Final Decision to Certify Hazardous Waste Environmental Technology
The following is excerpted from:
CALIFORNIA REGULATORY NOTICE REGISTER
Published Weekly by the Office of Administrative Law
Register 99, No. 44-Z
October 29, 1999
The California Environmental Protection Agency, Department of Toxic Substances Control (DTSC) has made a final decision to certify the following company’s hazardous waste environmental technology listed below:
P.O. Box 3399
Virginia Beach, VA 23454
Model 6000 Aerosolv® Aerosol Can Recycling System
Health and Safety Code section 25200.1.5 authorizes DTSC to certify the performance of hazardous waste environmental technologies. The purpose of the certification program is to provide an in-depth, independent review of technologies to facilitate regulatory and end-user acceptance. Only technologies that are determined to not pose a significant potential hazard to the public health and safety or to the environment when used under specified operating conditions may be certified.
DTSC makes no express or implied warranties as to the performance of the manufacturer’s product or equipment. The end-user is solely responsible for complying with all applicable federal, state, and local regulatory requirements. Certification does not limit DTSC’s authority to take any action necessary for protection of public health and the environment.
By accepting certification, the manufacturer assumes, for the duration of certification, responsibility for maintaining the quality of the manufactured equipment and materials at a level equal to or better than was provided to obtain certification and agrees to be subject to quality monitoring by DTSC as required by the statute under which certification is granted.
In accordance with the California Environmental Quality Act, an Initial Study was prepared that analyzed environmental impacts that may be caused by the certification decision (project). DTSC has prepared a Mitigated Negative Declaration based on the Initial Study and its determination that this project with mitigation measures would avoid or mitigate any effects to a point where no significant effect on the environment would occur. Copies of the Mitigated Negative Declaration and Initial Study are available for review at the address given below.
DTSC’s proposed decision to certify was published on June 25, 1999 in the California Regulatory Notice Register 99, Volume No. 19-Z, pp. 1278-1291. Comments were received during the public review and comment period. Responses to comments received have been prepared, and minor changes have been incorporated into the final certification decision, where appropriate. Additional information supporting DTSC’s final decision, including the Responses to Comments and the August 27, 1999 Draft Environmental Technology Verification Report, is available at:
California Environmental Protection Agency
Department of Toxic Substances Control
Office of Pollution Prevention and Technology Development
P.O. Box 806
301 Capitol Mall, 1st Floor Sacramento, California 95812-0806
A description of the technology to be certified, the certification statement and the certification conditions for the technology of the company listed above follows.
Model 6000 Aerosolv® Aerosol Can Recycling System
The Katec, Inc. MODEL 6000 AEROSOLV® AEROSOL CAN RECYCLING SYSTEM (hereinafter referred to the Aerosolv® System) is a waste aerosol can puncturing and draining technology. The technology punctures and drains waste aerosol cans while collecting their liquid contents in a storage drum and treating gases and vapors with a carbon filter. Treated waste aerosol cans are recycled as scrap metal. Recycling of the emptied cans is a condition of this certification. The collected liquids and used carbon filters are classified as hazardous or non-hazardous waste and managed accordingly. The system consists of four components: the Aerosolv® Puncturing Unit, a liquid collection drum, a coalescing filter and flexible hose, and a carbon canister. The liquid collection drum, a standard 55-gallon closed-head drum, is supplied by the user. Katec also provides an instruction manual on how to operate and maintain the system. A Colorimetric Indicator was included in the evaluation, but is not part of the system being certified.
Aerosolv® Puncturing Unit. The Aerosolv® Puncturing Unit screws into the 2-inch bung hole of a standard 55-gallon drum (i.e., the liquid collection drum). To operate the Aerosolv® Puncturing Unit, the spray nozzle is first removed from an aerosol can, then the can is placed upside down into the top of the unit. A sliding top plate assembly is swung over the can and then depressed to push the can down against a flat silicone gasket inside the unit. After the aerosol can is secured in place, a spring-loaded handle on the unit is pushed down to pierce the dome of the can with a carbide-tipped puncture pin in a manner specified in the instruction manual. As the can is emptied, vapors and gases pass from the collection drum through the coalescing filter into the carbon filter. After the contents of the can have been allowed to drain (approximately 30 seconds to two minutes), the can is removed from the unit and placed in a separate container.
