CA1141990A - Soda lime half life indicator - Google Patents
Soda lime half life indicatorInfo
- Publication number
- CA1141990A CA1141990A CA000350123A CA350123A CA1141990A CA 1141990 A CA1141990 A CA 1141990A CA 000350123 A CA000350123 A CA 000350123A CA 350123 A CA350123 A CA 350123A CA 1141990 A CA1141990 A CA 1141990A
- Authority
- CA
- Canada
- Prior art keywords
- temperature
- absorbent
- display means
- breathing
- soda lime
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- HUAUNKAZQWMVFY-UHFFFAOYSA-M sodium;oxocalcium;hydroxide Chemical compound [OH-].[Na+].[Ca]=O HUAUNKAZQWMVFY-UHFFFAOYSA-M 0.000 title claims description 27
- 230000002745 absorbent Effects 0.000 claims abstract description 39
- 239000002250 absorbent Substances 0.000 claims abstract description 39
- 230000029058 respiratory gaseous exchange Effects 0.000 claims abstract description 15
- 238000012545 processing Methods 0.000 claims abstract description 13
- 238000012544 monitoring process Methods 0.000 claims abstract description 8
- 230000000007 visual effect Effects 0.000 claims abstract description 8
- 239000002245 particle Substances 0.000 claims description 8
- 238000006243 chemical reaction Methods 0.000 claims description 7
- 239000003513 alkali Substances 0.000 claims description 3
- 229910001860 alkaline earth metal hydroxide Inorganic materials 0.000 claims description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 claims description 3
- 231100000252 nontoxic Toxicity 0.000 claims description 3
- 230000003000 nontoxic effect Effects 0.000 claims description 3
- 229910001854 alkali hydroxide Inorganic materials 0.000 claims 2
- 239000012530 fluid Substances 0.000 claims 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 44
- 229910002092 carbon dioxide Inorganic materials 0.000 description 34
- 239000007789 gas Substances 0.000 description 11
- 230000000694 effects Effects 0.000 description 10
- 239000001569 carbon dioxide Substances 0.000 description 9
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 description 6
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 4
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 4
- 240000006909 Tilia x europaea Species 0.000 description 4
- 235000011941 Tilia x europaea Nutrition 0.000 description 4
- 239000004571 lime Substances 0.000 description 4
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 3
- 239000000292 calcium oxide Substances 0.000 description 3
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 241001527902 Aratus Species 0.000 description 2
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 2
- 239000000920 calcium hydroxide Substances 0.000 description 2
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 2
- 239000000306 component Substances 0.000 description 2
- OVHKNYXHWWCVSW-UHFFFAOYSA-A decacalcium sodium henicosahydroxide decahydrate Chemical compound O.O.O.O.O.O.O.O.O.O.[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[Na+].[Ca++].[Ca++].[Ca++].[Ca++].[Ca++].[Ca++].[Ca++].[Ca++].[Ca++].[Ca++] OVHKNYXHWWCVSW-UHFFFAOYSA-A 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 230000004438 eyesight Effects 0.000 description 2
- 229910052744 lithium Inorganic materials 0.000 description 2
- 210000004072 lung Anatomy 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- HCUOEKSZWPGJIM-IYNMRSRQSA-N (e,2z)-2-hydroxyimino-6-methoxy-4-methyl-5-nitrohex-3-enamide Chemical compound COCC([N+]([O-])=O)\C(C)=C\C(=N\O)\C(N)=O HCUOEKSZWPGJIM-IYNMRSRQSA-N 0.000 description 1
- 229910001369 Brass Inorganic materials 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 230000001174 ascending effect Effects 0.000 description 1
- 239000010951 brass Substances 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000009189 diving Effects 0.000 description 1
- 210000004185 liver Anatomy 0.000 description 1
- 229910000000 metal hydroxide Inorganic materials 0.000 description 1
- 150000004692 metal hydroxides Chemical class 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000005043 peripheral vision Effects 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 239000013535 sea water Substances 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
-
- A—HUMAN NECESSITIES
- A62—LIFE-SAVING; FIRE-FIGHTING
- A62B—DEVICES, APPARATUS OR METHODS FOR LIFE-SAVING
- A62B18/00—Breathing masks or helmets, e.g. affording protection against chemical agents or for use at high altitudes or incorporating a pump or compressor for reducing the inhalation effort
- A62B18/08—Component parts for gas-masks or gas-helmets, e.g. windows, straps, speech transmitters, signal-devices
- A62B18/088—Devices for indicating filter saturation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
- B01D53/1412—Controlling the absorption process
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
- B01D53/1456—Removing acid components
- B01D53/1475—Removing carbon dioxide
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63C—LAUNCHING, HAULING-OUT, OR DRY-DOCKING OF VESSELS; LIFE-SAVING IN WATER; EQUIPMENT FOR DWELLING OR WORKING UNDER WATER; MEANS FOR SALVAGING OR SEARCHING FOR UNDERWATER OBJECTS
- B63C11/00—Equipment for dwelling or working underwater; Means for searching for underwater objects
- B63C11/02—Divers' equipment
- B63C11/18—Air supply
- B63C11/22—Air supply carried by diver
- B63C11/24—Air supply carried by diver in closed circulation
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N25/00—Investigating or analyzing materials by the use of thermal means
- G01N25/20—Investigating or analyzing materials by the use of thermal means by investigating the development of heat, i.e. calorimetry, e.g. by measuring specific heat, by measuring thermal conductivity
- G01N25/48—Investigating or analyzing materials by the use of thermal means by investigating the development of heat, i.e. calorimetry, e.g. by measuring specific heat, by measuring thermal conductivity on solution, sorption, or a chemical reaction not involving combustion or catalytic oxidation
- G01N25/4846—Investigating or analyzing materials by the use of thermal means by investigating the development of heat, i.e. calorimetry, e.g. by measuring specific heat, by measuring thermal conductivity on solution, sorption, or a chemical reaction not involving combustion or catalytic oxidation for a motionless, e.g. solid sample
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
- Y02C20/00—Capture or disposal of greenhouse gases
- Y02C20/40—Capture or disposal of greenhouse gases of CO2
Landscapes
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Engineering & Computer Science (AREA)
- Analytical Chemistry (AREA)
- General Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Pulmonology (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- General Chemical & Material Sciences (AREA)
- Immunology (AREA)
- Biochemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Physics & Mathematics (AREA)
- Physics & Mathematics (AREA)
- Pathology (AREA)
- Combustion & Propulsion (AREA)
- Business, Economics & Management (AREA)
- Emergency Management (AREA)
- Mechanical Engineering (AREA)
- Ocean & Marine Engineering (AREA)
- Gas Separation By Absorption (AREA)
Abstract
Abstract of the Disclosure The invention disclosed is an indicator for monitoring the capacity of a CO2 absorbent to absorb CO2. The indicator is typically used in asso-ciation with a closed circuit breathing apparatus, including a container for a CO2 absorbent. The indicator comprises temperature sensing means immersed in the absorbent, a temperature to voltage converter for converting a sensed temperature reading to an electrical voltage signal, temperature trend proces-sing means for processing said electrical voltage signal into a selected electrical output signal characteristic of a temperature trend; and display means for converting said selected electrical output signal to a predetermined visual display indicative of the capacity of the CO2 absorbent to absorb CO2.
