A humidity test can be interrupted by a water-supply problem long before the chamber reaches a mechanical service interval. Water selection, storage, contamination, and maintenance records belong in the laboratory operating plan. This checklist helps owners ask the right questions without substituting a generic internet recommendation for the manual supplied with their particular chamber.
Start with the model-specific water specification
Ask for the approved water type and quality range in writing. Include the measurement units, reference temperature where relevant, inlet pressure, supply arrangement, and any prohibited treatment additives. Tap water can introduce deposits, while very high-purity water is not automatically compatible with every water system. Softened, distilled, deionized, and reverse-osmosis water are not interchangeable labels.
ESPEC’s published water guidance illustrates both mineral-deposit concerns and material-compatibility concerns. Its numeric limits are manufacturer-specific; do not adopt them as a Bellue specification. Confirm the requirements for the exact humidifier, sensors, tank, and piping in your delivered configuration.
Assign ownership before the first long test
Write down who supplies water, who checks it, who replenishes a reservoir, and who responds outside normal working hours. A laboratory with a treated-water loop has different responsibilities from a laboratory using manually filled containers. Record the chamber asset number and the water source together so a facility change can be traced to the tests it might affect.
Use an approved, clean, labeled container if the equipment requires manual filling. Record the refill and any change of source. Do not assume that a container previously used for another laboratory liquid is acceptable merely because it has been rinsed.
Distinguish supply contamination from sample contamination
A clean incoming supply does not prove that collected condensate is clean. Test samples, coatings, fixtures, labels, and residues can contaminate water that has circulated through the chamber. Reuse should be limited to systems designed and approved for it, with the prescribed treatment and service procedure.
If an unusual residue or odor appears, preserve the test and maintenance logs and follow the site’s safe shutdown and contamination procedure. Ask the responsible engineer to review the sample materials and recent work. Avoid adding an improvised cleaner, biocide, or descaling chemical to an operating chamber.
Make the maintenance checklist observable
| Checkpoint | Useful record | Escalation trigger |
|---|---|---|
| Water supply | Source, approved quality check, refill, and supply alarms. | Unapproved source or a result outside the model’s limits. |
| Tank and accessible tubing | Visible condition observed using the approved inspection procedure. | Leakage, unexpected residue, or contamination. |
| Consumables | Filter or wick identification, if fitted, and replacement history. | Overdue service or a condition identified by the manual. |
| Humidity performance | Setpoint, actual temperature/RH, load, and alarm history. | A persistent deviation from the approved test limits. |
| Return to service | Work completed, checks performed, and release approval. | Unexplained alarms or incomplete verification. |
Scroll the table horizontally to view every column.
Use maintenance intervals that fit the equipment
Steam generators, water filters, humidity sensors, and wet-bulb wicks need different attention, and not every chamber includes all of them. Follow the supplied service schedule and revise the laboratory plan through the responsible maintenance team when duty cycle or contamination exposure changes. Manufacturer maintenance guidance also highlights sensor checks, cooling-system cleanliness, and safety-function checks; their procedures are not universal.
Separate operator inspection from technical service. Work around electrical components, hot water, steam, refrigeration, or removed guards should be performed only by qualified personnel under the equipment manual and site isolation procedures. This article is a planning checklist, not a disassembly or repair instruction.
Keep evidence when humidity goes out of tolerance
Record when the deviation began, its duration, the actual temperature and RH traces, alarms, door openings, and sample power state. Check the requested condition against the chamber’s approved temperature/humidity operating envelope. A nominal humidity range does not imply that every RH value is available at every temperature.
The test owner should decide whether the exposure remains valid, needs an authorized extension, or must be repeated. Do not silently reset a controller or edit a report to remove an interruption. Retaining the original trace makes the decision auditable.
Verify recovery before committing valuable samples
After maintenance, run the verification defined by the service procedure and laboratory quality system. Document the setup and whether the check is empty or representative-loaded. A clean reservoir alone is not evidence that the chamber, alarm response, and data recording are ready for a long unattended exposure.
Questions for Bellue before delivery
Request the model-specific water specification, utility drawing, consumables list, service-access requirements, and commissioning checks through Contact Bellue. Include expected operating hours and sample materials. For powered electronics, also review the THB chamber RFQ guide; water maintenance does not replace electrical-bias and condensation planning.
References and scope
These references provide general background. The delivered Bellue equipment manual and approved laboratory procedures govern actual limits, service methods, and intervals.