There’s an App for That! Estimating Respirator Cartridge Service Life

Whenever you put workers in an air-purifying respirator, it’s vital to know when they need to change their cartridges. Until passive visual end-of-service-life indicators become standard—something that has been a long time coming—employers must calculate, based on employee exposures and workplace factors, just how long a cartridge remains useful.

There are a number of computer-based tools available for making those calculations; most recently, the National Institute for Occupational Safety and Health (NIOSH) has updated its MultiVapor tool, which was last updated in 2009.

NIOSH’s New Program

The updated tool includes 66 new compounds, including TDI, MDI, and styrene. In addition, the organic vapor cartridge parameters have been updated to be more representative of commonly used cartridges.

NIOSH calls it an app, but you’ll actually need to download the MultiVapor software to a Windows PC for installation and use. Once that’s done, an industrial hygienist or other qualified professional can use the tool to estimate breakthrough times and service life for air-purifying respirator cartridges used to remove toxic organic vapors from breathed air.

NIOSH defines breakthrough time as the time following the first and continuous use of a cartridge after which the user of the cartridge could be exposed to a selected concentration of a harmful vapor; this is the consequence of the cartridge being used up.

Service life is the breakthrough time with, possibly, a safety factor applied.

In addition to disposable respirator cartridges, the tool can also be used for larger filters and for carbon beds of any size prepared for laboratory studies.

Required Inputs

Of course, the output you get is only going to be as good as the input you use. In order to properly calculate breakthrough times and service life, not just with NIOSH’s tool but also with any similar tool, app, or program, you’ll need to know:

• What cartridge you’re using. The MultiVapor tool will ask you for eight different parameters that apply to the activated carbon used in the cartridge. The program does come equipped with generic, preprogrammed values that you can use as estimates, but cartridge-specific values will give you better estimates of breakthrough time and service life.
• What workers are exposed to. You’ll have to enter the organic vapors workers are expected to encounter. Most of the data will be prepopulated, but you’ll need to know the average vapor concentration in parts per million (ppm). The program will let you enter up to five different vapors.
• What conditions of use apply. Temperature, relative humidity, the number of cartridges on the respirator and workers’ breathing rate are all important parts of the calculation. The program offers suggestions for breathing rates based on the physical demands of the work.

Given the information above, the program will calculate in minutes an estimated minimum and maximum breakthrough time for each contaminant. These can be included in your written respiratory protection program and change schedule documentation.

For more information on creating, updating, and enhancing your respiratory protection program, take a deep breath and plunge into Safety.BLR.com®.