IN THIS ISSUE: Portable Gas Detectors
There are two types of commercially used gas detectors: fixed and portable. Fixed detectors are primarily used in applications where the need for gas detection is permanent or over long periods of time. Portable gas detectors are used where the need is short and temporary. They may be hand-held or worn by someone entering a confined space or entering a potentially dangerous area. Most portable gas detectors are battery operated or rechargeable.They are designed to detect multiple gases simultaneously. The most common sensor configuration for a portable gas detector is carbon monoxide, hydrogen sulfide, flammable gas and oxygen.
Portable gas detectors use sensors to detect the presence or concentration of gasses in the air. Based on the voltage produced, the type and concentration of the gas can be estimated. Gas detectors use different types of sensors based upon what is being sampled. These include metal oxide,optical, electrochemical gas,capacitance-based, calorimetric, and acoustic.Portable gas detectors can have one or up to five sensors. These can detect a wide number of chemicals such as ammonia, carbon dioxide, carbon monoxide,
chlorine, hydrogen cyanide, hydrogen, nitric oxide, volatile organic compound, and many others.
All gas detectors require periodic calibration. When calibrating, each sensor is exposed to a calibration gas of aknown concentration of the gas, then adjusted to read that value. The best calibration gas concentration should be near the alarm level of the sensor in question, ensuring the highest accuracy at that level. A bump test, also known as a functional test, should be performed at the start of each day’s use. This procedure tests the alarms and sensors of a gas detector to be sure they are functional. One way to ensure proper instrument performance and reduce maintenance hassles is to use a docking or calibration station. These devices automate routine bump tests and calibrations plus download datalogs, update settings and firmware.
Portable gas detectors should have an audible, vibration, and/or visual alarm that is set for each of the sensors. Other features may include pre-entry pump and hoses for confined space entry, and data logging. It is important that employees receive initial and periodic training and are familiar with the information provided in manufacturer instructions. For confined space entry, it is especially important that the entrants include gas detection in their training as per applicable occupational standards.
Portable gas monitors can be useful and life saving devices. However, they must be configured with the correct sensor, properly maintained and calibrated, and used by employees who have the right training to use them correctly.
For more information on this topic and to discuss your company’s safety and industrial hygiene needs call OccuSafe at (214) 662-6005 or visit us at www.occusafeinc.com. OccuSafe Industrial Hygiene & Safety, Inc. provides skills and expertise to recognize, evaluate and control hazards and injuries in the areas of industrial hygiene, occupational safety and health. OccuSafe services companies of all sizes in a range of industries.
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