Description
This invention relates to the removal of carbon dioxide from a gas stream containing carbon dioxide, by means of a carbon dioxide absorbent, and in particular to a device which monitors the effectiveness of the carbon dioxide absorbent.
Carbon dioxide absorbents e.g. soda lime or otller suitable non-toxic alka]i and alkaline earth metal hydroxides, are conveniently employed in conjunction with closed circuit breathing apparatus to remove carbon dioxide from the breathing gas e.g~ of the type disclosed in Canadian Patent No.
787,693 which issued on 18 June 1978 to Lewis R. Phillips. Unfortunately, the user has no way of determining the percentage of carbon dioxide absorbent which has become exhausted. This problem is of particular significance to divers.
One solution is to have the diver surface after an arbitrarily determined length of time which is known to be "saEe". This solution often leads to waste of the carbon dioxide absorbent. Moreover, stuclies oE various batches of the same carbon dio~ide absorbent, in this case, so(la ]ime, has shown that the "safe" time can vary substantially. In fact, a recent supply of sotla lime ernl-loyed by (livers wns causln~ "blnckout" uEter about 20 minutes of use instea(l of a norma~ly expectecl 5n minutet; for thl` same amount of soda lime under the same conclitions.
A means for indicating when the effectiveness of a CO2 absorbent is substantially exhausted is disclosed in United States Patent 2,270,025 which issued on 13 January 1942 to John R. RullofE. ~his teaching involved the coating of the CO2 absorbent in this case soda lime, with an indicator material which is of one colour at the alkalinity of soda lime, and another colour at tlle alkalinity of sodium carbonate, as present in soda lime under the conditions of actual use. As the soda lime absorbs CO2 and is converted to carbonate, the colour of the indicator changes to give an indication of the extent oi exhaustion of soda li~e. Unfortunately, the colour inclicator is only useful in somo general purpose applications e.g. inside a submarine where the colour change can be easily observed. On the other hand, in a closed circuit breathing apparatus, the CO2 absorbent is enclosed in a canister, and even if the colour change could be monitored it is not sufEiciently precise for that purpose.
9C~
~nottlcr obvious problem o:E such an indicating means i9 that even if the colour change could be olserve(l by a diver, the observation of a gradual colour change is quite subjective and should the colour change be instaneous as in the case of some such indicators, a diver could conceivably "blackout"
before he reached the sur.Eace.
According to the invention, an apparatus Eor removing C02 from a gas stream is contemplated, the apparatus comprising a container having a gas i.nlet and a gas outlet and a C02 absorbent selected from the group con- ``
sisting oE soda lime and other suitab].e non-toxic alkali and alkaline earth 10 metal hydroxides di.sposed in said container, the improvement comprising provi-ding an indicator for monitoring the capacity of the absorbent to absorb C02, said indicator comprising temperature sensing means immersed in said absorbent for monitoring the temperature profile of the heat generated by the chemical rcactlon of hydroxide an(l C02; temperature to voltage converter means for con-verting a sensed temperattlre reading to an e].ectri.cal voltage signal; tempera-ture Lrend processing means Eor processing said electrical voltage signal into a selected electrical output signcll characterisl:ic of a temperature trend; and displny means lor convertlng snid selected e]~ecl:rical OUtpllt signal to a visual display indi.cative of the capacity oE the C02 absorbent to al)sorb CO2.
It has been .Eound that three parameters play major roles in the behaviour o.E soda lime. These are, particle size, gas flow.rate and tempera-ture~ The intcrrelationsllip of these parameters finds practical expression in which is called the "act.ivity" of socla lime. In addition to '`activity"
a term "half life" of soda lime will be used hereinafter.
"Activity" is defined as the number of liters of CO2 absorbed by a given weight (700 grams) of soda lime as a 5~O CO2 ~ 95% 2 gas mixture flows througll it at a rate of 32 liters per minute up to the time that 1% CO2 appears in the effluent gas stream. "~lalf life" is defined as half the time taken to obtain the activity number and indicates when the absorbent's capacity to 30 absorb C02 has declined by 50%.
Some quantitive information on soda lime and other CO2 absorbents is given i.n tables I - V which follow.
