A temperature altitude chamber typically refers to a chamber designed to control air temperature and absolute pressure during the same test stage. Manufacturers also use altitude test chamber for equipment with both controls. If your procedure requires combined exposure, ask whether the proposed chamber can hold your target temperature and pressure together, within tolerance, for the specified time with the intended specimen load.
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What is the difference between a temperature altitude chamber and an altitude test chamber?
The names overlap because manufacturers describe their equipment differently. Start with the variables your test plan requires the chamber to control at each stage.
| Test requirement | What the equipment must do | What to confirm |
|---|---|---|
| Low-pressure exposure | Reach and hold the specified absolute pressure while meeting any ambient conditions stated in the procedure | Pressure tolerance, hold time and any required pressure transition rates |
| Temperature and low pressure applied in separate stages | Meet the conditions specified for each stage and follow the required sequence | Whether the procedure permits a transfer between chambers and whether transfer or recovery time is limited |
| Temperature and low pressure applied simultaneously | Reach and maintain both targets during the same stage | The achievable temperature-pressure pair, tolerances and hold time at the specified load |
A packaged item may need low-pressure exposure under prescribed ambient conditions. A powered electronics assembly that must operate in cold, low-pressure air needs both conditions held during the operating check.
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What should a datasheet confirm for combined testing?
Ask the supplier to confirm each required temperature and absolute-pressure pair under the intended load. A datasheet that lists −40°C as its lower temperature limit and 1 kPa as its minimum pressure leaves the combined point of −40°C at 1 kPa to be verified. A temperature-pressure operating envelope or a written confirmation of the specific points can help define what the supplier will verify at acceptance. For powered specimens, include the operating heat load and mounting arrangement. If the procedure requires specimen temperature stabilization, agree on where and how to measure it.
How to verify a combined temperature and low-pressure test point
Write the acceptance rule before the factory acceptance test (FAT). Use the same rule in the request for quotation (RFQ) so suppliers can quote against the same operating conditions.
Illustrative FAT acceptance criterion. With the agreed powered load installed, maintain chamber air at −20°C ±2°C and absolute pressure at 30 kPa ±1 kPa for 60 consecutive minutes. Start the hold once both variables satisfy the stabilization criteria in the test plan. If the plan also requires the specimen to stabilize, verify that condition before starting the hold.
These values and the timeline below are illustrative. Use your test procedure to set the limits for your project.
| Specify in the RFQ | Check in the FAT record |
|---|---|
| Targets, tolerances and measurement locations | Time-aligned measured chamber air temperature and absolute pressure from the agreed measurement points |
| Stabilization rule, hold duration and permitted deviations | A marked hold window and a record covering the entire interval at the agreed logging rate |
| Specimen, mounting, power state and heat load | The documented load used during FAT, including any agreed substitute and what it represents |
| Required transition sequence or rates, if applicable | The relevant temperature, depressurization and recovery stages, checked against the agreed profile |
Read the two traces on the same time axis
- Find when both conditions qualify. In this example, pressure enters its allowable band of 29–31 kPa absolute at minute 12. Chamber air enters its allowable band of −22°C to −18°C at minute 18. If the agreed stabilization criteria are met at minute 20, that is the start of the hold.
- Check the entire hold. If both readings meet the agreed limits from minute 20 through minute 80, the chamber meets the example hold requirement. If either reading leaves its band during that interval, the proposed window fails the example's continuous-hold rule. Follow the test plan's agreed restart or retest procedure.
- Confirm what was loaded. Match the trace to the recorded power state, mounting arrangement and heat load. Where a substitute load was agreed, review the results within the limits of that substitution. Keep the specimen's functional results in a separate record so the equipment acceptance and specimen pass criteria can each be checked.
<!-- IMAGE 3 | Synchronized temperature and pressure traces | See production notes -->
Which IEC standard covers low pressure and combined exposure?
| Standard | Scope relevant to this comparison |
|---|---|
| IEC 60068-2-13:2021, Test M | Low air pressure testing for specimens exposed to reduced pressure during transportation, storage or service |
| IEC 60068-2-39:2015 | Combined testing involving temperature, or temperature and humidity, together with low air pressure |
Use the edition and procedure specified by the customer or test plan to define the conditions and acceptance criteria. Where humidity is required at reduced pressure, confirm that the proposed configuration can control it at the requested temperature-pressure combination.
Sources: IEC 60068-2-13:2021 and IEC 60068-2-39:2015.
Request a GDJZ review for your combined test profile
Send ITM-LAB the target temperature and absolute pressure for each hold stage, the allowed deviations, the stabilization and hold requirements, and any specified transition rates. Include the specimen dimensions, mounting arrangement, weight, power state and operating heat load. With that information, you can request confirmation of the required operating points, discuss the configuration and agree on how the combined conditions will be verified at FAT.
The GDJZ Series lists a published temperature range of −40°C to +150°C and pressure capability down to 1 kPa. Combined performance is reviewed for the proposed configuration and load. The GDJZ-535L-B shown here is a delivered 535 L reference configuration with internal dimensions of 850 × 900 × 700 mm (W × H × D) and an external industrial chiller.
<!-- IMAGE 4 | Actual GDJZ-535L-B with external chiller | See production notes -->
Explore the GDJZ chamber and request a configuration review
For a wider comparison of capacity, thermal rates and procurement requirements, see the engineer’s buying guide to temperature and low-pressure test chambers.
Frequently asked questions
Can an altitude test chamber control temperature and pressure at the same time?
Yes, if the equipment is configured for simultaneous control and can maintain the required pair under the specified load. Request confirmation of the temperature and absolute pressure together, with the tolerance and hold time.
Can an empty-chamber trace verify a test with a powered specimen?
An empty-chamber trace establishes performance for the recorded empty-chamber conditions. For a powered test, request a trace with the agreed specimen or a representative load. Document what the load represents, including heat dissipation, placement and any relevant airflow restrictions.
Should I specify altitude or absolute pressure in my RFQ?
Use the target absolute pressure in kPa when the procedure provides it. If the requirement is given only as an altitude, identify the governing procedure or agreed conversion basis and have the supplier confirm the corresponding absolute pressure before quoting.
