If you're in an industry where gas detectors are essential (oil and gas, refineries, chemical plants, or confined spaces), you know that these devices are lifesavers, but knowing when to bump and calibrate between brands can be a pain. They're only as reliable as their last calibration, and depending on who you ask, that can be anywhere from once a month to every six months. Skipping or delaying calibration can lead to false readings, failed alarms, or worse: undetected hazards that put lives at risk. When that happens, everyone is getting dragged in by the lawyers, and you need to make sure your ducks are in a row.
At Ideal Calibrations, we've calibrated and repaired thousands of gas monitors from brands like Honeywell BW, MSA, RKI, Industrial Scientific, and others. We've seen firsthand how sensor drift, environmental exposure, and everyday wear can throw off accuracy. In this guide, we'll break down the guidelines from the manufacturers so you know how often to calibrate and how to record your date.
Why Calibration Timelines Matter: The Basics
A bump test (or function check) exposes the detector to a known gas concentration to verify sensors and alarms work. It's quick—usually 30 seconds—and confirms the unit isn't blocked or dead. A calibration check quantifies accuracy against traceable gas (usually 1-2 minutes of gas on the monitor until it stabilizes and referencing how close your values are to your cylinder). A full calibration adjusts the sensors to match the gas in your precisely.
The Occupational Safety and Health Administration (OSHA) and the International Safety Equipment Association (ISEA) set the foundation. OSHA's 2024 Safety and Health Information Bulletin (SHIB 11-26-2024) emphasizes verifying detector accuracy before each day's use to prevent exposure to toxic gases, oxygen deficiency, or flammables. ISEA's Statement on Validation of Operation echoes this: perform a bump test or calibration check daily, and full calibration at regular intervals per manufacturer guidelines.
Why daily bumps? Sensors drift due to age, contamination (e.g., silicones, phosphates), temperature swings, or high-gas exposure. Sometimes they just stop working one morning for no discernible reason. You never know what the other guys using your detector have exposed it to. Some guys think it’s funny to check the exhaust on their trucks and overrange the sensor. They’re not going to tell you they broke it, they’re just going to put it back on the shelf.
Electrochemical sensors (for toxics like CO or H2S) drift faster than catalytic bead LEL sensors, but LEL sensors as a rule are more prone to poisoning from the environment. Exotic sensors, like those used for HCl, Cl2, and NH3, are even more prone to random problems. General rule: bump daily, calibrate monthly, and calibrate if your detector starts acting strange. This will fix 95% of your issues.
Now, let's look at timelines by manufacturer. These are pulled from user manuals, our experience servicing these units, and direct communications with reps. Always check your model's manual for exact details, as timelines can vary by sensor type and usage.
Universal Requirements (What Every Manufacturer Agrees On)
1. Daily Bump Test – Required Across OSHA, ISEA & Manufacturers
Every detector, every shift. Hazmat, confined space, fire service, industrial — all treated the same by OSHA. ISEA reinforces the same rule. This means either exposing your monitor to gas manually or putting it in a docking station (some units, like MSA’s Pulse series, have a breath check option).
2. NIST-Traceable Gas Only
Manufacturers require it, and NIST defines the traceability chain for accuracy. Ideal Calibrations cylinders meet this requirement.
3. Immediate Calibration After Exposure or Abuse
Triggers include:
- Over-range gas exposure
- Drops, impacts, submersion
- Extreme temperatures or humidity
- Sensor replacement
- Custody changes (this is a big one that people ignore. Remember, you never know what he did with it)
- Contamination (silicones, solvents, corrosives)
4. Calibration Gas Must Be In-Date
Reactive gases fade faster, especially H₂S and Cl₂. Always check the expiration date on your cylinder. Expiration dates are not suggestions. If you get audited and they find you were using expired gas, you’re going to get fried.
Honeywell (BW Technologies) Calibration Recommendations
Honeywell, through its BW Technologies line, is a powerhouse in portable gas detection. Models like the GasAlertMax XT II, GasAlertMicroClip, and BW Solo are staples in oil rigs, refineries, and water treatment plants. Honeywell's GasBook (a 116-page guide) stresses calibration for safety in high-risk areas like confined spaces.
- Bump Test: Daily before use, as per OSHA/ISEA. Honeywell recommends using their MicroDock II or Intellidox for automated testing.
