Use and maintenance of high and low temperature humidity test chamber

With the development of people in the fields of military, aerospace and navigation, many equipment will work in high temperature, temperature and humidity test chamber. In this environment, equipment will face greater challenges. The stability of the equipment has an important influence on the operation of the equipment.

The high and low temperature humidity test chamber (hereinafter referred to as the high and low temperature humidity test chamber) is used to test the performance of materials in aerospace and marine products under high temperature, damp heat and other environments. Its structure and working principle have certain particularities.

1. Use a high and low temperature test chamber
Before conducting environmental experiments, it is necessary to master the properties, experimental procedures, experimental conditions and experimental techniques of the tested samples. 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 must read the operation manual in detail many times to avoid operation errors, which will cause the equipment to fail to operate normally, cause errors in the test data, and damage the samples 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 selection of high and low temperature humidity chambers should be determined according to the actual conditions of the experimental samples. The volume between the laboratory and the test subject should always be in a reasonable ratio. When conducting experiments on the heated sample, its volume should be less than 10% of the effective volume of the experimental calibration. The proportion of the unheated test sample to the effective volume of the laboratory should be 20%.

The location of the sample should 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 and low temperature humid chambers:

(1) During use, ensure that the high and 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 chamber 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 and low temperature humidity box is running at low temperature, it is best to dry the equipment at 60°C for 30 minutes, and then open the door to prevent the evaporator from freezing or affecting the measurement time of subsequent experiments.

7) During operation, in order to ensure the safety of equipment and operators, over-temperature protectors and circuit breakers should be checked regularly.

8) In addition to full-time personnel, professional electricians are also required to participate in the maintenance and inspection of the equipment.

2. Repair and maintenance of common problems
Frequently asked questions about maintenance of high and low temperature and 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 and the cause of the failure should be eliminated one by one.

If the temperature rises slowly, check the air circulation system and observe the opening status of the adjustment plate in the air circulation system.

If the temperature rises too fast, the rotation of the air circulation channel needs to be detected. If the temperature rises too fast, the PID tuning parameters need to be adjusted.

If the temperature rises directly to the 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 and ambient temperature of the equipment 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 laboratory is dry before low temperature testing. If the workshop is dry, put the test samples into the laboratory, and check whether there are too many samples stacked in the laboratory, which causes the laboratory ventilation cycle to fail to meet the requirements.

2.2 Equipment maintenance content
The main contents of equipment maintenance include preventive maintenance and predictive maintenance. Of the two types of preventive maintenance, the maintenance that needs to be done once a week includes cleaning the drip tray and the laboratory body for condensed water. Maintenance required by customers in special areas includes: cleaning humidification water pipes, flushing systems or medium cooling water pipes. Maintenance that needs to be done every six months includes cleaning the air cooling equipment (condenser), maintenance that needs to be done every year, cleaning the scale inside the humidifier, cleaning the AC (high current) contactor for maintenance of the electrical control cabinet. At the same time, the lubricating oil used by the compressor should be replaced every 2-3 years. Predictive maintenance mainly includes weekly maintenance, monthly maintenance and quarterly maintenance.

Weekly maintenance includes: checking the balance pressure and suction and discharge pressure of the compressor, checking the color of the oil in the compressor, and checking the oil body. Monthly maintenance included. Check the compressor discharge and suction temperatures, the liquid mirror and discharge temperatures in the condenser, and the temperature difference between the incoming and outgoing water in the cold water pipe. Check the heating rate and cooling rate of the device. Check the operating current of the compressor motor quarterly.

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 and low temperature humidity chambers in the future.

3. Conclusion

Environmental Chamber Manufacturer is a special refrigeration equipment, its use, maintenance and repair should start from refrigeration, electrical control, thermal engineering and so on. In the process of use, attention should be paid to the usage specifications. When repairing, the faults that may be caused by the operation should be eliminated first, and then the faults existing in 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.