A temperature humidity chamber should be selected around the test program it must run. Volume, temperature range, and price are useful starting points, but they do not establish performance with the actual fixtures, occupied cable ports, powered samples, or humidity transitions. Put those conditions in the RFQ before comparing suppliers.
This checklist helps reliability labs, QA teams, and overseas procurement teams describe the required chamber, installation, records, and acceptance evidence. It applies to standard climate work and identifies when powered or higher-risk samples need a separate engineering review.
01 Start with the real profile, not the headline chamber range
Send the temperature and humidity setpoints, dwell periods, transitions, repeat count, and required operating schedule. Identify the standard or internal procedure and its contractually required edition. State whether dwell timing starts when chamber air reaches the condition or when a defined sample measurement does; use the rule in the governing method.
- Required temperature and relative humidity pairs, including transitions
- Steady-state or cyclic exposure, duration, and allowable interruptions
- Heating and cooling rate separately, with the temperature interval and measurement location
- Powered state, duty cycle, and heat dissipation at each stage
- Measurement tolerances, sensor positions, and required stabilization evidence
Ask for the supplier’s temperature–humidity operating envelope. Separate headline temperature and RH ranges do not guarantee that every combination is available. Humidity control also depends on temperature; a temperature-only low-temperature rating should not be read as a humidity rating at that condition.
02 Document the load and fixture condition
Catalog performance may be stated for an empty chamber or another defined load. Your test program uses samples, shelves, fixtures, harnesses, and sometimes powered equipment. Ask the supplier to state the quoted load condition and identify any performance that still requires demonstration. Include dimensions, materials, thermal mass, placement, and heat dissipation rather than total mass alone.
Confirm shelf and floor load ratings, internal usable dimensions, and the full route from receiving area to the installed position. Avoid choosing capacity from liters alone. A supplier should review the proposed arrangement before committing to loaded performance.
03 Define humidity and temperature performance at the required conditions
Specify the conditions that are difficult for your program: pull-down with thermal mass, humidity stability with sealed occupied ports, or recovery after a permitted interruption. Chamber control-sensor readings and sample temperatures are different measurements. Name both where the method needs them.
Compare stability over time, spatial uniformity, and deviation from the target as separate quantities. Require the supplier to identify how each is measured, at which points, under which load, and with what instrument uncertainty. A single headline accuracy figure cannot answer all of these questions.
Define door-opening and recovery requirements only where they belong in the procedure; opening a chamber can interrupt a qualification exposure. Confirm condensation requirements and permitted sample handling. For fast transitions, compare the loaded requirements with the rapid temperature change chamber route. An average air ramp rate does not establish a linear rate throughout the interval or the rate achieved inside a sample.
04 Plan records, alarms, and sample risk
Define the required sampling interval, timestamp handling, sensor channels, export format, retention, alarm history, and response to power loss. If records are subject to a regulated or customer-controlled process, agree the required controls and evidence; a data-export feature alone does not prove compliance.
- Who supplies and controls DUT power, measurement equipment, and interlocks?
- Which independent sample sensors and shutdown functions are required?
- How are alarm states recorded, communicated, and reset?
- What happens after a utility failure or loss of monitoring?
- Which site exhaust, gas, pressure, fire, or fragment provisions need engineering review?
Agree protection requirements and operating limits with the supplier and the site’s responsible engineering team. Verify alarm and interlock behavior using an approved simulation during acceptance; do not create a hazardous DUT failure merely to demonstrate the system.
05 Check installation and service scope before final price
Confirm supply voltage, phase, frequency, rated current, protective devices, room heat rejection, ambient operating limits, water quality, drainage, and any cooling-water or compressed-air requirements. Verify floor loading, door swing, service access, shipping dimensions, and installation responsibility.
Request the model’s maintenance schedule, consumables, calibration approach, spare-parts availability, warranty exclusions, and support arrangements. Clarify which utilities and external equipment the price includes. Compare total installed scope and recurring service requirements with the same assumptions across suppliers.
06 Make acceptance evidence part of the RFQ
Agree factory and site acceptance criteria before ordering. Define representative samples or approved dummy loads, occupied-port configuration, measurement positions, stabilization rules, tolerances, heating and cooling intervals, run duration, and the records to deliver. Where a requirement is not demonstrated at the factory, assign the site test and responsibility explicitly.
The acceptance package can include calibration records, loaded climate traces, approved alarm and power-loss simulations, data-export checks, installation checks, manuals, and training. Record deviations and retest rules. Chamber FAT/SAT acceptance demonstrates the agreed equipment scope; it does not by itself qualify the DUT or certify a product to a test standard.
Send suppliers a concise package: governing method, profile, load drawing, heat dissipation, ports and interfaces, measurement plan, risk information, utilities, acceptance criteria, delivery requirements, and exclusions. Ask each supplier to mark confirmed requirements, assumptions, optional items, and requirements needing further validation.
07 Build a shortlist around the test program
Use Bellue’s temperature humidity chamber route for standard climate programs and the environmental chamber overview when comparing chamber families. Share future capacity or faster-transition needs so the quotation can identify an expansion path.
Send Bellue the test profile and load layout, together with ports, powered state, utilities, and acceptance requirements. A clear scope helps the supplier identify gaps and gives procurement a basis for comparing the same deliverables.