CA1100419A - Organic vapor respirator cartridge end-of-service indicator system and method - Google Patents
Organic vapor respirator cartridge end-of-service indicator system and methodInfo
- Publication number
- CA1100419A CA1100419A CA293,496A CA293496A CA1100419A CA 1100419 A CA1100419 A CA 1100419A CA 293496 A CA293496 A CA 293496A CA 1100419 A CA1100419 A CA 1100419A
- Authority
- CA
- Canada
- Prior art keywords
- shell
- indicator
- agent
- sorbent
- carrier
- 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
Abstract
ORGANIC VAPOR RESPIRATOR CARTRIDGE
END-OF-SERVICE INDICATOR SYSTEM AND METHOD
Abstract of the Disclosure Providing visual means of determining when organic vapor/gas respirator cartridges have exhausted their capacity to provide respiratory protection at or below a hazard con-centration level. In inorganic oxidizing agent supported on a translucent carrier is incorporated in a respirator cartridge to oxidize organic vapor or gas contacting the agent in passing through the cartridge and to undergo a concomitant color change that can be observed as an indication of cart-ridge end-of-service life.
END-OF-SERVICE INDICATOR SYSTEM AND METHOD
Abstract of the Disclosure Providing visual means of determining when organic vapor/gas respirator cartridges have exhausted their capacity to provide respiratory protection at or below a hazard con-centration level. In inorganic oxidizing agent supported on a translucent carrier is incorporated in a respirator cartridge to oxidize organic vapor or gas contacting the agent in passing through the cartridge and to undergo a concomitant color change that can be observed as an indication of cart-ridge end-of-service life.
Description
Field of the Invention This inventlon relates to improvements in respirator cartridges with particular reference to means and method for indicating end-of-service life of organic vapor~gas respirator cartridges.
Summar~ of the Invention Broadly speaking the present invention provides the method of indicating end-of-service life of an organic vapor/
gas respirator cartridge having a shell containing an organic vapor/gas sorbent comprising: placing within the shell and adjacent the sorbent an indicator incorporating an organic ..
vapor/gas oxidizing agent supported in a substantial depth of a translucent carrier, the agent being characterized to undergo a drastic change in color concomitant with exposure to con-c~ntrations of organic vapors and gases substantially below a threshold limit value known to be safe to inhale; and arranging for the indicator to be visible from outside the cartridge shell whereby perception of the drastic change in color of the indicator may be taken as indication of end-of-service life of the respirator cartrldge.
~ he above method may be carried out by providing a respirator cartridge having a shell including perforated bottom and co~er sections and a wall extending therebetween, the bottom and cover sections permitting passage of air and gases through .:
the shell, and an organic vapor/gas sorbent within the shell between the bottom and cover for purif~ing the air and gases passing through the shell wherein the improvement comprises:
an organic vapor/gas oxidizing indicator agent characte.rized to undergo drastic change in color concomitant with exposure to ... ' ~' '.
'i~., .
sd/., -1-, ,:
~' , u~
concentra-tions of organic vapors and gases which are sub-stantially below a threshold limit value known to be safe to inhale; a -translucent carrier of substantial depth Eor supporti.ng the indicator agent, the carrier being porous and the agent being supported therewithin, the carrier with inclicator agent being disposed internally of the shell against the wall and surrounded by the sorbent for exposure to organic vapors and gases not absorbed by the sorbent; means for restraining the carrier against appreciable mixing with the sorbent; and window means in the shell through which the indicator agent may be viewed into the depth of the translucent carrier for ready perception of an incidence of color change of the agent and indication of an existing condition of exposure of the indicator agent to the unsafe concentrations of organic vapors and gases.
Thus, the present invention provides, in an organic vapor/gas respirator cartridge, visual.indicator means for determining when the cartridge has exhausted its capacity to provide respiratory protection at or below a ha~ar concentration le~el. The indicator comprises an organic vapor/gas oxidizing agent which undergoes a color change concomitant with exhaustion of the cartridge $orbent. The oxidizing agent is supported by a porous translucent carrier, e.g. granular silica gel.
