These are the questions TestEQ engineers are asked most often when a chamber is specified. The figures below are the published chamber specifications; the exact configuration is confirmed against the applicable test standard before order. Related detail is grouped by industry on the applications page.
How do I select the right environmental test chamber?
Four factors decide the model: chamber volume, temperature range, temperature change rate and the heat the test article generates. Volume: TestEQ chambers run from 100 L to 12,000 L; the usable space has to hold the sample without blocking the air circulation path. Temperature range: the published machine-level range is −75°C to +200°C, while individual series differ — for example the ETH temperature and humidity series is offered from −40°C or −70°C to +180°C, and the thermal cycle range is published to +200°C. Temperature change rate: standard high/low-temperature chambers run at about 2°C/min heating and 3°C/min cooling (average, empty chamber), rapid temperature change chambers are configured from 5°C/min up to 30°C/min, and HALT/HASS systems reach higher rates again. Heat load: the total heat dissipation of the loaded samples must be stated, because a live load changes both the achievable rate and the temperature distribution. TestEQ offers an optional product temperature control function that follows the sample temperature rather than the airflow alone.
What is the difference between temperature fluctuation, deviation and uniformity?
The three values describe different things. Temperature fluctuation (< ±0.5°C) is the variation of the temperature at a fixed set point over time. Temperature deviation (< ±2.0°C) is the difference between the actual temperature and the set or indicated value. Temperature uniformity (±0.5°C on the published machine-level specification, ≤2.0°C on some series) is the spread between measurement points at the same moment. TestEQ performance figures are referenced to IEC 60068-3-5, and are measured on an empty chamber at atmospheric pressure.
What is the highest temperature change rate available?
Rapid temperature change (RTC) chambers are configured from 5°C/min up to 30°C/min. For HALT/HASS work the ETH² series reaches an average heating and cooling rate of 70°C/min, with vibration from 5 to 100 GRMS over a 10 to 10,000 Hz frequency range. Standard chambers are slower — the EQT series is published at about 2°C/min heating and 3°C/min cooling (average, empty chamber). The rate achieved on a loaded product is lower than the empty-chamber figure; the optional product temperature control function can shorten the time considerably. In one published example, cycling the chamber between +80°C and −40°C, a sample surface reached −40°C in 16 minutes with product control instead of 50 minutes without it.
How does low air pressure (altitude) testing work, and how do pressure values relate to altitude?
Altitude chambers reproduce the reduced pressure a product meets at high altitude. TestEQ altitude systems simulate from ambient pressure up to the equivalent of 43,000 m, and can hold temperature and humidity in the same test space. Fast depressurization is possible: 4,550 m to 21,350 m within 15 seconds. The published depressurization rates are:
- site level (ambient) to 15,250 m in 10 min, reaching 11.6 kPa
- site level to 22,860 m in 20 min, reaching 4.0 kPa
- site level to 30,500 m in 30 min, reaching 1.0 kPa
The pressure range is site level to 500 Pa. Altitude deviation is ≤ ±2 kPa from site level to about 40 kPa, ≤ ±5 kPa from 40 to 4 kPa, and ≤ ±0.1 kPa from 4 to 1 kPa. The relevant method standards are IEC 60068-2-13 (Test M: Low Air Pressure) and the low-pressure procedures of MIL-STD-810.
What is the difference between thermal vacuum testing and low-pressure (altitude) testing?
Both reduce the chamber pressure, but they simulate different conditions. An altitude or low-pressure chamber reproduces the pressure a product meets in flight, transport or service — including the fast 4,550 m to 21,350 m decompression above — and can control temperature and humidity at the same time; it suits avionics, automotive electronics and other high-altitude equipment. A thermal vacuum chamber combines a high-vacuum environment with extreme temperature control for space and satellite hardware, and is used to evaluate material outgassing, thermal balance, electronic performance and long-term reliability under space-like conditions. Because the pressure level and the way heat is transferred differ, the two are specified separately.