Replaceable seals are provided at two locations to prevent releases of gases and liquids during puncturing: (1) a flat annular shaped gasket composed of silicone is set within the unit to provide a seal around the shoulder of the inserted can, and (2) two Viton O-rings seal the annulus around the puncture pin, which is replaceable and housed in a Teflon sleeve. A primary function of the two Viton O-rings is to retain grease packing around the puncture pin for smooth operation.
The body, cap and handle of the unit are cast aluminum. A lock knob located on the side of the unit turns a set screw onto the slide bar of the sliding top plate assembly to secure the aerosol can in place. The sliding top plate assembly consists of the cap, slide bar and sealing knob. The sealing knob, located on top of the cap, is turned to press the aerosol can further down into the unit onto the silicone gasket to form a seal, and to push open a spring-loaded check valve at the base of the unit. The check valve has a flat Teflon® seal which when open allows the contents from the punctured can to pass into the collection drum. When the can is removed, the valve is intended to seat against the bottom of the unit preventing or reducing escape of vapors when the unit is not in operation.
55-gallon closed-head drum. Liquids released from the punctured aerosol can are collected in a standard 55-gallon liquid collection drum. To ensure adequate headspace for discharged gases, the drum is changed when it has reached 70% of capacity (a minimum of 17 gallons or 10 inches of headspace).
Coalescing Filter. The coalescing filter screws into the 3/4-inch bung hole of the liquid collection drum and is connected to the carbon filter inlet with 2-inch diameter hose. Gases and vapors from the punctured cans pass from the liquid collection drum through the coalescing filter prior to entering the carbon canister. The coalescing filter is intended to coalesce aerosol droplets such that they drain back into the liquid collection drum, and to allow only vapors and gases to pass into the carbon filter.
Carbon Filter. The carbon filter is used to treat gases and vapors that are generated from the puncturing and draining operation. It is constructed from a 30-gallon high-density polyethylene drum and contains three layers of activated carbon, each approximately eight to ten inches thick. The carbon layers are separated by a total of four 2-inch layers of Dual Denier fiber. According to Katec, a total of 41 pounds of 4-millimeter pelletized activated carbon is used in the filter.
Instruction Manual. An instruction manual includes procedures and conditions required for this certification for operation and maintenance of the technology.
Basis for Certification
Evaluation Approach. The evaluation of the Aerosolv® System was designed to provide the data necessary to draw conclusions on the technology’s performance, reliability and safety. Additionally, the critical operating parameters and conditions related to the technology’s performance, reliability and safety were to be identified. The evaluation included a review of supporting documents and information submitted by Katec which describes their technology and its intended operation and maintenance, and a field test to provide independent data on the technology’s performance and safety. A key document which Katec submitted, the Aerosolv® 6000 Instruction Manual, was reviewed and will be revised as part of the certification process.
The field test was carried out at the U.S. Navy (Navy) Public Works Center, San Diego. The Navy is a Katec customer and agreed to provide facilities, staff, and waste aerosol cans from their hazardous waste storage facility for conducting the field test. Prior to commencing the field test, the Department of Toxic Substances Control (DTSC) prepared a Field Test Plan to identify specific field test objectives, data quality objectives, testing procedures, and roles and responsibilities for performing the field test. The Navy assumed overall responsibility for conducting the field test. DTSC staff provided independent oversight and were present to observe many, but not all, of the field test activities. The agreed-upon Field Test Plan specified that the Navy would record all measurements and observations made during the field test. Following the completion of the field test, the Navy submitted their report providing the field test data collected and a summary of field test results. The Navy also provided field log notes compiled by the Navy industrial hygienist during the field test. Additionally, DTSC staff observations made during the field test were included as part of the evaluation.
Previous versions of the technology which Katec has marketed did not contain the carbon filter component. Therefore, reliability and performance information was only obtained through the above referenced field testing. No data were available to assess long term reliability and performance of the specific Aerosolv® System being evaluated.
Field Test Objectives. The field test was designed to obtain quantitative data for verifying four specific objectives, and to provide an opportunity to observe the quality and reliability of the technology in operation. The four objectives are listed below.
- Removal Effectiveness. (a) Determine the ability of the Aerosolv® System to treat aerosol cans to less than 3.0% of the original can contents or capacity, the federal definition of an empty container; (b) Determine the Removal efficiency of the Aerosolv® System, the percent of the contents in untreated waste aerosol cans that the Aerosolv® System removes.
