US2506126A

US2506126A - Combined fire extinguishing and space ventilating device

Info

Publication number: US2506126A
Application number: US752658A
Authority: US
Inventors: Hilding V Williamson; James C Hesson
Original assignee: Cardox Corp
Current assignee: Cardox Corp
Priority date: 1947-06-05
Filing date: 1947-06-05
Publication date: 1950-05-02
Anticipated expiration: 1967-05-02

Description

y 9 0 H. v. WILLIAMSON ET AL 2,506,126

COMBINED FIRE EXTINGUISHING AND SPACE VENTILATING DEVICE 2 Sheets-Sheet 1 Filed June 5, 1947 hfamej 6170:1011

May 2, 1950 H. v. WILLIAMSON ET AL COMBINED FIRE EXTINGUISHING A SPACE VENTILATING DEVICE 2 Sheets-Sheet 2 Filed June 5, 1947 imyozt fildmy F Will "dJmes 617mm Patented May 2, 1950 UNITED STATES PATENT OFFICE 2,506,128 COMBINED FIRE Exrr GUrsmNo AND SPACE VENTILATING DEVICE Hildng V. Williamson and James C. Hesson, Chicago IlL, assignors to Cardox Corporation, Chi

ca'go, 111., a corporation of Illinois Application June 5,- 1947, serial No. 752,658

12 Claims. 1

This invention relates to new and useful improvements in a combined fire extinguishing and space ventilating device. In fighting fires burning in mines, tunnels, buildings used for industrial or residential pur-- poses, and the like, firemen are confronted with the principal problems of locating the fire under extremely adverse visibility and respiration conditions due to the presence of dense smoke; directly applying the extinguishing medium onto the exposed surfaces of the objects being con-' sumed by the fire; and introducing the extinguishing medium into inaccessible spaces or zones, such as hollow partitions, walls or floors, ventilating ducts, chimneys, or the like, in which the fires are burning. I

It is the primary object of this invention to provide a combined discharge device or nozzle assembly which, when attached to the end of a hose-line supplied with liquid carbon dioxide from a suitable source, can be employed for ventilating a room, tunnel, mine, or the like, to improve visibility and respiratory conditions for the firemen by displacing or exhausting the smoke and other gases; for directly applying the carbon dioxide to the exposed surfaces of combustible objects, or bodies of inflammable liquids; being consumed by the fire and to the exposed surfaces of surround ing objects or masses which have become overhead to effect extinguishment of the fire and to cool off all of said objects and masses to a temperature below the reignition temperature of the combustible objects and liquids; and for delivering the carbon dioxide to the interior of inaccessible spaces or zones to extinguish fires burning therein.-

A further object of the invention is the provision of a nozzle assembly which is operable to effect either the delivery of a mixture of carbon dioxide snow and vapor for direct application onto a fire, or the movement of a large volume of air, by means of a relatively small aspirating discharge of carbon dioxide, to bring about ventilatiofi of rooms, tunnels, mines or the like.

Still another object of the invention is to provide a discharge device which can be employed for extinguishing a fire burning in an inaccessible space, such as a hollow partition, wall, or floor, a ventilating duct, a chimney, or the like, either by delivering oarbon dioxide only to the interiorv of such a space to effect the complete extinguish- 2 exterior of the partition, wall, floor, etc; a large volume of air, that is propelled by a separate discharge of carbon dioxide, to assist in coolingthe involved combustible material to a temperature below its reignition point.

A still further object of the invention is the provision of a discharge nozzle which can be operated to effect the delivery of carbon dioxide at different rates. u

Other objects and advantages of the invention will be apparent during the course of the following description.

In the accompanying drawings forming a part of this specification and in which like numerals are employed for designating like parts throughout the same,

Figure 1 is a partly side elevational view and partly longitudinal sectional View of a combined fire extinguishing and space ventilating device that embodies this invention,

Figure 2 is a transverse sectional view taken on line 2--2 of Fig. 1,

D Figure 3 is atransverse sectional view taken on line 33 of Fig. 1. p

Figure dis a similar View to Fig. 1 but illustrates a modification of the invention,

Figure 5 is a transverse sectional view taken on line 5-5 ofFig. 4, and

Figure 6 is a transverse sectional view taken on line 6-5 of Fig. 4.

