US3773044A

US3773044A - Chemical breathing apparatus with alarm device

Info

Publication number: US3773044A
Application number: US00122658A
Authority: US
Inventors: R Wallace
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-03-10
Filing date: 1971-03-10
Publication date: 1973-11-20
Anticipated expiration: 1990-11-20

Abstract

Chemical breathing apparatus for use by humans and adapted to supply life-sustaining gases to the respiratory tract of a human and having a canister carrying a chemical sorbent for treating the gases to be utilized by the human and an electrically actuated alarm device including means for measuring the resistance of the chemicals for giving a warning as to how much longer the chemical will be effective for treating gases and vapors in hazardous atmospheres.

Description

United States Patent 1 1 Wallace NOV. 20, 1973 CHEMICAL BREATHING APPARATUS WITH ALARM DEVICE [76] Inventor: Richard A. Wallace, 43 Kingscote Garden, Stanford, Calif. 94305 [22] Filed: Mar. 10, 1971 [21] Appl. No.: 122,658

[52] US. Cl 128/1416, 23/281, 55/275,

340/235 [51] Int. Cl. A62b 7/10 [58] Field of Search 128/1426, 203, 146.2,

[56] References Cited UNITED STATES PATENTS 3,403,981 10/1968 Lemcke 128/191 7/1964 Patrick 340/235 8/1965 Miller 128/1426 Primary Examiner-Richard A. Gaudet Assistant Examiner-G. F. Dunne Attorney-Flehr, Hohbach, Test, Albritton 8L Herbert 5 7 ABSTRACT Chemical breathing apparatus for use by humans and adapted to supply life-sustaining gases to the respiratory tract of a human and having a canister carrying a chemical sorbent for treating the gases to be utilized by the human and an electrically actuated alarm device including means for measuring the resistance of the chemicals for giving a warning as to how much longer the chemical will be effective for treating gases and vapors in hazardous atmospheres.

13 Claims, 10 Drawing Figures Patented Nov. 20, 1973 3,773,044

4 Sheets-Sheet 1-3 BREATHING TIME IN MINUTES F I g 4 INVENTOR Richard A. Wallace Patented Nov. 20, 1973 3,773,044

4 Sheets-Sheet 5 15/ INVENTOR.

Richard A. Wallace Attorneys Patented Nov. 20, 1973 3,773,044

4 Sheets-Sheet 4 INHALATION TIME IN MINUTES F i g I0 SWHO NI BONVLSISHU IVOIWBHO EXHALATION TIME IN MINUTES INVENTOR.

Richard A. Wallace z iforneys SWHO NI BQNVLSIS'HU 'IVOIWBHO CHEMICAL BREATHING APPARATUS WITH ALARM DEVICE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to chemical breathing apparatus with an electrically actuated safety alarm device and more particularly to such chemical breathing apparatus in which the electrically actuated alarm device measures the resistivity of at least one chemical sorbent being utilized to ascertain when its resistivity is greatly decreased upon the absorption of moisture or, alternatively, irritant gases and vapors sorbed by the chemical sorbents within the gas-filter apparatus.

2. Description of the Prior Art 7 Chemical breathing apparatus has heretofore been provided. There are two types of chemical breathing apparatus: (1) the chemical oxygen-generating apparatus known as the Chemox; and (2) the gas filter apparatus for protection against harmful and irritant gases and vapors in contaminated atmospheres.

The oxygen-generating Chemox breathing apparatus utilizes a dial mechanical timer preset by the wearer. Such an indicator has been found to be relatively unreliable because it merely gives an indication of the passage of time and does not show the effective condition of the chemical sorbent in the canister. In addition, it has been found that the ringing of a bell alarm by the dial-timer often cannot be heard over the noise in the encironment in which the breathing apparatus is being used. It, therefore, can be seen that such prior indicating and warning means have very undesirable disadvantages.

Certain gas filter breathing apparatus has been provided with a window indicator in the canister. Normally, in such a window indicator, two pieces of paper of different colors are located side-by-side in the window. One paper is treated chemically to change color as it absorbs moisture. When it has changed sufficiently in color to match the paper, this should indicate that the chemical sorbent or chemical sorbents have lost or will shortly lose their effectivness. In order to make a proper observation of the colors, it is necessary that the window indicator be observed in daylight. In addition, because of the position of the window indicator, it is very difficult, if not impossible, for the wearer to observe the indicator while the mask is being worn. There is, therefore, a need for a chemical breathing apparatus with new and improved alarm safety means.

SUMMARY OF THE INVENTION AND OBJECTS The chemical breathing apparatus is for use by humans and is adapted to supply life-sustaining gases to the respiratory tract of the human from a gaseous environment in which the human is present. The apparatus consists of a canister adapted to be carried by the human. The canister contains at least one chemical sorbent for sorbing and/or neutralizing gases entering the canister and which will react with the chemical sorbent or chemical sorbents to treat the gases so they are more suitable for use by a human. The chemical sorbent or chemical sorbents undergo a progressive change as additional gases pass through the chemical. A fact mask is adapted to make connection with the respiratory tract of the patient for supplying gases to the respiratory tract of the patient. Means is connected to the face mask and to the canister for supplying gases passing through the canister to the face mask. Electrically actuated safety means is provided for giving an indication as to approximately how much longer the chemical sorbent will be effective in sorbing and neutralizing the gases.

In general, it is an object of the present invention to provide a chemical breathing apparatus which has an electrically actuated safety alarm device for giving an indication as to how much longer the chemical sorbent will be effective in sorbing, neutralizing and/or treating gases to be utilized by the wearer.

Another object of the invention is to provide apparatus of the above character which gives a good indication of the remaining service life for the canister.

Another object of the invention is to provide apparatus of the above character which will light a lamp to give the warning or safety alarm.

Another object of the invention is to provide apparatus of the above character in which the lamp will remain energized for a substantial period of time after it is first energized.

Another object of the invention is to provide apparatus of the above character in which it is possible periodically to check or inspect the effectiveness of the apparatus in storage.

Another object of the invention is to provide apparatus of the above character which will tell the wearer quite accurately while being worn the remaining time during which the apparatus will be effective.

Another object of the invention is to provide apparatus of the above character in which there is given an indication which is a direct measure of the amount of remaining unused chemical sorbent in the apparatus.