One or more windows are provided in the cartridge shell against which the carrier with its oxid.izing agent is placed for ease of observation and is otherwise surrounded by the usual organic vapor~gas sorbent, e.g. activated carbon.
With formulation of the indicator being such that its color change is drastic and concomitant with the organic vapor/
gas sorbency of the respirator cartridge at a point where '.'L.'~
sd~ 2-- - : , , , - . , , .: - . . , :
, effluent air contains a concentration of the vapor or gas at or above an acceptable threshold limit value (TLV), perception of the color change through the window indicates cartridge exhaustion, i.e. end-of-service life.
This ability to visually indicate a condition of low concentration o:E o.rganic vapors or gases in a cartridge effluent affords a positive and dependable method of indicati.ng ca.rtridge exhaustion. It overcomes the need for complicated time-consuming and less than.optimally,.reliable conventional administra-tive , .
~.. .
sd/~ -2A-. :
4~5~
control procedures, their uncertainties and/or those of other presently practiced approaches to the problem~
Details of the invention will become more readily apparent from the following description when taken in con-junction with the accompanying drawings.
IN THE DRA~INGS
-Fiy. 1 is a side elevational view of an organic vapox/gas respirator cartridge embodying an end-of-service indicator system according to the invention;
Fig. 2 is an enlarged cross-sec~ional view of the cartridge taken generally along line 2-2 of Fig. 1, and Fig. 3 is a fragmentary cross-sectional view taken from the position of line 3-3 in Fig. 2 and looking in the direction of the arrows~
DESCRIPTION O~ THE PREFERRED EMBODIMENTS
The present invention provides/ in an organic vapor/
gas respirator cartridge 10, an indicator 12 which may be used to determine end-of-service life of the cartridge.
The indicator 12 comprises an organic vapor/gas 20. oxidizing agent suppor-ted by a poxous translucent carrier 14 of, or~example, granular silica gel and undergoes a color change concomi-tant with exhaustion of the cartridge sorbent 16 which may, for example, comprise the customary activated gran-ular carbon. The oxidizing agent being, for example, a dried solution of sodium dichromate/ water and sulfuric acid deposit-ed upon and throughout th~ porous carrier 14 cannot be illus-trated in the drawings and, accordingly, the granular carrier 14 will be hereinafter referred to as indicator 14, .it being understood that a color change of the oxidizing agent will be perceived as a change of color of the translucent granular ., Pg/- - 3 -:, , , , ' ~'' '': '' . - :
carrier.
In a preferred embodiment of the invention, a conventional respirator car-tridge shell 18 is provided with one or more apertures 20~ each covered :internally or ex-ternally as illustrated with a transparent window 22 which, in its simplest form may comprise a strip of heavy-duty transparent plastic tape.
Behind each window 22 J i.e. internally of shell 18, and fixed to shell 18 is a foraminous barrier 24 of fine mesh plastic or metallic screen functioning to res-train indicator 14 in the illustrated position adjacent window 22 for viewing before, duxing and/or after use of cartridge 10. The usual organic vapor/gas sorbent 16 is caused to fill the remaining interior of shell 18 around barriers 24.
. Cartridge 10 is provided with foraminous opposite sides 26 and 28 which may, as illustrated, comprise a per~
forated cover 26 and a similarly perforated bottom 28. It is to be understood th.at the particular desi.gn of shell 18, including parts 26 and 28 may be ~aried to meet particular requirements without departure from the spirit of the invention. This-invention relates more parti:cularly to the adaptati.on of the above-described indicator 14 to respirator cartridges in ~eneral regardless of their shapes, $izes, types of vaporJgas sorbents and/or o-ther such design para meters.
Top and bottom fill pads 30 and 32 of porous material such as single or multipl.e layers of felt, gauze and/or other fabric ar~ provided to suppor.t the ac-tivated carbon sorbent 16, i.e. prevent loss of its particles of pg/, ~t finer mesh through foraminous parts 26 and 28 oE the respirator car-tridge.
