CA1158131A - Cartridge respirator with service life indicator - Google Patents
Cartridge respirator with service life indicatorInfo
- Publication number
- CA1158131A CA1158131A CA000377413A CA377413A CA1158131A CA 1158131 A CA1158131 A CA 1158131A CA 000377413 A CA000377413 A CA 000377413A CA 377413 A CA377413 A CA 377413A CA 1158131 A CA1158131 A CA 1158131A
- Authority
- CA
- Canada
- Prior art keywords
- indicator
- respirator
- cartridge
- sorbent bed
- colorimetric
- 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
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
-
- 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
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S55/00—Gas separation
- Y10S55/33—Gas mask canister
-
- 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
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S55/00—Gas separation
- Y10S55/34—Indicator and controllers
-
- 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
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S55/00—Gas separation
- Y10S55/35—Respirators and register filters
Abstract
161,441 CAN/LRS
Abstract Improvements in respirators and particularly in respirators containing visually observable indicator means for indicating the end of the service life of respirator cartridges for use in atmospheres containing hazardous vapors and/or gases are disclosed. In contrast to the prior art where indicator reliability may be reduced due to its incorporation in a localized pocket or in a window in the sorbent bed, the present invention utilizes a colorimetric indicator in sheet form which is positioned along the inner transparent sidewall of the respirator cartridge. This indicator reveals the remaining capacity of the entire sorbent bed rather than the condition of a small volume near the probe or window. In addition, the colorimetric indicators useful in the present invention undergo irreversible color changes when subjected to gases to be detected.
Abstract Improvements in respirators and particularly in respirators containing visually observable indicator means for indicating the end of the service life of respirator cartridges for use in atmospheres containing hazardous vapors and/or gases are disclosed. In contrast to the prior art where indicator reliability may be reduced due to its incorporation in a localized pocket or in a window in the sorbent bed, the present invention utilizes a colorimetric indicator in sheet form which is positioned along the inner transparent sidewall of the respirator cartridge. This indicator reveals the remaining capacity of the entire sorbent bed rather than the condition of a small volume near the probe or window. In addition, the colorimetric indicators useful in the present invention undergo irreversible color changes when subjected to gases to be detected.
Description
161,441 CAN/LRS
:
CARTRIDGE RESPIRATOR WITH SERVICE LIFE INDICATOR
Technical Field This invention relates to improvements in respirators and particularly to respirators containing means for indicating the end of the service life of respirator cartridges for use in atmospheres containing hazardous vapors and/or gases.
Background Art There is increasing interest by government agencies and the general public in protecting individuals against the harmful effects of toxic materials.
Respirators of the type employing filter cartridges or canisters are commonly used for protection against respiratory hazards which include toxic vapors and gases.
The respirator or only the cartridge is replaced when the end of service life indicator or device incorporated therein indicates insufficient adsorbent capacity remaining in the cartridge to justify its further or additional use.
Monitoring of personal exposure to hazardous materials is the subject of a number of studies of which the following are examples: Natusch, Sewell and Tanner, "Determination of H2S in Air--An Assessment of Impregnated Paper Tape Methods", Analytical Chemistry, volume 46, page 3 (1974); Schnakenberg, "A Passive Personal Sampler for Nitrogen Dioxide", Bureau of Mines Technical Progress Report 95 (1976); Ray, Carroll and Armstrong, "Evaluation of Small Color-Changing Carbon Monoxide Dosimeters", Bureau of Mines Rep. Invest. (1975); Palmer, "Personal Samplers for CO, NO and NO2 in Air", Bureau of Mines Report OFR 92-77 (1977) and Nichols, "Reactive Tapes for Automatic Environmental Analysis, Personal Vapor ~' 11581~1 Monitoring Badges for Industrial Workers", Mational Science Foundation Report NSF/RA - 780039 (1978).
-Colorimetric end of service life indicators areknown in the art. IJ.S. Patent No~ 4,154,586 ~and related German and British Patent Nos. 2,758,603 and 1,554,542, respectively) provide a visual means for indicating when vapor/gas cartridges have exhausted their capacity to provide respiratory protection at or below a hazardous concentration level. The indicator material comprises a catalytic agent for enhancing activation and reaction of the indicator agent.
U.S. Patent No. 1,537,519 discloses a ribbed window-type or a transparent canister wall respirator wherein the viewable absorbent is impregnated with an indicator. The patentee also discloses use of an indicator test strip (such as litmus paper) but only with the window-type canister. The patentee states that when use of his respirator is interrupted, the indicator may resume the color or appearance of the unspent indicator.
~nother window-type canister or cartridge with color changing indicator means incorporated therein is disclosed in U.S. Patent No. 3,966,440.
U.S. Patent No. 4,155,358 discloses a valveless chemical cartridge respirator for vinyl chloride monomer comprising a colorimetric end of service life indicator disposed across the path of air intake at the entrance of the cartridge.
U.S. Patent No. 4,146,887 discloses a gas or vapor sensing alarm device in an air purifying respirator for warning the wearer of hazardous levels of gases or vapors penetrating through the respirator cartridge.
These prior art end of service life indicators generally utilized granular cclorimetric indicator particles or other probes located in the sorbent bed. In contrast to the prior art where indicator reliability may be reduced due to its incorporation in a localized pocket or in a window in the sorbent bed, the present invention ~ 11581~1 utilizes an indicator means which reveals the remaining capacity of the entire sorbent bed rather than the condition of a small volume near the probe or window.
In addition, the colorimetric indicators useful S in the present invention undergo irreversible color changes when subjected to gases to be detected.
Summary of the Invention The present invention relates to a gas/vapor sorbent-containing cartridge or canister respirator con-taining a strip of colorimetric indicator fixed along asubstantial portion of the inner transparent sidewall of the cartridge or canister such that the indicator substance is oriented towards the sorbent bed. The colorimetric indicator may be a flat, sheet-like, self-supporting structure, porous throughout, or it may be coated onto a transparent substrate since the indicator substance is visually examined from the side oriented away from the sorbent bed. Vapors drawn into the sorbent bed react with the indicator substance causing a color change which corresponds'to the exhaustion of capacity of the sorbent bed. An irregular linear boundary forms between reacted and unreacted areas of the indicator substance.
This "leading edge" correlates with the channel patterns between adsorbent particles as the sorbent bed removes the hazardous gases or vapors passing through it. As use continues, this boundary moves in the direction of air flow from the front of the cartridge towards the back and the channel patterns of the reacted areas broaden and coalesce, indicating the areas of the sorbent bed which have been exposed to the hazardous vapors. The unreacted areas of the colorimetric indicator correspond to the portion of the sorbent bed which has not been exposed to the subject vapors and still has adsorp-tive capacity. The position of the boundary in relation to the depth of the sorbent bed relates directly to the unused capacity of the respirator. It is important that 81~1 the boundary on the colorimetric indicator indicates respirator failure before the "breakthrough" point of the hazardous gas or vapor.