Another object of the invention is to provide apparatus of the above character in which the alarm device is relatively inexpensive and can be easily manufactured.

Another object of the invention is to provide apparatus of the above character in which the alarm device is very reliable.

Another object of the invention is to provide an alarm device of the above character which can be adapted to apparatus already in the field.

Additional objects and features of the invention will appear from the following description in which the preferred embodiments are set forth in detail in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a front elevational view of a chemical oxygen-breathing apparatus with an electrically actuated alarm device incorporating the present invention.

FIG. 2 is a cross-sectional view taken along the line 22 of FIG. 1.

FIG. 3 is a circuit diagram of the electrically actuated alarm device utilized in the embodiment shown in FIGS. 1 and 2.

FIG. 4 is a graph showing the chemical resistance of the chemical sorbent utilized in a typical oxygen generating chemical breathing apparatus plotted against exhalation time in minutes.

FIG. 5 is a front elevational view of a fireman wearing a chemical gas-filter breathing apparatus with an electrically actuated alarm device incorporating another embodiment of the invention.

FIG. 6 is a cross-sectional view taken along the line 6-6 of FIG. 5.

FIG. 7 is a circuit diagram of the electrically actuated alarm device utilized in the embodiment shown in FIGS. and 6.

FIG. 8 is an isometric view in cross-section of a canister with another embodiment of the electrode means.

FIG. 9 is a graph showing the electrical resistance of a chemical sorbent in a typical gas-filter breathing apparatus plotted against exhalation time.

FIG. 10 is a graph showing the electrical resistance of a chemical sorbent in a typical gas-filter breathing apparatus plotted against inhalation time.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The chemical oxygen breathing apparatus with an electrically actuated alarm device is for use by humans and is adapted to supply lifesustaining gases to the respiratory tract of the human while the human is operating in a gaseous environment. The apparatus includes a canister 11 which consists of a shell 12 formed of a suitable material such as copper-plated steel. The shell 12 can be in the form of a deep-drawn receptacle or body 13 having a bottom open end which is closed by a bottom wall 14 that is secured to the body 13 by a seam 16. The receptacle or body 13 is provided with an open neck 17 at its upper end. An openended tube 18 extends downwardly into the shell 12 from the neck 18 as shown particularly in FIG. 2. The tube 18 is formed of a suitable material such as copper.

A suitable oxygen-evolving chemical sorbent 21 is provided within the shell 12. This chemical 21 fills most of the space within the shell 12 as also shown in FIG. 2. One chemical sorbent found to be particularly satisfactory is potassium superoxide. The lower portion of the chemical can be impregnated with a catalyst to speed the chemical reaction to generate oxygen.

A space 22 is provided beneath the chemical and at the bottom of the canister to permit circulation of the incoming breath through the chemical and to ensure minimum breathing resistance. Filters 23 are provided above and below the chemical and at the top and bottom of the canister to prevent tiny particles of the chemical from entering the breathing system of the human while the canister is being used. Yieldable means in the form of a spring 24 below the lower filter 23 urges the filter 23 upwardly to provide a space 25 below the lower filter 23 so that air passing through the tube 18 will be distributed over the entire exposed surface of the lower filter 23. When not in use, the canister is hermetically sealed to prevent air from coming into contact with the chemical sorbent within the canister.

The canister 11 is adapted to be inserted into a har ness assembly 26. The harness assembly 26 consists of a rigid backing plate or frame 27 that has an insulated canvas covering 28 mounted on the same which is open at the bottom end and which is adapted to receive the canister 11. The harness assembly also includes upper and lower straps 29 and 31 which are adapted to encircle the body of the human user to hold the frame 27 against the front of the body of the user. In addition, there is provided another strap 32 which is secured to opposite sides of the frame 27 as shown and which is adapted to pass over the shoulders and back of the neck of the user. A U-shaped bracket 33 is pivotally mounted upon the covering 28 and is adapted to swing below the covering 28 as shown in FIG. 1. A screw 34 is threaded into the bracket and is provided with a knob 36. A plate 37 is mounted on the screw 34 and is adapted to engage the bottom of the canister.

A plunger assembly 41 is mounted upon the canister holder or covering 28 and includes a spring-located plunger (not shown) mounted within a hollow housing. The plunger is in the form of a cylindrical tube with a cone-shaped tip that is adapted to pierce an exposed copper foil provided in the neck 17 of the canister when the canister 11 is thrust upwardly against it by the force of the screw 34 operated by the user. The tip of the plunger is perforated to allow the exhaled breath of the user to enter the canister. The plunger in the form of the cylindrical tube communicates with the tube 18 provided within the canister so that the exhaled breath of the user will pass through the canister as hereinafter described.

Means in the form of a face piece assembly 46 is adapted to make a connection with the respiratory tract of the patient or user. The face piece assembly consists of a face mask 47 formed of suitable material such as rubber which is adapted to fit over the face of the user and form an air-tight seal therewith. The mask is provided with a strap assembly 48 for securing the mask to the head of the user. The mask is provided with lens 49 to give the user visibility through the mask. The mask is fitted with a mouthpiece assembly 51 to permit the wearer to carry on a communication while wearing the face piece assembly 46. A manifold assembly 52 is also connected to the face piece assembly by a pair of tubes 53 and 54. An exhalation valve (not shown) is mounted in the lefthand side of the manifold assembly 52 and is adapted to establish communication with an exhalation breathing tube 56 that is connected to the plunger assembly 41 as shown in FIG. 1. The right-hand side of the manifold assembly 52 is provided with an inhalation valve assembly (not shown) which is adapted to establish communication with an inhalation breathing tube 57 that is connected to a breathing bag 58. The manifold assembly 52 is also provided with a relief valve (not shown).

The breathing bag 58 is in the form of an inverted U and is secured to the canister frame or backing plate 27. An inlet tube 59 is provided on the right-hand side or lobe of the breathing bag 58 and is in communcation with the inhalation breathing tube 57. An outlet tube 61 is provided in the other or left-hand side or lobe of the breathing bag and is in communication with the outer housing of the plunger assembly 41 and with the interior of the canister 11 as shown particularly in FIG. 1. A timer 62 is carried by the canister frame. The timer is actuated by twisting a pointer 63 clockwise as far as it will turn. This automatically sets a bell to ring after 45 to minutes as desired.

A name plate holder 65 is secured to the canister holder 28 and carries certain instructions.