It should be apparent that the illustrated screen-ing at top and bottom of barrier 24 may be eliminated if desired. In such a case, sorbent 16 would first be brought to a level beneath barrier 24, indicator 14 is added there-above within the confines of the sides of barrier 24 and the cartridge finally completely filled with sorbent 16. In-dicator 14 would thus be held in place ~y top and bottom con-tact with the material oE sorbent 16 in the finished product.
In a preferred embodiment of the invention, in-dicator 14 is comprised of a reagent grade sodium dichromate and a rea~ent grade concentrated sulfuric acid suppoxted by the carrier of granular silica gel. The silica gel ~eing of from 3 to 3a mes~, for example, and inert, amorphous and porous is caused to absorb the sodium dichromate-sulfuric acid oxidizing agent, this absorpkion being purely physical.
An exemplary desira~le and highly effective for-mulation for indicator 14 comprises, i`n approximately the following proportions:
30 grams Na2Cr2Q7 30 ml concentrated H2SO~
- 200 ml distilled H2O
40 grams silica gel The sodium dichromate is preferably first dissolved in the water. The sulfuric acid is next slowly added to the sodium dichromate-water solut~on. The resulting mixture is then allowed to cool and, with constant stirring, the silica gel is added. A-Eter being allowed to stand for a substantial ~ period oE time, e.g. two hours, excess solution is decanted Pg/ - 5 -. - . :
::
- . . . ::: :
., -4~
~ff and the silica gel is dried, e.g, at approximatel~r225F in an air-circulating oven, for approximately 3 hours. The thus produced indicator 14 may be stored in a gas-tight container. It is to be understood that K2Cr207 may be subs-tituted for the sodium dichromate if desired~
Actual evaluations of the foregoing sodium dichromate indicator 14 formulation which exemplify its ability to indicate when low concentrat.ions of organic vapor/gas have penetrated cartridge 10 were conducted.
These involved passing through a freshly prepared cartri~ge 10. a challenge concentration of 1000 parts per million (ppm) by volume in each evaluation of a vapor selected :Erom one :
of three common groups of organic vapors, namely; an aro-matic c~pound (e.~g. benzene).; a chlorinated aliphatic compound (,e.g. l,l,l-trichloroeth.ane); and an aliphatic ketone t`e.g. butanone).. In each case, the challenge con-centration of 1000 ppm of vapor in air was caused to pass through the cartridge at a flow rate of appro~imately 64 liters per minute at 25 C and 5Q percent relative humidity.
~0 It was then determined when the concentration of vapor in the ef1uent air reached 5 ppm by volume.
It i`s pointed out that this,. e~.fluent concentration level was selected as a reference point for the reason that the a~ore-mentioned vapors have threshold llmit values (TLV~
far in excess of 5 ppm, as do many other organic vapors of the afore-mentioned three groups. Accordingly, this concen-tration indicates a conservative lower limit which may be ' considered as establishing a suitable criteria for an in-dica-tor system to respond to organic vapors. The TLV con-centration is a level recommended by the American Conference P~/.. : - 6 -.
''' .
of Governmental Industrial ~Iyqienists as being safe.
These evaluations were conducted both with and without hiqh humidity equilibration. In the former in-stances, the cartridges were preconditioned by passing 85 percent relative humidity air through them for approximately 6 hours at a flow rate of 25 liters per minute prior to testing. In all cases, the concentration of ~apor in the effluent cartridges were monitored by a calibrated Wilks Miran I Single Beam IR Gas ~ectr,al Photometer and the 5 ppm concentration level was correla-ted with a visual color change in the oxidizing agent.
