Preventive Measures for High and Low Temperature Test Chamber Testing

In order to achieve reproducibility, temperature tests must be designed in such a way that the highest or lowest temperature reached at a certain point in the high and low temperature test chamber is the same, regardless of the laboratory in which the test is conducted. For test designs with a shorter duration compared to the time required for the test sample to reach temperature stability, the following preventive measures should be considered:

1. Air velocity around the test sample:
The heat exchange efficiency between the air and the test sample in a high and low temperature test chamber depends on the air velocity. In high and low temperature tests, it is expected to accurately simulate the air velocity in the actual environment. However, due to limited knowledge of the actual environment and difficulty in confirming the air velocity in the test chamber, this simulation is usually not possible,

Therefore, it is generally necessary to conduct the test according to the “worst case” to cover various possibilities. When testing non heat dissipation test samples, higher air velocity leads to higher/lower test sample temperatures for low-temperature tests.

Therefore, it is recommended to use a high air velocity (preferably not less than 2M/S when measuring at no load) in a test chamber for conducting such tests. When testing heat dissipation test samples, if the hottest temperature of the test sample is higher than the surrounding air temperature, the higher air velocity will lower the temperature at that point.

Therefore, in most cases, whenever possible, this test should be conducted in a test chamber without forced air circulation (i.e. free air conditions), When the heating or cooling of the test chamber can only be achieved through air circulation, a forced air method can be used as a substitute.

2. Condition:
In order to achieve reproducibility, the temperature time process of the air in the test chamber must be well specified throughout the entire high and low temperature test chamber. When accurately simulating the actual environment, the temperature time process can be specially designed to simulate this situation. It should be noted that the temperature time process diagram is different from Test A and Test B in the following details:

a. At the beginning, the temperature range is relatively narrow (25 degrees plus or minus 3 degrees);
b. Establish the rate of temperature change in the air of the test chamber during the test temperature period;
c. The duration of the test is calculated from the time when the air temperature in the test chamber reaches the specified value.

What should I do if the cooler tube of the high and low temperature test chamber is abnormally hot?
1. Root cause
①. The placement position of the high and low temperature test chamber is too close to the wall;
②. The temperature of the gas in the room is too high;
③. Poor gas flow in the room;

④. Excessive dust and oil stains on the cooler;
⑤. There is oil or dirt blockage in the cooler memory;
⑥. There is partial blockage in the dry filtration device or capillaries.

The existence of the above elements reduces the heat dissipation characteristics of the cooler, preventing the surface heat of the cooler from being immediately discharged outward, resulting in an increase in the cooling temperature of the refrigerant and the heat generation on the wall thickness.

2. Clearing method
①. The placement position of the high and low temperature test chamber should be 60cm above and below the wall surface;
②. The gas temperature in the room should be maintained at 15-25 ° C;

③. The dust on the cooler can be removed with a feather duster; For accumulated oil stains, you can use a soft towel dipped in carbon tetrachloride to carefully scrub, without using too much force to prevent bending of the condensing tube or welding plate (wire) sheet metal. When removing dust and dirt from welding or stamping molds, it is not allowed to use needles to puncture and remove them.

The impact of frequent opening and closing of chamber doors in high and low temperature test chambers:
1. If the high and low temperature test chamber is being tested at ultra-low temperatures of -60 ℃, opening the equipment chamber door will cause cold airflow to spill out. If our fingers do not take any protective measures and touch the sample rack on the inner wall of the equipment chamber, they will be instantly frostbitten, and the frostbitten area will suddenly appear necrotic; In addition, opening the equipment box door in ultra-low temperatures can also cause frost on the evaporator, which can affect the cooling speed and may also cause damage to the compressor.

2. If the equipment is operating at a high temperature of 150 ℃ and the equipment chamber door is opened recklessly, the high-temperature gas will also instantly rush out of the instrument. If relevant safety measures are not taken properly, it may cause burns to our face, and even cause unnecessary fires if there are flammable materials that can easily ignite near the test instrument.

3. If the high and low temperature test chamber is conducting a high temperature and high humidity test, the pressure and steam in the instrument will increase to an extremely large size. If the equipment chamber door is opened at this time, there will be high temperature or high humidity steam rushing out of the equipment, which is likely to cause serious burns to the staff.

4. If the equipment requires multiple opening of the chamber door for sampling in the middle of the test, there is one method to solve it, which is to install two doors, one of which is an external door: it can provide insulation and sealing, and there is also an observation window; Another door is made of epoxy board or transparent hard plastic board, with a suitable small hole in the middle of the door for easy access to test samples. This way, the product can be effectively isolated and directly exposed to the air, and the temperature uniformity will not be affected by diffusion.

Temperature Humidity Chamber | Thermal Chamber | Climate Chamber is according to IEC60068-2-1 (GB/T2423.1) and IEC60068-2-2 (GB/T2423.2), IEC60068-2-78, IEC60598-1, GB/T2423.17, GB/T5170.2, GB/T5170.5. The climate chamber is used to test the CFL/LED which meets IES LM-80-08, electricity products, automative cars, home appications and mobiles.

What is Climate Chamber?

Climate chambers is used to simulate a temperature enviromental condistions, it may also be called environmental chambers or Thermal Chamber or Temperature Chamber. You can click the below videos to learn the details and also how to operate it.

Lisun Instruments Limited was found by LISUN GROUP in 2003. LISUN quality system has been strictly certified by ISO9001:2015. As a CIE Membership, LISUN products are designed based on CIE, IEC and other international or national standards. All products passed CE certificate and authenticated by the third party lab.

Our main products are Goniophotometer, Integrating Sphere, Spectroradiometer, Surge Generator, ESD Simulator Guns, EMI Receiver, EMC Test Equipment, Electrical Safety Tester, Environmental Chamber, Temperature Chamber, Climate Chamber, Thermal Chamber, Salt Spray Test, Dust Test Chamber, Waterproof Test, RoHS Test (EDXRF), Glow Wire Test and Needle Flame Test.

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