With the development of people in the military, aerospace, and navigation fields, many devices will work in high temperature, low temperature, and high humidity environments. In this environment, devices will face even greater challenges. The stability of the equipment has an important influence on the work of the equipment.
High-low temperature humidity Test Chamber (hereinafter referred to as high-low temperature humidity Test Chamber) is used to test the performance of materials in aerospace and marine products under high temperature, humid heat and other environments. Its structure and working principle have certain particularities.
1. Use a high-low temperature Humidity Chamber
Before conducting environmental experiments, it is necessary to master the performance of the tested samples, experimental procedures, experimental conditions and experimental techniques. At the same time, it is necessary to master the use technology of the equipment, clearly understand the structure of the equipment, especially the performance and operation of the controller. At the same time, the staff need to read the operation manual in detail many times to avoid operating errors, which will cause the equipment to fail to operate normally, cause test data errors, and sample damage during the test. In order to ensure the accuracy of the experimental data in the experiment, it is necessary to select reasonable equipment for the experiment. The choice of high-low temperature Humidity Chamber should be determined according to the actual situation of the experimental samples. The volume between the laboratory and the test subject should always be in a reasonable ratio. When conducting experiments on heated samples, their volume should be less than 10% of the effective volume of the experimental calibration. The ratio of the unheated test sample to the effective volume of the laboratory should be 20%.
During the experiment, the position of the measured object should be placed correctly. The position between the test object and the chamber wall should be kept more than 20 cm. If multiple samples need to be placed during the experiment, all samples should be placed on the same plane as much as possible.
The position where the sample is placed must not cause the air outlet and air outlet to be blocked, and at the same time keep a certain distance from the humidity sensor to ensure that the temperature is normal during the experiment. The following points should be paid attention to in the use of high-low temperature Humidity Chambers:
(1) During use, ensure that the high-low humidity heating box is safely grounded to avoid casualties caused by electrostatic induction.
(2) Do not touch the box with your hands during operation.
(3) Unless the door cannot be opened due to special reasons during the operation of the equipment, the following adverse consequences may occur:
1) The temperature inside the door is still very high
2) High temperature and high humidity will flush out of the chamber.
3) High temperature may cause fire alarm.
4) Lighting should be turned off unless necessary.
5) Try to avoid repeated opening within 15 minutes during use.
6) When the high-low temperature Humidity Chamber is running at low temperature, it is recommended to dry the equipment at 60°C for 30 minutes, and then open the door, so as not to freeze the evaporator or affect the measurement time of subsequent experiments
7) During operation, in order to ensure the safety of equipment and operators, the over-temperature protector and circuit breaker should be checked regularly.
8) In addition to full-time personnel, professional electricians are also required to participate in the maintenance and inspection of equipment.
2. Repair and maintenance of common problems
2.1 Frequently asked questions about maintenance of high-low temperature constant Humidity Chambers
During the high temperature test, if the test temperature does not reach the temperature value required by the test, the electrical system should be checked to eliminate the cause of the failure one by one.
If the temperature rises slowly, check the air circulation system and observe the opening state of the regulating plate in the air circulation system.
If the temperature rises too fast, it is necessary to detect the rotation of the air circulation channel, and if the temperature rises too fast, it is necessary to adjust the PID setting parameters.
If the temperature rises directly to over-temperature protection, it can be concluded that the controller is faulty, and the control instrument should be replaced in time.
When the low temperature does not meet the experimental requirements, it is necessary to observe the temperature change. Whether the temperature rises after falling to a certain value or whether the temperature drops slowly. The former is generally caused by the harsh environment of the drying equipment. The location of the equipment and the ambient temperature should be observed. If it cannot meet the working requirements of the equipment, it should be adjusted in time. If the latter, the equipment should be checked to see if the lab is dry before the low temperature test. If the working room is dry, put the test sample into the laboratory, whether there are too many test samples piled up in the laboratory, resulting in the failure of the laboratory ventilation circulation to meet the requirements.
2.2 Equipment maintenance content
The main content of equipment maintenance includes preventive maintenance and predictive maintenance. Of the two types of preventive maintenance, the ones that need to be performed on a weekly basis include: Cleaning the drain pan and the lab body for condensed water. The maintenance required by customers in special areas includes: cleaning the humidification water pipe, flushing system or medium cooling water pipe. The maintenance required every six months includes cleaning the air-cooling equipment (condenser), annual maintenance, cleaning the scale inside the humidifier, removing dust and maintaining the AC (high current) contactor of the electrical control cabinet. At the same time, the lubricating oil used in the compressor should be replaced every 2-3 years. Predictive maintenance mainly includes weekly maintenance, monthly maintenance and quarterly maintenance.
Weekly maintenance includes: check the balance pressure and suction and discharge pressure of the compressor, check the color of the oil in the compressor, and check the oil body. Monthly maintenance included. Check the discharge and suction temperatures of the compressor, the liquid mirror and discharge temperature in the condenser, and the temperature difference between the inlet and outlet water of the cold water pipe. Check how quickly the unit heats up and cools down. Check the operating current of the compressor motor every quarter.
Regular maintenance of the equipment can not only improve the stability of the equipment during operation and the accuracy of the experiment, but also prolong the service life of the equipment to a certain extent. Therefore, attention should be paid to the maintenance of high-low temperature Humidity Chambers in the future.
3. Conclusion
The high-low temperature humid heat box is a special refrigeration equipment. Its use, maintenance and repair should start with refrigeration, electrical control, thermal engineering and other aspects. During use, attention should be paid to usage specifications. During maintenance, the faults that may be caused by the operation should be eliminated first, and then the faults of the equipment itself should be repaired. After the equipment fails, it should be repaired on the basis of mastering the structure and working principle of the equipment. In addition, the maintenance of the equipment must be carried out on time, and the maintenance of the equipment cannot be ignored because the equipment has not failed for a period of time