In the drawings, wherein for the purpose of illustration are shown the preferred embodiments of this invention, and first particularly referring to Figs. 1 to 3 inclusive, the reference character I designates a pipe-line that is adapted to b coiinected to a suitable source of supply of iquid earben dioxide by means of a flexible hose line. or the like, not shown. The pipe-line I is illustrated in Fig. 1 as being formed with two outlet ends or branches 8 and 9 which are arranged in parallelism at their outer end portions or extremities.

The outlet end or branch 8 is connected to the valve l0;- of conventional design, that is provided with a valve body operating stem ll projecting from the casing of the valve. The valve l0, preferably, is or the spring-seated disc type so that the vane Steffi Ii, normally, will occupy the position illustrated in Fig. 1 and the disc body will be seated to prevent new of carbon dioxide through the valve. A mounting arm or bracket l2 proiects laterally from the casing of the valve l0 and has pivotally connected to its'o'uter end the squeeze-grip operating lever l3. When 1; e free end portion of this lever is moved toward the pipe-line I, the valve It! will be opened to allow carbon dioxide to pass therethrough.

A pipe section It is connected to the outlet side of the valve In and is formed at its outer end portion with a nozzle tip l5. The bore of the pipe section l4 and tip I5 is of special design. That is to say, the bore is reduced in diameter to form the reduced orifice l6. Axially outwardly of this orifice, the bore is of conical shape, or flares outwardly, at IT. This bore construction is provided so that the carbon dioxide delivered to the bore of the pipe section will be maintained in its liquid phase, due to the back pressure developed by the reduced orifice [6 which will retain the carbon dioxide at a pressure in excess of '75 pounds per square inch, absolute. The liquid carbon dioxide, in passing through the restricted orifice I6 and the flared bore portion IT, will be permitted to expand to atmospheric pressure and will be converted to a mixture of snow and vapor. The snow and vapor mixture, of course, will be discharged from the outer open end of the nozzle tip l5 as a jet or stream of relatively high velocity.

Supported on the nozzle tip [5 by means of the four radialfins l8, see Figs. 1 and 3, is a tubular shield Hi. This shield is of cylindrical shape throughout the major portion of its length; is entirely open at its outer end 20, and is provided with an outwardly flared, open inner end 2|. By inspecting Fig. 1, it will be seen that the shield I9 is so mounted on the nozzle tip l5 that the tip is concentrically positioned in the flared inner end portion of the shield and will direct the discharged jet or stream of mixed carbon dioxide vapor and snow axially of the shield IQ for release from the open outer end 2|] of the shield. The discharge extremity of the nozzle tip [5 is intended to be so located with respect to the open, flared end 2| of the shield that the discharged, relatively high velocity, jet or stream of carbon dioxide will suck or aspirate a substantial volume of air from the surrounding atmosphere into the flared end of the shield for discharge through the outer end 20 with the carbon dioxide that is released from the nozzle tip IS.

The nozzle tip l5 and shield I9 should be so proportioned and arranged that approximately 50 volumes of air will be caused to travel through the shield IS for each volume of carbon dioxide that is released into the shield from the discharge end of the nozzle tip l5. When operated in this way, it will be apparent that the apparatus so far described can be very successfully employed for ventilating rooms, tunnels, mines, or the like, to dispel or displace, and often times to exhaust, the dense smoke that is almost always present in the vicinity of a fire. The apparatus, therefore, is extremely efficient as a portable device for displacing the dense smoke from the vicinity of a fire so that the operator of the apparatus can more readily locate the seat of the fire.

After the smoke, and other gases, have been displaced, to improve visibility and respiratory conditions for the firemen, the apparatus can be employed for applying only the carbon dioxide vapor and snow mixture directly on the fire by closing the inner, flared end 2| of the shield l9. When the inner end of the shield is closed, it will act as a horn for preventing entrainment of air by the snow and vapor mixture flowing through the bore of the shield. By the time the carbon dioxide snow and vapor mixture has reached the discharge end 20 of the shield l9, its

4 velocity will have been reduced to such an extent that very little if any air will be entrained from the surrounding atmosphere by the carbon dioxide discharged from the shield.