The portion of the chemical breathing apparatus thus far described is conventional and is known under the trademark Chemox and is supplied by Mine Safety Appliances Company of Pittsburgh, Pa.

Means has been provided as a part of the chemical breathing apparatus in the form of electrically actuated alarm means for indicating approximately how much longer the apparatus will be effective in supplying treated life-sustaining gases to the respiratory tract of the user. Such means consists of a pair of

electrodes

66 and 67 in which the electrode 66 is in the form of a copper wire 68 which is covered with a layer 69 of a suitable insulating material. The copper rod or wire 68 can be of a suitable size such as 8 or 10 gauge. The insulation 69 for the copper wire can be of any suitable type which will withstand high temperatures. For example, the insulation can be formed of a polymer which will withstand temperatures of 100C. continuously. It is necessary that the insulation be able to withstand such a temperature because the chemical reaction which takes place during operation of the breathing apparatus is exothermic and generates a large amount of heat. The electrode 66 is positioned relatively precisely within the canister. In particular, it is positioned sufficiently far away from the side walls of the canister so that an appropriate resistance is developed between the two electrodes before the canister has been used. In addition, as hereinafter explained, the electrode 66 is positioned and has a length so it extends to a predetermined depth within the chemical sorbent 21. It can be readily appreciated that the greater the depth of penetration of the chemical by the electrode, the sooner the visual indicator will be energized. As can be seen from FIG. 2, the electrode 66 extends downwardly into the chemical 21 for a substantial distance and the tip of the same is free from insulation as shown in FIG. 2 and is exposed to the chemical sorbent.

The electrode 66 extends through an insulator 71 mounted in the top wall of the canister and is connected to a terminal 72. The other electrode 67 is the copper-plated canister itself. A connector 73 makes electrical contact with the copper plating on the canister and is connected to a terminal 74 for engaging the

terminals

72 and 74 and consists of snap-like connectors 76 which snap over the top of the

terminals

72 and 74 and which are carried by a flexible carrying ring 77. Wires 78 and 79 are connected to the connector 76 and form a part of a cable 81. One end of the cable 81 is connected to the socket 82 which carries a bayonet type lamp 83. The socket 82 with the lamp 83 are mounted in a bracket 84 which is secured to an alligator type clip 86. The clip 86 is adapted to clip onto any suitable part of the apparatus so that the lamp 83 can be readily viewed by the user of the apparatus. Thus, as shown in FIGS. 1 and 2, the clip 86 can be secured to the face mask 47 adjacent one of the lenses 49 so that when the lamp is lit, it will be readily noticed by the user of the apparatus. The other end of the cable is connected to snap-like connectors 87 also carried by a flexible ring or loop 88. The connectors 87 are adapted to be secured to the terminals 89 of a battery 91. The battery 91 is of a suitable type which is adapted for operating with the circuitry hereinafter described and for lighting the lamp 83. The battery 91 is removably secured in a spring-like bracket 92 which permits the battery to be readily inserted and removed. The bracket 92 is provided with a hook 93 which is adapted to hook over the plate 63.

A circuit diagram of an electrical circuitry is shown tus in conjunction with the electrically actuated alarm device may now be briefly described as follows. The chemical breathing apparatus can be donned by the user in a conventional manner. Thus, the

straps

29, 31 and 32 can be put in place. A canister 11 can be inserted in the canister holder 28 and punctured by the plunger assembly 41 as hereinbefore described. Normally, the electrically actuated alarm system is already mounted on the breathing apparatus. However, if not, it can be readily mounted on the chemical breathing apparatus by placing the battery 91 with its bracket 92 on the canister holder 28. The snap connectors 87 can be connected to the terminals of the battery and similarly the snap connectors 76 can be connected to the

electrodes

72 and 74. The lamp 83 can then be clipped in the desired position such as mounting the same on the mask 47 adjacent one of the eye pieces 49 or, alternatively, on the mouth-piece assembly 51.

The user is now in a position to don the face mask 47 whenever required as, for example, when entering a building which is on tire. The chemical breathing apparatus in this case is a self-generating oxygen breathing apparatus which operates independently of ambient air. The canister contains a chemical sorbent which upon contact with the moisture in the exhaled breath generates oxygen to meet the breathing requirements of the user and also absorbs exhaled carbon dioxide from the exhaled air of the user. In use of the breathing apparatus, the air travels in the path indicated by the arrows shown in FIG. 1. Thus, it passes downwardly through the exhalation tube 56 into the tube 18 and down and outwardly through the bottom of the tube into the space 25 where any increase in pressure is distributed uniformly, after which the air passes through the chemical 21 where the carbon dioxide is removed and the moisture in the air reacts with the chemical to generate oxygen.

Potassium superoxide is activated by moisture in the breath, liberates oxygen and produces potassium hydroxide which then reacts immediately with the carbon dioxide to form potassium bicarbonate. The gases passing through the canister thus have the carbon dioxide removed and have oxygen added which travels upwardly through the exterior of the housing of the plunger assembly 41, through the tube 61, into one lobe of the bag 58, after which it is distributed uniformly throughout the bag and enters the tube 59 and passes through the inhalation tube 57 into the inhalation valve assembly and then into the face piece 47, after which it enters the respiratory tract of the user through either the mouth or the nose of the user. The removal of carbon dioxide from the exhaled air and the generation of oxygen by the canister provides a supply of treated life-sustaining gases for the user from the recycled exhaled air. It can be appreciated that moisture from the exhaled air is absorbed by the chemical sorbent in the canister. The moisture is first absorbed by the bottom portion of the chemical and then the moisture travels upwardly as the bottom or lower portion of the chemical within the canister becomes saturated.