TABLE I
'' '-'~ . D ~ .9 E G; ~ R
: ~ RETAINED BYPARTICLE ~RA6~-OXY CALONA
SIEVE NUMBER SIZE` SODA LIME SODA LIME
6 4.78 to 3.36 MM16.4% 0.6%
8 3.36 to `2.36271.0% 60. %
12 2.362 to 1.6811.0% 36.0%
16 1.68 to 1.19 0.4% 2.4%
Table I gives information as to particle size ranges and ratios for two widely used soda limes, Draeger-oxy soda lime and Calona soda lime.
It can be clearly seen that there is a marked difference ln particle size distributions.
TABLE II
PARTICLE SIZE ACTIVITY A~ERAGE
. .......... . . .. _ .. .. . . . . _ 4.75 to 3.36 ~ 20.5 2().5 19 19 20.5 23.6 20.4 3.36 t~ 2.~62 4~.() l~7.0 46 52 35 47 45.5
Carbon dioxide absorbents e.g. soda lime or otller suitable non-toxic alka]i and alkaline earth metal hydroxides, are conveniently employed in conjunction with closed circuit breathing apparatus to remove carbon dioxide from the breathing gas e.g~ of the type disclosed in Canadian Patent No.
787,693 which issued on 18 June 1978 to Lewis R. Phillips. Unfortunately, the user has no way of determining the percentage of carbon dioxide absorbent which has become exhausted. This problem is of particular significance to divers.
One solution is to have the diver surface after an arbitrarily determined length of time which is known to be "saEe". This solution often leads to waste of the carbon dioxide absorbent. Moreover, stuclies oE various batches of the same carbon dio~ide absorbent, in this case, so(la ]ime, has shown that the "safe" time can vary substantially. In fact, a recent supply of sotla lime ernl-loyed by (livers wns causln~ "blnckout" uEter about 20 minutes of use instea(l of a norma~ly expectecl 5n minutet; for thl` same amount of soda lime under the same conclitions.
A means for indicating when the effectiveness of a CO2 absorbent is substantially exhausted is disclosed in United States Patent 2,270,025 which issued on 13 January 1942 to John R. RullofE. ~his teaching involved the coating of the CO2 absorbent in this case soda lime, with an indicator material which is of one colour at the alkalinity of soda lime, and another colour at tlle alkalinity of sodium carbonate, as present in soda lime under the conditions of actual use. As the soda lime absorbs CO2 and is converted to carbonate, the colour of the indicator changes to give an indication of the extent oi exhaustion of soda li~e. Unfortunately, the colour inclicator is only useful in somo general purpose applications e.g. inside a submarine where the colour change can be easily observed. On the other hand, in a closed circuit breathing apparatus, the CO2 absorbent is enclosed in a canister, and even if the colour change could be monitored it is not sufEiciently precise for that purpose.
9C~
~nottlcr obvious problem o:E such an indicating means i9 that even if the colour change could be olserve(l by a diver, the observation of a gradual colour change is quite subjective and should the colour change be instaneous as in the case of some such indicators, a diver could conceivably "blackout"
before he reached the sur.Eace.
According to the invention, an apparatus Eor removing C02 from a gas stream is contemplated, the apparatus comprising a container having a gas i.nlet and a gas outlet and a C02 absorbent selected from the group con- ``
sisting oE soda lime and other suitab].e non-toxic alkali and alkaline earth 10 metal hydroxides di.sposed in said container, the improvement comprising provi-ding an indicator for monitoring the capacity of the absorbent to absorb C02, said indicator comprising temperature sensing means immersed in said absorbent for monitoring the temperature profile of the heat generated by the chemical rcactlon of hydroxide an(l C02; temperature to voltage converter means for con-verting a sensed temperattlre reading to an e].ectri.cal voltage signal; tempera-ture Lrend processing means Eor processing said electrical voltage signal into a selected electrical output signcll characterisl:ic of a temperature trend; and displny means lor convertlng snid selected e]~ecl:rical OUtpllt signal to a visual display indi.cative of the capacity oE the C02 absorbent to al)sorb CO2.
It has been .Eound that three parameters play major roles in the behaviour o.E soda lime. These are, particle size, gas flow.rate and tempera-ture~ The intcrrelationsllip of these parameters finds practical expression in which is called the "act.ivity" of socla lime. In addition to '`activity"
a term "half life" of soda lime will be used hereinafter.
"Activity" is defined as the number of liters of CO2 absorbed by a given weight (700 grams) of soda lime as a 5~O CO2 ~ 95% 2 gas mixture flows througll it at a rate of 32 liters per minute up to the time that 1% CO2 appears in the effluent gas stream. "~lalf life" is defined as half the time taken to obtain the activity number and indicates when the absorbent's capacity to 30 absorb C02 has declined by 50%.
Some quantitive information on soda lime and other CO2 absorbents is given i.n tables I - V which follow.
TABLE I
'' '-'~ . D ~ .9 E G; ~ R
: ~ RETAINED BYPARTICLE ~RA6~-OXY CALONA
SIEVE NUMBER SIZE` SODA LIME SODA LIME
6 4.78 to 3.36 MM16.4% 0.6%
8 3.36 to `2.36271.0% 60. %
12 2.362 to 1.6811.0% 36.0%
16 1.68 to 1.19 0.4% 2.4%
Table I gives information as to particle size ranges and ratios for two widely used soda limes, Draeger-oxy soda lime and Calona soda lime.
It can be clearly seen that there is a marked difference ln particle size distributions.
