in the long-term contact with the user, it is often encountered that the user cannot distinguish the equipment whose approximate function boundaries are blurred, such as the drying oven, the high temperature test chamber, the air thermal aging box and the aging room (burning room). instruction of.
the high temperature test box is used for the high temperature adaptability test and high temperature stress test of the test sample, and can also be used as a drying box, but due to the large difference in indicators, the drying box cannot replace the high temperature test box.
the air thermal aging test box is used to conduct the air thermal aging test on the test sample, detect the aging speed of the test sample in the high temperature air environment, and evaluate the life of the test sample.
the aging room is generally used for the sophisticated screening of products before they leave the factory to pick out early-stage failed workpieces. mostly used in electrical and electronic products.
there is also an electric heating constant temperature incubator with low temperature requirements, which is mostly used in medical treatment and agriculture and forestry.
2. corresponding product standards
the current implementation standard of drying oven is jb/t5520-91 "technical conditions of drying oven";
high temperature test chamber current implementation standard gb/t11158-2008 "high temperature test chamber technical conditions"
air thermal aging test box current implementation standard jb/t7444-94 "air thermal aging test box"
the current implementation standard of electric heating constant temperature incubator yy0027-90 "electric heating constant temperature incubator"
there is no special product standard for aging room, generally refer to gb/t11158-2008 "technical conditions for high temperature test chamber"
3. similarities and differences of indicators
3.1 drying oven
temperature fluctuation: ±1℃
temperature uniformity: ±3.5% (natural convection, maximum nominal temperature)
±2.5% (forced convection, maximum nominal temperature)
temperature stability: 2℃ (24h, ≤200℃, ≤2m3)
1% (24h, >200℃, ≤2m3)
3℃（24h，≤200℃，>2m3）
1.5% (24h,>200℃,>2m3)
air exchange rate: adjustable
3.2 high temperature test chamber
temperature fluctuation: ≤1℃
temperature gradient: ≤2℃
temperature deviation: ±2℃
3.3 air thermal aging test chamber
temperature fluctuation: ≤1.5℃ (forced convection)
≤2.5℃ (natural convection)
temperature uniformity: ≤7°c (forced convection, maximum temperature 300°c)
≤10℃ (forced convection, maximum temperature 500℃)
temperature stability: ≤5℃ (24h)
air exchange rate: ≤100times/h or 100～200times/h (adjustable within the range, forced convection)
≤50times/h (adjustable within the range, natural convection)
3.4 aging room
since the aging room has no product standards and the operating temperature is not high, generally refer to the indicators of the high temperature test box:
temperature fluctuation: ≤1℃
temperature uniformity: ≤2℃ (according to gb/t11158-98 index)
temperature deviation: ±2℃
air exchange rate: adjustable
4. differences in configuration
4.1 heating
at present, nickel-cadmium alloy wire is generally used for heating, which has the characteristics of small heat capacity, oxidation resistance and long service life. some drying ovens use iron-chromium-aluminum wire, that is, ordinary electric furnace wire, which has a relatively short service life. if the test sample has certain corrosive or volatile substances precipitated, it should be equipped with a stainless steel heating tube.
4.2 blast
except for the natural convection drying oven and the aging oven, the air blast of the drying oven is generally relatively small.
4.3 ventilation
natural convection drying boxes and aging boxes rely on ventilation dampers to form convection, and naturally open ventilation holes.
the forced air drying oven and the high temperature test chamber do not have high ventilation requirements, but they are equipped with adjustable ventilation dampers for faster cooling.
the forced convection air thermal aging test box has to be equipped with a forced ventilation blower due to the requirements of the air exchange rate test index, and measures to adjust the air volume are set on the circuit.
when the aging room is working, the test product is powered on, which will generate heat. in order to balance the temperature, a ventilation fan must be installed.
4.4 structure
due to the high temperature field requirements of the high temperature test chamber, the laminar flow design is generally adopted.
the air thermal aging test chamber will have uncertain temperature field under different ventilation conditions, so there are products equipped with rotating test sample shelves.
the aging room generally needs to consider the situation of the test rack or the test vehicle.
5. determine what kind of equipment is needed from the usage requirements
due to the different configurations of equipment, the price difference is also large, so users must know their own needs when purchasing equipment, so as to avoid the equipment sold back cannot be used because the indicators cannot be met, or the cost performance is not cost-effective.
a common drying oven can be purchased for the drying, colloid curing and annealing of workpieces that do not require high temperature deviation. if the temperature deviation requirements are high in the process, a high temperature test chamber should be purchased.
the air thermal aging test chamber should be purchased only if the use conditions have clear requirements for the ventilation volume index. for those who only require proper ventilation and have no clear indicators, you can purchase a drying oven or a high temperature test chamber. generally, equipment below 300°c is equipped with a ventilation damper.