To enable the flared end 2| of the shield to be closed when desired, a disc or plate 22 is provided and is slidably mounted on the pipe section M by means of the sleeve 23. Fitted over this sleeve is a handle 24 that is formed of any suitable insulating material. This handle 24 is formed with a bead 25 at its inner end which is engageable by the latch 26 for restraining the handle, and its associated disc or plate 22, in the dotted line position illustrated in Fig. 1. When in this retracted position, the disc or plate 22 will not close the flared inner end 2| of the shield l9 and the apparatus can be employed to effect ventilation of a room, tunnel, mine, or the like. When the disc or plate 22, and its associated handle 24 and sleeve 23, are in the full line position of Fig. 1, no air will be drawn into the flared open end 2| of the shield and the apparatus will function as a fire extinguishing nozzle or discharge device by means of which a mixture of carbon dioxide snow and vapor can be directly applied to a fire. The low pressure, or partial vacuum, that will be established in the flared inner end portion of the shield, inwardly of the disc or plate 22, will function to tightly hold the periphery of the disc plate 2| in contact with the curved inner sligrface of the flared end portion 2| of the shield The outlet end or branch 9 of the pipe-line 1 has connected thereto a second valve 21 which is of the same construction as the previously described valve ID. This valve 21, therefore, has the projecting stem 28 that is operated b the squeeze-grip lever 29 pivotally mounted on the bracket or arm 3|] projecting laterally from the casing of the valve 21.

A discharge tube 32 of any desired length is connected to the discharge side of the valve 2'! and extends in close parallelism with the shield |9. Fins 33 and 34 are provided for inter-connecting the shield l9 and the tube 32 so that each one of these last two mentioned elements will brace and reinforce the other. It will be appreciated that if the shield l9 were not braced by the tube 30 it would not be strong enough to withstand the rough handling fire extinguishing apparatus normally is subjected to.

The outer end of the discharge tube 32 is closed by the pointed plug 35. Inwardly of this plug, the end portion of the tube 32 is provided with any desired number of laterally opening ports 36 through which carbon dioxide may be released to form a discharge of snow and vapor for fire extinguishing purposes.

Firemen very frequently are confronted with the problem of extinguishing a fire that is burning in inaccessible spaces or zones, such as hollow partitions, walls or floors, ventilating ducts, chimneys, or the like. When conventional discharge apparatus is employed in an endeavor to extinguish such an inaccessible fire, it is necessary for the firemen to chop a hole through the exposed side of the space or zone to permit the fire extinguishing medium to be introduced.

The sharpened end plug 35 of the tube 32 is employed for piercing the exposed side of the inaccessible space or zone in which the fire is burning so that the discharge ports 36 may be located in said space or zone. When so positioned, opening of the valve 21 will permit the carbon dioxide discharge of snow and vapor to be released into thespace or zone for efiecting extinguishment of the fire. V V

It will be appreciated by those experienced in the art that fires are extinguishable either by smothering the fire, so-that the combustible material being consumed will not be provided with sufiicient om gen to support combustion, or by cooling the combustible material so as to lower its temperature below the ignition point of the material. Fires burning in inaccessible spaces or zones, such as hollow partitions, walls, floors, or the like, usually are detected or indicated by the heating of the exposed sides of said spaces or zones. Consequently, the pointed end of the discharge tube 32 should be forced through the hottest part of the exposed side so that the discharged carbon dioxide will be delivered at the seat of the. fire.

It has been determined that extinguishment of a fire burning in hollow partitions, walls, or floors and ventilating ducts, chimneys, or the like, can be more readily and rapidly accomplished if a heat absorbing fluid is caused to flow over the exposed side of the inaccessible space or zone through which the pointed end of the discharge tube 32 has been forced. Therefore, while the discharge tube 32 is being employed for delivering fire extinguishing carbon dioxide to the interior of the inaccessible space or zone, the nozzle tip l5 and shield i9 may be employed for impinging a heat absorbing fluid against the exposed side of said space or zone. Ordinarily, the shield I9 will be employed for this purpose with its inner end left open so that the heat absorbing fluid will be air that is projected by the discharge of carbon dioxide from the nozzle tip !5. The temperature of the air that is expelled from the outer end of the shield 49, of course, will be lowcred substantially by its contact with the extreinely cold carbon dioxide that is discharged from the nozzle tip l5. However, if the fire has actually burnt through the exposed side of the inaccessible space or zone, the inner flared end 2| of the shield 59 may be closed by the plate or disc 22 so that nothing but a mixture of carbon dioxide snow and vapor will be discharged from the outer end 2B of the shield to effect extinguishment of the exposed fire.

The combined fire extinguishing and space ventilating device of Figs. 4 to 6 inclusive differs from the device of Figs. 1 to 3 inclusive only by the provision of a different form of valve, and its operating mechanism, for the nozzle tip so that the rate of discharge of carbon dioxide from this tip can be varied. Consequently, new refernce characters only will be applied to the elements that differ structurally from those already described in connection with Figs. 1 to 3 inclusive.