TABLE II
PARTICLE SIZE ACTIVITY A~ERAGE
. .......... . . .. _ .. .. . . . . _ 4.75 to 3.36 ~ 20.5 2().5 19 19 20.5 23.6 20.4 3.36 t~ 2.~62 4~.() l~7.0 46 52 35 47 45.5
2.362 to l.h8 55 3fi ~l 44 4l~ 4fi 44.3 Table II shows the very marked relationship between activity and particle size. As one might expect, activity goes Up as particle size goes do~n. The reason of course being tlle greater surface to mass ratios as particle size decre~ses.
TABLE III
DR9EGER-OXY SODA LI~IE
FLOW RATE ACTtVITY AVERAGE
,, .. , . .. .... _ 32.0 l/Min 63. 66. 65 65. 49 59.5 14.75 75.6 75.6 79.0 76,7 ar~/ ~n o~k 11~1'3~3~
Table l[I shows the major differences irl activity which result from differences in flow rate. Draeger-oxy soda lime is the material used for this series of trials.
TABLE IV
LITHIUM IIYDROXIDE
FLOW RATE ACTIVITY AVERAGE
_.
32.0 l/Min 29.6 28.2 300 29.3 ~ 75 47.3 ~6.5 ~5 ~i7.3 46.5 Table IV shows results of a series of trials using lithium hydroxide as the C02 absorbent~ It should also be noted that the activity of Draeger-oxy soda lime is much greater than that o~ lithium hydroxide under comparable ~Low r~te conditiorls.
~US~R13ENT ACTIVITY AT
__ Lithium ~Iydroxide 10.5 51.6 105 102 ~0 Draeger-Oxy Soda Lime 9.0 39.0 60.5 110 Table V compares activities of Draeger-oxy soda lime at the tempera-ture shown. Within the temperature ranges shown, it is evident that higher temperature results in higher activi-ty~
It became apparent in the course of work with soda lime that there is a clear temperature cycle through which a charge of soda lime passes in the course of its use by a diver. It is believed that the reason for the temperature cycle is the exothermic reaction first of water vapour with calcium oxide to produGe calcium hydroxide and the subsequent reaction of calcium hydroxide with carbon dioxide to produce calcium carbonate and water, according
TABLE III
DR9EGER-OXY SODA LI~IE
FLOW RATE ACTtVITY AVERAGE
,, .. , . .. .... _ 32.0 l/Min 63. 66. 65 65. 49 59.5 14.75 75.6 75.6 79.0 76,7 ar~/ ~n o~k 11~1'3~3~
Table l[I shows the major differences irl activity which result from differences in flow rate. Draeger-oxy soda lime is the material used for this series of trials.
TABLE IV
LITHIUM IIYDROXIDE
FLOW RATE ACTIVITY AVERAGE
_.
32.0 l/Min 29.6 28.2 300 29.3 ~ 75 47.3 ~6.5 ~5 ~i7.3 46.5 Table IV shows results of a series of trials using lithium hydroxide as the C02 absorbent~ It should also be noted that the activity of Draeger-oxy soda lime is much greater than that o~ lithium hydroxide under comparable ~Low r~te conditiorls.
~US~R13ENT ACTIVITY AT
__ Lithium ~Iydroxide 10.5 51.6 105 102 ~0 Draeger-Oxy Soda Lime 9.0 39.0 60.5 110 Table V compares activities of Draeger-oxy soda lime at the tempera-ture shown. Within the temperature ranges shown, it is evident that higher temperature results in higher activi-ty~
It became apparent in the course of work with soda lime that there is a clear temperature cycle through which a charge of soda lime passes in the course of its use by a diver. It is believed that the reason for the temperature cycle is the exothermic reaction first of water vapour with calcium oxide to produGe calcium hydroxide and the subsequent reaction of calcium hydroxide with carbon dioxide to produce calcium carbonate and water, according
3~V
to the following reactiotls.
CaO ~ 112O-~ Ca(O~1~2 ~ 16 0 Kcal (o )2 2 ~ 3 2 ~ 25.8 Kcal.
The combined reaction lll.ly be written, CaO + H2O + CO2 ~ CaCo3 + 2 -~ 41.8 Kca:l.
In the drawings which serve to illustrate embo(liments of the inven-tion~ Figure 1 is a schcmatic illustration of a typical closed circuit breath- ..
ing apparatus includi.nl/ an indicator according to the invention.
Figure 2 :i9 ~I scllemlti.c il.lustration of a sodl :I.ime llalf life -L0 indicator according to the present invention which is empioyed in conjunction with a closed circuit brc~tb;ll~ apparatus;
Figure 3 is a grclph illustrating the temperature cycles occurring insi~lo the CO2 absorl)-.~nl; cont~i.ni.ng c.anister oE the cLosed circuit breathing apl)aratus, and Figures 4A to lLC .lllustrnte a circult cliagr~u~ oE one practical embodiment of the :inventl.on.
Re:Eerring to l;`:lg~lle 1, the iLlustrated typ.lcnL closed circuit breath-:Lng apl)aratus ope:rllte~ as Eol:l.ows. Pure oxygen i.s l.cd a~ a pre(leterm:Lned rate from the oxygen cy:lln~ler l.0 thl-ollgll the reducing valve VREn intd the rebreath-ing bag (counter-lung). The diver inhales deeply taking oxygen from the counter lung, throu~h Lhe canister 12 containing CO2 absorbent 14, through the flexible tubing lfi and Eace mask l8 and fina].ly to his lungs. The diver then exhales deeply to drive the respired gases over the same path, the CO2 absorbent removing the CO~ produced by the body. The blow-off valve 20 provides for pressure equali~ation when the diver is ascending.
Temperature sensing means 30, e.g. a suitable thermistor, (a thermo-couple could also be used~ is located within the cannister 12, immersed in the C2 absorbent 14, typically soda lime, in an area of maximum heat concentration and minimum heat loss. The preferred location is basically the centre of the con~ainer.
