Why can’t the temperature and humidity of the environment box can’t go up or down?
How to solve the bad uniformity? This article gives you a professional answer about the temperature and humidity failure of the climate chamber and its solution.
Why can’t we reduce the humidity in the constant-temperature and humidity chamber?
The main reasons are:
Refrigeration system failure
Humidity sensor problems
Improper equipment choice.
High environmental load
Control system defects
These fall into two areas: hardware failures and operational or maintenance issues.
Equipment hardware failure.
Refrigeration system abnormalities.
Refrigerant leaks or compressor failures can cause low evaporator temperatures. This makes it hard to condense moisture efficiently.
Condenser accumulation of dust or poor heat dissipation affects cooling efficiency.
Failure of humidity control components.
Not possible to remove the adverb. This leads to inaccurate detection.
Control issues can trigger a failure in the humidification system. This may cause the solenoid valve to malfunction or lead to clogged water pipes.
Operation and maintenance problems
Environmental and load factors.
If the test chamber door opens often or if the outside humidity is too high, it can lead to too much moisture.
There are too many items in the box. It exceeds the equipment’s dehumidification capacity.
Equipment parameter settings.
The air volume is too high. This leads to a small temperature difference between the incoming and outgoing air. As a result, the dehumidification efficiency drops.
Someone changed the expansion valve opening, which disrupts the refrigerant flow.
Missing maintenance.
Filter clogging is not cleaned, or evaporator icing is not dealt with.
Long-term failure to calibrate the sensor or replace aging parts.
Key faults checklist
|
Faults
|
Checklist | Solution |
|
Humidity continues at high levels
|
Gauze Absorption Status Sensor position |
Replacement of special linen gauze Adjustment of hanging position |
|
Unable to dehumidify when refrigeration is running
|
Refrigerant Pressure
Compressor status |
Detect leaks and replenish refrigerant Repair compressor |
Why does the humidity of the constant temperature and humidity chamber not increase?
The main reasons are:
Water supply system issues
Humidification system failure
Sensor problems
Blocked air circulation
You can solve an improper temperature setting through step-by-step troubleshooting and targeted maintenance.
AtmoExplorer-ChiuVention Constant Temperature and Humidity Chamber
Core failure causes and solutions
Abnormal water supply systems.
-Check the water level in the tank. If it’s too low, don’t add distilled water. Use tap water only if the level is sufficient.
Check the water pipe blockage: clean or replace the blocked pipe to ensure smooth water flow.
Check the pump’s working condition. Make sure the motor and impeller are normal. If not, replace the parts.
Humidification system failure.
Electrode humidifier: clean the electrode surface scale or replace the damaged electrode.
– Steam humidifier: Check the heating element’s resistance value. Fix any damaged steam pipes.
-Insufficient humidification: Reduce the number of samples or choose a higher-powered model.
Sensor and control problems.
Check the gauze for wetness and replace it regularly.
Clean the sink float valve.
– Humidity sensor calibration: Compare readings with a standard hygrometer. Replace the sensor if the readings are abnormal.
– Control system check: Test the solid-state relay. Check the meter output signal. Repair any line failures.
Environmental and setting factors.
Ensure the fan functions properly and eliminate any obstructions from the air duct.
– Temperature matching change: For low-temperature tests, lower the humidity target value. Humidity and temperature have a positive correlation.
Why the constant temperature and humidity chamber temperature can not be reduced?
The first issue is with the programmable constant temperature and humidity test chamber.
It can’t cool down. When we set the machine to -40 degrees, it remained at room temperature. There were no alarms or error messages on the display.
Solution: Determine this time because the machine compressor can’t start to cool down.
The compressor might be burned out. So, you need to contact the manufacturer for maintenance.
The second situation occurs when the machine can cool down but can’t reach the set temperature.
In this case, two situations may arise:
The compressor lacks refrigerant medium. This is similar to air conditioning that doesn’t cool well when the refrigerant is low.
Solution: This time, we need to add a refrigeration medium to the machine.
When the lab temperature is above 25 degrees, it can impact machine cooling. High temperatures reduce the compressor’s cooling capacity.
