Though there are many recommendations in place when using gas meter detection equipment, there are not OSHA gas meter calibration requirements. There are many independent variables to consider that make it difficult to establish required guidelines for every company when the usage of these meters for one varies in frequency compared to others. Therefore, the first suggestion is to follow the manufacturer’s suggested guidelines for testing and use. Understanding what is needed for a specific company in terms of testing depends on a few things, which we will outline below.
To properly calibrate a four-gas monitor, it would cost over $6.50 worth of calibration gas. It would also take about five minutes per meter. If a company has hundreds of detectors, it isn’t necessarily practical to test very frequently.
Therefore, OSHA and ANSI (American National Standards Institute) don’t have firm requirements in place. This lack of requirements has saved many companies time and money they would otherwise spend checking these meters. However, this does leave businesses open to taking a bit more risk with their equipment.
Possible Issues With Sensors
Manufacturer guidelines can be a bit unclear at times. OSHA recommends referring some manufacturers to the International Safety Equipment Association (ISEA) who suggests that sensor accuracy is verified each day, at minimum. The advisory pertains more to bump testing than full calibration.
If the detector has an on-screen countdown of 180 days, the monitor technically doesn’t need to be calibrated in the interim (according to the manufacturer). A company that produces a single gas monitor may say it is self-calibrating and doesn’t need to be touched for a full two years. The problem with this is that they both use the same sensor, so if the sensor fails, neither are being calibrated.
Bump Test vs. Full Calibration
When verifying the accuracy of instruments such as Major Safety’s multi-gas monitor for confined space applications and any other gas meters, either a bump test or full calibration will be appropriate depending on specific conditions. Knowing the difference between the two will allow you to decide which is necessary for a given situation. Both tests need to be done in an environment with fresh air.
To verify calibration using a bump test, the instrument is exposed to a specified concentration of test gas that is high enough to trigger the alarm. The reading is compared to the quantity of gas that is actually present. If the response indicated is an acceptable tolerance range based on the definite concentration, calibration is verified.
If the bump test fails to meet the acceptable tolerance range, you must perform a full calibration. Calibration gas should be traceable to and certified by the NIST (National Institute of Standards and Technology). Depending on how frequently this equipment is used, some companies may run a full calibration every thirty days, while others will calibrate only every four to six months.
Overall, there aren’t any set OSHA gas meter calibration requirements. However, companies should evaluate how frequently they need to test based on their needs and exposures. Always refer to manufacturer and safety organization guidelines for help in making these decisions.