How Often Should You Calibrate a Gas Detector?

There's no single legal answer to "how often should I calibrate," and that trips people up. OSHA doesn't set a fixed calibration interval for gas detectors — it defers to the manufacturer's recommended schedule for the specific instrument you own. Most manufacturers land somewhere around a 180-day (six-month) full calibration cycle, but that's a starting point, not a universal rule.

What actually determines your interval

• Manufacturer guidance for your specific detector model — always the first place to check.
• How harsh your environment is: sensors exposed to high humidity, extreme temperatures, or frequent gas contact degrade faster.
• Sensor age: all electrochemical and catalytic sensors have a finite lifespan, and drift accelerates near end of life.
• Any known exposure event: if a sensor was hit with a gas leak or an unusually high concentration, calibrate it before returning it to service, regardless of schedule.

The practical approach

Start with your manufacturer's suggested interval, then adjust based on what you observe. If a sensor consistently reads accurately at the zero and span points at each check, you can often extend the interval. If it's drifting, tighten it. This is also why a daily bump test matters between full calibrations — the International Safety Equipment Association (ISEA) recommends bump testing before each day's use, since a bump test catches a non-responsive sensor in seconds, while a full calibration corrects for drift.

Bottom line: calibration frequency is a risk-management decision, not a fixed clock. Document your interval, follow it consistently, and adjust based on real performance data.

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