Solution: First, lower the air conditioning temperature. Then, turn on the machine.
No problem with the electrical system; continue to check the refrigeration system.
Solution: First, check the low temperature of the two refrigeration units. Then, look at the compressor’s exhaust and suction pressure. If the values are low and suction pressure rises, the main refrigeration unit needs refrigerant.
Check the main unit compressor’s exhaust and suction pipelines by hand.
The exhaust pipeline is warm. The suction pipeline feels normal and has no frost.
Solution: This also indicates a lack of refrigerant in the main unit.
Check if the refrigeration compressor starts while the test chamber is running.
We cannot maintain the temperature as is. If it starts, that means the main power supply to the compressors is fine. There’s no issue with the electrical system.
The cause of the failure is still unknown. Also, the control process of the test box needs checking. It’s important to confirm the cause of failure if the test box has two refrigeration units.
One unit is for the main system, and the other is for the auxiliary. When the cooling rate is high, both units operate together. At the start of the temperature maintenance phase, both units run at the same time. When the temperature stabilizes, the auxiliary unit shuts off. Then, the main unit keeps the temperature stable.
If the main unit leaks, it will make the cooling effect of the main unit less effective. The two units operate simultaneously during cooling. Usually, temperature stabilization does not reduce the cooling rate. When the auxiliary unit stops, the main unit can’t cool. This happens during the temperature maintenance stage. This causes the air in the test chamber to heat up slowly. When the temperature hits a set point, the control system restarts the auxiliary unit. It cools the air down to about -55℃, then stops again.
Why does the temperature in the constant temperature and humidity test box fluctuate?
Constant temperature and humidity chamber sealing degree
A gap in the box sealing strip or a leak in the thermostat box door can impact the temperature uniformity of the test box. So, the sealing strip needs to meet strict requirements. It must resist both high and low temperatures.
To solve the uneven temperature issue, focus on sealing the box. This prevents air leaks. Also, choose high-quality insulation materials. Good insulation is crucial for maintaining an even temperature and humidity. Poor insulation can lead to big temperature changes in the box.
Constant temperature and humidity box structure
A constant temperature and humidity chamber can be hard to design. Sometimes, achieving a uniform and symmetrical layout is tricky. This can affect indoor heat convection and cause temperature differences inside.
To fix temperature differences, consider these points:
The sample’s volume, weight, and placement matter.
Standards say the sample volume should be less than 1/5 of the interior space to allow for good airflow.
The sample’s area on the windward side must be less than 1/3 of that side’s cross-sectional area.
Don’t place the test products near air ducts, as this can disrupt airflow.
Make sure the samples are placed steadily for smooth testing.
Pay attention to air convection inside the box during the test. If the test object is too big or not set up right, it can lead to a large temperature uniformity issue.
Constant temperature and humidity chamber circulation system
The constant temperature and humidity test chamber uses a wind circulation system. This system improves temperature uniformity inside the chamber. An air conditioning duct is located at the rear. It heats air via a heating tube. A long-axis motor drives a stainless steel, multi-winged centrifugal wind wheel. This wheel stirs the air evenly. Finally, air exits through louvered outlets, ensuring even temperatures throughout.
To fix uneven temperatures, lower the temperature difference between the air supply. This helps minimize airflow impacts on the room’s temperature. It also better protects against temperature variations. Increasing the air supply can lower the temperature difference. It also helps reduce indoor air flow.
Constant temperature and humidity box internal heat transfer.
The test box wall has several features like a threading hole, detection holes, and test holes. These create local heat transfer. As a result, the box temperature is uneven. This unevenness hurts both radiation and convection heat transfer. As a result, temperature uniformity suffers.
Enhance temperature consistency by increasing the accuracy of the temperature and humidity box. This helps cut down on temperature fluctuations.
For heating, adjust the PID at regular intervals to manage the rise in temperature.
For cooling, use thermal balance methods to stabilize temperature changes.
For more information on the application of a constant temperature and humidity chamber?
Or textile testing machines, contact us:
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