The supply pipe-line Ed has connected thereto the T-coupling 31 to which the outlet end or branch 8a and the outlet or branch 9a are connected.

A T-shaped casing 38 is connected to the outer end of the outlet or branch 8a. In one opening oi this casing 38 the pipe section 64a isconnected. The outer end of this pipe section is properly shaped to provide the nozzle tip 15a that is formed with a conical or flared bore portion Ila. A restricted orifice and tapered valve seat ifid, also, is formed in the bore of the nozzle tip Ica.

Associated with this orifice and seat [6a is a needle valve 38 that is carried by the long stem 49 which extends through the bore of the pipe sectionl la and the casing 38; Guide vanes M are formed on the stem 48 adjacent the needle valve 6 i 39 to support the needle valve at all times-concehtiically with-the valve seat and orifice Hid.

The remaining opening or the casing 38 has fastened therein the hollow plug 4'2 through which projects the outer end of the valve stem in. Packing material 43 is positioned in the bore of the plug 42 and is compressed by the packing nut 45 to prevent leakage of carbon dioxide around the valve stem #0. A stop pin 46 is passed through the valve stem 4B to provide a seat for one end of the compression spring '4'! that surrounds the valve stem 40 and bears at its other end against the inner face of the plug 42. It will be appreciated, therefore, that the spring 6'! and seat 46 will function normally to urge the needle valve 39 toward the cooperating surface of the combined orifice and valve seat I600.

The outer end of the valve stem 40 has connected thereto one arm of the squeeze-grip lever 48 which is employed for moving the needle valve to away from the valve seat and orifice ltd. This lever 48 is supported by a bracket arm 19 that is formed on the plug 42.

With this needle valve mechanism, it will be appreciated that the rate of discharge of carbon dioxide from the end of the nozzle tip lba may be varied to any extent desired by proper manipulation of the operating lever 48, and that discharge of the carbon dioxide may be stopped entirely by releasing the lever 48 and permitting the spring 41 to completely seat the needle valve 39. This control over the rate of discharge of the carbon dioxide from the nozzle tip 15a into the shield 99 is a very desirable feature because it permits different rates of flow of carbon dioxide to be employed for effecting the extinguishment of fires and for efiecting the ventilation of rooms, tunnels, mines, or the like.

In this assembly, the same plate or disc 22, and its supporting sleeve '23 and operating handle 24, are provided for controlling the flared open end 2! of the tubular shield l9.

All of the remaining elements of this combined discharge apparatus are the same as those described in connection with the embodiment of the invention illustrated in Figs. 1 to 3 inclusive and, for that reason, the same reference numerals will be applied thereto without repeating the description of the same.

It is to be understood that the apparatus shown in Figs. 4 to 6 inclusive will function in the same manner as the apparatus disclosed in Figs. 1 to 3 inclusive for extinguishing fires and ventilating such spaces as rooms, tunnels, mines or the like.

It is to be understood that the forms of this invention herewith shown and described are to be taken as preferred examples of the same, and that various'changes in the shape, size, and arrangement of parts may be resorted to without departing from the spirit of the invention of the scope of the subjoined claims.

Having thus described the invention, we claim:

1; A fire extinguishing and space ventilating device of the type described, comprising a pipe section adapted to be connected to a source of supply of liquid carbon dioxide, a nozzle tip on the end of the pipe section for releasing the carbon dioxide as a relatively high velocity jet, a tubular shield open at both ends, means for mounting the nozzle tip in the open inner end portion of the shield so as to direct its jet of carbon dioxide longitudinally of the shield'for discharge to the atmosphere from its open outer end, means for opening and closing the inner open end 01 the shield at the will of the operator,

and valve means for controlling the flow of carbon dioxide through the pipe section.

2. A fire extinguishing and space ventilating device of the type described, comprising a pipe section adapted to be connected to a source of supply of liquid carbon dioxide, a nozzle tip on the end of the pipe section for releasing the carbon dioxide as a relatively high velocity jet, a tubular shield open at both ends and having one open end flared outwardly, means for mounting the nozzle tip in the bore of the tubular shield adjacent its flared end portion so as to direct the jet of carbon dioxide longitudinally of the shield for discharge to the atmosphere from its remaining open end, a disc slidably mounted on the pipe section for movement into and out of a position for closing the flared open end of the shield, and valve means for controlling the flow of carbon dioxide through said pipe section.

