Thursday: Bump Testing vs. Calibration for Gas Monitors
Why a multi-gas monitor that simply turns on isn't necessarily protecting you from a confined space fatality.
Just because a portable multi-gas monitor powers on and shows zero on its display does not mean it is functioning. If the electrochemical sensors inside have been poisoned by silicone, coated in dust, or have simply aged out, the display will still read safe levels even if the worker is standing in a lethal cloud of H2S.
This is why the daily “Bump Test” is absolutely non-negotiable before executing a confined space entry. A bump test is a brief exposure to a known concentration of test gas to physically verify that the sensors respond and that the audible/visual alarms trigger. It proves the monitor will scream when it needs to.
However, a bump test does not test accuracy. That is what a full Calibration achieves. Calibration exposes the instrument to a certified concentration of calibration gas and adjusts the unit’s internal algorithms to match the exact reading. Over time, sensors naturally degrade and drift. If you only bump test, the monitor might alarm eventually, but it won’t trigger at the exact low-level OSHA limits required to get you out safely.
Never skip the morning bump test, and rigorously track your 30-day (or manufacturer specified) calibration cycles.