Selection of the installation site of the rapid temperature change test chamber:
The distance from the adjacent wall can smoothly give full play to the role and characteristics of the environmental test chamber. The long-term temperature of 15 ~ 45 °C and the relative environmental humidity exceeding 86% should be selected. site.
The working temperature of the installation site must not change significantly.
It should be installed on a leveling surface (use a level to determine the level on the road during installation).
It should be installed in a site without sun exposure.
It should be installed in a site with excellent natural ventilation.
It should be installed in areas where flammable materials, explosive products and high-temperature heat sources are eliminated.
It should be installed in a site with less dust.
Install it as close as possible to the switching power supply of the power supply system.
High and low temperature test chamber may encounter a variety of problems in the process of use, the following is a summary of potential faults and their causes from different perspectives:
1. Core system failure
Temperature out of control
Reason: PID control parameters are out of balance, ambient temperature exceeds the design range of the equipment, multi-zone temperature interference.
Case: In a special environment workshop, the external high temperature causes the refrigeration system to overload, resulting in temperature drift.
Humidity is abnormal
Reason: poor water quality of humidification leads to scaling and nozzle blockage, failure of ultrasonic humidifier piezoelectric sheet, and incomplete regeneration of dehumidification desiccant.
Special phenomenon: reverse condensation occurs during high humidity test, resulting in the actual humidity in the box being lower than the set value.
2. Mechanical and structural problems
Air flow is disorganized
Performance: There is a temperature gradient of more than 3℃ in the sample area.
Root cause: the customized sample rack changed the original design air duct and the accumulation of dirt on the centrifugal fan blade led to the destruction of dynamic balance.
sealing failure
New failure: the magnetic force of electromagnetic sealing door decreases at low temperature, and the silicone sealing strip becomes brittle and cracks after-70℃.
3. Electrical and control system
Intelligent control failure
Software level: After firmware upgrade, the temperature dead zone setting error occurs and the historical data overflow causes the program to crash.
Hardware level: SSR solid state relay breakdown causes continuous heating and bus communication is subjected to inverter electromagnetic interference.
Security protection vulnerabilities
Hidden dangers: the synchronous failure of the triple temperature protection relay and the false alarm caused by the expiration of the refrigerant detector calibration.
4. Challenges of special working conditions
Specific temperature shock
Problem: -40℃ to +150℃ rapid conversion of the evaporator weld stress cracking, thermal expansion coefficient difference resulting in the failure of the observation window seal.
Long-term operation attenuation
Performance degradation: after 2000 hours of continuous operation, the compressor valve plate wear leads to a decrease of 15% in refrigeration capacity and drift of ceramic heating tube resistance value.
5. Environmental and maintenance impact
Infrastructure adaptation
Case: The power oscillation of PTC heater caused by the fluctuation of power supply voltage and the water hammer effect of cooling water system damaged the plate heat exchanger.
Preventive maintenance blind spots
Lesson: Ignoring the positive pressure of the box leads to water entering the bearing chamber and biofilm growth and blockage in the condensate discharge pipe.
6. Pain points of emerging technologies
New refrigerant application
Challenges: system oil compatibility problems after R448A replaces R404A, and high pressure sealing problems of subcritical CO₂ refrigeration systems.
IoT integration risks
Fault: The remote control protocol is maliciously attacked, resulting in program tampering and cloud storage failure, resulting in the loss of test evidence chain.
Strategy recommendations
Intelligent diagnosis: configure vibration analyzer to predict the failure of compressor bearing, and use infrared thermal imager to scan the electrical connection points regularly.
Reliability design: key components such as evaporator are made of SUS316L stainless steel to improve corrosion resistance, and redundant temperature control modules are added to the control system.
Maintenance innovation: implement a dynamic maintenance plan based on operating hours, and establish an annual refrigerant purity testing system。
The solutions to these problems need to be analyzed in combination with the specific model of the equipment, the use environment and the maintenance history. It is recommended to establish a collaborative maintenance mechanism including the OEM of the equipment, third-party testing institutions and user technical teams. For key test items, it is recommended to configure a dual-machine hot standby system to ensure the continuity of testing.
(1) Equipment installation and commissioning
On-site service: technical personnel will deliver the goods free of charge and complete the mechanical assembly, electrical wiring and debugging. The debugging parameters shall meet the temperature and humidity, salt spray deposition amount and other indicators in the customer's technical agreement.
Acceptance criteria: provide a third-party measurement report, and unqualified equipment shall be returned or replaced directly. For example, the rain test box shall pass 100% acceptance.