Results of the evaluations ~e,re t AT 5 ppm VAPOR
CONC~NTRATION IN
COLOR OF INDICATOR 14 E~FLUENT FROM
VAPO~ BEFORE VAPOR TEST CARTRIDGE l0
Summar~ of the Invention Broadly speaking the present invention provides the method of indicating end-of-service life of an organic vapor/
gas respirator cartridge having a shell containing an organic vapor/gas sorbent comprising: placing within the shell and adjacent the sorbent an indicator incorporating an organic ..
vapor/gas oxidizing agent supported in a substantial depth of a translucent carrier, the agent being characterized to undergo a drastic change in color concomitant with exposure to con-c~ntrations of organic vapors and gases substantially below a threshold limit value known to be safe to inhale; and arranging for the indicator to be visible from outside the cartridge shell whereby perception of the drastic change in color of the indicator may be taken as indication of end-of-service life of the respirator cartrldge.
~ he above method may be carried out by providing a respirator cartridge having a shell including perforated bottom and co~er sections and a wall extending therebetween, the bottom and cover sections permitting passage of air and gases through .:
the shell, and an organic vapor/gas sorbent within the shell between the bottom and cover for purif~ing the air and gases passing through the shell wherein the improvement comprises:
an organic vapor/gas oxidizing indicator agent characte.rized to undergo drastic change in color concomitant with exposure to ... ' ~' '.
'i~., .
sd/., -1-, ,:
~' , u~
concentra-tions of organic vapors and gases which are sub-stantially below a threshold limit value known to be safe to inhale; a -translucent carrier of substantial depth Eor supporti.ng the indicator agent, the carrier being porous and the agent being supported therewithin, the carrier with inclicator agent being disposed internally of the shell against the wall and surrounded by the sorbent for exposure to organic vapors and gases not absorbed by the sorbent; means for restraining the carrier against appreciable mixing with the sorbent; and window means in the shell through which the indicator agent may be viewed into the depth of the translucent carrier for ready perception of an incidence of color change of the agent and indication of an existing condition of exposure of the indicator agent to the unsafe concentrations of organic vapors and gases.
Thus, the present invention provides, in an organic vapor/gas respirator cartridge, visual.indicator means for determining when the cartridge has exhausted its capacity to provide respiratory protection at or below a ha~ar concentration le~el. The indicator comprises an organic vapor/gas oxidizing agent which undergoes a color change concomitant with exhaustion of the cartridge $orbent. The oxidizing agent is supported by a porous translucent carrier, e.g. granular silica gel.
One or more windows are provided in the cartridge shell against which the carrier with its oxid.izing agent is placed for ease of observation and is otherwise surrounded by the usual organic vapor~gas sorbent, e.g. activated carbon.
With formulation of the indicator being such that its color change is drastic and concomitant with the organic vapor/
gas sorbency of the respirator cartridge at a point where '.'L.'~
sd~ 2-- - : , , , - . , , .: - . . , :
, effluent air contains a concentration of the vapor or gas at or above an acceptable threshold limit value (TLV), perception of the color change through the window indicates cartridge exhaustion, i.e. end-of-service life.
This ability to visually indicate a condition of low concentration o:E o.rganic vapors or gases in a cartridge effluent affords a positive and dependable method of indicati.ng ca.rtridge exhaustion. It overcomes the need for complicated time-consuming and less than.optimally,.reliable conventional administra-tive , .
~.. .
sd/~ -2A-. :
4~5~
control procedures, their uncertainties and/or those of other presently practiced approaches to the problem~
Details of the invention will become more readily apparent from the following description when taken in con-junction with the accompanying drawings.
IN THE DRA~INGS
-Fiy. 1 is a side elevational view of an organic vapox/gas respirator cartridge embodying an end-of-service indicator system according to the invention;
Fig. 2 is an enlarged cross-sec~ional view of the cartridge taken generally along line 2-2 of Fig. 1, and Fig. 3 is a fragmentary cross-sectional view taken from the position of line 3-3 in Fig. 2 and looking in the direction of the arrows~
DESCRIPTION O~ THE PREFERRED EMBODIMENTS
The present invention provides/ in an organic vapor/
gas respirator cartridge 10, an indicator 12 which may be used to determine end-of-service life of the cartridge.