When the chemical within the canister has been approximately 2/3 to 3/4 utilized, the moisture from the exhaled air will begin to reach the electrode 68 which causes the chemical to serve as an electrolyte whereby electricity will begin to flow between the electrodek under the influence of the potential applied across the electrodes by the battery 91. When the chemicalsorbent 21 is dry, its resistance is very high as, for example, several million ohms. The resistance decreases as the amount of moisture in the chemical increases. The resistance also decreases as the moisture absorption takes place because of the increase in temperature of the chemical sorbent caused by heat generated by the exothermic heat of absorption reaction. A curve which is representative of the drop in resistance in the chemical sorbent, potassium superoxide, plotted against breathing time is shown in H6. 4. As can be seen from FIG. 4, the resistance drops relatively rapidly with time so that after approximately 25 minutes, a minimum resistance of slightly below 10,000 ohms is reached. At this point, the resistance is a minimum. Slightly above this lowermost point as determined by the parallel resistor 96, the current flow is sufficient to light the lamp 83. Once the lamp 83 is lit, it will remain lit for a substantial moisture period of time. It will be noted from the curve shown in FIG. 4 that after a period of time the resistance begins to increase gradually. It is believed that this is due, in part, to the fact that gradually more and more of the chemical sorbent has reacted with the moisture and also, in part to a decline in temperature of the potassium superoxide sorbent within the hot canister.

The user of the apparatus knows as soon as the light has come on that he only has a limited period of time left during which the chemical breathing apparatus will supply him with sufficient oxygen. This, therefore, gives a warning to the user that he has only a very limited period of time as, for example, minutes before he must leave the area. Within a very short period of time thereafter, the chemical breathing apparatus will fail because it will supply insufficient oxygen to support human life. In other words, the chemical will all be used up or reacted.

This electrically actuated alarm means can be the sole warning means or it can be supplemental to the mechanical timer alarm 62 which is provided with the chemical breathing apparatus. It can be appreciated that in tires where there is a great deal of smoke and a lack of light and also because of noise, a wearer of the chemical breathing apparatus may be unable to read or hear the timer type alarm 62. In addition, the timer 62 would not give an accurate indication of the amount of time that is actually left in the remaining chemical sorbent in the canister 11. The electrically actuated alarm means gives a much more accurate indication of the chemical sorbent remaining because the electrically actuated alarm means will not be operated until a predetermined portion of the chemical has been utilized as determined by the depth of the electrode 66. The wearer of the chemical breathing apparatus will imme diately become aware when the lamp 83 is lit because it is in front of the eye piece or lens 49. Thus, the user will receive an alarm even though he may be in an environment in which there is very little or no light and in which there is a great deal of noise. In the event that the wearer is overcome in such a situation, the lamp 83 will also indicate to rescuers the location of the user.

By way of example, in one embodiment of the apparatus, the resistor 96 had a value of 180,000 ohms. The lamp was an NE-6'7 neon bulb. The battery 91 had a suitable voltage output such as 67% volts. The adjustable resistor simulates the chemical sorbent 21 in the canister 11. it was found that when the resistance of the chemical 21 in the canister was reduced to approximately 19,000 ohms as set by the parallel resistor 96,

the lamp 83 was lit to give the indication of the impending exhaustion of the oxygen generation. As pointed out previously, the time required before the lamp will be lit can be adjusted by positioning of the electrode 66. In addition, it can be adjusted by the voltage on the battery 91 and it also can be changed by the value of the parallel resistance 96. As the parallel resistance is increased, the neon lamp 83 will be fired at a lower resistance and after a greater period of time. By way of example, when the resistance 96 had a value of 180,000 ohms, the lamp 83 fired at 12,000 ohms and had a period of use by the wearer of approximately 21 minutes. With this resistor, the light remained on after the canister was completely used up. When the resistance 96 was reduced to 120,000 ohms, the lamp fired at 8,000 ohms or after approximately 30 minutes of use by the wearer. The light remained on for a pierod of ap proximately 40 minutes.

It should be appreciated that other means than that shown can be utilized for connecting the battery to the lamp and to the electrodes.

Thus, it can be seen that the lamp 83 serves as electrically actuated alarm means which has many advantages over the mechanical timer type alarm 62 previously provided. It is relatively light and compact and merely requires the use of a power supply in the form of a battery and a pair of electrodes. Such alarm means is relatively simple and gives a very positive indication of the impending exhaustion of oxygen generation by the can ister. The alarm means can be readily removed from the apparatus if desired.

The pushbuttom 97 is provided for testing the electrical circuitry to be sure that it is operative before the wearer goes into a hazardous location.

Another embodiment of the chemical breathing apparatus is shown in FIGS. 5 and 6 and is typically called the Universal All-Service Model Type N which utilizes a filter type canister 101. This filter canister is generally a conventional type such as supplied by Mine Safety Appliances of Pittsburgh, Pa; by Wilson Products Div. of Electric Storage Battery, lnc., Reading, Pa.; and by Acme, Inc., Pittsburgh, Pa. The canister 101 consists of a drawn steel oval-shaped body 102 which has been copperplated. A bottom closure wall 103 is provided for closing the open end of the body 102 and is connected to the body 102 by a seam 104. A plurality of chemical sorbents are provided within the canister 10] and are arranged in layers in the canister 101. Thus, there is provided a large layer 106 formed of Hopcalite which acts as a catalyst to convert carbon monoxide to carbon dioxide by uniting the oxygen in the air to the carbon monoxide thus forming carbon dioxide which is a relatively harmless gas. The Hopcalite also has considerable absorbing powers for organic vapors and acid gases.

Screens

107 and 108 are provided above and below the Hopcalite layer 106. A suitable drying agent 109 is positioned immediately above the Hopcalite and is formed of a suitable material such as pure anhydrous calcium chloride and serves to prevent moisture from reaching the Hopcalite from the top side. Another screen 111 is provided above the drying agent 109 and a high efficiency filter 112 is provided above the screen 111. A molecular sieve 113, such as silica gel, is positioned below the screen 108 and serves as an absorber of ammonia and also as a drying agent to prevent moisture from reaching the Hopcalite. A screen 114 is provided below the molecular sieve 113.

A caustite layer 116 is provided below the screen 114 and is a soda lime which is a mixture of caustic soda (NaOI-I) plus lime [Ca(OI-I) A screen 117 is provided below the layer 116 and a layer 118 formed of activated charcoal is provided for absorbing organic vapors. A screen 119 is provided below the layer 118. An ultra high efficiency filter 120 is mounted in the bottom of the canister and is provided for filtering toxic dust, fumes, mist, fogs and smokes including radioactive particulates. The bottom closure member 108 is provided with an opening 121 which is sealed when the canister is not in use to permit outside ambient air to enter. A spring 122 is provided in the upper end of the canister for holding the chemical layers in position in the canister. The canister 101 is provided with a window indicator which warns the user when the canister is no longer effective against carbon monoxide.