(2) Customer training system
Operation training: covers equipment start and stop, program setting and daily maintenance, customized for different user scenarios such as quality inspection institutions and automobile enterprises.
Deep maintenance training: including fault diagnosis (such as troubleshooting of humidity system in high and low temperature and humidity test chamber) and spare parts replacement to improve customers' independent maintenance ability.
(3) Technical support and response
Instant response: respond to repair demand within 15 minutes, and solve routine faults within 48 hours (negotiate with remote areas).
Remote diagnosis: through video guidance or remote access software, quickly locate the problem (such as abnormal dust concentration in the sand test chamber).
(4) Spare parts supply and maintenance
Make spare parts plan, give priority to the supply of wear and tear parts from cooperative units (such as China Railway Inspection and Certification Center, China Electronics Technology Group), and reduce downtime.
Non-manual damage is free of charge during the warranty period, and paid services are provided after the warranty period with transparent charges.
When the Guangdong Hongzhan ice water impact test chamber is used in summer, the following matters should be paid special attention to to ensure the stable operation of the equipment and the accuracy of the test results:
1. Environment and heat dissipation management
Enhance ventilation and heat dissipation High temperature in summer is easy to lead to the decrease of equipment heat dissipation efficiency. Ensure that at least 10cm space is reserved around the equipment to promote air circulation. If the equipment adopts air cooling system, the condenser surface dust should be cleaned regularly to prevent poor heat dissipation and overheating of the compressor.Control the environmental temperature and humidity. Avoid placing the equipment in the direct sunlight area. It is recommended that the laboratory temperature be kept at 25±5℃ and the humidity be lower than 85%. High temperature and high humidity environment may accelerate the accumulation of frost or condensation water on the equipment, so it is necessary to increase the dehumidification measures.
2. Refrigeration system maintenance
Water quality and tank management Bacteria are easy to breed in summer, so use deionized water or pure water to avoid hard water scaling and blocking pipes. It is recommended to change the tank water every 3 days, and empty and clean the tank before long-term disuse.Refrigeration efficiency monitoring High temperature environment may lead to overload operation of the refrigeration system. The compressor oil condition should be checked regularly to ensure sufficient refrigerant. If the water temperature exceeds the set value (such as 0~4℃), the machine should be stopped immediately for troubleshooting.
3. Frosting and defrosting treatment
Prevent frost aggravation When the humidity is high in summer, the frost rate inside the equipment may accelerate. It is recommended to perform a manual defrosting process after 10 cycles: set the temperature to 30℃ and keep it for 30 minutes, and then drain water to clean the ice crystals on the evaporator surface.
Optimize the test interval to avoid continuous long-term low temperature testing. It is recommended to reserve 15 minutes of buffer time between high temperature (e.g., 160℃) and ice water shock cycle to reduce the impact of thermal stress on the equipment.
4. Adjustment of operation specifications
Parameter setting optimization According to the characteristics of the summer environment, the normal temperature recovery stage time can be shortened appropriately (the reference standard is to complete the temperature switch within 20 seconds), but it must ensure that it meets the requirements of GB/T 2423.1 or ISO16750-4 standards.Safety protection should be strengthened. Anti-freezing gloves and goggles should be worn during operation to avoid the adhesion of hands and low-temperature parts caused by sweating. Before opening the door after high temperature test, the temperature inside the box should be confirmed to be below 50℃ to prevent scalding from hot steam.
5. Emergency and long-term shutdown preparation
Fault response If the equipment has E01 (temperature out of tolerance) or E02 (water level abnormal) alarm, you should immediately cut off the power supply and contact the technical support of the manufacturer. Do not disassemble the refrigeration pipeline by yourself.Long-term protection When not used for more than 7 days, the water tank should be emptied, power should be cut off and dust cover should be covered. At the same time, power should be on for 1 hour every half a month to keep the circuit board dry.
Through the above measures, the impact of high temperature and humidity environment in summer on the ice water shock test chamber can be effectively reduced to ensure the reliability of test data and the service life of the equipment. The specific operation details should be adjusted according to the equipment manual and actual working conditions.