3. A fire extinguishing and space ventilating device of the type described, comprising a pipe section adapted to be connected to a source of supply of liquid carbon dioxide, a nozzle tip on the end of the pipe section for releasing the carbon dioxide as a relatively high velocity jet, e, tubular shield open at both ends, means for mounting the nozzle tip concentrically in the open inner end portion of the shield so as to direct its jet of carbon dioxide axially of the shield for discharge to the atmosphere from the open outer end of the shield, a plate slidably mounted on the pipe section for movement into and out of a position for closing the inner open end of the shield, an insulated handle connected to the slidable plate for moving the latter, latch means for restraining movement of the plate when it is out of its position for closing the inner open end of the shield, and valve means for controlling the flow of carbon dioxide through said pipe section.

4. A fire extinguishing and space ventilating device of the type described, comprising a pipe section adapted to be connected to a source of supply of liquid carbon dioxide, a nozzle tip on the end of the pipe section for releasing the carbon dioxide as a relatively high velocity jet, a tubular shield open at both ends and having one of its open ends flared outwardly, means for mounting the nozzle tip concentrically in the bore of the tubular shield adjacent its flared end portion so as to direct its jet of carbon dioxide axially of the shield for discharge to theatmosphere from the remaining open end, a disc slidably mounted on the pipe section for movement into and out of a position for closing the flared open end of the shield, an insulated handle slidable along the pipe section with the said disc, means mounted on the pipe section and engageable with said handle for restraining movement of the disc when the latter is out of its position for closing the flared open end of the shield, and valve means for controlling the flow of carbon dioxide through said pipe section.

5. A fire extinguishing and space ventilating device of the type described, comprising a pipe section adapted to be connected to a source of supply of liquid carbon dioxide, a nozzle tip on the end of the pipe section fo releasing the carbon dioxide as a high velocity jet, a tubular shield open at both ends, means for mounting the nozzle tip concentrically in the open inner end portion of the shield so as to direct its jet of carbon dioxide axially of the shield for discharge to the atmosphere from its open outer end, a plate slidably mounted on the pipe section for movement into and out of a position for closing the inner open end of the shield, said nozzle tip having a tapered valve seat formed in its bore, a needle valve slidable in the bore of the pipe section and having a stem extending exteriorly of the pipe section, and a handle for manipulating the valve stem to adjust the needle valve relative to its seat to vary the rate of discharge of carbon dioxide from the nozzle tip.

6. A fire extinguishing and space ventilating device of the type described, comprising a pipe section adapted to be connected to a source of supply of liquid carbon dioxide,'a nozzle tip on the end of the pipe section for releasing the carbon dioxide as a relatively high velocity jet, a tubular shield open at both ends and having one of its open ends flared outwardly, means for mounting the nozzle tip concentrically in the bore of the tubular shield adjacent its flared end portion so as to direct its jet of carbon dioxide axially of the shield for discharge to the atmosphere from the remaining open end, a disc slidably mounted on the pipe section for movement into and out of a position for closing the flared open end of the shield, said nozzle tip having a tapered valve seat formed in its bore, a needle valve slidable in the bore of the pipe section and having a stem extending exteriorly of the pipe section, and a handle for manipulating the valve stem to adjust the needle valve relative to its seat to vary the rate of discharge of carbon dioxide from the nozzle tip.

7. A fire extinguishing and space ventilating device of the type described, comprising a pipeline adapted to be connected to a source of supply of liquid carbon dioxide and having two outlet branches, a manually operable valve connected to each branch outlet, a pipe section connected to one of said valves, a nozzle tip on the end of the pipe section for releasing carbon dioxide as a relatively high velocity jet, a tubular shield open at both ends, means for mounting the shield on the nozzle tip with the latter positioned concentrically in the open inner end portion of the shield 50 as to direct its jet of carbon dioxide axially of the shield for discharge to the atmosphere from its outer open end, a discharge tube connected to the remaining valve and arranged to extend in close parallelism with the tubular shield and to terminate beyond its outer open end, said tube having laterally opening carbon dioxide discharge ports formed in its outer end portion and having a pointed plug closing its outer end, and reinforcing means connecting the tubular shield to said discharge tube.