31L r3 ~ O
Figure 2 is A S Lmplifie(1 sche111atic illustration of a device accord-ing to the invention. It will be seen that a temperature sensing means serves to monitor a temperature trend profile in the container 12 resulting from the exothermic chemical reaction occuring within the container. The temperature trend profile will be discussed in more detail hereina-fter.
Information Erom the temperature sensor 30 is fed to a temperature to voltage converter 41 which converts the sensed temperature reading to an clectrical voltage signal.
The electricnl voltage signal is then fed to temperature trend processing means 42 which processes the input signal into one of four different selected output signals respectively indicative of the effectiveness of the C2 absorbent i.e. its capacity to absorb C02.
The temperature trend processing means 42 monitors the state of the so(1a lime, by determini1lg the rate of change of its temperature, and direction of Lhis change (i.c. if the tem1~erature is incraasirlg or decreasing). The conditions present in L11c soda lime canister 12 are convenicntly visually represented ~y a light emi-ting dioide (LED) 22, located in the diver~s face mask 18. The LED 22 i-~ mour1ted nonr the outor edge .-r tlle viewing winclow so as not to hindcr tlle divcr~s normal vision. The state oE the LED when located in this position can be monitored by peripheral vision rather than requiring direct vision. , Thcsc four diEferent selected output signals are:
a) wl1en the temperature of soda lime is increasing, the LED blinks rapidly;
b) when temperature of the soda lime is constant, the LED blinks once every ten seconds;
c) when temperature of the soda lime is decreasing, the LED blinks once every second; and d~ when prevailing temperature of tlle soda lime is less than or equal to the highest tempcrature attained, for more tllan three minutes, the LED is on continuously. The LED wilL remain on evcn if the temperatl1re were to exceed the previous maximum. Reinitialization can only be accomplished by turning the power off, then on again.
Additional safety features are provided:
a) sho~lld the thermistor become shorted or open due to mechanical failure or the ingress of sea water into the canister, the LED will come on after three minu te s;
b) should the d.c. battery supply vo]tage be too low for proper circuitry operation, the LED will immediately turn on.
The electronics, including the temperature to voltage converting means 41, the temperature trend processing means 42 and dc power supply 43 are located in a brass pressure case 24, 245 mm. long and 45 mm. in- diameter.
A waterproof switch on one end of this case turns the system on and off. Two e1ectrical1y conducting cables~ one 23 to the LRD 22 ancl one 25 to the thermis-tor 30 te.g. a YSI No. ~ 105) come into the pressure case 24 throclgll waterproof seals. The pressure case is securecl wlth a rope to a convenient spot on the Eront o~ tlle diver's c1earallce diving and breatlling a~-paratus.
FLgurc 2 also sllows n battery voltage monLtor Ullit 45 and a sensor monitor unit 46. Tlle EunctLon of the battery voltage monitor 45 is to detect when the battery voltage falls below a predetermined value, and then to ener-gise the LED 22 continuously to indicate a "danger" situation. The sensor monitor unit 46 is sensitive to the output from the temperature-to-voltage converter 41, and should that OUtpllt fall outsicle permissible limits (indicating a probable sensor failure), energizes the LED 22 continuously to indicate a ~clanger~ situation.
Figure 3 is a graph illustrating the temperature profile of the exothermic reactions for two different C02 absorbents. It should be mentioned that the temperature cycles shown were obtained in t'he laboratory with a one way flow of 5% C02-95% 2 gas mixture. In actual use, the gas flow is of course tied directly to the divers breathing cycle.
It will be seen in the graph that the temperature rises rapidly at irst ancl begins to level o after about 20 minutes of use~ The temperature then remains for a time (clepending upon the type of C02 absorbent employed) and then begins to fall off. The "half-life" is reached as the temperature begin~ to fall off and the diver should note, at this point, 50% of his life support ~ystem has been e~p~nded.
It will be appreciated by those skilled in this art that Figure 2 i9 schematic only, and that the electrical circuit must include other compo-nents. An example is the need to isolate from one another the various inputs to the LED 22. Fig~lre 4 is a complete circ~lit diagram sho~ing one way in whicll the arrangement of Figu~ 2 can be reali~ed in practice. The following list identifi~s the components shown in Figure 4.
REFERENCE DESCRIPTION
NU~IERAL
22 l`llERrllSTOR YSI N~. 44105 LIGIIT E~IIT~`LN(. DIODE
61 9 VOLr l~l~r~RY
62 VOLTACE RE;EEUENCE AD 580 6~ POSITIVE VOLl`AGE OUTPUT AT +9 VOLTS
64 CIRCUIT TO PROVIDE -9 VOLTS POWER SUPPLY (IIEX, INVERTER CD 4049) 65 NECATIVE VOLl`AGE OUTPUT AT -9 VOLTS .
BATTERY VOLTAGE PIONITOR INCLUDING
71 OPEF~ATIONAL AMPLIFIER LA 741 81 OPERATIONAL A~PLIFIER lB 741 MISCELLANEOUS
RESISTORS Rl 392 O~IS 1% ACCURACY
R2 IK OI~IS
R3 12K OI~IS
~ 2741~ OI~S
R5 100K OI~IS
R6 10K 01~1S
R7 100K OIIMS 1% ACCURACY
R8 68.1K OI~S 1% ACCURACY
R9 l21K O~S 1% ACCURACY
R10 47.5K OI~S 1% ACCURACY
Rll 470K OI~IS
R12 l()K O~lS
R13 1.2K OI~S
R14 39.2K OHMS 1% ACCURACY
R15 10K OI~S 1% ACCURACY
Ul6 100K OI~IS
CAl'ACITORS
.