To provide a margin of safety, it is preferred that penetration of the boundary to about 4/5 of the total bed depth be taken to indicate imminent failure of the respirator.
The present invention simplifies the determina-tion of the colorimetric indicator end point in cartridge or canister respirators. The color change appears as a distinct boundary which moves in a linear dimension rather than depending merely on a difference in color or color intensity. ~his distinct boundary allows for apprising the condition of the sorbent bed throughout the entire perimeter of the cartridge or canister as well as through-out its depth. The capacity of the respirator is not reduced as occurs in devices which require incorporation of the indicator material in a localized pocket. Inspec-tion of the colorimetric indicator reveals the remaining capacity of the sorbent bed rather than the condition of a small volume near the probe. The present invention allows for reuse of cartridge or canister respirators having re-maining protective capacity. Migration of vapors from exposed to unexposed portions of the sorbent bed between uses is visually detectable as a new and less irregular boundary and the remaining capacity of the respirator cartridge or canister is therefore apparent. In the present invention the colorimetric indicator is located where leakage of hazardous gas is most likely to occur, i.e., against the sidewall of the cartridge or canister, providing a further safeguard for the respirator wearer.
The present invention includes respirators having shells of different designs. They may be of a disposable-type or they may have replaceable canisters or cartridges. In all cases the canister or cartridge sidewall i5 transparent so that the colorimetric indicator is viewable therethroughr ` 11581~1 According to the present invention, therefore, there is provided a respirator for protection against toxic airborne material in the atmosphere comprising a shell, a canister or cartridge having a transparent sidewall within which is supported a gas/vapor sorbent bed, and a colorimetric indica-tor comprising a flat, sheet-like, self-supporting structure or said colori-metric indicator is coated onto a transparent substrate in a dry coating weight in the range of 13 to 62 g/m2 positioned along a substantial portion of the inner transparent sidewall of said respirator canister or cartridge such that the colorimetric indicator substance is oriented towards the sorbent bed, said colorimetric i.ndicator capable of undergoing an irreversible change in color concomitant with exposure to concentrations of toxic vapors and gases which appears as an irregular linear boundary formed between reacted and unreacted areas of the indicator substance which is viewable through the sidewall of said respirator canister or cartridge to visually indicate remaining capacity of the sorbent bed for said toxic airborne material.
-4a-, -~` 11581~
Brief Description of the Drawings In the accompanying drawing which illustrates the invention:
FIG. 1 is a front elevational view of a chemical cartridge respirator with colorimetric indicator sheet material fixed along the inner transparent sidewall, with parts thereof broken away.
FIG. 2 is an enlarged sectional view of a portion of the respirator cartridge of FIG. 1.
Detailed Description of the Invention The present invention relates to a respirator having a shell within which is supported a gas/vapor sorbent bed for removal of toxic airborne material from the atmosphere. The respirator contains a cartridge or canister having a transparent sidewall with a colorimetric indicator in strip form positioned along a substantial portion of its inner transparent sidewall such that the colorimetric indicator substance is oriented towards the sorbent bed. The colorimetric indicator is a self-supporting structure, porous throughout, or it has a transparent backing and is viewable through the entire sidewall of the respirator cartridge. The colorimetric indicator is capable of undergoing an irreversible change in color concomitant with exposure to concentrations of toxic vapors and gases which appears as an irregular linear boundary formed between reacted and unreacted areas of the indicator substance and is effective to indicate remaining capacity of the sorbent bed for said toxic airborne material.
Referring more particularly to FIGS. 1 and 2 of the drawing, 10 denotes a respirator comprising a plastic molded shell 11 having a chemical cartridge 12--with trans-parent sidewall 14, valve 13, and attachment bands 15.
Along the front edge of the inner side of sidewall 14 is - 35 positioned colorimetric indicator 16 comprising colorimetric indicator substance 18 coated on transparent bacXing 20. As indicated by arrows 22 (FIG. 2), the stream of air and gases and/or vapors passes through cartridge 12 when in use, coming into contact with sorbent bed 24 and colorimetric indicator 16. Linear boundary 26, visually observable through transparent sidewall 14 and transparent backing 20 indicates the depth of penetration of the hazardous gas into the cartridge and the remaining adsorbent capacity of the cartridge bed.
8acking 20, coated with colorimetric substance 18, is transparent. Suitable backing materials include polyester film, polycarbonate film, polypropylene film, vinyl films, and cellulosics.
Bench tests to determine indicator life and respirator service life were conducted by passing air containing a known concentration of challenge gas or vapor through the canister or cartridge and continuously analyzing the air exiting from the canister or cartridge with a detector calibrated for the challenge gas in ques-tion. Test air was humidified by passage over a vessel containing water at a temperature adequate to produce the desired relative-humidity. Acrylonitrile vapors (see EXAMPLES 4, 5, 6, and 7 below) were generated by feeding the liquid by variable speed syringe pump into a solvent vaporization chamber through which test air was swept.
Chlorine (see EXAMPLES 1 and 2 below) and sulfur dioxide (see EXAMPLES 1 and 3 below) were bled into the test air from cylinders of pure gas through mass flow controllers.
Concentration of challenge gas or vapor in the test stream and exiting from the canister or cartridge was determined with a suitable analytical instrument. Acrylonitrile was determined by a total hydrocarbon analyzer equipped with a flame ionization detector. Sulfur dioxide was determined by gas phase infrared spectrometry. Chlorine was deter-mined with an oxidant monitor using a microcoulomb sensor.
The invention is further illustrated by the following e~amples. As mentioned above, to provide a margin of safety, penetration of the boundary to about 4/5 -" 11581~11 of the total bed depth is taken to indicate imminent failure of the respirator.
EXAMPLE l A slurry of 33g of 33% alumina (Alcoa H-151~), S Aluminum Co. of America, aluminum oxide, surface area >350 m2/g) in water, 67g of 339~ kaolin (clay) in 1096 ethanol, 500mg indonl-ellol sodium salt, 200mg lithium hydroxide and 2g of 9% polyvinyl alcohol (Elvanol 71~30'9, DuPont, medium molecular weight, fully hydrolyzed) was 10 coated onto 50 micrometers thick polyester film base backing at 100 micrometer thickness wet. After air drying the sheet was cut into strips 2.54 cm wide; one such strip was laid along the inner sidewall, touching the front edge, of a clear plastic cartridge 3.2 cm deep and fixed 15 in position with adhesive tape. The cartridge was loaded with acid gas sorbent. Air containing 500 ppm sulfur dioxide at 50% relative humidity was passed through the cartridge at a flow rate of 64 liters per minute as prescribed in the standard National Institute of 20 Occupational Safety and Health (NIOSH) service life test.
