Tips for choose appropriate SSD chamber
Tips for choosing an appropriate SSD chamber
The selection of the environmental test chamber should be based on the test samples and test standards or regulations, and the test chamber suitable for the sample size, temperature and humidity range, and national standards should be selected. This article describes in detail how to choose the appropriate test chamber size, temperature and humidity range, cooling method, etc.
1. Chamber size
When the tested product (components, components, parts, or a complete machine) is put into the constant temperature and humidity chamber for testing, in order to ensure that the surrounding environment of the tested product can meet the environmental test conditions specified in the test specification, the working size of the climate chamber is different from the tested product. The following rules should be followed between the outline dimensions:
a. The volume of the tested product (W×D×H) shall not exceed (20～35)% of the effective working space of the test chamber (20% is recommended). It is recommended to use no more than 10% for products that generate heat during the test.
b. The ratio of the windward cross-sectional area of the tested product to the total area of the test chamber working room on this cross-section is not greater than (35-50)% (35% is recommended).
c. The distance between the outer contour surface of the tested product and the wall of the test chamber should be kept at least 100-120 mm (120 mm is recommended).
The above three-point provisions are actually interdependent and unified. Taking a 1 m³ cube test chamber as an example, an area ratio of 1:(0.35~0.5) is equivalent to a volume ratio of 1:(0.207~0.354). 100～150mm from the box wall is equivalent to a volume ratio of 1:(0.343～0.512).
To sum up the above three points, the working chamber volume of the climate environmental test chamber should be at least 3 to 5 times the outer volume of the tested product.
However, we have miniatured size ranged from 10~42L test chambers, which is ideally designed for the options for SSD test. temperature change rate for both heating and cooling speed can be 3~20 ℃/min (both linear speed or average spped is OK)
2. Temperature range
The temperature range of MENTEK can reach -70°C to 150°C. This temperature range can usually meet the temperature test needs of most domestic military and civilian products. Unless there are special needs, such as products installed close to heat sources such as engines, the upper temperature limit cannot be blindly increased. Because the higher the upper limit temperature, the greater the temperature difference inside and outside the box, and the worse the uniformity of the flow field inside the box. The available studio volume is also smaller. On the other hand, the higher the upper limit temperature value is, the higher the heat resistance requirement is for the thermal insulation material (such as glass wool, etc.) in the interlayer of the box wall. The higher the requirements for the tightness of the box, the increase in the production cost of the box, while the low temperature involves the cost of the product. The lower the low temperature, the greater the power and cooling capacity of the refrigeration system and the corresponding equipment cost.
3. Humidity range
In the above temperature range, the MENTEK humidity range can reach 10% ~ 98% RH. Generally speaking, for the same moisture content, the higher the temperature, the smaller the relative humidity. For example, if the moisture content is 5 g/kg (meaning that 1 kg of dry air contains 5 grams of water vapor), when the temperature is 29 °C, the relative humidity is 20% RH; when the temperature is 6 °C, the relative humidity is 90% RH; when the temperature drops below 4 °C and the relative humidity exceeds 100%, condensation will occur in the box. If the humid heat test box does not have a dehumidification system and the humidity range is 60 ~ 98% RH, this type of test box can only do high humidity tests, but its price is much lower.
4. Cooling method
There are two cooling methods: air cooling and water cooling. Which cooling method to choose should be determined according to the actual situation of the laboratory. When conditions permit, water cooling is a preferred option because its performance will be better and more stable.