The indicator 12 comprises an organic vapor/gas 20. oxidizing agent suppor-ted by a poxous translucent carrier 14 of, or~example, granular silica gel and undergoes a color change concomi-tant with exhaustion of the cartridge sorbent 16 which may, for example, comprise the customary activated gran-ular carbon. The oxidizing agent being, for example, a dried solution of sodium dichromate/ water and sulfuric acid deposit-ed upon and throughout th~ porous carrier 14 cannot be illus-trated in the drawings and, accordingly, the granular carrier 14 will be hereinafter referred to as indicator 14, .it being understood that a color change of the oxidizing agent will be perceived as a change of color of the translucent granular ., Pg/- - 3 -:, , , , ' ~'' '': '' . - :
carrier.
In a preferred embodiment of the invention, a conventional respirator car-tridge shell 18 is provided with one or more apertures 20~ each covered :internally or ex-ternally as illustrated with a transparent window 22 which, in its simplest form may comprise a strip of heavy-duty transparent plastic tape.
Behind each window 22 J i.e. internally of shell 18, and fixed to shell 18 is a foraminous barrier 24 of fine mesh plastic or metallic screen functioning to res-train indicator 14 in the illustrated position adjacent window 22 for viewing before, duxing and/or after use of cartridge 10. The usual organic vapor/gas sorbent 16 is caused to fill the remaining interior of shell 18 around barriers 24.
. Cartridge 10 is provided with foraminous opposite sides 26 and 28 which may, as illustrated, comprise a per~
forated cover 26 and a similarly perforated bottom 28. It is to be understood th.at the particular desi.gn of shell 18, including parts 26 and 28 may be ~aried to meet particular requirements without departure from the spirit of the invention. This-invention relates more parti:cularly to the adaptati.on of the above-described indicator 14 to respirator cartridges in ~eneral regardless of their shapes, $izes, types of vaporJgas sorbents and/or o-ther such design para meters.
Top and bottom fill pads 30 and 32 of porous material such as single or multipl.e layers of felt, gauze and/or other fabric ar~ provided to suppor.t the ac-tivated carbon sorbent 16, i.e. prevent loss of its particles of pg/, ~t finer mesh through foraminous parts 26 and 28 oE the respirator car-tridge.
It should be apparent that the illustrated screen-ing at top and bottom of barrier 24 may be eliminated if desired. In such a case, sorbent 16 would first be brought to a level beneath barrier 24, indicator 14 is added there-above within the confines of the sides of barrier 24 and the cartridge finally completely filled with sorbent 16. In-dicator 14 would thus be held in place ~y top and bottom con-tact with the material oE sorbent 16 in the finished product.
In a preferred embodiment of the invention, in-dicator 14 is comprised of a reagent grade sodium dichromate and a rea~ent grade concentrated sulfuric acid suppoxted by the carrier of granular silica gel. The silica gel ~eing of from 3 to 3a mes~, for example, and inert, amorphous and porous is caused to absorb the sodium dichromate-sulfuric acid oxidizing agent, this absorpkion being purely physical.
An exemplary desira~le and highly effective for-mulation for indicator 14 comprises, i`n approximately the following proportions:
30 grams Na2Cr2Q7 30 ml concentrated H2SO~
- 200 ml distilled H2O
40 grams silica gel The sodium dichromate is preferably first dissolved in the water. The sulfuric acid is next slowly added to the sodium dichromate-water solut~on. The resulting mixture is then allowed to cool and, with constant stirring, the silica gel is added. A-Eter being allowed to stand for a substantial ~ period oE time, e.g. two hours, excess solution is decanted Pg/ - 5 -. - . :
::
- . . . ::: :
., -4~
~ff and the silica gel is dried, e.g, at approximatel~r225F in an air-circulating oven, for approximately 3 hours. The thus produced indicator 14 may be stored in a gas-tight container. It is to be understood that K2Cr207 may be subs-tituted for the sodium dichromate if desired~
Actual evaluations of the foregoing sodium dichromate indicator 14 formulation which exemplify its ability to indicate when low concentrat.ions of organic vapor/gas have penetrated cartridge 10 were conducted.