The indicator changed color from dark blue to white on exposure to sulfur dioxide; the depth of penetration into the sorbent bed (boundary line on indicator sheet material) at various times is given in TABLE 1.
TABLE l Boundary Penetration Exposure Time Minimum Maximum 16 min. .32 cm 1.3 cm 44 min. 1.3 2.5 60 min. 1.9 2.5+
72 min. 2.5+ 2.5+
After 72 minutes exposure, the entire strip of indicator had changed to white and sulur dioxide in the air exiting from the respirator had reached 5 ppm, ~- 11581~1 indicating respirator failure.
A similar response was observed when chlorine was substituted for sulfur dioxide as the challenge gas.
Chlorine vapors, however, penetrated the sorbent bed more slowly and the service life was longer.
Two formulations were separately prepared by mixing 260g toluene, 50g silica gel (Syloid 244~, Davison Chemical, surface area >300 m2/g), 20g polyvinyl butyral (PVB) (Butvar B-76~, Monsanto, molecular weight 45,000 to 50,000, butyral content 88%) and 0.525g benzoyl leuco methylene blue (Formulation A); and 150g toluene, 150g titanium dioxide and 20g PVB (Formulation B). lOg of Formulation A and 0.45g of Formulation 8 were mixed to 15 produce a homogeneous suspension which was coated on 50 micrometers thick polyester film base at 100 micrometer wet thickness. A 2.54 cm strip of the dried coated film was attached inside a clear plastic cartridge as in EXAMPLE 1 and the cartridge was filled with acid gas 20 sorbent. The cartridge was challenged with 500 ppm chlorine in air at 50~ relative humidity flowing at 64 lpm. The exposed areas of the indicator changed from white to blue as chlorine penetrated the sorbent bed.
33g attagel (attapulgite clay) was added to 200g water, 333mg sodium salt of indophenol and 1.5g sodium hydroxide. The mixture was dispersed in a 1/2 liter jar with 300g of 1 cm balls by ball milling for 1 hour. The dispersion, uniformly blue in color, was coated on 50 30 micrometers thick polyester backing which had been primed using a high voltage corona so that the backing was water wettable. The film was coated 100 micrometers thick wet and dried to a coating weight of 25 g/m2. The drying was effected by a 14 amp hot air heat gun.
The indophenol/clay coated indicator film pre-I t581~1 g pared above was cut into strips 2.54 cm wide and a strip fixed to the inner sidewall of a clear plastic cartridge as described in EXAMPLE 1. The cartridge was loaded with commercial FCA~ ~hetlerite (Pittsburgh Activated Carbon, division of Calgon Corp., subsidiary of Merck and Co., Inc.). Air containing 500 ppm sulfur dioxide, 50%
relative humidity at 25C, was passed through the cartridge at a flow rate of 64 lpm. Effluent air was analyzed for sulfur dioxide content and the condition of the indicator, as the indicator color changed from dark blue to white, was noted at several times during the service life test. Data is given in TABLE 2.
Penetration of ~oundary on Indicator Time Minimum Maximum 5 min. 0 .95 cm 16 min. 1.3 cm 2.22 cm 32 min. 1.3 cm 2.S+ cm 44 min. 2.2 cm 2.5+ cm 74 min. 2.5+cm 2.5+ cm (indicator failure) After 80 minutes exposure to the challenge airstream, the respirator failed with the concentration of sulfur dioxide in the effluent air reaching 5 ppm.
A coating formulation was prepared from 60g 33%
alumina (Alcoa H-151~, Aluminum Co. of America) in water, 3.3g bentonite clay, 1~25g potassium permanganate and 150g water and coated on 50 micrometers thick polyester film base to provide a dry coating weight of 13 g/m2 Strips of the film cut to 2.54 cm widths were fitted in clear plastic cartridges as in EXAMPLE 1 after which the cartridges were loaded with granular activated carbon.
11~81~1 The cartridges were challenged with air at 50% relative humidity containing acrylonitrile (AN) at various concentrations and flow rates as given in the table below. The indicator changed from purple to light tan when exposed to acrylonitrile vapor. The indicator endpoint was reached when no purple color remained on the indicator. Respirator life refers to time elapsed until 4 ppm AN was present in air exiting from the respirator. The data are given in TABLE 3.
Acrylonitrile Indicator Life and Respirator Life Data ~Clay-Based Coating) AN Indicator Respirator Concentration Air Flow Life Life 1,000 ppm 64 lpm 65 min. 82 min.
1J 000 ppm 32 lpm 173 min. 185 min.
1,000 ppm 16 lpm 270 min. 350 min.
235 ppm 64 lpm 230 min. 275 min.
The data indicated that, as expected, changes in the concentration of AN and changes in its flow rate caused corresponding, but inverse, changes in indicator life and respirator life. In all cases the indicator failed before the respirator.
Vinyl chloride respirators with granular indicator material comprised of potassium permanganate deposited on alumina, prepared and constructed as described in United States Patent No. 4,155,358, were challenged ' . ' 11581~1 with acrylonitrile in air at 50% relative humidity at concentration and air flow conditions noted below.
Indicator life and respirator service life were determined. In all cases, the indicator life was too 5 short compared to respirator ~-ervice life (5 ppm penetration) to be useful and the data are set forth in TABLE 4.
Acrylonitrile Indicator Life and Respirator Life AN Indicator Respirator Concentration Air Flow Life Life 1,000 ppm 64 lpm<0.5 min. 50 min.
235 ppm 64 lpm2.0 min. 275 min.
ppm 64 lpm5.0 min. >200 min.
ppm 64 lpm15.0 min. >200 min.
235 ppm 16 lpm10.0 min. >200 min.
The data indicate that this prior art vinyl chloride respirator was not suitable for use with AN due 20 to the extremely short indicator life.
Three samples made as described in EXAMPLE 4 were exposed to 1,000 ppm A'7 in air at 50% relative humidity flowing at 64 lpm for different lengths of time. One 25 sample was exposed for 5 minutes, another for 10 minutes and another for 20 minutes. These partially used respirators were set aside in closed polyethylene bags except for brief test periods after 1, 3, 6 and 14 days.
During these tests, air at 50% relative humidity but 30 without added AN vapor, was passed through the cartridges at 64 lpm. The effluent air was analyzed for AN and indicator condition (depth of boundary penetration~ was noted. Results are given in TABLE 5.
