September 2, 2022
Constant temperature and humidity test chamber
Constant temperature and humidity test box, also known as constant temperature and humidity test machine, constant temperature and humidity test box, programmable humidity and heat alternating test box, constant temperature machine or constant temperature and humidity box, is used for testing the performance of materials in various environments. This material is heat-resistant, cold-resistant, dry-resistant and moisture-resistant. It is suitable for testing the quality of electronics, electrical appliances, mobile phones, communications, instruments, vehicles, plastic products, metals, food, chemicals, building materials, medical care, aerospace and other products.
How it works
The constant temperature and humidity test box consists of two parts: temperature regulation (heating, cooling) and humidification. Through the rotating fan installed on the top of the box, the air is discharged into the box to realize gas circulation and balance the temperature and humidity in the box. The data collected by the built-in temperature and humidity sensor in the box is transmitted to the temperature and humidity controller (micro Information processor) to edit and process, and issue temperature and humidity control instructions, which are completed by the air heating unit, the condensation pipe and the heating and evaporation unit in the water tank.
The temperature adjustment of the constant temperature and humidity box is to collect data through the built-in temperature sensor in the box, adjust the temperature controller (micro information processor), and connect the air heating unit to increase the temperature or adjust the refrigeration solenoid valve to reduce the temperature inside the box, so as to reduce the temperature inside the box. to the temperature required for control. The humidity adjustment of the constant temperature and humidity box is to collect data through the built-in humidity sensor in the body, adjust the humidity controller (micro information processor), connect the heating element of the water tank, and increase the humidity in the box or adjust the refrigeration by evaporating the water in the water tank. Solenoid valve to achieve dehumidification to achieve the required humidity control.
The constant temperature and humidity box is equipped with multiple protection measures; the temperature system is equipped with an over-temperature protector under the condition that the maximum safe allowable temperature can be set, and the air heating element can be automatically powered off when the rotating fan stops; the humidification system can be adjusted according to the water level of the humidification tank The power supply is stopped when the temperature is lowered; the refrigeration system also stops working with the increase of the temperature of the box (over 40 ℃) or the increase of humidity.
In terms of box structure, the constant temperature and humidity test box is processed and formed by CNC machine tools, which is beautiful and novel in appearance, and adopts non-reaction handles, which is easy to operate. The studio is made of high-grade stainless steel with mirror panel, and the outer tank of the box is sprayed with A3 steel plate. The ultra-fine thermal insulation cotton is filled between the outside of the box and the inner tank, which has a good temperature insulation effect and effectively reduces the temperature fluctuation rate in the test box. In addition, the anti-aging silicone rubber sealing strip is tightly sealed, so that the box has no fog leakage. produce. Due to the harsh environment in the test box, in order to observe the situation in the test box clearly, Wuhan Shangshi selected multi-layer tempered glass for the observation window, and set up a separate lighting lamp and fog brush in the observation window to maintain a good observation field. , monitor the test situation at any time. Of course, in order to collect test data, the box is specially equipped with a 50mm or 100mm diameter test hole, which can be connected to recorders, printers and computers.
The control system of the test box can be said to be the heart of the entire equipment, in charge of cooling, heating, humidity control, circulation, and control.
In terms of refrigeration, the compressor is an imported compressor. The refrigeration system consists of a high temperature part and a low temperature part, each part is a relatively independent refrigeration system. The evaporation of the refrigerant in the high temperature part absorbs the heat of the refrigerant from the low temperature part and evaporates; the evaporation of the refrigerant in the low temperature part absorbs heat from the object to be cooled (the air in the test machine) to obtain the cooling capacity. The high temperature part and the low temperature part are connected by an evaporative condenser, which is both the condenser of the high temperature part and the condenser of the low temperature part.
The heating system adopts a completely independent nickel-chromium alloy electric heating type, with high resistivity, small resistance temperature coefficient, small deformation at high temperature and not easy to embrittle, its own heating temperature can reach 1000 ~ 1500 ℃, long service life.
Humidification is the most important part of the constant temperature and humidity test box which is different from the high and low temperature test box. The constant temperature and humidity test box adopts an external isolation type, all stainless steel boiler type shallow surface evaporative humidifier. The dehumidification method adopts mechanical refrigeration and dehumidification, which cools the air to below the dew point temperature, so that the water vapor greater than the saturated moisture content condenses and precipitates, thus reducing the humidity.
Air supply circulation system: The air circulation system consists of a temperature-resistant and low-noise air-conditioning motor and a multi-blade centrifugal wind wheel. It provides the circulation of air in the test machine.
Intelligent temperature and humidity controller
The control system is the core of the comprehensive test box, which determines the heating rate, precision and other important indicators of the test machine. Most of the controllers of the testing machine use PID control, and a small number of them use a combination of PID and fuzzy control. Because the control system basically belongs to the category of software, and this part generally does not have problems during use.
Meet the standards
⒈ GB11158 Technical Conditions of High Temperature Test Chamber
⒉ GB10589-89 Technical Conditions of Low Temperature Test Chamber
⒊ GB10592-89 Technical conditions of high and low temperature test chamber
⒋ GB/T10586-89 Technical Conditions of Damp Heat Test Chamber
⒌ GB/T2423.1-2008 Low temperature test chamber test method
⒍ GB/T2423.2-2008 Test method for high temperature test chamber
⒎ GB/T2423.3-2006 Damp heat test chamber test method
⒏ GB/T2423.4-2008 Test method for alternating damp heat
⒐ GB/T2423.22-2002 Test method for temperature change
⒑ IEC60068-2-1.1990 Low temperature test chamber test method
⒒ IEC60068-2-2.1974 High temperature test chamber test method
⒓ GJB150.3 high temperature test
⒔ GJB150.4 low temperature test
⒕ GJB150.9 Damp heat test