These involved passing through a freshly prepared cartri~ge 10. a challenge concentration of 1000 parts per million (ppm) by volume in each evaluation of a vapor selected :Erom one :
of three common groups of organic vapors, namely; an aro-matic c~pound (e.~g. benzene).; a chlorinated aliphatic compound (,e.g. l,l,l-trichloroeth.ane); and an aliphatic ketone t`e.g. butanone).. In each case, the challenge con-centration of 1000 ppm of vapor in air was caused to pass through the cartridge at a flow rate of appro~imately 64 liters per minute at 25 C and 5Q percent relative humidity.
~0 It was then determined when the concentration of vapor in the ef1uent air reached 5 ppm by volume.
It i`s pointed out that this,. e~.fluent concentration level was selected as a reference point for the reason that the a~ore-mentioned vapors have threshold llmit values (TLV~
far in excess of 5 ppm, as do many other organic vapors of the afore-mentioned three groups. Accordingly, this concen-tration indicates a conservative lower limit which may be ' considered as establishing a suitable criteria for an in-dica-tor system to respond to organic vapors. The TLV con-centration is a level recommended by the American Conference P~/.. : - 6 -.
''' .
of Governmental Industrial ~Iyqienists as being safe.
These evaluations were conducted both with and without hiqh humidity equilibration. In the former in-stances, the cartridges were preconditioned by passing 85 percent relative humidity air through them for approximately 6 hours at a flow rate of 25 liters per minute prior to testing. In all cases, the concentration of ~apor in the effluent cartridges were monitored by a calibrated Wilks Miran I Single Beam IR Gas ~ectr,al Photometer and the 5 ppm concentration level was correla-ted with a visual color change in the oxidizing agent.
Results of the evaluations ~e,re t AT 5 ppm VAPOR
CONC~NTRATION IN
COLOR OF INDICATOR 14 E~FLUENT FROM
VAPO~ BEFORE VAPOR TEST CARTRIDGE l0
2-Butanone orange dark green or ~lack ~meth~lethylketonel l,l,l-Trichloroethane orange dark green or black Benzene orange dark green 2-Butanone orangea dark green or blacka l,l,l-Trichlo~oethane orangea dark green or blacka Benzene orangea dark greena a=indicates results af-ter high humidity equilibration.
The oxidatlon recluction reactions for orqanic vapors causing indicator l4 color change are, a-t least to some degree catalyzed by light passing into and throuqh the translucent silica gel granules.
It should be apparent from the foregoing that the inc1icator system of the present invention is reaaily adaptable to ~arious types and/or forms of respirator cartridges other than that s~own herein for purposes of illustra-tion and that - ~ ~ 7 . :: : :
- . . : : :. . . . . ~ .
, : ' ' - .-: :. '. , : -4~
various modifications and adaptations of the precise chemical and mechanical forms oE the invention here shown and described may also be made to sui`t particular requirements withou-t departure from the scope of the in-vention. For example, -the cartridge shell 18 may be form-ed in part or entirely of a transparent material with the shell itself ~unctioning as window 22. Also, in connection with matters of selecting a proper carrier for indicator 14, the carrier may comprise an opaque material such as 10porous pum;ce or a molecular sieve. In such a case, how-ever, only the exterior coating of the oxidizing agent will serve as the color indicator.
pg/ !i~ - 8 -, . . . .
:' ': - ' , :'' . ~ '
The oxidatlon recluction reactions for orqanic vapors causing indicator l4 color change are, a-t least to some degree catalyzed by light passing into and throuqh the translucent silica gel granules.
It should be apparent from the foregoing that the inc1icator system of the present invention is reaaily adaptable to ~arious types and/or forms of respirator cartridges other than that s~own herein for purposes of illustra-tion and that - ~ ~ 7 . :: : :
- . . : : :. . . . . ~ .