-1 1$81~1 TA~LE 5 Acrylonitrile Desorption Data Initial Time ~lapsed Concentration Penetration of Exposure After Initial of AN in Boundary on 5TimeExposure Effluent Air Indicator Strip Minimum Maximum 5 min. 0 day 0 ppm 0.16 cm 1.11 cm 5 min. 1 day 0 ppm 1.3 cm 1. 4 cm 5 min. 3 day 0 ppm 2.2 cm 2.5 cm 105 min.6 day o ppm 2.5+ cm 2.5+ cm 5 min.16 day 0.6 ppm 2.5+ cm 2 .5+ cm 10 min.0 day 0 ppm 0.64 cm 1. 9 cm 10 min.1 day 0 ppm 1.9 cm 2.5 cm 10 min.3 day 0 ppm 2.5+ cm 2.5+ cm 1510 min.6 day 0.4 ppm 2.5+ cm 2.5+ cm 10 min.14 day 6.2 ppm 2.5+ cm 2.5+ cm 20 min.0 day 0 ppm 0.64 cm 1.9 cm 20 min.1 day 1.4 ppm 2.5+ cm 2.5+ cm 20 min.3 day 1.4 ppm 2.5+ cm 2.5+ cm 2020 min.6 day 10 ppm 2.5+ cm 2.5+ cm 20 min.14 day 40 ppm 2.5+ cm 2.5+ cm The data in the third column show that migration of AN occurs with time even under static air conditions.
Longer initial exposure times and longer lapse times after initial exposure contributed to desorption of acrylonitrile from the cartridge sorbent bed and subsequent failure of the respirator. In all cases the indicator warned of respirator failure before it occurred.
~1~81~1 The following coating formulations were prepared.
A. 80 gms 3% bentonite clay in water gms 36~ alumina (Alcoa H-151~, Aluminum Co. of Lmerica) slush in water 0.84 gms potassium permanganate B. 80 gms 3% bentonite clay in water 40 gms 36% alumina (Alcoa H-151~, Aluminum Co. of America) slush in water 0.42 gms potassium permanganate C. 80 gms 3% bentonite clay in water 26 gms 36% alumina (Alcoa H-151~, Aluminum Co. of America) slush in water 0.55 gms potassium permanganate Each sample was coated on 50 micrometers thick polyester film base at an orifice of 100 micrometers.
Indicator strips were mounted in cartridges as described in EXAMPLE 4 and challenged with air containing 10 ppm AN
and 50% relative humidity at 64 lpm flow. Indicator response in terms of color change, depth of boundary penetration after 20 minutes exposure and boundary penetration after two days aging of the partially used cartridge was identical for all three indicator samples.
Two other indicators were made by coating Formulation A at 50 micrometer orifice and 250 micrometer orifice. Response of these indicators in loaded cartridges to a challenge of 10 ppm AN in air at 64 lpm after 20 minutes was identical.
The data indicate that coating weight, permanganate loading and alumina/bentonite ratios can be varied to a certain extent without serious effect on 1 1~8131 indicator response. Varying coating thickness by a factor of 5, change in permanganate loading by a factor of 2, and change in alumina/bentonite ratio from 6/1 to 4/1, gave no change in results indicating that there was latitude in coating composition.
:
CARTRIDGE RESPIRATOR WITH SERVICE LIFE INDICATOR
Technical Field This invention relates to improvements in respirators and particularly to respirators containing means for indicating the end of the service life of respirator cartridges for use in atmospheres containing hazardous vapors and/or gases.
Background Art There is increasing interest by government agencies and the general public in protecting individuals against the harmful effects of toxic materials.
Respirators of the type employing filter cartridges or canisters are commonly used for protection against respiratory hazards which include toxic vapors and gases.
The respirator or only the cartridge is replaced when the end of service life indicator or device incorporated therein indicates insufficient adsorbent capacity remaining in the cartridge to justify its further or additional use.
Monitoring of personal exposure to hazardous materials is the subject of a number of studies of which the following are examples: Natusch, Sewell and Tanner, "Determination of H2S in Air--An Assessment of Impregnated Paper Tape Methods", Analytical Chemistry, volume 46, page 3 (1974); Schnakenberg, "A Passive Personal Sampler for Nitrogen Dioxide", Bureau of Mines Technical Progress Report 95 (1976); Ray, Carroll and Armstrong, "Evaluation of Small Color-Changing Carbon Monoxide Dosimeters", Bureau of Mines Rep. Invest. (1975); Palmer, "Personal Samplers for CO, NO and NO2 in Air", Bureau of Mines Report OFR 92-77 (1977) and Nichols, "Reactive Tapes for Automatic Environmental Analysis, Personal Vapor ~' 11581~1 Monitoring Badges for Industrial Workers", Mational Science Foundation Report NSF/RA - 780039 (1978).
-Colorimetric end of service life indicators areknown in the art. IJ.S. Patent No~ 4,154,586 ~and related German and British Patent Nos. 2,758,603 and 1,554,542, respectively) provide a visual means for indicating when vapor/gas cartridges have exhausted their capacity to provide respiratory protection at or below a hazardous concentration level. The indicator material comprises a catalytic agent for enhancing activation and reaction of the indicator agent.
U.S. Patent No. 1,537,519 discloses a ribbed window-type or a transparent canister wall respirator wherein the viewable absorbent is impregnated with an indicator. The patentee also discloses use of an indicator test strip (such as litmus paper) but only with the window-type canister. The patentee states that when use of his respirator is interrupted, the indicator may resume the color or appearance of the unspent indicator.
~nother window-type canister or cartridge with color changing indicator means incorporated therein is disclosed in U.S. Patent No. 3,966,440.
U.S. Patent No. 4,155,358 discloses a valveless chemical cartridge respirator for vinyl chloride monomer comprising a colorimetric end of service life indicator disposed across the path of air intake at the entrance of the cartridge.
U.S. Patent No. 4,146,887 discloses a gas or vapor sensing alarm device in an air purifying respirator for warning the wearer of hazardous levels of gases or vapors penetrating through the respirator cartridge.
These prior art end of service life indicators generally utilized granular cclorimetric indicator particles or other probes located in the sorbent bed. In contrast to the prior art where indicator reliability may be reduced due to its incorporation in a localized pocket or in a window in the sorbent bed, the present invention ~ 11581~1 utilizes an indicator means which reveals the remaining capacity of the entire sorbent bed rather than the condition of a small volume near the probe or window.
In addition, the colorimetric indicators useful S in the present invention undergo irreversible color changes when subjected to gases to be detected.
Summary of the Invention The present invention relates to a gas/vapor sorbent-containing cartridge or canister respirator con-taining a strip of colorimetric indicator fixed along asubstantial portion of the inner transparent sidewall of the cartridge or canister such that the indicator substance is oriented towards the sorbent bed. The colorimetric indicator may be a flat, sheet-like, self-supporting structure, porous throughout, or it may be coated onto a transparent substrate since the indicator substance is visually examined from the side oriented away from the sorbent bed. Vapors drawn into the sorbent bed react with the indicator substance causing a color change which corresponds'to the exhaustion of capacity of the sorbent bed. An irregular linear boundary forms between reacted and unreacted areas of the indicator substance.
