965. Divided and this application October 1 21, 1944, Serial No. 559,818

This invention relates generally to fire detecting systems of the fluid expansion type which are responsive to dangerous temperatures. ,The invention relates'more particularly to systems utilizing aero tubing for detecting dangerous rises in temperature and also includes attachments for detecting fixed temperatures regardless of the rate of rise thereof;

'This application is a division of my copending application, Serial No. 267,965, filed April 15, 1939,

- Patent No. 2,378,135 for "Fixed temperature responsive devices."

This type of system is sometimes required where abnormally high but safe temperatures occur, such as in factories where furnaces create high ambient temperatures which do not mean that a fire condition exists. This situation also arises in bakeries, forge shops and various other enclosures where local heat sources cause extreme changes of temperature. In these particular enclosures, the aero tube system operating on the rate-of-change principle may be used for detecting dangerous temperatures in a large part of the enclosure, but in local areas such as those around a furnace or even it is necessary to use a fire detecting device which operates at a fixed temperature regardless of the rate of rise thereof.

Fixed temperature detecting devices for use in connection with the aero tube systems have been suggested in the prior art, but they do not meet the requirements of a safe fire. detection system. In the first place, these attachments should not change the volume of the aero tube system to such an extent that the amount of area or number of enclosures which an acre tube as circuit can safely cover is reduced. If the attachments develop leaks or if they operate to detect a fire, they must not disable the system or change its operating characteristics to such an extent that a fire may occur without an alarm being given. Furthermore, the previous attachments suggested in the priorart have been of complicated structure and expensive to manufacture;

Accordingly, the principal object of this invention is to provide an attachment adapted for use in a rate-of-rise-of-temperature detecting system for actuating said system at a fixed temperature regardless of the rate of rise thereof.

A further object of this invention is to provide an attachment for an acre tube system which is adaptedto detect a fixed temperature regardless of its rate'of rise without affecting the rate-ofrise characteristics of said aero tube system.

Another object of this invention is to provide a 55 this formof protection ismore economical than 8 Claims. (01. m -sssi fixed temperature detecting device in an aero tube system which does not cause a leak in, or a ,change in the operating characteristics of, said system when a leak in the attachment occurs.

Still another object of this invention is to provide an improved fire. detecting attachment for use in aero tube systems which generates and re-' leases a pressure impulse at a fixed temperature regardless of the-rate of rise thereof.

A still further object of this invention is to pro vide a fire detecting attachment for aero tube systems which operates at a fixed temperature and which does not disable the aero tube system either when said attachment operates or when a-leak occurs in the attachment.

A still further object is to provide a fixed tem- I perature fire detecting attachment, which, after it has operated for a fixed temperature alarm, can still operate as a rate-of-rise element in the interim until the fixed temperature element is replaced. I

Another object of this invention is to provide a visible indication of operation of a fixed temperature attachment in anaero tube system.

A still further object of this invention is to simplify the construction of fixed temperature fiuid pressure generating devices for use in aero tube systems.

Further objects and advantages of this invention will be obvious to those skilled in the art from an inspection of the following specification and accompanying drawing, wherein:

Fig. 1 illustrates an acre-tube system including a cross-section of the preferred embodiment of a fixed temperature detecting device constructed in accordance with this invention:

Fig. 2 is a plan view of a modification of the detecting device shown in Fig. 1 with parts cut away to show other parts in section;

Fig. 3 is a plan view partly in section of am. other modification of this invention; v

Fig. 4 is a still further modification of this invention showing parts thereof in section; and

Fig. 5 is a still further modification of this invention showing parts thereof in section and embodying a different mode of operation.

As described above, this invention pertains to a fixed temperature detecting device for .use in or combined with aero-tube fire detecting systems and finds its greatest use in enclosures wheresudden or gradual extreme temperature changes occur .which might be dangerous under certain conditions but which are safe in the particular location, and also finds use in enclosures ,wnere the use of the aero-tube system. These conditions arise within enclosures such as factory buildings where furnacesor ovens cause extremely high and extremely sudden temperature changes.

avoided without jeopardizing fire protection orresponse to actual fire occurrence in the premises. I

This invention may also be applied where only a fixe'd temperature detecting system is desired by using aero-tubing for connecting a, number of detectors together and to a central point; In this type of system the aero-tube may be insulated or otherwise protected'from ambient temperature changes so that an alarm occurs at a fixed temperature regardless of the rate of rise,

thereof.