The body 102 of the canister is provided with a neck 122 which is adapted to be connected to the lower end of a flexible breathing tube 123 by a coupling 124. The upper end of the tube 123 is connected to a face piece assembly 126 by a coupling 127. The face piece assembly is provided with a mouthpiece assembly 128. It is also provided with a lens 129 which provides panoramic vision to the user of the apparatus. The face piece is adapted to be secured to the head of the wearer by a strap assembly 131. A harness assembly 132 is provided for mounting the canister 101 on the front of the wearer and includes a strap 133 adapted to be secured about the waist of the wearer as shown in FIG. and a strap 134 adapted to extend over the shoulders of the wearer and behind the neck of the wearer.

The portion of the chemical breathing apparatus thus far described in conjunction with FIGS. 5 and 6 is conventional. However, with the present invention, electrically actuated alarm means is also provided for giving an indication as to how much longer the canister will be effective for treating the gases which are to be utilized by the wearer or user. Such means takes the form of a pair of electrodes in which one of the electrodes is in the form of a rod 141 that is mounted in the canister and extends downwardly into the chemical sorbents in the canister. The other electrode is the body 102 and the bottom closure 103 of the canister which is provided with a ground lug 142. The rod 141 is in the form of 8 or gauge copper wire 143 covered by a layer 144 of high temperature insulation of a suitable type such as a polymer. The rod 141 extends to a suitable depth within the chemicals and, as shown in FIG. 6, the insulation from the wire 143 is removed in two locations to expose two portions 143a and 143b of the wire 143. The bare portion 143a is in the drying layer 109 immediately above the Hopcalite layer and the portion 143b is disposed in the caustite layer. The rod 141 is mounted on a terminal 146 which extends through the top wall of the body 102 of the canister 101. A clip 147 is secured to the terminal 146 and another clip 148 is secured to the ground lug 142. The

clips

147 and 148 are connected by

wires

149 and 151 to a small power supply 170. The power supply 150 consists of a housing 152 which can be clipped to the harness assembly 132 as shown in FIG. 5. The printed circuit board 153 is mounted within the housing and is connected to a battery 154 carried by a clip 156 within the housing. The printed circuit board 153 and the battery 154 are connected by conductors 157 and 158 to a lamp socket 159 which is mounted upon a clip 161. A lamp 162 is mounted within the socket 159 and is of a suitable type such as a 6 volt incandescent lamp. The clip 161 is adapted to be secured in a location so that the lamp 162 can be readily viewed by the user of the apparatus. Thus, as shown in FIGS. 5 and 6, the clip has been secured to the brim of a helmet 164 so that the lamp is clearly visible to the wearer. It also should be readily apparent that the clip can be readily secured to other parts of the apparatus where it would still be readily visible to the wearer.

The circuit which is utilized for energizing the lamp 162 is shown in FIG. 7 and is mounted on the printed circuit board 153. The circuit includes a resistor 166 that represents the variable resistance of a chemical sorbent in the canister and a fixed resistor 167 having a predetermined value approximately 4 6 times as great as the resistance of the chemical sorbent to provide resistance ratios ranging from 4 to 1 to 6 to l. The junction between the two

resistors

166 and 167 is connected to the base of a transistor Q1. The emitter of the transistor Q1 is connected to the base of a transistor Q2. The collector of the transistor Q1 is connected to one side of the lamp 162 and to the collector of the transistor Q2. The emitter of the transistor Q2 is connected to one side of the resistance 167.

There is provided a pushbutton 171 in series with a fixed resistor 172 of a suitable value such as 5000 ohms which are in parallel with the resistance 166 representing the canister for testing the circuit to see whether or not the circuit is operative and also to ascertain whether or not the lamp 162 can be energized by the circuit.

Operation and use of the chemical breathing apparatus may now be briefly described as follows. The chemical breathing apparatus can be donned by the wearer in a conventional manner as shown in FIG. 2. The seals (not shown) are removed from the neck of the canister 101 as well as from the opening 121 in the bottom of the canister so that air can pass therethrough. The user can then press the pushbutton 171 to be sure that the circuit is operative. The clip 161 is secured at a convenient location and the face piece is then placed over the head of the user. The user is then in a position to enter the zone in which he desires to utilize the chemical breathing apparatus. During inhalation by the wearer of the apparatus, air enters the opening 121 in the bottom of the canister 101 and passes into the interior. The air is thoroughly purified, first by the filter 119, and through the various other layers of chemical sorbents in the canister, and then through the filter at the top, through the breathing tube 123 into the face piece, and thence into the respiratory tract of the user. The air in passing through the canister is thoroughly purified by the filters which remove the large particle size dust, fumes, mists, fogs and smoke. The layers of chemicals absorb or chemically neutralize harmful gases and vapors.

During exhalation, the air is expelled from the face piece through the exhalation valve 128 which, because of its location and design, permits conversation between the wearer and others. It also serves as a drain for moisture which may condense from the breath on the face piece. A check valve (not shown) fitted at the top of the canister prevents exhaled air from reentering the canister and being rebreathed.

The Hopcalite causes the carbon monoxide to oxidize to carbon dioxide by flameless combustion or catalysis. Thus, the canister will gen noticably hot in the presence of carbon monoxide, in proportion to the amount of gas passing through the canister. Generally, filter canisters of this type are for respiratory protection against a specific gas or group of gases which the canister is designed in areas where there is sufficient oxygen to sustain life 16 percent by volume) and where the total toxic gas concentration does not exceed 2 percent volume.

Some of the chemicals utilized in such filter canisters are particularly hygroscopic and rapidly become ineffective when they come in contact with moisture. The electrically actuated alarm system which iis provided as a part of the chemical breathing apparatus is provided for sensing accumulation of moisture in the canister. When the chemicals are dry, the resistance is very high. The moisture begins to penetrate the chemicals from the bottom and gradually moves upwardly in the chemicals as the chemicals on the bottom become saturated. At the time the moisture reaches the bottom exposed portion 1415b of the electrode 141, the resistance of the chemical will decrease very rapidly to permit operation of the battery-operated transistor switch transistors Q1 and Q2 and to energize lamp 162. The transistor Q1 can be of the 2N3565 NPN type. It is a small signal sili con, high gain transistor. The transistor Q2 can be TIP31A NPN silicon power transistor. The two transistors Q1 and Q2 act as a voltage operated switch. Whenever the control voltage across the resistor 167 sees the firing voltage of the transistor switch (approximately 1.4 volts), then the transistor switch turns on thereby allowing current to flow through the lamp 162. Thus, the decrease in chemical sorbent resistance 166 within the canister will tend to increase the voltage developed across the fixed resistor 167, thus turning on the lamp 162. The energization of the lamp 162 will first be seen as a red wire glow which will gradually be transformed to a bright light as the resistance is decreased between the portion 143a and the canister and the circuit is completed through the ground terminal 142. The energization of the lamp 162 will be immediately visible to the wearer and will warn him that he only may have a certain amount of effective time for the filter cansiter. This will indicate to him that he must plan to leave the area in sufficient time so that the canister will remain effective until he is able to reach a safe area.