This "leading edge" correlates with the channel patterns between adsorbent particles as the sorbent bed removes the hazardous gases or vapors passing through it. As use continues, this boundary moves in the direction of air flow from the front of the cartridge towards the back and the channel patterns of the reacted areas broaden and coalesce, indicating the areas of the sorbent bed which have been exposed to the hazardous vapors. The unreacted areas of the colorimetric indicator correspond to the portion of the sorbent bed which has not been exposed to the subject vapors and still has adsorp-tive capacity. The position of the boundary in relation to the depth of the sorbent bed relates directly to the unused capacity of the respirator. It is important that 81~1 the boundary on the colorimetric indicator indicates respirator failure before the "breakthrough" point of the hazardous gas or vapor.
To provide a margin of safety, it is preferred that penetration of the boundary to about 4/5 of the total bed depth be taken to indicate imminent failure of the respirator.
The present invention simplifies the determina-tion of the colorimetric indicator end point in cartridge or canister respirators. The color change appears as a distinct boundary which moves in a linear dimension rather than depending merely on a difference in color or color intensity. ~his distinct boundary allows for apprising the condition of the sorbent bed throughout the entire perimeter of the cartridge or canister as well as through-out its depth. The capacity of the respirator is not reduced as occurs in devices which require incorporation of the indicator material in a localized pocket. Inspec-tion of the colorimetric indicator reveals the remaining capacity of the sorbent bed rather than the condition of a small volume near the probe. The present invention allows for reuse of cartridge or canister respirators having re-maining protective capacity. Migration of vapors from exposed to unexposed portions of the sorbent bed between uses is visually detectable as a new and less irregular boundary and the remaining capacity of the respirator cartridge or canister is therefore apparent. In the present invention the colorimetric indicator is located where leakage of hazardous gas is most likely to occur, i.e., against the sidewall of the cartridge or canister, providing a further safeguard for the respirator wearer.
The present invention includes respirators having shells of different designs. They may be of a disposable-type or they may have replaceable canisters or cartridges. In all cases the canister or cartridge sidewall i5 transparent so that the colorimetric indicator is viewable therethroughr ` 11581~1 According to the present invention, therefore, there is provided a respirator for protection against toxic airborne material in the atmosphere comprising a shell, a canister or cartridge having a transparent sidewall within which is supported a gas/vapor sorbent bed, and a colorimetric indica-tor comprising a flat, sheet-like, self-supporting structure or said colori-metric indicator is coated onto a transparent substrate in a dry coating weight in the range of 13 to 62 g/m2 positioned along a substantial portion of the inner transparent sidewall of said respirator canister or cartridge such that the colorimetric indicator substance is oriented towards the sorbent bed, said colorimetric i.ndicator capable of undergoing an irreversible change in color concomitant with exposure to concentrations of toxic vapors and gases which appears as an irregular linear boundary formed between reacted and unreacted areas of the indicator substance which is viewable through the sidewall of said respirator canister or cartridge to visually indicate remaining capacity of the sorbent bed for said toxic airborne material.
-4a-, -~` 11581~
Brief Description of the Drawings In the accompanying drawing which illustrates the invention:
FIG. 1 is a front elevational view of a chemical cartridge respirator with colorimetric indicator sheet material fixed along the inner transparent sidewall, with parts thereof broken away.
FIG. 2 is an enlarged sectional view of a portion of the respirator cartridge of FIG. 1.
Detailed Description of the Invention The present invention relates to a respirator having a shell within which is supported a gas/vapor sorbent bed for removal of toxic airborne material from the atmosphere. The respirator contains a cartridge or canister having a transparent sidewall with a colorimetric indicator in strip form positioned along a substantial portion of its inner transparent sidewall such that the colorimetric indicator substance is oriented towards the sorbent bed. The colorimetric indicator is a self-supporting structure, porous throughout, or it has a transparent backing and is viewable through the entire sidewall of the respirator cartridge. The colorimetric indicator is capable of undergoing an irreversible change in color concomitant with exposure to concentrations of toxic vapors and gases which appears as an irregular linear boundary formed between reacted and unreacted areas of the indicator substance and is effective to indicate remaining capacity of the sorbent bed for said toxic airborne material.
Referring more particularly to FIGS. 1 and 2 of the drawing, 10 denotes a respirator comprising a plastic molded shell 11 having a chemical cartridge 12--with trans-parent sidewall 14, valve 13, and attachment bands 15.
Along the front edge of the inner side of sidewall 14 is - 35 positioned colorimetric indicator 16 comprising colorimetric indicator substance 18 coated on transparent bacXing 20. As indicated by arrows 22 (FIG. 2), the stream of air and gases and/or vapors passes through cartridge 12 when in use, coming into contact with sorbent bed 24 and colorimetric indicator 16. Linear boundary 26, visually observable through transparent sidewall 14 and transparent backing 20 indicates the depth of penetration of the hazardous gas into the cartridge and the remaining adsorbent capacity of the cartridge bed.
8acking 20, coated with colorimetric substance 18, is transparent. Suitable backing materials include polyester film, polycarbonate film, polypropylene film, vinyl films, and cellulosics.
Bench tests to determine indicator life and respirator service life were conducted by passing air containing a known concentration of challenge gas or vapor through the canister or cartridge and continuously analyzing the air exiting from the canister or cartridge with a detector calibrated for the challenge gas in ques-tion. Test air was humidified by passage over a vessel containing water at a temperature adequate to produce the desired relative-humidity. Acrylonitrile vapors (see EXAMPLES 4, 5, 6, and 7 below) were generated by feeding the liquid by variable speed syringe pump into a solvent vaporization chamber through which test air was swept.
Chlorine (see EXAMPLES 1 and 2 below) and sulfur dioxide (see EXAMPLES 1 and 3 below) were bled into the test air from cylinders of pure gas through mass flow controllers.
Concentration of challenge gas or vapor in the test stream and exiting from the canister or cartridge was determined with a suitable analytical instrument. Acrylonitrile was determined by a total hydrocarbon analyzer equipped with a flame ionization detector. Sulfur dioxide was determined by gas phase infrared spectrometry. Chlorine was deter-mined with an oxidant monitor using a microcoulomb sensor.
The invention is further illustrated by the following e~amples. As mentioned above, to provide a margin of safety, penetration of the boundary to about 4/5 -" 11581~11 of the total bed depth is taken to indicate imminent failure of the respirator.
EXAMPLE l A slurry of 33g of 33% alumina (Alcoa H-151~), S Aluminum Co. of America, aluminum oxide, surface area >350 m2/g) in water, 67g of 339~ kaolin (clay) in 1096 ethanol, 500mg indonl-ellol sodium salt, 200mg lithium hydroxide and 2g of 9% polyvinyl alcohol (Elvanol 71~30'9, DuPont, medium molecular weight, fully hydrolyzed) was 10 coated onto 50 micrometers thick polyester film base backing at 100 micrometer thickness wet. After air drying the sheet was cut into strips 2.54 cm wide; one such strip was laid along the inner sidewall, touching the front edge, of a clear plastic cartridge 3.2 cm deep and fixed 15 in position with adhesive tape. The cartridge was loaded with acid gas sorbent. Air containing 500 ppm sulfur dioxide at 50% relative humidity was passed through the cartridge at a flow rate of 64 liters per minute as prescribed in the standard National Institute of 20 Occupational Safety and Health (NIOSH) service life test.