8. A fire extinguishing and space ventilating device of the type described, comprising a pipeline adapted to be connected to a source of supply of liquid carbon dioxide and having two outlet branches, a, manually operable valve connected to each one of said outlet branches, a pipe section connected to one of said valves, a nozzle tip on the end of the pipe section for releasing carbon dioxide as a relatively high velocity jet, a tubular shield upon at both ends, means for mounting the shield on the nozzle tip with the latter positioned concentrically in the open end portion of the shield so as to direct its jet of carbon dioxide axially of the shield for discharge to the atmosphere from its outer open end, a plate slidably mounted on the pipe section for movement into and out of aposition for closing the inner open end of the shield, a discharge tube connected to the remaining valve and arranged to extend in close parallelism with the tubular shield and to terminate beyond its outer tube.

open end, said tube having laterally opening carbon dioxide discharge ports formed in its outer end portion and having a pointed plug closing its outer end, and reinforcing means connecting the tubular shield to said discharge tube.

9. A fire extinguishing and space ventilating device of the type described, comprising a pipeline adapted to be connected to a source of supply of liquid carbon dioxide and having two outlet branches, a manually operable valve connected to each outlet branch, a pipe section connected to one of said valves, a nozzle tip on the end of the pipe section for releasing carbon dioxide as a relatively high velocity jet, a tubular shield open at both ends, means for mounting the shield on the nozzle tip with the latter positioned concentrically in the open inner end portion of the shield so as to direct its jet of carbon dioxide axially of the shield for discharge to the atmosphere from its outer open end, a

ischarge tube connected to the remaining valve, said tube having laterally opening carbon dioxide discharge ports formed in its outer end portion, and a pointed plug closing the outer end of the 10. A fire extinguishing and space ventilating device of the type described, comprising a pipeline adapted to be connected to a source of supply of liquid carbon dioxide and having two outlet branches, a pipe section connected to one of said outlet branches, a nozzle tip on the end of the pipe section for releasing carbon dioxide as a relatively high velocity jet, tubular shield open at both ends, means for mounting the nozzle tip concentrically in the open inner end portion of the shield so as to direct its jet of carbon dioxide axially of the shield for discharge to the atmosphere from its open outer end, a plate slidably mounted on the pipe section for movement into and out of a position for closing the inner open end of the shield, said nozzle tip having a tapered valve seat formed in its bore, a needle valve slidable in the bore of the pipe section and having a stem extending exteriorly of the pipe section, a handle for manipulating the valve stem to adjust the needle valve relative to its seat to vary the rate of discharge of carbon dioxide from the nozzle tip, a manually operable valve connected to the remaining outlet branch,

a discharge tube connected to the manually operable valve and arranged to extend in close parallelism with the tubular shield and to terminate beyond its outer open end, said tube haviii ing laterally opening carbon dioxide discharge ports formed its outer end portion and having a pointed plug closing its outer end, and reinforcing means connecting the tubular shield to said discharge tube.

11. A fire extinguishing and space ventilating device of the type described, comprising a pipeline adapted to be connected to a source of supply of liquid carbon dioxide and having two outlet branches, a pipe section connected to one of said branches, a nozzle tip on the end of the pipe section for releasing carbon dioxide as a relatively high velocity jet, a tubular shield open at both ends, means for mounting the shield on the nozzle tip with the latter positioned concentrically in the open inner end portion of the shield so as to direct its jet of carbon dioxide axially of the shield for discharge to the atmosphere from its outer open end, and a discharge tube connected to the remaining branch and arranged to extend in close parallelism with the tubular shield and to terminate beyond its outer end, said tube having laterally opening carbon dioxide discharge ports formed in its outer end portion and having a pointed plug closing its outer end.

12. A fire extinguishing and space ventilating device of the type described, comprising a pipe section adapted to be connected to a source of supply of liquid carbon dioxide, a nozzle tip on the end of the pipe section for releasing the carbon dioxide as a relatively high velocity jet, a tubular shield open at both ends, means for mounting the nozzle tip in the open inner end portion of the shield so as to allow air to enter said open inner end and so as to direct its jet of carbon dioxide longitudinally of the shield for discharge to the atmosphere from its open outer end, means in addition to the nozzle tip mounting means for opening and closing the inner open end of the,

shield, and valve means for controlling the flow of carbon dioxide through the pipe section.

HILDING V. WILLIAMSON. JAMES C. HESSON.

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

UNITED STATES PATENTS Number Name Date 7 2,130,745 Rosenbauer Sept. 20, 1938 2,216,071 Ensminger Sept. 24, 1940 2,411,231 Rundle Nov. 19, 1946