An exposed portion 143a is also provided on the electrode 141 and is provided for the purpose in the event the wearer becomes sick to his stomach and vomits, or when the wearer erroneously attaches a different manufacturers breathing tube to another manufacturers canister, or for some reason moisture comes through the neck of the canister and starts penetrating the chemical sorbent from the top. As soon as moisture is absorbed by the chemicals, this will be detected by the exposed portion 143a and a circuit can be established through the chemical sorbent serving as an electrolyte to the side wall of the canister and to ground to activate the transistors Q1 and O2 to again energize the lamp 162. This again will warn the wearer that he only has a certain amount of time before the moisture will penetrate down to the Hopcalite and thus warns him that the canister will only be effective for a certain period of time so that he again must leave the area and be in a safe place before the breathing apparatus becomes ineffective.

By positioning the electrodes in the desired location in the chemical sorbent, it is possible to program into the electrically actuated alarm system a predetermined amount of time after which the breathing apparatus will no longer be effective. It is important to note that this electrically actuated alarm system is directly responsive to the work function which is placed on the apparatus by the user himself and thus gives a much more accurate indication as to how much longer the breathing apparatus will be effective in treating the gases. This is true because the harder the breathing apparatus is worked by the wearer, the more mosture as well as harmful gases will be brought into the canister filter.

In addition, the alarm device is very effective to give an accurate warning when the breathing apparatus is being utilized in a damp or steamy atmosphere. In such conditions, more moisture will be brought into the canister and the breathing apparatus will be effective for a shorter period of time. This will be indicated by the alarm device.

The types of construction which are shown in the previous embodiments are types in which the alarm device can be incorporated in existing breathing apparatus. This can be readily accomplished merely by inserting an electrode through the top wall of the canister and by making an appropriate ground connection.

When it is desired to incorporate the alarm device as a part of the breathing apparatus when the breathing apparatus is being manufactured, a construction of the type shown in FIG. 8 or FIG. 6 can be utilized.

In FIG. 8 there is shown another embodiment of the electrodes for use in electrically actuated alarm devices of the type shown in FIG. 6 and utilized with a canister generally of the type shown in FIG. 6. As shown therein, the terminal 146 is connected to an insulated wire 176 which is connected at 177 to an additional conducting screen 178 which is positioned in the middle of the layer 109 between the screens 107 and 111 and generally parallel to the same. Another wire 181 is connected to the wire 176 and is connected to another additional screen 182 at 183. The screen 182 is positioned in the middle of the layer 116 parallel to the

screens

114 and 117. It can be seen that the two conducting

screens

178 and 182 are disposed above and below the Hopcalite layer 106 and are connected in parallel to the terminal 146.

With this type of construction, it can be seen that the wires can be secured to the

additional screens

178 and 182 and the screens inserted during assembly of the canister at the manufacturing plant.

The operation of this embodiment of the invention is very similar to that hereinbefore described. The two

screens

178 and 182 connected in parallel serve as one of the electrodes, whereas the canister itself serves as the other electrode to which the grounding strap 142 is secured. The

screens

178 and 182 are positioned in such a manner that they are above and below the Hopcalite and, therefore, will detect the presence of moisture in the chemicals they are in contact with. Thus, the screens will sense the presence of moisture coming from either direction above or below the Hopcalite. When the resistivity of the chemicals in which the screens 178 and/or 182 is reduced sufficiently, the lamp 162 will light to indicate to the wearer that there is only a certain amount of effective time left in the filter canister.

With the construction shown in FIG. 8, it can be seen that very little cost will be added to the canister in providing the electrodes in the form of the

screens

178 and 182 and the connecting wires for the electrically actuated alarm means.

In FIGS. 9 and 10 are shown representative results which can be obtained with an electrode system of the type shown in FIG. 8. FIG. 9 shows the curve which was obtained utilizing a Mine Safety Appliances Model SW All-Service Filter Canister in which a copper mesh probe having a size of 1% inch by 2% inches was inserted in the middle of the anhydrous calcium chloride layer 109. During the test, the check valve which prevents exhaled air from reentering the canister was removed from the top of the canister. Continuous heavy exhalation by the user into the canister created the curve which is shown in FIG. 9. From the curve, it can be seen that the resistivity remained relatively high for approximately 40 minutes and then it dropped very sharply to approximately 10,000 ohms. This served to indicate that the moisture penetrated to the level of the screen which made the calcium chloride extremely conductive so that the resistance dropped. The resistivity remained at this level for a considerable period of time as can be seen from the curve and thus once the light was energized, it remained on. By the abruptness of the drop in the resistance, it can be seen that the screen electrode is very sensitive in sensing the penetration of moisture into the calcium chloride sorbent.

In another test of the invdntion which is shown in FIG. 10, the same type of canister as was used in FIG. 9 was utilized. The copper screen conductivity probe /z inch by 2% inches in size was inserted in the middle of the anhydrous soda lime (caustite) layer. In this case, exhaled air was introduced through the bottom of the canister by heavy breathing. It can be seen that the resistance remained very high for approximately 50 minutes and then dropped very sharply to slightly over 10,000 ohms again indicating that as soon as the moisture reached the screen conductivity probe, the conductivity was quite good and the circuit was operated to energize the lamp 162. As can be seen, the resistance thereafter remained relatively constant so that the lamp 162 remained energized.

It should be apparent that the resistivity values are dependent upon a number of factors, for example, the separation of the electrodes; the length and size of the electrode mesh are also important factors.

In any event, it can be seen that the electrically actuated alarm device is very effective as a safety device and gives a very accurate indication as to the remaining effective life of the canister. Repeatable results can be readily obtained so that the alarm device can be considered to be reliable.

