US2973040A

US2973040A - Fire extinguisher

Info

Publication number: US2973040A
Application number: US606058A
Authority: US
Inventors: Kenneth B Covert
Original assignee: Safe Inc
Current assignee: Safe Inc
Priority date: 1956-08-24
Filing date: 1956-08-24
Publication date: 1961-02-28
Anticipated expiration: 1978-02-28

Description

Feb. 28, 1961 K. B. COVERT FIRE EXTINGUISHER Filed Aug. 24, 1956 gende/'Z551 E @dal/2f FIRE EXTINGUISHER Kenneth B. Covert, Marinette, Wis., assignor to Safe,

Incorporated, Marinette, Wis., a corporation of Wiscousin Filed Aug. 24, 1956, Ser. No. 606,058

Claims. (Cl. 169-31) rl'his invention relates to tire extinguishers and more particularly to a novel dry powder tire extinguishing composition adapted to be expelled from a pressurized container.

There has long been recognized in the re extinguishing industry the need for an improved, hand-sized dry powder-type fire extinguisher which is useful in homes, industrial locations, in the armed services and particularly in automobiles 4and other motor vehicles. Such a lire extinguisher should desirably be safe to use for many different types of lires in order that it attain a wide scope of use.

The National Board of Fire Underwriters has classilied incipient lires into three classes:

Class A fren-Those in ordinary combustible material where the quenching and cooling effects of quantities of water or solutions containing a large percentage of water are of primary importance.

Class B fires-Those in oils, greases, flammable liquids, etc., where the blanketing or smothering effect of the extinguishing agent is of greatest importance.

Class C fires-Those incipient tires in electrical equipment where the non-conducting property of the extinguishing agen-t is of prime importance. Dry powder chemical extinguishers are generally rated for classes B and C and will reduce a class A blaze to embers which can be easily controlled with Water.

The biggest problem facing users of dry powder chemicals for fire extinguishing has been the efficient application of the chemical to the fire area. In this regard both the range of the re extinguisher and the area or pattern which it covers are of prime importance. The range of the tire extinguisher should be sutcient so that the user need not approach the lire too closely and should be reasonably consistent and constant so that the stream of extinguisher will not overshoot or undershoot the lire area. The pattern of the re extinguisher stream is also most important for the reason that it is desirable to place as much as possible of the re extinguishing powder in the lire area.

To utilizer dry powder chemicals more effectively, attempts have been made to expel a liquid-like slurry of the powder in a propellant such as a Freon from a pressurized contaner. The thought behind this attempt was that, after the slurry was expelled from the contaner, the propellant would evaporate leaving a dry powder residue. This slurry was thought to be somewhat in the nature of an aerosol in which a liquid is expelled as an emulsion in a Freon propellant. After the latter evaporates, the liquid residue remains. When this theory was applied to powder-type iire extinguishers, however, it was found that, while a substantial amount of the powder was expelled and directed into the lire area, the lire extinguishing characteristics were poor and, in in fact, were no better than the characteristics obtained with the Freon propellant alone. It was found that the Freom generally about 90% of the total weight of the mixture, was not evaporating rapidly enough and fice was itself acting as the lire extinguishing agent. A further disadvantage in the slurry type of re extinguisher was that it required a substantial amount of shaking before it could be used because the wet powder had a tendency to cake in the can.

Propellants, such as carbon dioxide, nitrogen, etc., which are gases at room temperature and at the pressures permissible in the containers of the type referred to herein have also been employed. The results obtained with these propellants are unsatisfactory since there is a strong initial blast or rapid discharge which rapidly falls olf in intensity. As a result, a large part of the powder misses the fire area entirely and, more often than not, is not even expelled from the container.

it is an object of the present invention to provide a self-contained, single use, hand-size lire extinguisher which is efficient in its operation of projecting a large amount of a lire extinguishing powder into a tire area and with substantially complete discharge from the container.

Another object of the present invention is to provide a powder-type fire extinguisher which affords a smooth and steady discharge into a lire area, with a constant range and coverage pattern and without under-shooting or over-shooting the lire.

A further object of the present invention is to provide a powder-type tire extinguisher of the foregoing char: acteristics which is ready for use at all times without shaking or other preliminary treatment.

Still another object of the present invention is to pro-A vide a powder-type tire extinguisher of the foregoing type in which the powder in the container is not Wet and when expelled, is ready for use as an effective fire extinguishing agent,

Still a `further object of the present invention is to provide a powder-type fire extinguisher of the above type in which the most economical use of propellant isv made while substantially all of the powder is discharged.

Other objects and advantages of the present invention will become apparent from the following detailed description, taken in connection with the accompanying drawings wherein:

Figure l is a graphical representation of the relationship between the percentage of the -re extinguishing powder discharged from a container and the weight ratio of the amount of lire extinguishng powder to the amount of propellant.

Fig. 2 is an elevation view, partly in section, of a dry powder fire extinguisher and showing its valve in a normally closed position.