How do I choose between a two-zone and a three-zone thermal shock chamber?
Both move a product between a hot and a cold environment to expose it to sudden temperature transitions; the ETS series covers two-zone and three-zone designs. A two-zone chamber moves the basket between a high-temperature zone and a low-temperature zone; a three-zone chamber uses a hot zone, a low-temperature zone and an air-operated damper to switch between them. Basket volumes run from 23 L to 125 L and chamber volumes from 70 L to 300 L. The high-temperature zone is preheated over +60°C to +200°C (rising +60°C to +200°C within 20 minutes) and the low-temperature zone is precooled over −78°C to 0°C (+20°C to −75°C within 70 minutes); temperature recovery time is ≤5 minutes. Shock range is grouped by model suffix: -40W covers +60°C to +150°C against 0°C to −40°C, with -55W and -65W at the lower end. Choose on the volume to be transferred, the required transfer time, and whether an ambient dwell is part of the profile.
Do I need humidity control?
Add humidity when the qualification standard or the product’s service environment calls for damp heat, condensation or humidity cycling, or when moisture-related failure modes such as corrosion, insulation loss or electrochemical migration have to be reproduced. TestEQ humidity chambers cover 10% to 98% RH, with humidity uniformity ±1.0% RH and relative humidity deviation ≤ ±3.0% RH above 75% RH and ≤ ±5.0% RH at or below 75% RH. If the programme is purely temperature (high/low temperature or thermal shock), a temperature-only chamber is sufficient. Note that the humidity figures do not apply to temperature-only chambers.
What are the installation requirements?
The chamber needs sufficient laboratory floor space, a floor drain for condensate, and an appropriate laboratory ambient temperature. Published performance is measured at 50 Hz and 23.9°C laboratory conditions. The standard power supply is AC 380 V, 3-phase, 4-wire plus protective earth, and water is supplied by pump lift (water tanks of 40 L or 60 L are used on some models). Larger and higher-power systems also carry a stated cooling-water circulation requirement. Where a vacuum pump is fitted, it is not included in the exterior dimensions or the noise figures.
How is performance verified and accepted?
Performance is defined on an empty chamber at atmospheric pressure, and TestEQ publishes fluctuation, deviation and uniformity figures referenced to IEC 60068-3-5. Acceptance is based on those stated figures at the agreed set points. Because heat generated by a load changes both the achievable change rate and the temperature distribution, a loaded acceptance test has to be agreed separately from the empty-chamber figures. Detailed technical requirements are confirmed with the local sales representative before order.
What service and spare parts support is available?
TestEQ has sales and service offices in Dongguan, Xi’an, Beijing and Shanghai, covering South, Central, East, South-west, North-west and North-east China, with factory support behind them. The 7" touch-screen controller provides fault alarms with cause and handling prompts, over-temperature protection, power-failure protection, timer functions and self-diagnostics, which supports remote diagnosis. Spare-part and service arrangements for a specific model are confirmed with the local office.
How does an engineered-to-order project work?
TestEQ designs and manufactures non-standard test equipment to user requirements. The standard series covers a large part of the market, but chambers can be configured for special chamber sizes, temperature ranges, combined stress (temperature, humidity, vibration, altitude) and interface requirements. The process starts with the technical requirements — test article, applicable standard, test conditions and duration — so that the correct chamber is selected. The listed models are not exhaustive.
What limits apply to sample loading?
Sample weight is limited by the shelf or table. The three-combined series uses stainless shelves on heavy-duty rails with a standard load of 50 kg and a heavy-duty option up to 100 kg; thermal shock shelves carry 20 kg standard and up to 50 kg heavy-duty; HALT/HASS table loading is 55, 70, 95 or 150 kg depending on model. A sample must not block the air circulation path, and the heat it generates has to be stated: with a live load, product temperature can lag the airflow temperature by 20°C or more. These chambers are not used for flammable, explosive or corrosive test articles, or for biological specimens; contact the factory for special items.