1. Dust adhering to the condenser can cause the high-pressure switch of the compressor to trip and issue false alarms. Therefore, dust attached to the cooling grid of the condenser can be removed with a vacuum cleaner every month, or by using a hard-bristled brush after turning on the machine, or by blowing it off with a high-pressure air nozzle.2. The area around the machine and the ground at the bottom should be kept clean at all times to prevent a large amount of dust from being sucked into the unit or reducing equipment performance and causing accidents.3. When opening or closing the door or taking samples from the test chamber, do not touch the sealing strip on the door.4. The core of the constant temperature and humidity test chamber - the refrigeration system should be inspected once a year. Check for leaks in the copper tubes and at each joint and interface. If there are any, inform the manufacturer.5. The humidifier and water tank should be cleaned frequently to avoid scaling and affecting steam emission. Clean them after each test. Timely descaling helps extend the lifespan of the humidification tube and ensures smooth water flow. When cleaning, use a copper brush and then rinse with water.6. The distribution room should be cleaned and inspected more than once a year. Loose nodes can put the entire equipment in a dangerous working state, burn out components, cause fires, alarms, and endanger lives.7. The dry and wet bulb wicks should be checked frequently. Replace them promptly if they become hard or dirty. It is recommended to replace them every three months.8. Inspection and maintenance of the water circuit. The water pipes in the water circuit are prone to clogging and leakage. Regularly check for leaks or blockages. If found, remove them promptly or notify the manufacturer.
One reason 1. Because the temperature of the constant temperature and humidity test chamber cannot be maintained, observe whether the refrigeration compressor can start when the test chamber is running, and whether the compressor can start when the environmental test equipment is running, indicating that the circuit from the main power supply to each compressor is normal and the electrical system has no problem.
2. There is no fault in the electrical system. Continue to check the refrigeration system. First, check whether the exhaust and suction pressure of the low temperature (R23) compressor of the two sets of refrigeration units are lower than the normal value, and whether the suction pressure is in the vacuum state, indicating that the refrigeration dose of the main refrigeration unit is insufficient.
3. Touch the exhaust pipe and suction pipe of the R23 compressor with your hand, and find that the temperature of the exhaust pipe is not high, and the temperature of the suction pipe is not low (no frost), which also indicates that the R23 refrigerant in the host is insufficient.
Another reason: 1. The cause of the failure has not been determined, and further confirmation is made in combination with the control process of the constant temperature and humidity test chamber. The test chamber has two sets of refrigeration units.
One is the main unit, and the other is the auxiliary unit. When the cooling rate is high, both units operate simultaneously at the beginning of the temperature maintenance phase. Once the temperature stabilizes, the auxiliary unit stops, and the main unit maintains the temperature. If the R23 refrigerant leaks from the main unit, its cooling efficiency will be significantly reduced. During the cooling process, both units operate simultaneously, ensuring stable temperatures and a gradual decrease in cooling rate. In the insulation phase, if the auxiliary unit stops, the main unit loses its cooling function, causing the air inside the test chamber to rise slowly. When the temperature reaches a certain level, the control system activates the auxiliary unit to cool down, after which the auxiliary unit stops again. The cause of the production failure has been identified as a low-temperature (R23) refrigerant leak from the main unit. Upon checking the refrigeration system for leaks, a crack was found on the valve stem of the hot gas bypass solenoid valve, measuring about 1cm in length. After replacing the solenoid valve and recharging the system with refrigerant, the system returned to normal operation. This analysis shows that the fault diagnosis follows a step-by-step approach, starting from the 'external' aspects and moving inward, then focusing on 'electricity' and finally on 'cooling.' A thorough understanding of the test chamber's principles and operational processes is essential for accurate fault diagnosis.
Condition one: environmental condition
1. Temperature: 15 ℃~35 ℃;
2. Relative humidity: not exceeding 85%;
3. Atmospheric pressure: 80kPa~106kPa
4. There is no strong vibration or corrosive gas around;
5. No direct sunlight exposure or direct radiation from other cold or heat sources;
6. There is no strong airflow around, and when the surrounding air needs to be forced to flow, the airflow should not be directly blown onto the equipment.
7.No magnetic field surrounding of the test chamber that may interference control circuit.
8.There is no high concentration of dust and corrosive substances around.
Condition two: Power supply condition
1. AC Voltage: 220V ± 22V or 380V ± 38V;
2. Frequency: 50Hz ± 0.5Hz.
Usage Conditions three: Water Supply Conditions
It is recommended to use tap water or circulating water that meets the following conditions:
1.Water Temperature: Not exceeding 30℃;
2.Water Pressure: 0.1MPa to 0.3MPa;
3.Water Quality: Complies with industrial water standards.
Usage Conditions four: load for test chamber
The test chamber load must simultaneously meet the following conditions:
1. Total Mass of Load: The mass of the load per cubic meter of workspace volume should not exceed 80 kg;
2. Total Volume of Load: The total volume of the load should not exceed 1/5 of the workspace volume;
3. Load Placement: On any cross-section perpendicular to the main airflow direction, the total area of the load should not exceed 1/3 of the workspace cross-sectional area. The load must not obstruct airflow.
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