Fig. lof the drawing shows a fixedtemperature detecting device for use in aero-tube systems such as that shown by and for the same purpose as described in the patent to F. M. Cowan, No. 2,100,183. This device is connected to the conventional system and consists of a cylindrical heat-collecting member I having heat-collecting fins 2 thereon and supported from the ceiling or wall 4 of an enclosure by the supporting member t. The upper end of cylindrical member I is closed by a cover member I having a tubular extension 8, the purpose of which will be described later. The cover I is attached to the cylindrical member I by means of a clamping collar 9. This form of construction allows the is therefore most economical to construct.

A tubular member If] is supported on the cover if and within the tubular member 8 and has a collar II thereon which presses a thin sealing member, for example, .comprising a sheet of foil I 2, or its equivalent, against the lower extremities of tube 8 whereby a firm support is obtained.

The sealed chamber thus formed within the tubuthe cylinder member I by means of the solder 28 which is responsive to or melted at a given fixed temperature, while the other end of spring member I8.is attached to the element I by means of a suitable fastening means, such as a rivet, a welded joint, or by solder 2| which may be responsive to a fixed temperature which is higher than that to which the solder 20 responds. The spring I8 is aflixed at one end to the member detecting device to be built up of stampings and I by solder 2| and then deformed by attaching the other end to member I by solder 20. A puncturing spike 23 is attached to the spring I8 for the purpose of puncturing the foil I2 when solder 2G is melted in response to its critical temperature. Thus. when a dangerous temperature occurs, the air within the heat-collecting member I expands in response to the accumulated heat,

. thereby creating a pressure on the foil I2. When to be sounded.

the solder 20 releases one end of the sprin, member I8, it resumes its original shape and forces feature of the invention, since the operating characteristics of the aero-tube system as a whole are changed very slightly, if at all, when one or a considerable number of the fixed temperature attachments are connected in the aero-tube sys tem. It should further be noted that leaks in the outside heat collecting element I cannot affect the operating characteristics of the aero-tube circuit, since the foil I2 completely seals the aerotube circuit. Therefore, even though one or more of the fixed temperature attachments may have leaks therein, the entire aero-tube circuit is in its normal operating condition.

Fig. 2 illustrates an alternative method of releasing a pressure impulse fromthe cylindrical chamber I when the predetermined operating temperature melts the solder 20. The spring member l8 operates a mechanical linkage 28 which forces the valve member 32 against the spring 34 to allow the passage of a pressure impulse through the passage 36 and to the aero tube system in the same manner as illustrated in Fig. 1. Valve member 32 cooperates with a seat formed, interiorly of externally threaded tubular member 30, th upper end of which is threaded into an enlarged portion of a fitting 3|, the bore 36 of which communicates with a member similar to member I5 of Fig. 1. This form of releasing member presents the same advantages as those shown in Fig. 1 except for the added advantage that the valve structure can automatically reseal the air chamber after solder 2| is melted. Thus, the volume of the aero tube system is not increased by the operation of a detecting attachment.

Fig. 3 shows still another modification of the invention'having a slightly different structure in that a heat collecting member 4| is supported from the member 6 by means of a spider 40. Within the heat collecting member I there is supported the bimetallic heat sensitive disc 43 for operating the valve 32 in the same manner as that shown in Fig. 2. Disc 43 flexes at a predetermined temperature to force the valve 32 to an open position and release a pressure impulse. When the temperature falls to normal, the disc 43 automatically restores the valve 32 to its closed position so that manual restoration is not necessary.

'Fig. 4 shows a similar construction with the exception that the bi-metallic member 43 operates a puncturing device 23 which punctures the foil I2 to release accumulated pressure at a critical temperature within the chamber 4|.

Fig. 5 shows a form of the invention involving a means for mechanically creating a pressure pulse within the aero tube system. This mechanical operation is accomplished by utilizing a, bellows 45 supported within a framework 40 and operated by-a bi-metallic disc 41 supported on the adjustable stop member 48 and connected to the belvalve stem 49 of valve 5|, which is of the same type as the valves shown in Figs. 2 and 3. When a predetermined temperature occurs, the bimetallic disc fiexes and compresses the \bellows 45, thereby creating pressure which may be released by valve 5| into the aero tube system 5 to thereby cause an alarm. This device is also automatically restored to normal.