The indicator changed color from dark blue to white on exposure to sulfur dioxide; the depth of penetration into the sorbent bed (boundary line on indicator sheet material) at various times is given in TABLE 1.
TABLE l Boundary Penetration Exposure Time Minimum Maximum 16 min. .32 cm 1.3 cm 44 min. 1.3 2.5 60 min. 1.9 2.5+
72 min. 2.5+ 2.5+
After 72 minutes exposure, the entire strip of indicator had changed to white and sulur dioxide in the air exiting from the respirator had reached 5 ppm, ~- 11581~1 indicating respirator failure.
A similar response was observed when chlorine was substituted for sulfur dioxide as the challenge gas.
Chlorine vapors, however, penetrated the sorbent bed more slowly and the service life was longer.
Two formulations were separately prepared by mixing 260g toluene, 50g silica gel (Syloid 244~, Davison Chemical, surface area >300 m2/g), 20g polyvinyl butyral (PVB) (Butvar B-76~, Monsanto, molecular weight 45,000 to 50,000, butyral content 88%) and 0.525g benzoyl leuco methylene blue (Formulation A); and 150g toluene, 150g titanium dioxide and 20g PVB (Formulation B). lOg of Formulation A and 0.45g of Formulation 8 were mixed to 15 produce a homogeneous suspension which was coated on 50 micrometers thick polyester film base at 100 micrometer wet thickness. A 2.54 cm strip of the dried coated film was attached inside a clear plastic cartridge as in EXAMPLE 1 and the cartridge was filled with acid gas 20 sorbent. The cartridge was challenged with 500 ppm chlorine in air at 50~ relative humidity flowing at 64 lpm. The exposed areas of the indicator changed from white to blue as chlorine penetrated the sorbent bed.
33g attagel (attapulgite clay) was added to 200g water, 333mg sodium salt of indophenol and 1.5g sodium hydroxide. The mixture was dispersed in a 1/2 liter jar with 300g of 1 cm balls by ball milling for 1 hour. The dispersion, uniformly blue in color, was coated on 50 30 micrometers thick polyester backing which had been primed using a high voltage corona so that the backing was water wettable. The film was coated 100 micrometers thick wet and dried to a coating weight of 25 g/m2. The drying was effected by a 14 amp hot air heat gun.
The indophenol/clay coated indicator film pre-I t581~1 g pared above was cut into strips 2.54 cm wide and a strip fixed to the inner sidewall of a clear plastic cartridge as described in EXAMPLE 1. The cartridge was loaded with commercial FCA~ ~hetlerite (Pittsburgh Activated Carbon, division of Calgon Corp., subsidiary of Merck and Co., Inc.). Air containing 500 ppm sulfur dioxide, 50%
relative humidity at 25C, was passed through the cartridge at a flow rate of 64 lpm. Effluent air was analyzed for sulfur dioxide content and the condition of the indicator, as the indicator color changed from dark blue to white, was noted at several times during the service life test. Data is given in TABLE 2.
Penetration of ~oundary on Indicator Time Minimum Maximum 5 min. 0 .95 cm 16 min. 1.3 cm 2.22 cm 32 min. 1.3 cm 2.S+ cm 44 min. 2.2 cm 2.5+ cm 74 min. 2.5+cm 2.5+ cm (indicator failure) After 80 minutes exposure to the challenge airstream, the respirator failed with the concentration of sulfur dioxide in the effluent air reaching 5 ppm.
A coating formulation was prepared from 60g 33%
alumina (Alcoa H-151~, Aluminum Co. of America) in water, 3.3g bentonite clay, 1~25g potassium permanganate and 150g water and coated on 50 micrometers thick polyester film base to provide a dry coating weight of 13 g/m2 Strips of the film cut to 2.54 cm widths were fitted in clear plastic cartridges as in EXAMPLE 1 after which the cartridges were loaded with granular activated carbon.
11~81~1 The cartridges were challenged with air at 50% relative humidity containing acrylonitrile (AN) at various concentrations and flow rates as given in the table below. The indicator changed from purple to light tan when exposed to acrylonitrile vapor. The indicator endpoint was reached when no purple color remained on the indicator. Respirator life refers to time elapsed until 4 ppm AN was present in air exiting from the respirator. The data are given in TABLE 3.
Acrylonitrile Indicator Life and Respirator Life Data ~Clay-Based Coating) AN Indicator Respirator Concentration Air Flow Life Life 1,000 ppm 64 lpm 65 min. 82 min.
1J 000 ppm 32 lpm 173 min. 185 min.
1,000 ppm 16 lpm 270 min. 350 min.
235 ppm 64 lpm 230 min. 275 min.
The data indicated that, as expected, changes in the concentration of AN and changes in its flow rate caused corresponding, but inverse, changes in indicator life and respirator life. In all cases the indicator failed before the respirator.
Vinyl chloride respirators with granular indicator material comprised of potassium permanganate deposited on alumina, prepared and constructed as described in United States Patent No. 4,155,358, were challenged ' . ' 11581~1 with acrylonitrile in air at 50% relative humidity at concentration and air flow conditions noted below.
Indicator life and respirator service life were determined. In all cases, the indicator life was too 5 short compared to respirator ~-ervice life (5 ppm penetration) to be useful and the data are set forth in TABLE 4.
Acrylonitrile Indicator Life and Respirator Life AN Indicator Respirator Concentration Air Flow Life Life 1,000 ppm 64 lpm<0.5 min. 50 min.
235 ppm 64 lpm2.0 min. 275 min.
ppm 64 lpm5.0 min. >200 min.
ppm 64 lpm15.0 min. >200 min.
235 ppm 16 lpm10.0 min. >200 min.
The data indicate that this prior art vinyl chloride respirator was not suitable for use with AN due 20 to the extremely short indicator life.
Three samples made as described in EXAMPLE 4 were exposed to 1,000 ppm A'7 in air at 50% relative humidity flowing at 64 lpm for different lengths of time. One 25 sample was exposed for 5 minutes, another for 10 minutes and another for 20 minutes. These partially used respirators were set aside in closed polyethylene bags except for brief test periods after 1, 3, 6 and 14 days.
During these tests, air at 50% relative humidity but 30 without added AN vapor, was passed through the cartridges at 64 lpm. The effluent air was analyzed for AN and indicator condition (depth of boundary penetration~ was noted. Results are given in TABLE 5.
