A bump test and a calibration are not the same thing, and confusing them is how a gas detector ends up trusted when it shouldn't be. A bump test is a quick go/no-go check that the sensors and alarms still respond to gas. A calibration is a measured adjustment that resets the detector's accuracy. Workers' lives depend on both being done on schedule. This guide explains the difference, how often each is required, the equipment you need, and when to hand the job to a calibration service.
What Is a Bump Test?
A bump test (also called a function test) is a brief check that applies a known concentration of target gas to a detector and confirms the sensors respond and the alarms activate. It is pass/fail: either the instrument reacts within tolerance and sounds its alarms, or it doesn't. A bump test does not adjust the detector's accuracy — it only verifies that the detector and its alarms are working before someone relies on it.
The reason a bump test matters is simple: a sensor can fail or drift silently. A detector that powers on and shows clean air readings can still be unable to detect a hazardous atmosphere if a sensor is poisoned, blocked, or dead. The bump test is the few-second insurance check that catches that failure before a worker enters a confined space or a hazardous area. For the underlying calibration requirements and schedules, see Gas Detector Calibration Requirements in Canada.
What Is Gas Detector Calibration?
Calibration is the measured adjustment that resets a gas detector's accuracy against a certified reference gas. The detector is exposed to a known concentration — for example, 50 ppm carbon monoxide — and its reading is adjusted so the displayed value matches the certified value. Unlike a bump test, calibration corrects sensor drift, restoring the instrument to accurate measurement across its range.
Sensors drift over time as a normal part of aging, and exposure to high gas concentrations, humidity, temperature swings, and contaminants accelerates it. A detector that hasn't been calibrated may still alarm, but at the wrong threshold — alarming late on a real hazard, or nuisance-alarming on clean air. Calibration is what keeps the numbers trustworthy.
Bump Test vs Calibration: What's the Difference?
The difference is verification versus adjustment. A bump test verifies the detector still responds; a calibration adjusts how accurately it responds. You bump test often and quickly; you calibrate less often and more thoroughly.
- Purpose: Bump test = "does it still respond and alarm?" Calibration = "is the reading accurate?"
- Result: Bump test = pass/fail. Calibration = a measured adjustment of the sensor's span.
- Frequency: Bump test = before each day's use. Calibration = on the manufacturer's schedule (commonly every 3–6 months) or after a failed bump test.
- Gas used: Both use certified calibration gas, but calibration depends on the certified concentration being exact, because the reading is set to it.
The two work together: frequent bump tests catch sudden failures between calibrations, and periodic calibration keeps accuracy from drifting. Skipping either breaks the safety case for the instrument.
How Often Should a Gas Detector Be Bump Tested and Calibrated?
Bump test before each day's use, and calibrate on the manufacturer's schedule or whenever the instrument fails a bump test. Most detector manufacturers and Canadian safety guidance — including CCOHS and the consensus practice reflected in CSA gas-detection guidance — treat the daily bump test as the baseline verification and periodic calibration as the accuracy reset.
- Before each day's use: bump test. If the detector hasn't been bump tested since its last calibration, treat the first bump test as due.
- Every 3–6 months (or per the manufacturer): full calibration. Some programs calibrate monthly for high-risk use; always follow the instrument manual where it is more stringent.
- Immediately, regardless of schedule: recalibrate after a failed bump test, a drop or impact, exposure to high gas concentrations or sensor poisons (silicones, solvents), or any repair.
What Equipment Do You Need to Bump Test and Calibrate?
You need three things: the right calibration gas, a demand-flow regulator, and a way to apply the gas — done manually or, better, with a docking station that automates and records it.
Calibration Gas
The gas must match your detector's target gases and the concentrations it's set to alarm on, and it must be certified (NIST-traceable). A four-gas detector typically needs a multi-gas mixture — for example LEL/methane, oxygen, carbon monoxide, and hydrogen sulfide in a single cylinder. ERE supplies Norlab calibration gases as custom and standard NIST-traceable mixtures in cylinder sizes from 17 to 221 litres (shipped within Canada). For how to choose the right mix, see Calibration Gas: Types, Mixtures, and How to Choose.
Demand-Flow Regulator
A demand-flow regulator delivers gas only when the sensor draws it, which suits aspirated and diffusion detectors and conserves cylinder gas. Fixed-flow regulators are used where a constant flow rate is required. Match the regulator to the cylinder valve (for example CGA 600 or C-10).
Docking and Calibration Station
A docking station automates bump testing and calibration, applies the gas, evaluates pass/fail, and logs every record automatically. The RKI SDM-03 docking station, for example, performs stand-alone or PC-controlled bump tests and calibrations for compatible monitors and stores the records for upload — turning a manual, easily-skipped task into a one-button routine with an audit trail.
Should You Calibrate In-House or Use a Calibration Service?
Calibrate in-house when you have the gas, regulators, and a docking station and the volume to justify them; use a calibration service when you don't, or when you want certified, documented work without managing gas inventory. Both are valid — the choice is about fleet size, in-house capability, and documentation requirements.
In-house calibration with a docking station is efficient for a fleet of detectors and gives you immediate turnaround. A calibration service makes sense for smaller fleets, mixed-brand instruments, or organizations that want certified records without stocking calibration gas (which ships only within Canada and has a shelf life). ERE provides instrument calibration and repair services across Canada for major gas detection brands, alongside the gas and docking equipment for teams that calibrate in-house — so you can choose the model that fits your operation.
What ERE Supplies for Gas Detector Maintenance
ERE Inc. has supplied gas detection and environmental instruments across Canada for 30+ years, and supports the full maintenance cycle from our Montreal facility with bilingual technical service. For in-house programs, ERE stocks NIST-traceable calibration gas in custom and standard mixtures, demand-flow regulators, and docking and calibration stations including the RKI SDM-03. ERE also sells and rents the portable gas detectors these consumables serve.
For teams that prefer to outsource, ERE's repair and calibration service handles calibration, bump testing, and repair for major brands with documented, certified results. Send your detector models and fleet size and our technical team will recommend the right mix of gas, docking equipment, or service.
Keep your gas detectors compliant with ERE.
ERE Inc. supplies calibration gas, docking stations, and a full calibration and repair service across Canada — with bilingual technical support. Tell us your detector models and fleet size and we'll recommend the right setup or service.
→ Request a Quote | 1-888-287-EREC | Repair & Calibration Services | sales@ereinc.com
Frequently Asked Questions
What is the difference between a bump test and a calibration?
A bump test is a quick pass/fail check that confirms a gas detector's sensors respond to gas and its alarms activate. A calibration is a measured adjustment that resets the detector's accuracy against a certified reference gas. The bump test verifies the detector still works; the calibration corrects how accurately it reads.
How often should you bump test a gas detector?
Before each day's use. A daily bump test is the baseline verification that catches a failed or drifted sensor before someone relies on the instrument. If a bump test fails, take the detector out of service and calibrate or repair it before use.
How often does a gas detector need to be calibrated?
On the manufacturer's schedule — commonly every 3 to 6 months — and immediately after a failed bump test, a drop or impact, exposure to high gas concentrations or sensor poisons, or any repair. Always follow the instrument manual where it specifies a more frequent interval.
What gas is used to calibrate a gas detector?
Certified, NIST-traceable calibration gas matched to the detector's target gases and alarm concentrations. A four-gas detector typically uses a multi-gas mixture (LEL/methane, oxygen, carbon monoxide, and hydrogen sulfide) in one cylinder. The concentration must be exact because calibration sets the reading to it.
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Lire en français : Test fonctionnel ou calibration : le guide d'entretien des détecteurs de gaz au Canada