While the invention is susceptible of various modifications and alternative constructions, a certain illustrative embodiment will be described below in detail. It should be understood, however, that there is no intention to limit the invention to the specific form disclosed but, on the contrary, the intention is to cover all modifications, alternative constructions and equivalents falling within the spirit and scope of the invention as expressed in the appended claims.

ln accordance with the above objects of the present invention, it has been found that by employing a mixture comprising a powder of the type suitable for extinguishing vtires and a critical amount of dilluorodichloromethane (known by the trademark Breen-12), a volatile organic compound generally termed a propellant, that a highly efficient, improved lire extinguisher is produced. The two ingredients, mixed in critical proportions, are maintained in the container under a pressure such that the propellant is a saturated vapor at room temperature. There is, at the most, only a few droplets of liquid and substantially no wetting of the iire extinguishing powder. The mixed ingredients are confined at about the vapor pressure of the propellant, in a pressureftype container which is provided with a nozzle opening controlled by a suitable, manually operated single-shot valve. When the valve is opened the pressure in the container is released and the powder is carried or propelled outwardly throughY the nozzle in a continuous steady stream which may be directed at a tire area.

Forthe most satisfactory discharge of powder from a container of the above type, -an important relationship hasV been found to exist between the amount of dry powder and the amount of Freon-12 propellant. I havel found that if a given amount of powder is placed in a sealed container and an amount of Freon-IZ is added, so that the pressure resulting in the container is equal to the vapor pressure of Freon-l2 at room temperature and at the same time there is little or no wetting of the powder by the Freon-l that the most desirable conditions obtainfor eicient and effective discharge of the powder into a fire area when the extinguisher is used. The results of my discovery are presented in Fig. 2, which shows an empirical relationship between the percentage of the powder discharged from thecontainer and the weight ratio of the amount of powder to the amount of Freon-lZ propellant.

For example, in a can of the nominal 12 ounce size, having about 23 cubic inches of free space when empty, I employ about l2 ounces of dry powder such as sodium bicarbonate in iinely divided powder form. On this powder charge I add a charge of 14 grams of dichlorodiluoromethane known as Frech-12. 'This results in a pressure in the container of approximately 70 p.s.i. at about 70 F. No wetting of the powder is observed and, in fact, only one or two droplets of liquid Breen-l2 are observed to be present.

Upon discharging this composition by opening the single-shot valve on the container, I have found that I achieved a constant blast of powder having a range of about 8 feet, and covering an area of about 30 to 36 inches in diameter. Approximately 98% of the dry powder contents was discharged. This optimum amount of propellant added was found by placing the required amount of dry powder in a suitable container and adding the propellant. The propellant was added to the container of the powder until an amount was present which just indicated that there is a saturated gas in the container. It should be noted that I have attained a valuable added advantage of economy because I employ only a small amount of the most expensive ingredient, the propellant Freon-lZ. By adding less propellant than heretofore was thought to be necessary, I have not only achieved improved operation, but have substantially reduced the cost of the extinguisher. p

Through a series of experiments I have determined that a ratio of approximately 24 to 1 parts of powder per part of Freonl2 propellant results in a maximum discharge of about 98% of the powder from the container. Stated in another way, such a ratio provides a propellant weight equal to 4%% of the powder weight. In addition, the powder is expelled in a smooth, continuous stream lasting for about 5 to 7 seconds. This stream is coniined to a relatively small area and may be directed to a speciiic fire area for obtaining the maximum coverage and lire extinguishing elciency. The results of these experiments are presented in graphical form in Fig. l.

I have further determined, as shown in Fig. l, that the minimum desirable weight ratio is 18 parts of dry powder to one part of propellant (eg. 18 to 1). inversely restated, the propellant is by weight equal to 51/2% of the weight of the powder. Below this ratio the excess of propellant caused a substantial wetting of the powder with a resultant rapid drop-off in fire extinguishing eiciency. I have additionally determined that the maximum ratio should be about 40 parts of dry powder to one part of propellant (eg. 40 to l) and that above this ratio there was not enough propellant to discharge an economical amount of powder from the container. The percentage discharge obtained at the 40 to l ratio was approximately 70% of the contents in the container, as shown in Fig. 1. The propellant at this ratio equals 21/2% of the powder Weight.

When employing the optimum ratio of powder to propellant, namely 24 to l, I observed that during the initial discharge of powder, from about 8 feet away from the lire, that a minimum of 70% of the powder goes into the ire area without requiring the user to move towards the tire. On the other hand when gaseous propellants are used in similar proportions, such as carbon dioxide and nitrogen, I found that the initial blast tended to over-shoot the lire area under similar circumstances and that less than 50% of the initial blast fell into the area.

I prefer to confine my composition in a pressurized container 1G of the type shown in Fig. 2 of the drawing. The container shown comprises a can having a body portion 12 and a suitable attached concave bottom wall 13. An outlet valve 15 is desirably secured in an opening in the top Wall 16 of the can. Such a valve is described in more detail in Patent 2,785,838 issued March l0, 1957, on a co-pending application, Serial No. 462,639, filed October 18, 1954, and assigned to the assignee of the present invention. Briefly, this valve 15 comprises a dip tube 18 inserted and soldered into an aperture 19 in the can top 16 and extending in a gradually curved section towards one corner of the can.