Cl 0.0019 ~U:D
C2 1 ~tFD RED C~P
C3 0.0()19 MFD
OPERATIONAI, A~ll'LIFIERS
20 OP.l lA741 OP.2 lA741 op.3 LA741 op.4 ]A74l COUNTERS
CT.l CD 4020 CT.2 CD 4020 CT.3 UP COUNTER CD 4040 _ Dl IIS 1012 D2 IIS ~0l2 D3 HS 1()12 _ 9 _ 9~ ~
:LNTEGRATED CLRCUIT5 lC. 1 lO-BIT MIILTIPLYING D/A AD 7521 GATE:S
NAND 1) ~) Quad 2-INPUT CD 4011 NOR 1 QUAD 2 INPUT CD 4001 (3 DEVICE;S) ~ .
].0 Il . ,.
AND 1 TRIPLE~ 3-INPUT CD 4073 .
The positive and negative outputs 63 and 65 of the d.c. power supply are each apl)lie(l to a number of points indicated in Figure 4 respectively by positive (~) and negative (-).
The device according to the invention has been specifically described in relation to its use with soda lime as the C02 absorbent. It will be appreciated by those skilled in the art that the device would be equally operative with other C02 absorbents which result in a similar temperature clange profile within the cannister containing the CO~ absorbent. Accordingly - 1 0 - ;
the preferred embodiment described above is to be considered as illustrative and by no means restrictive.
to the following reactiotls.
CaO ~ 112O-~ Ca(O~1~2 ~ 16 0 Kcal (o )2 2 ~ 3 2 ~ 25.8 Kcal.
The combined reaction lll.ly be written, CaO + H2O + CO2 ~ CaCo3 + 2 -~ 41.8 Kca:l.
In the drawings which serve to illustrate embo(liments of the inven-tion~ Figure 1 is a schcmatic illustration of a typical closed circuit breath- ..
ing apparatus includi.nl/ an indicator according to the invention.
Figure 2 :i9 ~I scllemlti.c il.lustration of a sodl :I.ime llalf life -L0 indicator according to the present invention which is empioyed in conjunction with a closed circuit brc~tb;ll~ apparatus;
Figure 3 is a grclph illustrating the temperature cycles occurring insi~lo the CO2 absorl)-.~nl; cont~i.ni.ng c.anister oE the cLosed circuit breathing apl)aratus, and Figures 4A to lLC .lllustrnte a circult cliagr~u~ oE one practical embodiment of the :inventl.on.
Re:Eerring to l;`:lg~lle 1, the iLlustrated typ.lcnL closed circuit breath-:Lng apl)aratus ope:rllte~ as Eol:l.ows. Pure oxygen i.s l.cd a~ a pre(leterm:Lned rate from the oxygen cy:lln~ler l.0 thl-ollgll the reducing valve VREn intd the rebreath-ing bag (counter-lung). The diver inhales deeply taking oxygen from the counter lung, throu~h Lhe canister 12 containing CO2 absorbent 14, through the flexible tubing lfi and Eace mask l8 and fina].ly to his lungs. The diver then exhales deeply to drive the respired gases over the same path, the CO2 absorbent removing the CO~ produced by the body. The blow-off valve 20 provides for pressure equali~ation when the diver is ascending.
Temperature sensing means 30, e.g. a suitable thermistor, (a thermo-couple could also be used~ is located within the cannister 12, immersed in the C2 absorbent 14, typically soda lime, in an area of maximum heat concentration and minimum heat loss. The preferred location is basically the centre of the con~ainer.
31L r3 ~ O
Figure 2 is A S Lmplifie(1 sche111atic illustration of a device accord-ing to the invention. It will be seen that a temperature sensing means serves to monitor a temperature trend profile in the container 12 resulting from the exothermic chemical reaction occuring within the container. The temperature trend profile will be discussed in more detail hereina-fter.
Information Erom the temperature sensor 30 is fed to a temperature to voltage converter 41 which converts the sensed temperature reading to an clectrical voltage signal.
The electricnl voltage signal is then fed to temperature trend processing means 42 which processes the input signal into one of four different selected output signals respectively indicative of the effectiveness of the C2 absorbent i.e. its capacity to absorb C02.
The temperature trend processing means 42 monitors the state of the so(1a lime, by determini1lg the rate of change of its temperature, and direction of Lhis change (i.c. if the tem1~erature is incraasirlg or decreasing). The conditions present in L11c soda lime canister 12 are convenicntly visually represented ~y a light emi-ting dioide (LED) 22, located in the diver~s face mask 18. The LED 22 i-~ mour1ted nonr the outor edge .-r tlle viewing winclow so as not to hindcr tlle divcr~s normal vision. The state oE the LED when located in this position can be monitored by peripheral vision rather than requiring direct vision. , Thcsc four diEferent selected output signals are:
a) wl1en the temperature of soda lime is increasing, the LED blinks rapidly;
b) when temperature of the soda lime is constant, the LED blinks once every ten seconds;
c) when temperature of the soda lime is decreasing, the LED blinks once every second; and d~ when prevailing temperature of tlle soda lime is less than or equal to the highest tempcrature attained, for more tllan three minutes, the LED is on continuously. The LED wilL remain on evcn if the temperatl1re were to exceed the previous maximum. Reinitialization can only be accomplished by turning the power off, then on again.
Additional safety features are provided:
a) sho~lld the thermistor become shorted or open due to mechanical failure or the ingress of sea water into the canister, the LED will come on after three minu te s;
b) should the d.c. battery supply vo]tage be too low for proper circuitry operation, the LED will immediately turn on.
The electronics, including the temperature to voltage converting means 41, the temperature trend processing means 42 and dc power supply 43 are located in a brass pressure case 24, 245 mm. long and 45 mm. in- diameter.
