Test chamber volume selection:
When placing the tested product (components, components, parts or complete machine) into the test chamber for testing, in order to ensure that the atmosphere around the tested product can meet the environmental test conditions specified in the test specification, the working size of the test chamber is different from the outside of the tested product. The following rules should be followed between profile dimensions:
a) The volume of the product to be tested (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 section area of the tested product to the total area of the test chamber working room on the section is not greater than (35-50)% (35% is recommended).
c) The distance between the outer contour surface of the tested product and the test chamber wall should be kept at least 100-150mm (150mm is recommended).
The above three-point provisions are actually interdependent and unified. Taking a 1 cubic meter cube box as an example, the area ratio of 1:(0.35~0.5) is equivalent to the 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 volume of the working chamber of the environmental test equipment should be at least 3 to 5 times the outer volume of the tested product.