A nozzle 20 is formed by the upper section of the dip tube which extends above the can top and isvbent over at an angle from the horizontal to alord a smooth, uninterrupted passage with no abrupt changes in direction or cross-section.` The valve 15 comprises a valve element 21 which seats on the lower end of the dip tube 1S and is held in place by the internal pressure in the can. The element 21 is actuated to the open position by a straight section of resilient wire or stem 22 disposed for most of its length within the dip tube 1S. The upper end of the stem is iitted through a bore 24 inthe external dip tube portion or nozzle 20. The upper end of the stem is preferably ilattened out in nailhead fashion or provided with a suitable pushbutton 25. A protective cap 26 covers the valve and nozzle to prevent lan accidental discharge. 'Ihis cap is removed just prior to using the extinguisher.

To operate the valve, the can is grasped in the users hand and the head of the stem is depressed. The axial motion transmitted through the stern wire forces the valve element out of the end of the tube and the resilient valve stem tends to straighten out and move the plug laterally so it cannot be reclosed. The can, when used with a composition having the ratios described according to the present invention and when held in about a 45 position, aords a maximum expulsion of the powder charge.

There has been described a new and useful novel tire extinguishing package which is eiiicient in its operation and adapted for extinguishing small tires by means of a dry powder chemical. With the high ratio of dry powder to Freon-lZ propellant used, substantially all of the chemical is discharged in a smooth stream to provide an eiiicient tire-fighting device. This improved' re extinguisher produces a smooth and steady discharge of dry powder ire extinguishing chemical affording an eiective fire fighting device. This result is due to the heretofore unknown critical relationship between the amounts of propellant and dry powder used as fully described above. My improved ire extinguisher is handy and small, being dimensioned for grasping in the hand of the user. Accordingly, it is portable and especially well adapted for use in automobiles where gasoline tires are most likely to occur. The container is also adapted for mounting in convenient and strategic locations in a house or other building so that it is ready for instant and dependable use when an Yemergency arises.I

aovaoso By using only a small amount of "Freon-12 propellant in comparison to the amount of re extinguishing powder, I have produced a powder type re extinguisher having a number of important advantages. In particular, my ire extinguisher is a highly eiiicient, single-shot, bomb-like package capable of producing a continuous smooth and steady discharge of substantially all of the container dry powder int-o a lire area. Because only a small amount of propellant is used, my fire extinguisher is quite inexpensive tomanufacture and can be sold at a low cost.

I claim as my invention:

1. A package comprising a pressure-type container having a valve-controlled opening charged with a lireextinguishing dry powder and a gaseous propellant conned in the container under the vaporpressure of the propellant, the powder being sodium bicarbonate and the propellant being dichlorodiuoromethane in an amount from about 21/2% to about 5%% of the powder by weight.

2. A package comprising a pressure-type container having a valve-controlled opening charged with a lireextinguishing dry powder and a gaseous propellant conined in the container under the vapor pressure of the propellant, the powder being sodium bicarbonate and the propellant being dichlorodifluoromethane, the weight ratio of the powder to the propellant being in the range of from about 18-1 to about 40-1.

3. A powder-type lire extinguisher comprising a sealed vessel with a valve-controlled opening charged with so'- dium bicarbonate in the form of a nely divided dry powder and gaseous dichlorodiuioromethane as a propellant the powder and the propellant being confined under the vapor pressure of the propellant and the propellant being in the vicinity of 4% of the powder dry weight.

4. A powder-type fire extinguisher comprising a sealed vessel with a valve-controlled opening charged with sodium bicarbonate in the form of a iinely divided dry powder and gaseous dichlorodiliuoromethane as a propellant, the powder and the propellant being confined under the vapor pressure of the propellant, and the weight ratio of the powder to the propellant being approximately 24-1.

5. A pressurized dry powder dispenser comprising a pressure-type container having a normally closed discharge orifice and charged with a finely divided dry powder and gaseous dichlorodiiiuoromethane, the powdea and the dichlorodiuoromethane being coniined under the vapor pressure of the latter with the amount of the dichlorodilluoromethane being from about 21/2 to about 51/2 of the powder by weight.

References Cited in the file of this patent UNITED STATES PATENTS 1,839,658 Dugas Jan. 5, 1932 2,021,981 Bichowsky Nov. 26, 1935 2,529,092 Lodes Nov. 7, 1950 2,559,634 Keefe et al. July 10, 1951 2,785,838 Mayer Mar. 19, 1957

Claims

1. A PACKAGE COMPRISING A PRESSURE-TYPE CONTAINER HAVING A VALVE-CONTROLLED OPENING CHARGED WITH A FIREEXTINGUISHING DRY POWDER AND A GASEOUS PROPELLANT CONFINED IN THE CONTAINER UNDER THE VAPOR PRESSURE OF THE PROPELLANT, THE POWDER BEING SODIUM BICARBONATE AND THE PROPELLANT BEING DICHLORODIFLUOROMETHANE IN AN AMOUNT FROM ABOUT 2 1/2% TO ABOUT 5 1/2% OF THE POWDER BY WEIGHT.