A waterproof switch on one end of this case turns the system on and off. Two e1ectrical1y conducting cables~ one 23 to the LRD 22 ancl one 25 to the thermis-tor 30 te.g. a YSI No. ~ 105) come into the pressure case 24 throclgll waterproof seals. The pressure case is securecl wlth a rope to a convenient spot on the Eront o~ tlle diver's c1earallce diving and breatlling a~-paratus.
FLgurc 2 also sllows n battery voltage monLtor Ullit 45 and a sensor monitor unit 46. Tlle EunctLon of the battery voltage monitor 45 is to detect when the battery voltage falls below a predetermined value, and then to ener-gise the LED 22 continuously to indicate a "danger" situation. The sensor monitor unit 46 is sensitive to the output from the temperature-to-voltage converter 41, and should that OUtpllt fall outsicle permissible limits (indicating a probable sensor failure), energizes the LED 22 continuously to indicate a ~clanger~ situation.
Figure 3 is a graph illustrating the temperature profile of the exothermic reactions for two different C02 absorbents. It should be mentioned that the temperature cycles shown were obtained in t'he laboratory with a one way flow of 5% C02-95% 2 gas mixture. In actual use, the gas flow is of course tied directly to the divers breathing cycle.
It will be seen in the graph that the temperature rises rapidly at irst ancl begins to level o after about 20 minutes of use~ The temperature then remains for a time (clepending upon the type of C02 absorbent employed) and then begins to fall off. The "half-life" is reached as the temperature begin~ to fall off and the diver should note, at this point, 50% of his life support ~ystem has been e~p~nded.
It will be appreciated by those skilled in this art that Figure 2 i9 schematic only, and that the electrical circuit must include other compo-nents. An example is the need to isolate from one another the various inputs to the LED 22. Fig~lre 4 is a complete circ~lit diagram sho~ing one way in whicll the arrangement of Figu~ 2 can be reali~ed in practice. The following list identifi~s the components shown in Figure 4.
REFERENCE DESCRIPTION
NU~IERAL
22 l`llERrllSTOR YSI N~. 44105 LIGIIT E~IIT~`LN(. DIODE
61 9 VOLr l~l~r~RY
62 VOLTACE RE;EEUENCE AD 580 6~ POSITIVE VOLl`AGE OUTPUT AT +9 VOLTS
64 CIRCUIT TO PROVIDE -9 VOLTS POWER SUPPLY (IIEX, INVERTER CD 4049) 65 NECATIVE VOLl`AGE OUTPUT AT -9 VOLTS .
BATTERY VOLTAGE PIONITOR INCLUDING
71 OPEF~ATIONAL AMPLIFIER LA 741 81 OPERATIONAL A~PLIFIER lB 741 MISCELLANEOUS
RESISTORS Rl 392 O~IS 1% ACCURACY
R2 IK OI~IS
R3 12K OI~IS
~ 2741~ OI~S
R5 100K OI~IS
R6 10K 01~1S
R7 100K OIIMS 1% ACCURACY
R8 68.1K OI~S 1% ACCURACY
R9 l21K O~S 1% ACCURACY
R10 47.5K OI~S 1% ACCURACY
Rll 470K OI~IS
R12 l()K O~lS
R13 1.2K OI~S
R14 39.2K OHMS 1% ACCURACY
R15 10K OI~S 1% ACCURACY
Ul6 100K OI~IS
CAl'ACITORS
.
Cl 0.0019 ~U:D
C2 1 ~tFD RED C~P
C3 0.0()19 MFD
OPERATIONAI, A~ll'LIFIERS
20 OP.l lA741 OP.2 lA741 op.3 LA741 op.4 ]A74l COUNTERS
CT.l CD 4020 CT.2 CD 4020 CT.3 UP COUNTER CD 4040 _ Dl IIS 1012 D2 IIS ~0l2 D3 HS 1()12 _ 9 _ 9~ ~
:LNTEGRATED CLRCUIT5 lC. 1 lO-BIT MIILTIPLYING D/A AD 7521 GATE:S
NAND 1) ~) Quad 2-INPUT CD 4011 NOR 1 QUAD 2 INPUT CD 4001 (3 DEVICE;S) ~ .
].0 Il . ,.
AND 1 TRIPLE~ 3-INPUT CD 4073 .
The positive and negative outputs 63 and 65 of the d.c. power supply are each apl)lie(l to a number of points indicated in Figure 4 respectively by positive (~) and negative (-).
The device according to the invention has been specifically described in relation to its use with soda lime as the C02 absorbent. It will be appreciated by those skilled in the art that the device would be equally operative with other C02 absorbents which result in a similar temperature clange profile within the cannister containing the CO~ absorbent. Accordingly - 1 0 - ;
the preferred embodiment described above is to be considered as illustrative and by no means restrictive.
Claims (15)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In an apparatus for removing CO2 from a gas stream, said apparatus comprising a container having a gas inlet and a gas outlet and a CO2 absorbent selected from the group consisting of soda lime and other suitable non-toxic alkali and alkaline earth metal hydroxides disposed in said container, the improvement comprising: providing an indicator for monitoring the capacity of the absorbent to absorb CO2 said indicator comprising, temperature sensing means immersed in said absorbent for monitoring the temperature profile of the heat generated by the chemical reaction of the hydroxide and CO2;
temperature to voltage converter means for converting a sensed temperature rending to an electrical voltage signal;
temperature trend processing means for processing said electrical voltage signal into a selected electrical output signal characteristic of a temperature trend; and display means for converting said selected electrical output signal to a predetermined visual display indicative of the capacity of the CO2 absorbent to absorb CO2.
temperature to voltage converter means for converting a sensed temperature rending to an electrical voltage signal;
temperature trend processing means for processing said electrical voltage signal into a selected electrical output signal characteristic of a temperature trend; and display means for converting said selected electrical output signal to a predetermined visual display indicative of the capacity of the CO2 absorbent to absorb CO2.
