Workers cannot rely on their sense of smell to alert them to odorless hazards in the workplace. Exposure to excessive levels of toxic gas or an oxygen-deficient environment can cause workers serious illness and even death. Combustible gas explosions are often catastrophic, injuring or killing personnel and destroying property.1 Designed to protect workers from such unforeseen dangers, gas monitoring instruments are often utilized to measure, monitor and indicate the concentration of certain gases in the atmosphere.
It is vital to worker safety that these instruments are maintained and calibrated properly. In addition, performance of a daily bump test prior to operation of gas detectors is a best practice because it is the only method by which the entire system — instrument, sensors, flow path, power source, alarms and all electronics — can be checked to ensure it is functioning properly.
Instrument inaccuracy due to improper or irregular calibration can lead to serious accidents. Over time, the accuracy of gas detection instruments can diverge from their calibration settings in several ways. According to OSHA Safety and Health Information Bulletin 05-04-2004, the following are the potential failure modes that can be identified during a bump test:
1. Gradual chemical degradation of sensors and drift in electronic components that occur naturally over time.
2. Chronic exposures to, and use in, extreme environmental conditions, such as high/low temperature and humidity, and high levels of airborne particulates.
3. Exposure to high (over-range) concentrations of the target gases and vapors.
4. Chronic or acute exposure of catalytic hot-bead LEL sensors to poisons and inhibitors. These include: volatile silicones, hydride gases, halogenated hydrocarbons and sulfide gases.
5. Chronic or acute exposure of electro-chemical toxic gas sensors to solvent vapors and highly corrosive gases.
6. Harsh storage and operating conditions, such as when an instrument is dropped onto a hard surface or submerged in liquid. Normal handling/jostling of the equipment can create enough vibration or shock over time to affect electronic components and circuitry.
7. In addition to these, any general component failure. In addition to good maintenance practices, safety practices also need to be reinforced regularly. Far too often, gas alarms are viewed as a nuisance or an error and are ignored by workers. It is critical workers comprehend the detector is utilized for their safety. Following safety protocol when alarms are triggered is a vital safety practice and could prove to be lifesaving.
For more information on MSA’s safety products, including the ALTAIR® Family of Multigas Detectors, please visit www.MSAsafety.com or call (800) 672-9010.
1 U.S. Department of Labor, Occupational Safety and Health Administration, Verification Of Calibration for Direct-Reading Portable Gas Monitors, (05-04-2004), www.osha.gov/dts/shib/shib050404.html.