The present invention is also useful in connection with gas filter canisters for sorbing acid and basic irritable gases such as acidic chlorine (C1 bromine (Br sulphur dioxide (S hydrogen sulphide (H hydrochloric acid (I-lCl), sulphuric acid (H 80 phosgene (COCI sulfuryl fluoride (SO F sulfuryl chloride (SO CI and basic ammonia (NI-i and organic amines. It has been found that the present invention is useful for such filter canisters because the chemical sorbents which are utilized have their values of electrical resistance decrease upon the absorption of moisture and/or upon the absorption of acidic or basic gases or vapors. The absorption of moisture is not absolutely essential since the electrical resistance will decrease with only absorption of acid or basic gases or vapors.

Thus, the same type of safety device as herein disclosed in conjunction with the previous embodiments can be utilized with such filter canisters to obtain the same mode of operation and to thereby provide an electrically actuated alarm device which is very effective as a safety device and gives a very accurate indicationas to the remaining effective life of the canister. Certain representative tests utilizing canisters of this type will be set forth below.

A Mine Safety Appliance Model GML canister, filled with chemical sorbents consisting of layers of soda lime and activated charcoal, was used for protection against irritable chlorine vapor. The electrode which was inserted into this canister had exposed portions in the two soda lime or caustite layers. Before use of the canister, it was found that the electrical resistance of the top soda lime layer was million ohms and the lower soda lime layer had a resistance of 6 million ohms. In testing such a canister in a 1 percent by volume of chlorine gas with a percent relative humidity at 250C, it was found that the electrical resistance of the bottom or lower soda lime layer progressively decreased. However, the resistance decreased quite slowly at first and then decreased much more rapidly so that after a period of approximately 22 minutes, the resistance was 80,000 ohms. After 33 minutes, the resistance was still further reduced to 24,000 ohms, and at 38 minutes, the resistance was reduced to 9000 ohms. The circuitry for the alarm device was such that the lamp was energized to give a warning of the type hereinbefore set forth. As pointed out above, the alarm device can be preset to any desired value of chemical resistance which would be proportional to the amount of advance warning required by the user.

Another canister which was tested was identified as a L .1 0 s s sts l q by. M ssiafs y An.

pliance under Model GMC and consists of a mixture of activated charcoal and soda lime. The electrode was inserted in this mixture which had an electrical resistance of 4 million ohms. After using the canister in a breathing chamber containing 1 percent by volume of chlorine and 65 percent relative humidity at 25C. for a period of 38 minutes, it was found that the electrical resistance began to drop markedly and after 54 minutes, the resistance had dropped to approximately 13,000 ohms which caused the lamp to be energized.

Another canister was the Mine Safety Appliance Model GMD-SS used for protection against ammonia gas and organic amines and fog. Silica gel was used as a chemical sorbent. The initial electrical resistance of the anhydrous silica gel was approximately 200 million ohms. On use of the canister in an atmosphere containing 2% percent by volume of ammonia in a relatively moist atmosphere having a relative humidity of percent at a temperature of 20C., the resistance decreased slightly for approximately 55 minutes.

As the moisture and ammonia gas progressed through the silica gel and reached the exposed portion of the electrode in the silica gel sorbent, the electrical resistance began to drop markedly. After approximately minutes, the electrical resistance dropped to about 340,000 ohms which caused the warning lamp to be energized.

Satisfactory operation of the warning device was also obtained using it with a rocket propellant canister such as the type GMN-SSW of Mine Safety Appliance Company. The rocket propellant canister affords protection against nitric acid, dimethyl hydrazine, hydrazine, and hydrogen peroxide. Each canister contains the following layers of chemical sorbents: a top layer of activated charcoal, a middle layer of silica gel, and a bottom layer of soda lime. This canister is equipped with a window indicator and is manufactured by Mine Safety Appliance Co.

The electrode rod (8 gauge) was inserted from the canister top into the soda lime layer. The polymer insu lation was removed from two portions of the electrode rod. The lower electrode portion was exposed to the soda lime layer over a length of three-fourths inch from its tip. The polymer insulation was also removed from the upper portion of this same electrode over a length of one inch and exposed to the silica gel layer. The electrical resistance of the soda lime layer was measured to be 100 million ohms and that of the silica gel layer was 500 million ohms.

A small breathing chamber containing a simulated rocket propellant atmosphere consisting of 1 percent (by volume) of nitric acid vapor, /2 percent hydrazine, and 0.05 percent aniline and having a relative humidity of 70 percent at C. was inhaled into the canister, equipped with our visual warning device, preset to a sorbent resistance warning value of 150,000 ohms. On continued inhalations, the electrical resistance of the soda-lime layer remained essentially unchanged for a period of about 20 minutes. Thereafter, as the vapors progressed throughout the soda-lime layer, the electrical resistance decreased. After minutes, the electrical resistance of the soda lime was 30 million ohms and that of the silica gel was still high at 300 million ohms. After a period of 50 minutes of inhalations, the resistance of the silica gel began to drop.

At the end of 120 minutes, the canister was approaching exhaustion in this gaseous chamber. The electrical resistance of the sodalime layer was about 150,000 ohms and that of the silica gel was about 1 10 million ohms. The visual alarm device was then activated, as determined by preset electrical resistance values in the chemical sorbent layer.

The above examples are representative of what results can be obtained with canisters of this type.

It should be appreciated that in connection with the foregoing invention that the chemical breathing apparatus can be checked while it is in storage. in particular, the condition of the chemical sorbents in the oxygen generating canisters and in the gas mask filter canisters can be checked merely by measuring the value of the electrical resistance between the electrodes. Assuming that the electrode has been inserted during manufacture, this test can be accomplished readily and easily so as to make sure that the canisters are all in good condition and ready for use by firemen and the like.

Although the present invention has been described primarily in connection with humans, it should be appreciated that, if desired, the same principles can be utilized for breathing apparatus for animals such as dogs and horses.

it is apparent from the foregoing that there has been provided a new and improved chemical breathing apparatus with an electrically actuated alarm device which is particularly adapted for use with various chemical type canisters for giving an indication as to when only a certain predetermined effective time remains for use of the canister. The alarm device will give an accurate indication even though the breathing apparatus may be used in steamy or water-saturated areas. The alarm device will still give an accurate indication even though the total effective life of the canister is greatly reduced because of the high concentration of moisture in the air which is introduced into the canister.

