MSA’s Cartridge Change Test Program

OSHA’s new Respiratory Protection Standard 1910.134 requires that all cartridges have an ESLI (End-of-Service-Life Indicator), or a cartridge change (or change-out) schedule must be established.

(Here are the related text and some links to documents you may wish to review.)

MSA is making progress in determining chemical cartridge service life data for employers to use in developing these cartridge change schedules.

Descriptive vs. predictive models

At MSA, a descriptive model is being developed to determine when to change your Comfo® or Advantage® Cartridges. A descriptive model is more accurate than a predictive model, because it requires more data to “describe” the performance of a cartridge. A predictive model, like the Wood’s equation, uses less data to “predict” cartridge performance. That is why predictive models have a higher percentage of errors associated with them.

Chemicals being tested

We have divided our testing into two phases. For Phase 1, we took all the organic substances in the Response® Respirator Selector guide, put them into categories and subcategories, then tested representative compounds from each classification. We also tested acid gases, bases, and formaldehyde for GMA, -C, and -E cartridges for Comfo and Advantage respirators. All chemicals are being tested at multiple concentrations, humidities, and flow rates. Phase 1 has yielded hard service-time test data.

Results for your use

You can see, on the tables that follow, the cartridge performance for the range of chemical concentrations, humidities, and flow rates. You can use these tables, along with your work-site-specific data, to determine an appropriate cartridge change-out schedule. Some notes, warnings, and explanations precede this material.

Next phase

During Phase 2, we will use this hard data as well as cartridge lot variability and service time performance information to generate a more detailed descriptive model that our customers can use. We plan to have Phase 2 testing completed by the end of 1998.

Please note:

• Service time is the measured or estimated period of time before breakthrough of an airborne contaminant (gas or vapor) for a specific chemical cartridge under specified conditions of the test.
• The service time data presented in this investigation applies only to MSA respirators. It should be used as a guide only for determining an appropriate respirator cartridge change-out schedule as required for compliance with OSHA's Respiratory Protection Standard (29 CFR 1910. 134).
• The data presented in this investigation were gathered under closely controlled laboratory testing conditions, utilizing a limited number of cartridge samples. Although the cartridges were tested against a broad range of challenge conditions, many factors affecting the users’ overall respiratory protection must be taken into account when determining the change-out schedule.
• With relation to analogous chemical structures (chemical families), employers can rely on service life values from other chemicals having a similar chemical structure to the contaminant under evaluation (test chemical) for breakthrough. (From OSHA Directive CPL 2-0.120 (Inspection Procedures for the Respiratory Protection Standard) APPENDIX A: CHANGE SCHEDULES GUIDE -- A LISTING OF METHODS --9-25-98)

WARNING

Do not use the data presented in this study as the sole factor in determining the respirator cartridge change-out schedule. An appropriate change-out schedule must be developed by a knowledgeable professional. It should be based on additional factors including the actual workplace conditions, work practices and other conditions which may affect respiratory protection. Failure to determine an appropriate change-out schedule can cause overexposure and result in serious personal injury or death.

Precautions When Using Data to Establish Your Change Schedule

The following is a partial list of factors which may affect the usable cartridge service life and/or the degree of respiratory protection attainable under actual workplace conditions. These factors should be considered when developing a cartridge change-out schedule.

• Type of contaminant(s)
• Contaminant concentration
• Relative humidity
• Breathing rate
• Temperature
• Changes in contaminant concentration, humidity, breathing rate and temperature
• Mixtures of contaminants: (1) multiple contaminants present simultaneously versus (2) alternate usage of the same cartridges against different contaminants on different occasions
• Accuracy in the determination of the conditions
• The contaminant concentration in the workplace can vary greatly. Consideration must be given to the quality of the estimate of the workplace concentration.
• Cartridge storage conditions (exposure to trace levels of contaminants and humidity and elevated temperatures)
• Storage conditions between multiple uses of the same respirator cartridges. It is recommended that the chemical cartridges be replaced after each work shift. Contaminants adsorbed on a cartridge can migrate through the carbon bed without airflow. Desorption of the contaminant (including those with poor warning properties) after partial use of the chemical cartridge can occur after a short period (hours) without use (e.g., overnight) and result in a non-use exposure to someone nearby.
• Age of the cartridge
• Condition of the cartridge and respirator
• Respirator and cartridge selection
• Respirator fit
• Respirator assembly, operation, and maintenance
• User training, experience and medical fitness
• Warning properties of the contaminant
• The quality of the warning properties should be considered when establishing the chemical cartridge change schedule. Good warning properties may provide a secondary or back-up indication for cartridge change-out. Change schedules for contaminants with poor warning properties may require a greater safety factor than a contaminant with good warning properties.
• Other conditions specific to the particular user and/or workplace

Things to remember when interpreting our cartridge test data:

1) The test temperature is 75° F.
2) The test flow rate is 64 liters per minute. This is considered a heavy work rate. Generally, flow rate is proportional to cartridge service life.
3) Humidity decreases the service time for organic vapor cartridges and increases the service time for acid gas cartridges.
4) Chemicals from the same family will have equal or greater performance time as the tested chemical.
5) The maximum cartridge change-out time recommended is one shift or that specified by an OSHA substance-specific standard.
6) Test concentrations were selected based on the PEL and the IDLH of that chemical. The relationship between concentration and service time is not linear.

While Phase 2 of our model is under construction, OSHA’s automation of the Wood’s Equation on their web page can help you make estimates of MSA’s cartridge service life at concentrations between our tested levels. The table below will facilitate your using OSHA’s automated Wood’s Equation.

Come back to the MSA cartridge test data to verify that the cartridge service time from the Wood’s Equation makes sense.

1. Print this page
2. Go to this OSHA site: http://www.osha.gov/SLTC/etools/respiratory/change_schedule.html
3. Quickly review this page.
4. Click on “The Advisory Genius” in the left-hand menu and follow instructions.

Don’t forget to check the results for sensibility with our test data!
PRINT THIS PAGE.

Respirator Test Data Index