There are many types of environmental testing equipment, but the most commonly used environmental testing equipment is high-temperature, low-temperature and humidity test chambers. Nowadays, it is more popular to use a combination of high-temperature, low-temperature and humidity test chambers — constant temperature and humidity test chambers, its repair It is more difficult than other environmental testing equipment and it is representative.
Let's take the cold and heat shock testing machine as an example to talk about the structure of the constant temperature and humidity test chamber and some common mistakes and troubleshooting methods.
(1) The structure of common constant temperature and humidity test chambers
In addition to operating correctly according to the operating procedures, test personnel should also understand its structure. The thermal shock testing machine consists of a box body, an air circulation system, a cooling system, a heating system and a humidispeed control system. The air circulation system generally adopts a structure that can adjust the direction of air supply; the humidification system takes care of boiler humidification and surface evaporation; the cooling and dehumidification system adopts the cooling structure of the air conditioner; the heating system adopts electric fin heating and electric furnace wire direct heating Two structures; the temperature and humidity test method adopts the wet and dry bulb test method, and the direct measurement method of the humidity sensor is also used; the control and display operation interface adopts separate temperature and humidity independently, and temperature and humidity combined controls and other methods.
(2) Some common mistakes and troubleshooting methods of constant temperature and humidity test chamber:
1. In high temperature test, if the temperature change does not reach the test temperature value, you can checken electrical system and eliminate the faults one by one. If the temperature rises very slowly, check the airflow system to see if the airflow control damper is open normally, otherwise check if the airflow motor is running normally. If the temperature overshoot is , the PID adjustment parameters need to be adjusted. If the temperature rises directly, the over-temperature protection means that the controller is defective and the control instrument needs to be replaced.
2. If the device fails suddenly during the test operation, the corresponding error display prompt will appear on the control instrument and an audible alarm prompt will sound. The operator can quickly check what kind of error it belongs to in the troubleshooting chapter of the operation and use of the device, and then ask professionals to quickly troubleshoot to ensure the normal progress of the test. otherMore environmental test equipment is used
3. When the low temperature can not reach the test index, you need to observe the temperature change, whether the temperature drops very slowly or the temperature tends to rise after the temperature reaches a certain value is the former to check whether the studio is dried before the cold test, so that the studio is kept dry, and then put the test samples into the studio and then tested, can not fully circulate , after eliminating the above reasons, must be checked whether it is there is a fault in the refrigeration system, so it is necessary to entrust the manufacturer's qualified personnel to carry out the maintenance. The latter phenomenon is caused by the poor operating environment of the device The ambient temperature and the location of the device (the distance between the back of the case and the wall) must meet the requirements (this is specified in the user manualline of the device).
4. In the Damp-Heat test, the actual humidity reaches 100%, or the actual humidity deviates greatly from the target humidity and the value is much lower. The former phenomenon: It may be If the gauze on the wet bulb sensor is dry, check Make sure there is no water in the wet bulb sensor tank. The water level in the tank is automatically controlled by a water level controller. Check whether the water supply system of the water level controller is normal Is it working properly? Another possibility is that the wet ball gauze will harden the gauze due to long-term use or the purity of the water system, which will not allow the gauze to absorb water and dry. You only need to replace or clean the gauze to eliminate the above phenomena. The latter phenomenon is mainly that the humidification system does not work. Check the water supply systemsystem of the humidification system, whether there is a certain amount of water in the water supply system, whether the water level control is used to control the water level of humidification boiler is normal, and whether the water level in the humidification boiler is normal. If all the above items are normal, check the electrical control system, which requires professional maintenance personnel to overhaul.
5. If the low temperature does not meet the test index, you need to observe the temperature change, whether the temperature drops very slowly, or the temperature tends to rise after reaching a certain value, the former should be checked, perform low temperature. Whether to dry the work space before the test, keep the work space dry, and then put the test specimens in the work space before the test, whether the test specimens are placed in the work space too much, so that the wind cannot fully circulate in the work space, wellAfter the exclusion of the above reason, it is necessary to check whether there is a fault in the refrigeration system, so it is necessary to ask the manufacturer's qualified staff to overhaul it.
The latter phenomenon is caused by the poor environment of use of the device. The ambient temperature and the location of the device (the distance between the back of the case and the wall) must meet the requirements (they are specified in the device). Operation manual).
The environmental test equipment should be maintained regularly, the refrigeration system condenser should be cleaned regularly, the moving parts should be lubricated according to instructions, the electrical control should be regularly maintained and inspected, etc. These tasks are essential.