Bump testing versus calibration — GX-3R Pro
- Instrument: identify the model being tested or calibrated. Similar housings can contain different sensor configurations.
- Controls: check the controls and settings before use, and prepare the test-gas connection according to the manual for this model.
Response testing and calibration are different tasks
A bump test checks response to a specified gas, including alarms. Calibration adjusts the reading against a known concentration. Both use test gas, but their purposes and outcomes differ; one undifferentiated completion box hides that distinction.
Depending on settings, a GX-3R Pro bump test may be followed by calibration. Retain the initial result separately from the adjustment and final result. Repeated failures are difficult to identify if the pre-adjustment condition is discarded.
Test gas is part of the measurement chain
A known gas must reach the sensor before its response can be assessed. Check gas identity, concentration, expiry and instrument settings. Residual cylinder pressure does not establish the certified concentration after expiry. Gas used for another instrument is not automatically suitable.
The regulator, tubing and adapter deliver the gas. Disconnection or blockage can resemble a sensor failure. Adjusting the sensor to compensate for unsuitable delivery corrupts the reference for later measurements. Use the specified flow and connection method.
Keep BUMP, AIR and gas calibration separate
BUMP checks response under test conditions, AIR adjusts the clean-air reference, and gas calibration compares and adjusts against a known concentration. Air adjustment does not demonstrate gas response: a sensor with reduced sensitivity can still show a low value in clean air.
The Korean manual’s default BUMP interval of 30 days is a menu setting. It is not a universal permission to test only every 30 days. Pre-use checks, checks after exposure or impact and periodic maintenance must follow the applicable instructions and conditions.
The BUMP tolerance in page 66 of the Korean manual uses a different basis for oxygen than for other gases. Do not copy one channel’s pass range to another. Since a tolerance change can alter the outcome for the same response, retain the settings and their revision history.
Page 100 separates the bump result from subsequent calibration on the display, using P and F for pass and fail. Read both to distinguish initial response from the adjusted state. Recording only the final pass can erase evidence that adjustment was needed.
Conditions for a valid test
The specified test concentration and instrument entry must agree for each channel. A mixed-gas cylinder does not necessarily test every installed sensor. Document the sensor, gas mixture, adapter and settings together so another operator can reproduce the method.
Do not use contaminated workplace air as a reference. Test in clean surroundings where released test gas will not accumulate. Follow stabilisation instructions after major environmental changes, and choose a location where test alarms cannot be confused with a process leak.
Automatic calibration after a failed bump test is a separate setting. Confirm that the actual configuration matches the authorised test workflow. Check the test mode after exchanging instruments or restoring settings so adjustment does not occur unexpectedly.
The manual calls for separate gas bags for different gases or concentrations. Residual gas can compromise the reference mixture. Identify containers and connections appropriately when preparing tests for multiple channels.
For ESR-A1CP, the manual specifies separate CO and H₂ adjustments. Do not record both as adjusted from one exposure merely because they are associated with one sensor. This instruction applies to that configuration, not to instruments without it.
| Task | Purpose | Record |
|---|---|---|
| BUMP | Response to specified gas | Channel pass or fail |
| AIR | Clean-air reference | Conditions and completion |
| Calibration | Adjust to known concentration | Before, after and retest |
Record results channel by channel
Before testing, inspect the inlet, filter, battery and alarm indications. Afterwards, record each channel’s pass or fail and alarm status. Marking the whole device normal despite one failed channel can return an instrument without a required capability.
Where automatic calibration produces a pass, preserve the initial failure, adjustment and subsequent test as one sequence. Do not overwrite the failure with the final value. Record any cylinder or adapter change so delivery problems can be distinguished from sensor problems.
A gas challenge and alarm response are separate from startup display and buzzer checks. Startup checks can support electronic and indication checks but do not replace the gas path from inlet to sensor. Separate fields make omissions visible.
Separate scheduled maintenance from use decisions
The Korean manual separates daily checks, monthly alarm tests and periodic maintenance. Its maintenance guidance of at least once per 1 year, ideally every 6 months, is not one interval for every test. An outside-service schedule does not justify postponing action on a failed pre-use test.
Link service results to the serial number, sensor types, gas concentration and expiry, before-and-after results, replaced parts and retest. A due-date label helps locate evidence; it cannot override a fault indication or a missing channel.
Manufacturer replacement tables give recommended intervals under specified conditions. Contamination, impact, immersion or deteriorating response requires assessment of present condition rather than waiting for a calendar date. Reissue requires completion of the checks associated with the repair.
After sensor contamination, available combustible-gas conversions may be restricted. On return from service, check the usable gas settings and restrictions as well as power-up. Do not assume the former conversion remains valid.
Investigate gas delivery separately from the sensor. Check identity, concentration, expiry, regulator, adapter and settings; unresolved failure needs service. Widening a tolerance to obtain a pass does not restore the required capability.
A replacement record needs more than the part name. Link the channel and defect to the post-repair test supporting return to service. Recurring-fault review depends on the repeated failure conditions, not merely a count of repairs.
Connect service evidence with field records
A confined-space instrument must be capable of measuring the required oxygen and hazardous gases. A service certificate does not establish a suitable sampling location or task conditions. Including the device identity in field records connects measurements to the relevant service history.
Service evidence addresses whether the instrument is ready for its specified use; a field record identifies who obtained what result, where and when. Connect them by instrument identity and review affected measurements if a fault is discovered during use.