The warning device can be readily observed by the wearer and will give a true indication as to how much longer the canister will be effective for treating the gases introduced into the canister. it certainly is much more reliable than the color indicator which is difficult to read and certainly difficult to observe during the time that the canister is being worn. The alarm device is directly responsive to the amount of air which passes through the canister. The screens which are utilized make possible good contact with the chemical while still permitting the air to readily pass through the screen.

It should be appreciated that in the foregoing examples, the canister itself was utilized as one of the electrodes. it should be appreciated that if it is desired to not use the canister one of the electrodes, additional electrodes can be placed within the canister to serve this function. The alarm device can be utilized for checking the condition of the canister before it is used.

l claim:

1. In a chemical breathing apparatus with an electrically actuated alarm device for use by a human and adapted to supply life-sustaining gases to the respiratory tract of the human who is operating in a gaseous environment, a canister adapted to be carried by the human, said canister containing at least one chemical sorbent through which gases to be treated in the canister must pass, a face piece adapted to be placed over the face of the wearer and having communication with the respiratory tract of the wearer, means forming a fluid flow passage between the canister and the face piece so that treated gases which are treated by the canister can travel to the face piece to be utilized by the wearer, electrode means in contact with the chemical sorbent in the canister and being in the form of spaced apart electrodes, one of said electrodes being positioned only in the upper portion of the chemical sorbent so that the chemical sorbent disposed generally in the upper one-half portion of the canister presents a high resistance between the electrodes, signalling means connected in series with the electrodes and means for applying a potential to the electrodes to give an indication when the resistance of the chemical sorbent between the electrodes is substantially reduced to thereby give an indication of the remaining effective life of the canister.

2. A breathing apparatus as in claim 1 wherein said signalling means includes a lamp mounted on the breathing apparatus in a position where it can be readily viewed by the wearer of the apparatus.

3. A breathing apparatus as in claim 1 wherein said canister is of the filter type and is adapted to be opened to the atmosphere to permit atmospheric air to be drawn into the canister to be treated so that it can be utilized by the wearer.

4. A breathing apparatus as in claim 1 wherein said chemical sorbent is provided for generating oxygen and wherein said means establishing communication between the canister and the face piece include means for introducing exhaled air into the canister where it is recirculated through the canister to remove the carbon dioxide and to introduce oxygen so that the exhaled air can be reused by the wearer.

5. A breathing apparatus as in claim 1 together with means for testing said alarm device to see whether or not it is operative.

6. A breathing apparatus as in claim 1 wherein at lwats two different chemical materials are utilized and in which chemical sorbents are disposed in layers in the canister and wherein said first named electrode is disposed in one of said layers.

7. A breathing apparatus as in claim 1 wherein said alarm device is readily detachable.

8 In a chemical breathing apparatus with an electrically actuated alarm device for use by a human and adapted to supply life sustaining gases to the respiratory tract of the human who is operating in a gaseous environment, a canister adapted to be carried by the human, said canister containing at least one chemical sorbent through which gases to be treated in the canister must pass, a face piece adapted to be placed over the face of the wearer and having communication with the respiratory tract of the wearer, means forming a fluid flow passage between the canister and the face piece so that treated gases which are treated by the canister can travel to the face piece to be utilized by the wearer, electrode means in contact with the chemical sorbent in the canister and being in the form of spaced apart electrodes, one of said electrodes being positioned only in the upper portion of the chemical sorbent so that the chemical sorbent presents a high resistance between the electrodes, signalling means connected in series with the electrodes and direct current power supply means for applying a potential to the electrodes to give an indication when the resistance of the chemical sorbent between the electrodes is substantially reduced to thereby give an indication of the remaining effective life of the canister.

9. A chemical breathing apparatus as in claim 8 wherein said direct current power supply means is in the form of a battery.

10. In a chemical breathing apparatus with an electrically actuated alarm device for use by a human and adapted to supply life-sustaining gases to the respiratory tract of the human who is operating in a gaseous environment, a canister adapted to be carried by the human, said canister containing at least one chemical sorbent through which gases to be treated in the canister must pass, a face piece adapted to be placed over the face of the wearer and having communication with the respiratory tract of the wearer, means forming a fluid flow passage between the canister and the face piece so that treated gases which are treated by the canister can travel to the face piece to be utilized by the wearer, electrode means in contact with the chemical sorbent in the canister and being in the form of spaced apart electrodes so that the chemical sorbent presents a high resistance between the electrodes, signalling means connected in series with the electrodes and means for applying a potential to the electrodes to give an indication when the resistance of the chemical sorbent between the electrodes is substantially reduced to thereby give an indication of the remaining effective life of the canister, said electrode means being in the form of one electrode extending into the chemical sorbent and the other electrode being in the form of a body with the chemical sorbent disposed in the body.

11. A breathing apparatus as in claim 10 wherein said first named electrode is in the form of a screen-like element disposed in the chemical sorbent.

12. A breathing apparatus as in claim 10 wherein said first named electrode makes electrical contact with two spaced layers.

13. A breathing apparatus as in claim 12 wherein said first named electrode is in the form of a pair of spaced, generally parallel screen-like members which are connected in parallel and which are disposed in separate spaced layers.

Claims

7. A breathing apparatus as in claim 1 wherein said alarm device is readily detachable. 8 In a chemical breathing apparatus with an electrically actuated alarm device for use by a human and adapted to supply life sustaining gases to the respiratory tract of the human who is operating in a gaseous environment, a canister adapted to be carried by the human, said canister containing at least one chemical sorbent through which gases to be treated in the canister must pass, a face piece adapted to be placed over the face of the wearer and having communication with the respiratory tract of the wearer, means forming a fluid flow passage between the canister and the face piece so that treated gases which are treated by the canister can travel to the face piece to be utilized by the wearer, electrode means in contact with the chemical sorbent in the canister and being in the form of spaced apart electrodes, one of said electrodes being positioned only in the upper portion of the chemical sorbent so that the chemical sorbent presents a high resistance between the electrodes, signalling means connected in series with the electrodes and direct current power supply means for applying a potential to the electrodes to give an indication when the resistance of the chemical sorbent between the electrodes is substantially reduced to thereby give an indication of the remaining effective life of the canister.