Programmable constant temperature and humidity test chamber is a precision equipment used to simulate complex environmental conditions such as temperature, humidity, and cyclic changes. It is widely used for product reliability testing in fields such as electronics, automotive, aerospace, etc. To ensure the stable operation of the equipment and the accuracy of the test results, the following operating procedures must be strictly followed:
1、 Preparation before operation
Environmental condition inspection
The equipment should be placed indoors with good ventilation and no strong electromagnetic interference, with an ambient temperature of 5-35 ℃ and humidity ≤ 85% RH, avoiding direct sunlight or proximity to heat sources.
Ensure that the distance between the equipment and walls or other devices is ≥ 30cm for easy heat dissipation and maintenance.
Equipment status confirmation
Check if the power supply (AC220V ± 10%, 50/60Hz) is stable and if the grounding wire is reliably connected.
Confirm that the water level in the tank is between the "MAX" and "min" marks to avoid dry burning of the heating tube due to water shortage.
Check if the drainage pipe is unobstructed to prevent condensation from accumulating and affecting equipment operation.
Sample pretreatment
The sample needs to be cleaned and dried to avoid surface moisture or impurities affecting temperature and humidity uniformity.
The sample volume should not exceed one-third of the effective volume of the test chamber, and should be kept at a distance of ≥ 10cm from the chamber wall and sensors to prevent obstruction of airflow circulation.
2、 Parameter Setting and Program Programming
Basic parameter setting
Temperature range: Set the target temperature according to the testing standards (such as IEC60068-2-1), usually from -70 ℃ to+150 ℃ (depending on the equipment specifications).
Humidity range: Set the target humidity (such as 20% RH to 98% RH), be aware that low temperature and high humidity (such as+5 ℃, 95% RH) may cause condensation, and evaluate the sample tolerance in advance.
Heating and cooling rate: Set according to testing requirements (such as 1 ℃/min to 5 ℃/min) to avoid equipment overload or sample thermal stress damage caused by too fast a rate.
Program programming steps
Segmented setting: Input multiple temperature and humidity curves (such as high temperature and high humidity → low temperature and low humidity → cycle) through the control panel or upper computer software, and each time segment can be accurate to the minute level.
Loop control: Set the number of loops (such as 100) or total testing time (such as 720 hours), support infinite loop mode (manual stop required).
Slope control: Set a slope in the temperature/humidity change section (such as a heating slope of 2 ℃/min) to ensure a smooth change process and reduce impact on the sample.
3、 Operation monitoring and exception handling
real-time monitoring
View current temperature and humidity, operating time, program stages, and other parameters through the control panel or remote monitoring system.
Regularly record key data (such as every 30 minutes) for subsequent analysis.
Abnormal alarm and handling
Overtemperature alarm: When the temperature exceeds the set value ± 2 ℃, the equipment automatically cuts off the heating power and alarms. It is necessary to check whether the heating tube, temperature sensor, or ventilation port is blocked.
Abnormal humidity: If the humidity remains below the set value, check whether the humidifier water level and nozzle are blocked; If the humidity is too high, check if the dehumidification system (such as the condenser) is working properly.
Communication failure: If the device loses contact with the upper computer, check whether the RS485/232 interface and communication cable are damaged, or restart the device to restore the connection.
Emergency shutdown
Press the "Emergency Stop" button on the control panel, and the device will immediately stop all heating, humidification, and cooling functions, but the fan will continue to run for rapid cooling.
After emergency shutdown, the sensor needs to be recalibrated to avoid parameter drift affecting subsequent testing.
4、 Maintenance and upkeep
routine maintenance
Cleaning: Wipe the inner and outer surfaces of the box with a dry cloth every week, and clean the observation window with a neutral cleaner every month to avoid scratches.
Drainage: After each test, open the drainage valve to drain the accumulated water in the water tank and pipeline to prevent bacterial growth.
Calibration: Annually commission a third-party organization to calibrate temperature and humidity sensors to ensure measurement accuracy meets standards (such as temperature ± 0.5 ℃, humidity ± 2% RH).
Key component replacement cycle
Humidifier: Replace every 2000 hours (or adjust according to water hardness) to prevent scale from clogging the nozzle.
Refrigerant: Supplement every 5 years (or based on pressure gauge readings) to ensure refrigeration efficiency.
Fan belt: Check the tightness every 10000 hours and replace it if necessary to avoid excessive vibration.
Long term disuse treatment
Drain the accumulated water in the water tank and pipeline, clean the box and turn off the power.
Power on once a month (2 hours each time) to prevent electrical components from being damaged by moisture.
5、 Safety precautions
Operational Security
Do not open the box door while the equipment is running to avoid high temperature burns or low temperature frostbite.
Wear heat-resistant gloves when moving samples to prevent high-temperature surfaces from coming into contact with the skin.
Electrical safety
Regularly check whether the power cord is damaged and the grounding resistance is ≤ 0.1 Ω to prevent the risk of leakage.
Avoid using equipment during thunderstorms to prevent lightning strikes from damaging the control system.
environmental requirements
Waste refrigerants must be handed over to professional institutions for recycling, and it is prohibited to discharge them indiscriminately to damage the ozone layer.
Samples containing heavy metals (such as lead-acid batteries) need to be treated separately to avoid environmental pollution.