In the modifications illustrated in Figs. 1, 2 and 4 it is evident that the temperature responsive devices are capable of only one operation, since the foil of Figs. 1 and 4 and the spring l8 of Figs. 1 and 2 must be restored'to operative condition. In order to quickly locate the particular.detecting device which operated in response to a dangerous fire condition, a spot of wax is placed within the indentation 21 on the lower face of the cylindrical member I, see Figs. 1 and 2. The lower face of the cylindrical member I may be stamped with a star-shaped pattern or with any other pattern to provide small indentations such as 25 and 26 which communicate with the indentation 21. Thus, when a high temperature occurs, the wax normally located within the indentation 21 will fiow, through the indentations Z5 and 26 by capillary action and subsequently harden, thereby providing a visible indication of the inoperative condition of the particular detecting device which has operated to cause an alarm. This saves a practically complete repair of a large number of the detecting units within a given aero tube circuit in orderv to locate the operated detecting unit.

From the above description it is evident that the fixed temperature detecting device may be connected to an aero tube system of the conventional type without changing the operating characteristics thereof. In each of the modifications of this invention the heat collecting chamber is completely sealed from the remainder of the aero tube circuit whereby leaks in the attachment itself do not affect the operating characteristics of the entire system.

- a device carried by said member to contact and act positively on said closuremeans for unsealing said chamber to release accumulated heat-generated gas pressure upon the occurrence of a. predetermined temperature change regardless of the rate of rise thereof.

- 2. A fire detecting device comprising a chamber containing a gas which is responsive to tempera ture changes, a frangible. seal for sealing said chamber, a member within said chamber and having a part thereof effectively anchored relative to said chamber, said member being movable in response to heat and while so anchored, and a device carried by said member to contactand act positively on said seal for unsealing said chamber to release accumulated heat-generated gas said chamber.

' thereof.

pressure upon the occurrence of a predetermined temperature change regardless of the rate of rise 3. A fixed temperature fire detecting device comprising a heat collecting member having an outlet and enclosing a chamber, a closure within said chanrber for preventing the escape of gas from said chamber and means within said chamber adapted to open said closure comprising a bimetallic disc adapted to fiex upon the occurrence of a predetermined temperature to thereby allow the escape of accumulated heat-generated gas pressure.

4. A fixed temperature the detecting device comprising a heat collecting member having an outlet and enclosing a chamber, a valve within said chamber for closing the outlet of said chamber, and a'bi-metallic discwithin said chamber connected to said valve and adapted to flex upon the occurrence of a predetermined temperature to thereby open said valve and release the accumulated heat-generated gas pressure within A fixed temperature fire detecting device comprising a heat collecting member having an outlet and enclosing a chamber, a valve within said chamber for closing the outlet of said chamber and a thermostatic element within said chamber for operating said valve to open said outlet upon the occurrence of a. predetermined temperature.

create gas pressure therein.

7. A fixed temperature fire detecting device comprising a. heat collecting member defining a chamber having therein a; bellows enclosing a chamber containing a heat responsive gas and a thermostatic element within said chamber connected to said bellows for collapsing it at a predeterminedtemperature whereby gas pressure is generated within said chamber.

8. In a control arrangement for an abnormal temperature'p'rotective gas tube system remaining inactive upon a. gradual increase of the internal tube pressure operative to exert a protective action upon a sudden rise of said pressure, and having a. tube portion connected to said system and located adiacent to a space exposed to abnormal excessive temperatures, a gas discharge vessel containing a charge of normally noncondensible' gas, a valve including a valve member movable between an open and closed position for establishing and dis-establishing an intercommunicating passage between said vessel and said tube system, and thermostatic means controlling the operation of said valve so as to maintain said I vessel disconnected from the tube system and operative at a predetermined excessive tempera-' ture to open said valve for suddenly increasing I the pressure in said tube portion for actuatin said system, said thermostatic means being operative upon a predetermined reduction of temperature to recluse said valve.

FRANCIS C. EVANS.

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