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In the world of industrial safety, we love our gadgets. We buy the latest four-gas
monitors, clip them to our collars, and wait for the “beep” that tells us everything is fine.
But here’s the cold, hard truth I tell every crew I train at RedLine Safety: A gas detector
is only as good as the last time you proved it worked.
I’ve seen guys walk onto a job site, look at their monitor, see the “OK” icon, and drop
into a vault. That’s not safety—that’s a prayer. To survive a confined space, you need to
understand the difference between Bump Testing and Full Calibration. They aren’t the
same thing, and skipping either one is a recipe for disaster.
The Bump Test: The “Go/No-Go” Check
Think of a bump test like checking your brakes before you pull out of the driveway. You
aren’t measuring exactly how many feet it takes to stop; you’re just making sure the
pedal works.
A Bump Test is a brief exposure of the sensor to a known concentration of gas. You
aren’t looking for extreme accuracy here. You’re looking for two things:
- Does the sensor react to the gas?
- Do the alarms (audible, visual, and vibrating) actually trigger?
The RedLine Rule: OSHA and many reputable manufacturer say you should bump test
every single day before use. If you drop that monitor or it gets hit with a heavy surge of
dust, bump it again. It takes 30 seconds. Your life is worth 30 seconds.
Full Calibration: The Precision Tune-Up
If the bump test is checking the brakes, Calibration is the master mechanic hooking
your car up to a computer to ensure every system is firing at 100% efficiency.
Over time, gas sensors suffer from “drift.” Factors like extreme temperatures, humidity,
and “poisoning” from silicone or lead vapors can cause the sensor to lose its baseline.
Calibration resets the monitor’s internal scale.
During a calibration, the monitor is exposed to a certified “Span Gas.” The instrument
compares its reading to the known concentration in the bottle and adjusts itself to
match.
Frequency: Usually every 30 to 180 days, depending on the manufacturer and
the harshness of your environment.
The Goal: Accuracy. You want to know that when the screen says $19.5%
Oxygen, it’s actually $19.5%, not 20.1% that happens to be “close enough.”
Why You Can’t Have One Without the Other
I get asked all the time: ” if I calibrate every month, why do I need to bump test every
day?”
Because a monitor can pass a calibration on Monday and “die” on Tuesday. If a sensor
filter gets clogged with mud or a sensor fails internally, the screen might still look
normal, but it’s effectively “blind” to the gas. A calibration from two weeks ago won’t tell
you that. Only a bump test will.
Conversely, a bump test might tell you the alarm works, but it won’t tell you if the sensor
has drifted so far that it’s no longer reading hazardous levels accurately.
The Bottom Line
In a confined space, the atmosphere can turn on you in a heartbeat. Your gas detector
is your only lifeline.
- Bump Test before every shift to ensure it works.
- Calibrate on a schedule to ensure it’s accurate.
If you treat your monitor like a life-saving tool instead of a vibrating pager, you’ll ensure
that at the end of the day, everyone on your team goes home to their families.
Stay safe and watch your air.
Michael Ramer
RedLine Safety Inc.