- System Capture Efficiency. Establish whether the Aerosolv® System captures the gaseous and liquid contents removed from the waste aerosol cans (DTSC used 90% as a capture efficiency target during field testing).
- Carbon Filter Effectiveness. (a) Determine the total mass of the contents from waste aerosol cans processed by the Aerosolv® System that results in carbon filter saturation; (b) Measure the total organic vapor concentrations in carbon filter breakthrough emissions to serve as the basis for establishing appropriate criteria for replacement of the carbon filter during operation of the technology; (c) Assess the adequacy of the procedures for determining when the carbon filter is spent and needs replacement.
- Assess Worker Health & Safety. Determine the capability of the Aerosolv® technology to operate in compliance with levels and standards established in state and federal regulations for protection of worker health and safety.
Aerosol Can Products Evaluated. Katec and the Navy requested that the performance of the Aerosolv® System be evaluated for three categories of aerosol can products: paints; hydrocarbon cleaners and lubricants; and chlorinated solvent cleaners. The Navy provided two lines of paint, manufactured by LHB Industries, St. Louis, MO, for testing: Eco Sure and So Sure. Eco Sure paints are a line of low VOC, high solids enamel and primer paints. So Sure paints are standard lacquer and enamel paints. Due to the wide variety of colors and dates of manufacture of paints selected by the Navy, it was not possible to predetermine with certainty all ingredients that might have been in the paints. The paints tested were found to contain a mixture of aromatic and aliphatic hydrocarbons such as toluene, xylenes, and naphtha; low and medium boiling point ketones such as acetone and methyl ethyl ketone; paint solids; and occasionally dichloromethane. Some of the paints included dimethyl ether propellant, while others included propane/butane/isobutane propellant. The Navy identified a Corrosion Preventative Compound (CPC) manufactured by LHB Industries to represent the hydrocarbon cleaners and lubricants. Field test results showed that the CPC contained a mixture of aliphatic and aromatic hydrocarbons, small amounts of chlorinated solvents, possibly some ketones, and Freon-11 and Freon-12 propellants. To represent the chlorinated hydrocarbon solvent cleaner for the field test, the Navy selected Brakleen, manufactured by CRC Chemicals, Warminster, PA. The Brakleen contained tetrachloroethene, small amounts of trichloroethene, and carbon dioxide propellant, along with other, undetermined ingredients.
Field Test Activities and Results. A series of seven (7) test runs were conducted to evaluate the Katec Aerosolv® System for treating the three types aerosol can products, three on paints and two each on the CPC and Brakleen. During the seven test runs a total of 2270 waste aerosol cans were punctured and drained using the Aerosolv® technology. This included 1690 paint aerosol cans, 350 CPC aerosol cans, and 230 Brakleen aerosol cans. Averages of can fullness were 26%, 11% and 33% for the three paint test runs, 42% and 87% for the two CPC test runs, and 22% and 100% for the two Brakleen test runs.
Two Total Vapor Analyzers (TVAs), operating in the Flame Ionization Mode, were used during each of the seven field test runs while aerosol cans were being punctured and drained. The TVA’s were used to measure and record total hydrocarbon emissions concentrations at a fixed location near the puncturing unit and at the carbon filter exhaust port. The fixed TVA at the Aerosolv® Puncturing Unit was placed in the downwind direction at an elevation no more than 6 inches above the elevation of the puncturing unit. A drum scale was used to weigh the Aerosolv® System at the beginning and end of each test run and whenever the carbon filter was changed out. The system was weighed in two parts: (1) the Aerosolv Puncturing Unit, liquid collection drum and coalescing filter, and (2) the carbon filter, Colorimetric Indicator and connecting hose. All waste aerosol cans used for the seven test runs were weighed both before and after being punctured and drained. A wind speed sensor with a 1 mph threshold was set to continuously monitor windspeed during each of the test runs while aerosol cans were being punctured and drained.
In addition, Navy Industrial Hygiene staff collected area and breathing zone air monitoring samples to evaluate worker exposure during operation of the Aerosolv® System. OHSA Methods 07 and 48 were used for sample collection and analysis. For each of the three product types, long and short term exposure samples were analyzed for the target constituents expected to be contained in the specific aerosol can product being tested. Details on all specific activities conducted by the Navy Industrial Hygiene staff during the field test and their corresponding results are presented in the Navy’s January 28, 1999 report, “Aerosolv® Aerosol Can Recycling Technology, Field Test Demonstration, Summary of Results, August 5, 1998 – November 29, 1998, Navy Public Works Center Environmental Department, San Diego”.