2. Apparatus according to claim 1, wherein the temperature sensing means is a thermistor.
3. Apparatus according to claim 2, wherein the display means is a light emitting diode.
4. Apparatus according to claim 3, wherein the CO2 absorbent is soda lime.
5. Apparatus according to claim 1, including d.c. power supply means and monitor circuit means electrically associated with said d.c. power supply and said display means, for detecting when the power supply voltage falls below a set value and then to energize the display means to exhibit a predetermined visual display.
6. Apparatus according to claim 1, 3 or 5, including sensor monitor circuit means electrically associated with said temperature-to-voltage converter and said display means, for monitoring the output signal from said temperature-to-voltage converter and when said output signal falls outside set permissible limits, energizes the display means to exhibit a predetermined visual display.
7. In a closed circuit underwater breathing apparatus, comprising a breathing tube through which a diver may inhale and exhale breath-ing gas;
a re-breathing bag;
a canister containing a CO2 absorbent selected from the group consisting of soda lime and other suitable non-toxid alkali and alkaline earth metal hydroxides, disposed between said breathing tube and said re-breathing bag, such that fluid communication from said re-breathing bag to said breathing tube is achieved through said cannister;
inlet means in said re-breathing bag, a breathing gas reservoir;
gas conduit means for fluid communication between said inlet means and said breathing gas reservoir;
one-way valve means in said gas conduit means to permit breathing gas flow from said breathing gas reservoir to said re-breathing bag; and blow-off valve means connected with said re-breathing bag to permit pressure equalization, the improvement comprising providing an indicator comprising, temperature sensing means immersed in said absorbent for monitoring the temperature profile of the heat generated by the chemical reaction of the hydroxide and CO2;
temperature to voltage converter means for converting a sensed temperature reading to an electrical voltage signal;
temperature trend processing means for processing said electrical voltage signal into a selected electrical output signal characteristic of a temperature trend; and display means for converting said selected electrical output signal to a predetermined visual display indicative of the capacity of the CO2 absorbent to absorb CO2.
a re-breathing bag;
a canister containing a CO2 absorbent selected from the group consisting of soda lime and other suitable non-toxid alkali and alkaline earth metal hydroxides, disposed between said breathing tube and said re-breathing bag, such that fluid communication from said re-breathing bag to said breathing tube is achieved through said cannister;
inlet means in said re-breathing bag, a breathing gas reservoir;
gas conduit means for fluid communication between said inlet means and said breathing gas reservoir;
one-way valve means in said gas conduit means to permit breathing gas flow from said breathing gas reservoir to said re-breathing bag; and blow-off valve means connected with said re-breathing bag to permit pressure equalization, the improvement comprising providing an indicator comprising, temperature sensing means immersed in said absorbent for monitoring the temperature profile of the heat generated by the chemical reaction of the hydroxide and CO2;
temperature to voltage converter means for converting a sensed temperature reading to an electrical voltage signal;
temperature trend processing means for processing said electrical voltage signal into a selected electrical output signal characteristic of a temperature trend; and display means for converting said selected electrical output signal to a predetermined visual display indicative of the capacity of the CO2 absorbent to absorb CO2.
8. Apparatus according to claim 7, wherein said temperature sensing means is a thermistor.
9. Apparatus according to claim 8, wherein said temperature to voltage converter and said temperature trend processing means are disposed in a water-tight container, including water-tight electrical connections from said ther-mistor to said temperature to voltage converter and from said temperature trend processing means to said display means.
10. Apparatus according to claim 9, wherein said display means is a light-emitting diode located in the diver's face mask.
11. Apparatus according to claim 8, wherein the display means is a light emitting diode.
12. Apparatus according to claim 11, wherein the CO2 absorbent is soda lime.
13. Apparatus according to claim 12, including d.c. power supply means and monitor circuit means electrically associated with said d.c. power supply and said display means, for detecting when the power supply voltage falls below a set value and then to energize the display means to exhibit a predetermined visual display.
14. Apparatus according to claim 13, including sensor monitor circuit means electrically associated with said temperature-to-voltage converter and said display means, for monitoring the output signal from said temperature-to-voltage converter and when said output signal falls outside set permissible limits, energizes the display means to exhibit a predetermined visual display.
15. Apparatus according to claim 1 or 7, wherein the CO2 absorbent is soda lime of an average particle diameter of 1.68 - 3.36 m.m.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000350123A CA1141990A (en) | 1980-04-21 | 1980-04-21 | Soda lime half life indicator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000350123A CA1141990A (en) | 1980-04-21 | 1980-04-21 | Soda lime half life indicator |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1141990A true CA1141990A (en) | 1983-03-01 |
Family
ID=4116733
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000350123A Expired CA1141990A (en) | 1980-04-21 | 1980-04-21 | Soda lime half life indicator |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1141990A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5634426A (en) * | 1995-02-22 | 1997-06-03 | Tomlinson; Bruce | Absorption depletion indicators for anesthetic gas administration systems |
| GR1006177B (en) * | 2007-11-20 | 2008-12-02 | Αναργυρος Αναργυρου | Device for the measurement of expiry date of filters of gases masks and of filters of collective protection. |
-
1980
- 1980-04-21 CA CA000350123A patent/CA1141990A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5634426A (en) * | 1995-02-22 | 1997-06-03 | Tomlinson; Bruce | Absorption depletion indicators for anesthetic gas administration systems |
| GR1006177B (en) * | 2007-11-20 | 2008-12-02 | Αναργυρος Αναργυρου | Device for the measurement of expiry date of filters of gases masks and of filters of collective protection. |
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| MKEX | Expiry |