- Full Calibration: Every 180 days (6 months) for most models in normal conditions. For the BW Max XT II, which features a pumped design for confined spaces, Honeywell advises monthly calibrations in heavy-use scenarios like drilling platforms, but highly recommends a dock such as the Intellidox in this case.
Honeywell’s Recommended Gas Blend:
20 ppm Hydrogen Sulfide
100 ppm Carbon Monoxide
50% LEL Methane
18% Oxygen
Balance Nitrogen
Gas cylinder for Honeywell BW Technologies units available here:
MSA Calibration Guidelines
MSA's Altair series, like the Altair 4XR and Altair 5X, are rugged favorites for mining, power generation, and commercial buildings. MSA's XCell sensors are designed for stability, but they still require regular checks.
- Bump Test: Daily, aligning with ISEA. MSA's Galaxy GX2 docking station makes this easy, but most of their monitors have an option to manually bump with an electronic record.
- Full Calibration: Every 6 months (180 days) for standard use. In high-vibration environments like wind energy manufacturing, drop to 90 days. Toxic/flammable sensors should be calibrated post-replacement or after over-range events.
- Special Notes: MSA Xcell LEL sensors use a dual catalytic bead that switches every time the unit is full zeroed. We recommend calibrating twice per session to hit both bead sets due to the Altair X series units switching between beads every zero procedure.
Gas cylinder for MSA Altair Series units available here:
RKI Instruments Calibration Timelines
RKI's GX-3R and Gas Tracer are compact and versatile, ideal for confined spaces in chemical plants or biogas generation while being easy to repair and maintain.
- Bump Test: Daily before entry, per standards.
- Full Calibration: Every 90 days for most sensors. For PID VOC sensors, calibrate every 30 days due to lamp sensitivity. In mining or excavation (Methane/CO risks), RKI suggests monthly if dust is heavy.
- Special Notes: RKI’s SDM calibration system defaults to this 90 day standard
Gas cylinder for RKI GX Series units available here:
Industrial Scientific (ISC) Recommendations
ISC's Ventis MX4 and Tango TX1 are built for harsh industries like refineries and landfills. Their iNet program offers predictive maintenance and quick unit replacements.
- Bump Test: Daily, easier with their DSXi docking station. Dual Sense units like the Tango series with two of the same sensor can be bumped as desired between calibrations if a daily bump check is not available
- Full Calibration: Monthly
Gas cylinder for Industrial Scientific units available here:
Factors Influencing Calibration Frequency
Timelines aren't one-size-fits-all. Adjust based on:
- Environment: Harsh (e.g., offshore rigs with H2S) = more frequent (30 days).
- Sensor Type: Electrochemical = 30-90 days; Catalytic = 90-180 days.
- Usage: Daily wear accelerates drift.
- Events: Over-range, drops, or storage in heat/cold? Calibrate immediately.
- Regulations: OSHA mandates verification; some industries (e.g., mining) require monthly logs. Your company may have their own internal procedures and guidelines you need to follow. Often, for liability reasons, you must maintain at least the minimum standard required by your gas detection manufacturer.
If you want to make life easy, use docking stations for automation and logging—essential for audits. If cost is an issue, you can use our free gas detector bump and calibration log
Common Mistakes and Best Practices
- Using Expired Gas: Always check dates; reactive gases fade.
- Wrong Regulators: Match flow rates (fixed flow 0.25-1.5lpm regulators for diffusion units, demand flow for pumped units). Available here:
- Skipping Zeros: Zero in fresh air away from exhaust.
- No Logs: Document everything OSHA loves records.
- DIY Overkill: If it fails twice, send it to pros like us. (Form here)
Best practice: Bump daily, calibrate monthly as a baseline. Use NIST-traceable gas from Ideal Calibrations for accuracy.
Ready to Stay Compliant?
Shop Calibration Gas →
Get Your Calibration Gas Regulator →
Whether you’re prepping for OSHA audits or keeping your crew safe, Ideal Calibrations has the gas, gear, and guidance you need.-
Stay Safe, Stay Calibrated
Confused on any of the above? Send us a note via our chat or through a contact form. Need help fast? Give us a call at 734-956-0539. We’re always here to help.