During each of the three sets of test runs composite liquid samples were collected from the liquid collection drum and analyzed by independent laboratories using EPA Method 8260, a GC/MS analysis. Results from the liquid sample analyses showed that the aerosol can products treated included chemical constituents not included in the Navy’s area and breathing zone air monitoring. For the paint test runs these include dichloromethane, 4-methyl-2-pentanone (methyl isobutyl ketone), and tetrachloroethene, for the CPC test runs this included dichloromethane, and for the Brakleen test runs this included 1,1,1-trichloroethane. DTSC’s certification includes specific conditions 2, 3 and 4 to control the nature of the constituents to be treated. The results for each of the four established objectives of field test were as follows:
1a. Removal Effectiveness.
The field tests evaluated the capability of the Aerosolv® System to treat aerosol cans to less than 3.0% of the original can contents, the federal definition of an empty container. The 3% criterion was evaluated using a subset of all the cans tested. For each aerosol can product category evaluated 75 cans were randomly selected from the inventory of treated aerosol cans. The selected cans were cleaned to remove any remaining residuals after treatment, then dried and weighed to determine their tare weights. Removal effectiveness was calculated for each can based on its weight before and after treatment and its tare weight. Because of discrepancies in the recorded pre- and post-treatment weights, several of the selected cans had to be excluded from the analysis.
The upper 95% confidence limit of the mean fraction (percentage) of the original contents remaining in the treated cans was determined for each product category. The objective was considered met if the upper 95% confidence limit of the mean was less than 3%, the federal definition of an empty container.
Paint Product Category. Based on the set of 73 randomly selected cans, 5 of 19 cans from Test Run #1, and 1 of 13 cans from Test Run #3 had greater than 3% of the original can contents remaining after treatment. All 41 cans from Test Run #2 contained less than 3% after treatment. The mean and standard deviation for the fraction remaining in the aerosol cans after treatment were determined for each paint test run. The upper 95% confidence limit of the means were calculated to be 3.41%, 0.99%, and 2.25% in Test Runs #1, #2, and #3, respectively. Thus, in one of the three paint test runs the Aerosolv® System did not meet Objective 1a. For Test Run #1 the confidence was only 77% that the mean was 3% or less (i.e., the upper 77% confidence limit of the mean was 3%). The varied removal effectiveness may be due to the differences between the types of waste aerosol paints treated in the three test runs. Test Runs #1 and #3 involved the treatment of Eco Sure brand paints which include high solids paints, while Test Run #2 involved treatment of So Sure brand paints with lower solids content. Additionally, the waste aerosol cans treated during Test Runs #1 and #3 averaged 21.8% full and 19.1% full, respectively, which were significantly fuller than the average 9.1% fullness of cans treated during Test Run #2.
The Field Test Plan specified three replicate test runs. As discussed above, the aerosol cans treated during the three test runs differed in terms of the products tested and the average fullness. Therefore, it is not appropriate to combine the results from all three test runs. Since the aerosol cans treated in Test Runs #1 and #3 appear similar it may be appropriate to combine these results. The upper 95% confidence limit of the mean for Test Runs #1 and #3 combined is 2.81%. Thus, specific condition 5 restricting the use of the technology to cans which are less than 25% full was imposed.
Hydrocarbon Lubricant & Cleaners Category. Field test results show that the Aerosolv® System removed residuals in CPC aerosol cans to an average of 0.84% of their original contents (upper 95% confidence limit), well below 3%, the federal definition of an empty container.
Chlorinated Solvent Category. The Field Test Plan required that all cans selected for this determination contain significantly greater than the 3% criterion or federal definition of an empty container. Field test data indicate that the Brakleen aerosol cans selected by the Navy from Test Run # 6 for determining removal effectiveness contained an average of less than 2% of their original net contents. Therefore, the aerosol cans selected would have achieved Objective 1a before treatment and no conclusions can be drawn from this data regarding removal effectiveness. However, a review of the pre and post-treatment weights of fuller (>3%) Brakleen aerosol cans treated during Test Runs #6 and #7 and the tare weight data for Brakleen aerosol cans would indicate that the Aerosolv® System removed or emptied the residuals to below the 3% criterion.