, : ' ' - .-: :. '. , : -4~
various modifications and adaptations of the precise chemical and mechanical forms oE the invention here shown and described may also be made to sui`t particular requirements withou-t departure from the scope of the in-vention. For example, -the cartridge shell 18 may be form-ed in part or entirely of a transparent material with the shell itself ~unctioning as window 22. Also, in connection with matters of selecting a proper carrier for indicator 14, the carrier may comprise an opaque material such as 10porous pum;ce or a molecular sieve. In such a case, how-ever, only the exterior coating of the oxidizing agent will serve as the color indicator.
pg/ !i~ - 8 -, . . . .
:' ': - ' , :'' . ~ '
Claims (7)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A respirator cartridge having a shell including perforated bottom and cover sections and a wall extending therebetween, said bottom and cover sections permitting passage of air and gases through the shell, and an organic vapor/gas sorbent within said shell between said bottom and cover for purifying said air and gases passing through said shell wherein the improvement comprises:
an organic vapor/gas oxidizing indicator agent characterized to undergo drastic change in color concomitant with exposure to concentrations of organic vapors and gases which are substantially below a threshold limit value known to be safe to inhale;
a translucent carrier of substantial depth for sup-porting said indicator agent, said carrier being porous and said agent being supported therewithin, said carrier with indicator agent being disposed internally of said shell against said wall and surrounded by said sorbent for exposure to organic vapors and gases not absorbed by said sorbent;
means for restraining said carrier against appreciable mixing with said sorbent; and window means in said shell through which said indicator agent may be viewed into the depth of said translucent carrier for ready perception of an incidence of color change of said agent and indication of an existing condition of exposure of said indicator agent to said unsafe concentrations of organic vapors and gases.
an organic vapor/gas oxidizing indicator agent characterized to undergo drastic change in color concomitant with exposure to concentrations of organic vapors and gases which are substantially below a threshold limit value known to be safe to inhale;
a translucent carrier of substantial depth for sup-porting said indicator agent, said carrier being porous and said agent being supported therewithin, said carrier with indicator agent being disposed internally of said shell against said wall and surrounded by said sorbent for exposure to organic vapors and gases not absorbed by said sorbent;
means for restraining said carrier against appreciable mixing with said sorbent; and window means in said shell through which said indicator agent may be viewed into the depth of said translucent carrier for ready perception of an incidence of color change of said agent and indication of an existing condition of exposure of said indicator agent to said unsafe concentrations of organic vapors and gases.
2. The improvement according to claim 1 wherein said carrier is a porous granular silica gel and said oxidizing indicator agent is supported upon and within said silica gel and comprises a formulation of sodium dichromate, sulfuric acid and water from which the liquid constituents have been evaporated.
3. The improvement according to claim 2 wherein potassium dichromate is substituted for said sodium dichromate.
4. The improvement according to claim 2 wherein said indicator agent is formulated of the following approximate pro-portions of ingredients:
30 grams Na2Cr2O7 30 ml concentrated H2SO4 200 ml distilled H2O
and said ingredients are supported by approximately 40 grams silica gel.
30 grams Na2Cr2O7 30 ml concentrated H2SO4 200 ml distilled H2O
and said ingredients are supported by approximately 40 grams silica gel.
5. The improvement according to claim 1 wherein said retaining means includes foraminous barrier means adjacent said window means, said barrier means retaining said translucent carrier in place against said window means and preventing appreciable mixing thereof with said vapor/gas sorbent.
6. The improvement according to claim 5 wherein said cartridge includes a plurality of said window means and barrier means, the latter supporting said indicator agent in each case.
7. The method of indicating end-of-service life of an organic vapor/gas respirator cartridge having a shell containing an organic vapor/gas sorbent comprising:
placing within said shell and adjacent said sorbent an indicator incorporating an organic vapor/gas oxidizing agent supported in a substantial depth of a translucent carrier, said agent being characterized to undergo a drastic change in color concomitant with exposure to concentrations of organic vapors and gases substantially below a threshold limit value known to be safe to inhale; and arranging for said indicator to be visible from out-side said cartridge shell whereby perception of said drastic change in color of said indicator may be taken as indication of end-of-service life of said respirator cartridge.