-1 1$81~1 TA~LE 5 Acrylonitrile Desorption Data Initial Time ~lapsed Concentration Penetration of Exposure After Initial of AN in Boundary on 5TimeExposure Effluent Air Indicator Strip Minimum Maximum 5 min. 0 day 0 ppm 0.16 cm 1.11 cm 5 min. 1 day 0 ppm 1.3 cm 1. 4 cm 5 min. 3 day 0 ppm 2.2 cm 2.5 cm 105 min.6 day o ppm 2.5+ cm 2.5+ cm 5 min.16 day 0.6 ppm 2.5+ cm 2 .5+ cm 10 min.0 day 0 ppm 0.64 cm 1. 9 cm 10 min.1 day 0 ppm 1.9 cm 2.5 cm 10 min.3 day 0 ppm 2.5+ cm 2.5+ cm 1510 min.6 day 0.4 ppm 2.5+ cm 2.5+ cm 10 min.14 day 6.2 ppm 2.5+ cm 2.5+ cm 20 min.0 day 0 ppm 0.64 cm 1.9 cm 20 min.1 day 1.4 ppm 2.5+ cm 2.5+ cm 20 min.3 day 1.4 ppm 2.5+ cm 2.5+ cm 2020 min.6 day 10 ppm 2.5+ cm 2.5+ cm 20 min.14 day 40 ppm 2.5+ cm 2.5+ cm The data in the third column show that migration of AN occurs with time even under static air conditions.
Longer initial exposure times and longer lapse times after initial exposure contributed to desorption of acrylonitrile from the cartridge sorbent bed and subsequent failure of the respirator. In all cases the indicator warned of respirator failure before it occurred.
~1~81~1 The following coating formulations were prepared.
A. 80 gms 3% bentonite clay in water gms 36~ alumina (Alcoa H-151~, Aluminum Co. of Lmerica) slush in water 0.84 gms potassium permanganate B. 80 gms 3% bentonite clay in water 40 gms 36% alumina (Alcoa H-151~, Aluminum Co. of America) slush in water 0.42 gms potassium permanganate C. 80 gms 3% bentonite clay in water 26 gms 36% alumina (Alcoa H-151~, Aluminum Co. of America) slush in water 0.55 gms potassium permanganate Each sample was coated on 50 micrometers thick polyester film base at an orifice of 100 micrometers.
Indicator strips were mounted in cartridges as described in EXAMPLE 4 and challenged with air containing 10 ppm AN
and 50% relative humidity at 64 lpm flow. Indicator response in terms of color change, depth of boundary penetration after 20 minutes exposure and boundary penetration after two days aging of the partially used cartridge was identical for all three indicator samples.
Two other indicators were made by coating Formulation A at 50 micrometer orifice and 250 micrometer orifice. Response of these indicators in loaded cartridges to a challenge of 10 ppm AN in air at 64 lpm after 20 minutes was identical.
The data indicate that coating weight, permanganate loading and alumina/bentonite ratios can be varied to a certain extent without serious effect on 1 1~8131 indicator response. Varying coating thickness by a factor of 5, change in permanganate loading by a factor of 2, and change in alumina/bentonite ratio from 6/1 to 4/1, gave no change in results indicating that there was latitude in coating composition.
Claims (5)
1. A respirator for protection against toxic airborne material in the atmosphere comprising a shell, a canister or cartridge having a transparent sidewall within which is supported a gas/vapor sorbent bed, and a colorimetric indicator comprising a flat, sheet-like, self-supporting structure or said colorimetric indicator is coated onto a transparent substrate in a dry coating weight in the range of 13 to 62 g/m2 positioned along a substantial portion of the inner transparent sidewall of said respirator canister or cartridge such that the colorimetric indicator substance is oriented towards the sorbent bed, said colorimetric indicator capable of undergoing an irreversible change in color concomitant with exposure to concentrations of toxic vapors and gases which appears as an irregular linear boundary formed between reacted and unreacted areas of the indicator substance which is viewable through the sidewall of said respirator canister or cartridge to visually indicate remaining capacity of the sorbent bed for said toxic airborne material.
2. The respirator according to claim 1 wherein said transparent substrate of said colorimetric indicator is a flexible polyester film.
3. The respirator according to claim 1 wherein said colorimetric indicator comprises a clay mineral binder.
4. The respirator according to claim 1 wherein said colorimetric indicator substance comprises an indicator dye selected from potassium permanganate, sodium salt of indophenol, and benzoyl leuco methylene blue.
5. A respirator according to claim 1 wherein said canister or cartridge is replaceable.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US161,441 | 1980-06-20 | ||
| US06/161,441 US4326514A (en) | 1980-06-20 | 1980-06-20 | Cartridge respirator with service life indicator |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1158131A true CA1158131A (en) | 1983-12-06 |
Family
ID=22581181
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000377413A Expired CA1158131A (en) | 1980-06-20 | 1981-05-12 | Cartridge respirator with service life indicator |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US4326514A (en) |
| EP (1) | EP0042736A1 (en) |
| JP (1) | JPS5734869A (en) |
| CA (1) | CA1158131A (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US4421719A (en) * | 1980-06-20 | 1983-12-20 | Minnesota Mining And Manufacturing Company | Colorimetric indicators |
| US4488547A (en) * | 1982-09-07 | 1984-12-18 | Kenneth R. Bowers, Jr. | Face mask |
| US4793365A (en) * | 1984-09-14 | 1988-12-27 | R. J. Reynolds Tobacco Company | Smoking article |
| US5012805A (en) * | 1988-06-09 | 1991-05-07 | Muckerheide Myron C | Surgical mask barrier apparatus |
| CA2020503C (en) * | 1990-07-05 | 1998-11-17 | Jacques Lesage | Chemical cartridge for protective respiratory mask |
| US5109838A (en) * | 1990-07-19 | 1992-05-05 | Elam James O | Visually monitored anesthesia breathing circuit |
| DE4132680C2 (en) * | 1991-10-01 | 1994-02-10 | Draegerwerk Ag | Respirator mask with inner half mask and pollutant indicator |
| WO1994019056A1 (en) * | 1993-02-27 | 1994-09-01 | Paul Hartmann Ag | Respiratory system protection |
| WO1995012432A1 (en) * | 1993-11-05 | 1995-05-11 | Purecab Australia Pty. Ltd. | Respiratory filter indicator |
| US5634426A (en) * | 1995-02-22 | 1997-06-03 | Tomlinson; Bruce | Absorption depletion indicators for anesthetic gas administration systems |
| US6468222B1 (en) | 1999-08-02 | 2002-10-22 | Healthetech, Inc. | Metabolic calorimeter employing respiratory gas analysis |