1b. Removal Efficiency
Removal efficiency, the percent of the waste aerosol can contents that the Aerosolv7 System removed, was evaluated for each product category. The 95% lower confidence limit of the mean removal efficiency for each product category was determined based on the results for the groups of randomly selected treated cans from each test run.
Paints Aerosol Can Products. The lower 95% confidence limit of the mean removal efficiency determined for paint test runs was 77.2% in Test Run #1, 81.6% in Test Run #2, and 83.7% in Test Run #3.
Hydrocarbon Lubricant & Cleaners Category. The lower 95% confidence limit of the mean removal efficiency determined for the two CPC test runs was 97.8% .
Chlorinated Solvent Category. The lower 95% confidence limit of the mean removal efficiency determined for one of two Brakleen test runs was 61.8%. This relatively low result is due to the near-empty waste aerosol cans selected from Test Run # 6 for this analysis. The calculated removal efficiency becomes proportionately less when the denominator (can fullness) is reduced, as is the case with near-empty cans.
2. System Capture Efficiency.
System capture efficiency, the percent of the contents removed from the cans that the Aerosolv7 System captures either as liquids or adsorbed on the carbon filter, was determined for each product type. Using the weights of the aerosol cans before and after treatment and weights of the liquid collection drum and carbon filter assemblies, capture efficiency was measured to within +/- 1% for each test run conducted. The lower 90% confidence limit of the mean capture efficiency was determined for each set of test runs.
Paint Products Category. The capture efficiencies measured for paints in Test Runs #1, #2 and #3 were 88.5%, 84.0% and 94.9%, respectively. The mean of the capture efficiencies measured for the three paint test runs was 89.1% with a standard deviation of 5.5% and a lower 90% confidence limit of 83.2%.
Hydrocarbon Lubricant & Cleaners Category. The capture efficiencies measured for CPC products in Test Runs #4 and #5 were 96.9% and 97.0%. The mean capture efficiency for the two CPC test runs was 96.9% with a standard deviation of 0.1% and a lower 90% confidence limit of 96.8%.
Chlorinated Solvent Category. The capture efficiencies measured for Brakleen in Test Runs #6 and #7 were 97.0% and 99.0%. The mean capture efficiency for the two Brakleen test runs was 98.0% with a standard deviation of 1.5% and a the lower 90% confidence limit of 94.9%.
3. Carbon Filter Effectiveness.
The Field Test Plan specified changeout of the carbon filter (i.e., replacement) when the total hydrocarbon concentration in the exhaust reached 10% of the inlet concentration, or when concentration levels specified in the field test Health & Safety Plan for protection of worker health and safety were exceeded. When the changeout criterion was reached, the carbon was considered to be saturated and to have reached its useful capacity.
For test runs involving paints and CPC’s the carbon filter inlet concentrations were expected to approach 100% as propellants and vapor displace the air initially present in the system. For these test runs the carbon filter was replaced when the total hydrocarbon concentration in the exhaust reached 10% or 100,000 ppm. For the test runs involving Brakleen composed primarily of tetrachloroethene and carbon dioxide propellant, the maximum inlet concentration was expected to be 20,000 ppm based on tetrachloroethene’s vapor pressure of 14 mm Hg. Thus, for the Brakleen tests runs the carbon filter was to be replaced when exhaust concentrations measured 2000 ppm with the TVA FID.
A new unused carbon filter and Colorimetric Indicator were installed at the start of each set of test runs for each product type, and during each test run when the carbon changeout criterion was reached. Prior to use of the carbon filter, the carbon filter assembly (carbon filter, Colorimetric Indicator and assembly hose) was weighed. During each test run the TVA FID was used to measure total hydrocarbon concentrations between the carbon filter exhaust port and the Colorimetric Indicator. When concentrations exceeded 2000 ppm during Test Runs #1 through #5, the TVA monitor was equipped with a 50:1 diluter and recalibrated. With the 50:1 diluter installed, a TVA reading of 2000 ppm indicates an actual concentration of 100,000 ppm. When exhaust concentrations consistently exceeded 100,000 ppm or 10% of the inlet concentration, the carbon filter was considered spent and replaced. The spent carbon filter assembly was then disconnected and weighed to determine the mass of vapors and gases which had been adsorbed by the carbon filter. The test run was continued after a fresh carbon filter and Colorimetric Indicator were installed. Use of a carbon filter was continued through a subsequent test run(s) for the same product type until the changeout criterion was reached. During each test run, the specific aerosol cans treated while each carbon filter was being used were recorded in the Navy Industrial Hygienist’s field log. Field Test results for carbon filter effectiveness for the three product types are discussed below.