placing within said shell and adjacent said sorbent an indicator incorporating an organic vapor/gas oxidizing agent supported in a substantial depth of a translucent carrier, said agent being characterized to undergo a drastic change in color concomitant with exposure to concentrations of organic vapors and gases substantially below a threshold limit value known to be safe to inhale; and arranging for said indicator to be visible from out-side said cartridge shell whereby perception of said drastic change in color of said indicator may be taken as indication of end-of-service life of said respirator cartridge.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US75710577A | 1977-01-05 | 1977-01-05 | |
| US757,105 | 1977-01-05 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1100419A true CA1100419A (en) | 1981-05-05 |
Family
ID=25046371
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA293,496A Expired CA1100419A (en) | 1977-01-05 | 1977-12-20 | Organic vapor respirator cartridge end-of-service indicator system and method |
Country Status (6)
| Country | Link |
|---|---|
| JP (2) | JPS5385993A (en) |
| BR (1) | BR7800046A (en) |
| CA (1) | CA1100419A (en) |
| DE (1) | DE2758603A1 (en) |
| GB (1) | GB1554542A (en) |
| HK (1) | HK22181A (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 |
| US9751038B2 (en) | 2013-03-15 | 2017-09-05 | 3M Innovative Properties Company | End of service life indicating systems for layered filter cartridges |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4326514A (en) * | 1980-06-20 | 1982-04-27 | Minnesota Mining And Manufacturing Company | Cartridge respirator with service life indicator |
| US4365627A (en) * | 1980-09-22 | 1982-12-28 | The Dow Chemical Company | Filter-type respirator canister |
| GB2119659B (en) * | 1982-04-28 | 1985-10-02 | Mine Safety Appliances Co | Breathing device having irreversible moisture indicator |
| DE3445639A1 (en) * | 1984-12-14 | 1986-06-26 | Drägerwerk AG, 2400 Lübeck | COLORIMETRIC INDICATOR TO INDICATE THE EXHAUST OF GAS FILTERS |
| DE3610492A1 (en) * | 1986-03-27 | 1987-10-01 | Draegerwerk Ag | RESPIRATOR |
| US4886058A (en) * | 1988-05-17 | 1989-12-12 | Minnesota Mining And Manufacturing Company | Filter element |
| WO1994019056A1 (en) * | 1993-02-27 | 1994-09-01 | Paul Hartmann Ag | Respiratory system protection |
| 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 |
| US8955515B2 (en) * | 2009-10-23 | 2015-02-17 | 3M Innovative Properties Company | Patterned chemical sensor having inert occluding layer |
| 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 |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1725893A (en) * | 1924-12-05 | 1929-08-27 | Mine Safety Appliances Co | Indicating gas-mask canister |
| US3966440A (en) * | 1975-06-03 | 1976-06-29 | Catalyst Research Corporation | Colorimetric vinyl chloride indicator |
-
1977
- 1977-12-20 CA CA293,496A patent/CA1100419A/en not_active Expired
- 1977-12-27 JP JP15675977A patent/JPS5385993A/en active Pending
- 1977-12-27 DE DE19772758603 patent/DE2758603A1/en not_active Ceased
-
1978
- 1978-01-03 GB GB7178A patent/GB1554542A/en not_active Expired
- 1978-01-04 BR BR7800046A patent/BR7800046A/en unknown
-
1981
- 1981-05-21 HK HK22181A patent/HK22181A/en unknown
-
1986
- 1986-07-09 JP JP10436686U patent/JPS6218156U/ja active Pending
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 |
| US9751038B2 (en) | 2013-03-15 | 2017-09-05 | 3M Innovative Properties Company | End of service life indicating systems for layered filter cartridges |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5385993A (en) | 1978-07-28 |
| GB1554542A (en) | 1979-10-24 |
| DE2758603A1 (en) | 1978-07-20 |
| HK22181A (en) | 1981-05-29 |
| BR7800046A (en) | 1978-08-15 |
| JPS6218156U (en) | 1987-02-03 |
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Legal Events
| Date | Code | Title | Description |
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| MKEX | Expiry |