| US6497756B1 (en) | 2000-09-12 | 2002-12-24 | North Safety Products, Inc. | Service life indicator for respirator cartridge |
| JP4209194B2 (en) * | 2001-03-29 | 2009-01-14 | コーニンクレッカ フィリップス エレクトロニクス エヌ ヴィ | Permeability measurement and inspection method and measurement and inspection apparatus |
| US20030105407A1 (en) * | 2001-11-30 | 2003-06-05 | Pearce, Edwin M. | Disposable flow tube for respiratory gas analysis |
| USD478660S1 (en) | 2002-07-01 | 2003-08-19 | Healthetech, Inc. | Disposable mask with sanitation insert for a respiratory analyzer |
| US6979361B2 (en) * | 2002-07-17 | 2005-12-27 | Gueorgui Milev Mihayiov | End of service life indicator for fluid filter |
| ATE333237T1 (en) * | 2002-09-16 | 2006-08-15 | Aerocrine Ab | GAS CLEANER |
| CA2509909C (en) * | 2002-12-20 | 2011-05-24 | Fiso Technologies Inc. | Method and sensor for detecting a chemical substance using an optically anisotropic material |
| US7442237B1 (en) * | 2004-09-16 | 2008-10-28 | The United States Of America As Represented By The Secretary Of The Army | Multi-agent end-of-service-life indicator for respirator filters |
| US8067110B2 (en) * | 2006-09-11 | 2011-11-29 | 3M Innovative Properties Company | Organic vapor sorbent protective device with thin-film indicator |
| US8328903B2 (en) * | 2008-05-30 | 2012-12-11 | Scott Technologies, Inc. | Determining effluent concentration profiles and service lives of air purifying respirator cartridges |
| EP2307103B1 (en) * | 2008-06-30 | 2018-12-19 | 3M Innovative Properties Company | Respirator system comprising an exposure indicating device |
| US7860662B2 (en) * | 2008-12-17 | 2010-12-28 | Scott Technologies, Inc. | Systems and methods for determining filter service lives |
| US8336543B2 (en) * | 2009-05-22 | 2012-12-25 | 3M Innovative Properties Company | Filter cartridge having cover for masking service life indicator |
| US8225782B2 (en) * | 2009-05-22 | 2012-07-24 | 3M Innovative Properties Company | Filter cartridge having location-registered view window for end-of-service-life-indicator (ESLI) |
| US8365723B2 (en) * | 2009-05-22 | 2013-02-05 | 3M Innovative Properties Company | Filter cartridge having cone of visibility for end-of-service-life-indicator (ESLI) |
| US8955515B2 (en) * | 2009-10-23 | 2015-02-17 | 3M Innovative Properties Company | Patterned chemical sensor having inert occluding layer |
| AU2011235311B2 (en) * | 2010-04-02 | 2013-09-26 | 3M Innovative Properties Company | Filter systems including patterned optical analyte sensors and optical readers |
| WO2011123403A1 (en) * | 2010-04-02 | 2011-10-06 | 3M Innovative Properties Company | Filter systems including optical analyte sensors and optical readers |
| US9061224B2 (en) | 2010-06-09 | 2015-06-23 | Cummins Filtration Ip Inc. | System for monitoring and indicating filter life |
| US8534123B2 (en) | 2010-06-17 | 2013-09-17 | Cummins Filtration Ip Inc. | Engine air filter replacement indication system |
| KR20130117775A (en) | 2010-09-23 | 2013-10-28 | 쓰리엠 이노베이티브 프로퍼티즈 컴파니 | Porous chemical indicator for gaseous media |
| EP2622321A4 (en) * | 2010-10-01 | 2014-03-19 | 3M Innovative Properties Co | Portable monitor for end of service life indication |
| CN103140749B (en) * | 2010-10-01 | 2016-03-30 | 3M创新有限公司 | For making the method that serviceable life, terminal was associated of monitoring device and filter cylinder |
| EP2665547B1 (en) * | 2011-01-20 | 2021-04-21 | Scott Technologies, Inc. | Conformal split planar flow air purifying filter |
| CN103443616B (en) | 2011-03-28 | 2017-05-31 | 3M创新有限公司 | Sensor comprising masking layer adhesive |
| US9192795B2 (en) | 2011-10-07 | 2015-11-24 | Honeywell International Inc. | System and method of calibration in a powered air purifying respirator |
| US9808656B2 (en) | 2012-01-09 | 2017-11-07 | Honeywell International Inc. | System and method of oxygen deficiency warning in a powered air purifying respirator |
| US9498656B2 (en) | 2012-07-11 | 2016-11-22 | B/E Aerospace, Inc. | Aircraft crew member protective breathing apparatus |
| US9751038B2 (en) | 2013-03-15 | 2017-09-05 | 3M Innovative Properties Company | End of service life indicating systems for layered filter cartridges |
| EP3528918B1 (en) * | 2016-10-21 | 2022-08-03 | Micropore, Inc. | Adsorbent cartridge with accurate visual indicator |
| DE102018203842A1 (en) * | 2018-03-14 | 2019-09-19 | Robert Bosch Gmbh | Sensor day for the detection of fine dust particles and dust mask |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1725893A (en) * | 1924-12-05 | 1929-08-27 | Mine Safety Appliances Co | Indicating gas-mask canister |
| US1537519A (en) * | 1924-12-05 | 1925-05-12 | Yablick Max | Indicating gas-mask canister |
| DE1135299B (en) * | 1954-12-30 | 1962-08-23 | Dr Hugo Stoltzenberg | Filter for respiratory protection devices or the like with a grainy filter material and a transparent filter housing |
| DE1134291B (en) * | 1956-05-28 | 1962-08-02 | Draegerwerk Ag | Procedure for indicating the approaching exhaustion of respiratory protection filters and suitable filters |
| DE977558C (en) * | 1957-11-19 | 1967-02-02 | Bundesrep Deutschland | Transparent filter insert for breathing apparatus |
| US4155358A (en) * | 1976-12-13 | 1979-05-22 | Minnesota Mining And Manufacturing Company | Respirator |
| CA1100419A (en) * | 1977-01-05 | 1981-05-05 | John A. Jones | Organic vapor respirator cartridge end-of-service indicator system and method |
| US4265635A (en) * | 1978-07-07 | 1981-05-05 | E. I. Du Pont De Nemours And Company | Gaseous contaminant dosimeter with diffusion device therefor and method |
| US4269804A (en) * | 1979-08-24 | 1981-05-26 | E. I. Du Pont De Nemours And Company | Self-contained gaseous contaminant dosimeter |
-
1980
- 1980-06-20 US US06/161,441 patent/US4326514A/en not_active Expired - Lifetime
-
1981
- 1981-05-12 CA CA000377413A patent/CA1158131A/en not_active Expired
- 1981-06-18 EP EP81302760A patent/EP0042736A1/en not_active Ceased
- 1981-06-19 JP JP9516681A patent/JPS5734869A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5734869A (en) | 1982-02-25 |
| EP0042736A1 (en) | 1981-12-30 |
| US4326514A (en) | 1982-04-27 |
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