Paint Aerosol Can Products. During the paint test runs a total of 5 filters were saturated and required changeout. The average (mean) amount of aerosol can contents processed by the Aerosolv® System before each filter became saturated was 33.7 lbs. with a standard deviation of 8.9 lbs. Therefore, the system can process 25.2 lbs of paint aerosol can contents before the filter is saturated (lower 90% confidence limit).
The average (mean) number of aerosol cans processed by the Aerosolv® System before each filter became saturated was 313 cans with a standard deviation of 131 cans. Using the number of cans to assess filter capacity without indicating the fullness of the cans processed would be misleading. The average fullness of cans processed for each of the filters saturated varied from 9% for Filter #3 to 30% for Filter #9. The average fullness of the 1564 cans processed during the use of the 5 saturated carbon filters was 17%. Therefore, the system can process at least 187 waste aerosol paint cans (lower 90% confidence limit) with an average fullness of 17% before the filter is saturated.
Carbon Capacity was also evaluated in terms of mass of volatiles from aerosol paint products adsorbed prior to changeout (saturation). For the saturated filters the average mass adsorbed was 6.4 lbs with a standard deviation of 0.9 lbs. Therefore the carbon filter can adsorb 5.6 lbs before it becomes saturated (lower 90% confidence limit).
Hydrocarbon Lubricant & Cleaners Category. Only one of the two carbon filters used, filter # 5, was saturated during the two CPC test runs. This filter adsorbed 12.1 lbs while the Aerosol® System processed 250 waste aerosol cans with an average fullness of 42% before this carbon filter was replaced. Filter #6 which was also used did not reach capacity at the end of Test Run #6. At the end of this test run 100 waste aerosol cans with average fullness of 87% had been processed and the filter had adsorbed 11.3 lbs. These results indicate that the carbon filter had about a 60% greater capacity for this type of aerosol can product than for the paint products tested. This is consistent with the fact that the CPC tested contained halogenated propellants which are expected to adsorb strongly to carbon. Other hydrocarbon lubricant and cleaner products may not contain propellants which adsorb strongly to carbon, and consequently carbon filter capacity for these products would be less.
Chlorinated Solvent Category. Only one carbon filter was used during the two Brakleen test runs and it did not reach saturation. At the end of the two test runs during which this filter was used, 230 waste aerosol cans with 38% average fullness had been processed. Only 1.8 lbs were adsorbed onto the filter, indicating it had more capacity. These results would be expected for Brakleen aerosol can products since (1) the propellant, carbon dioxide, is not adsorbed by carbon, and (2) the primary ingredient, tetrachloroethene, is a relatively high boiling liquid which would not be expected to volatilize a great deal over the short duration of these two test runs.
Carbon Breakthrough Emissions. The total hydrocarbon concentrations in carbon filter emissions at breakthrough were measured to serve as the basis for establishing appropriate criterion for replacement of the carbon filter during operation of the technology. Generally, once concentrations measured in the carbon exhaust reached a few hundred ppm there was a relatively rapid increase in concentration to the 100,000 ppm carbon changeout criterion. For carbon filter #1, for example, carbon filter emission concentrations reached 200 ppm after 291 cans, but then reached 100,000 ppm in about 60 minutes of operation while processing only 27 additional aerosol cans.
Colorimetric Indicator. Additionally, Katec’s Colorimetric Indicator was periodically checked to determine if any significant color change occurred which would indicate breakthrough and that the carbon filter had reached capacity. The Colorimetric Indicators that were used never indicated any observable color change during their use in all of the field test runs. Katec claimed that their Colorimetric Indicator could be used to monitor the carbon filter and to indicate when the carbon filter has become saturated and needs to be replaced. The operator is supposed to check a clear window in the side of the cartridge for a color change. A label next to the window shows adjacent black and bright pink colors which are supposed to represent whether the cartridge is expended or not. Katec refers to the Colorimetric Indicator as a “carbon cartridge.” The indicator material consists of hydrated zeolite (clinoptilolite) granules impregnated with 6% by weight of potassium permanganate. The indicator material is manufactured by Cameron Yakima, Inc. and is sold primarily for odor control. Potassium permanganate, purple in color, is an oxidizing age