How to operate the constant temperature and humidity test chamber

1、 Operating program:

1. Turn on the user air switch, then turn on the main power switch (NFB) of the device, and finally turn on the power key.

2. Draw when the temperature and humidity meter displays normally; You can pre plan the program settings to be executed in order to smoothly set the testing conditions.

3. The set values of temperature, humidity, and time should be consistent with the requirements of the user's tested sample.

4. The setting of various functions of temperature and humidity instruments must be operated by dedicated personnel or in accordance with the instructions of the temperature and humidity instruments.

5. After setting up all functions, the machine door must be closed tightly before it can operate normally.

6. When starting the machine, be sure to pay attention to the direction of the motor and the direction of the three-phase motor.

7. Press the operation switch of the controller to operate the machine according to the set temperature and humidity testing conditions.

8. When the temperature and humidity meet the requirements of the user's product and the machine needs to be shut down, the temperature and humidity meter switch of the controller must be turned off before the product can be removed and placed from it.

9. For instructions on program settings and fixed value control, please refer to the controller operation manual; For specific operation of the temperature and humidity meter, please refer to the manual of the temperature and humidity meter.

10. This machine is equipped with a window observation light. If you want to check the situation inside the box, please press the observation light switch, and the light inside the box will immediately turn on.

11. If a fault occurs, the display screen of this machine will immediately show the location of the fault, and the buzzer will sound. After the fault is resolved, please press the (REST) button on the screen (reset switch), and then restart the testing machine.

2、 PID control principle:

1. The Pingheng temperature and humidity control system controls SSR in a PID manner to ensure that the heating and humidification capacity of the system is equal to the heat and humidity loss.

2. The temperature measurement signal from the wet and dry bulb is input through A/D conversion to the controller CPU and RAN for comparison and output to the I/O board. The I/O board issues instructions to activate the air supply system and refrigeration system. At the same time, PID controls the SSR to either heat or humidify the SSR, ensuring that the heat and humidity are evenly distributed through the air supply system testing box to achieve constant temperature and humidity control.

3. Install and adjust the four horizontal feet at the bottom of the fuselage on a flat and vibration free ground to balance the fuselage, facilitate drainage of the inner box, and prevent abnormal noise (please check with a spirit level).

4. Do not expose this device to direct sunlight and maintain indoor air circulation.

5. Please place the machine body in a separate space and do not place it in public places or near flammable, explosive, or perishable chemicals to avoid fire and personal injury in case of malfunction.

6. The supply and drainage pipelines should be shortened as much as possible.

7. Please avoid setting up in dirty and dusty places. The ambient temperature and humidity should be maintained between 10 ℃ and 30 ℃, with a relative humidity of 70 ± 10%, in order for the machine to operate optimally. The consequences may include slow cooling or inability to meet low temperature requirements, and unstable temperature control.

8. No debris should be placed on the top of the aircraft to prevent heavy objects from falling and causing personal injury or property damage.

9. Do not hold the electrical box, wires, or motor as a pivot point during transportation to prevent damage, looseness, or accidental failure of the electrical box.

10. The maximum inclination of the body should be below 30 degrees, and the body must be firmly secured to prevent it from falling, crushing, damaging or smashing the human body and property.

3、 Comparison between Controller CPU and RAN:

The compressor is the heart of the refrigeration system, which sucks in low-temperature and low-pressure gas, turns it into high-temperature and high-pressure gas, condenses it into liquid to release heat, and takes away the heat through the fan. Therefore, the equipment is under the influence of hot air, then throttled to become low-pressure liquid, and finally becomes low-temperature and low-pressure gas through the evaporator before returning to the compressor; The refrigerant absorbs heat in the evaporator to complete the gasification process and absorb heat, achieving the purpose of refrigeration and completing the cooling process.

The temperature measurement signal from the wet and dry bulb is input through A/D conversion to the controller CPU and RAN for comparison and output to the I/O board. The I/O board issues instructions to activate the air supply system and refrigeration system. At the same time, PID controls the SSR to either heat or humidify the SSR, ensuring that the heat and humidity are evenly distributed through the air supply system testing box to achieve constant temperature and humidity control.

The water level in the water tank should not be too high, as it may cause water to overflow; The low water level in the water tank causes the wet bulb test cloth to absorb water abnormally, affecting the accuracy of the wet bulb. Keep the water level about six or seven minutes full. The adjustment of the water level in the water tank can adjust the height of the water tank (by adjusting the screws on both sides).

Please do not adjust the set values of the two over temperature protectors inside the distribution box casually. They have already been adjusted at the factory. This protection switch is used to protect the heating and humidification tubes from air burning and water shortage alarms. Setpoint=Temperature Setpoint+20 ℃~30 ℃.

4、 Characteristics of the constant temperature and humidity test chamber:

1. The box is processed and formed by CNC machine tools, with a beautiful and novel shape, and adopts non reactive handles for easy operation.

2. The inner lining of the box is made of imported high-grade stainless steel (SUS304) mirror panel or 304B argon arc welding, and the outer lining of the box is made of A3 steel plate sprayed with plastic.

3. Adopting a microcomputer temperature and humidity controller, the temperature and humidity control are precise and reliable.

4. There is a large observation window with lighting to keep the inside of the box bright, and double-layer glass is used to clearly observe the situation inside the box at all times.

5. The temperature limit alarm system automatically interrupts when the temperature exceeds the limit, ensuring the safe operation of the experiment without any accidents.

6. Optional recorder, printer can print and record set parameters and scan temperature and humidity change curves, 4-20mA standard signal.

7. A test hole with a diameter of 50mm is provided on the left side of the box.

5、 Working principle of refrigeration:

The refrigeration cycle of Aisili adopts the inverse Caryol cycle, which consists of two isothermal processes and two adiabatic processes. The process is as follows: the refrigerant is adiabatically compressed to a higher pressure by the compressor, consumes work to increase the exhaust temperature, and then the refrigerant exchanges heat with the surrounding medium through the condenser isothermal, transferring heat to the surrounding medium. After the refrigerant undergoes adiabatic expansion through the shut-off valve, the temperature of the refrigerant decreases. Finally, the refrigerant absorbs heat from the object at a higher temperature through the evaporator, causing the temperature of the cooled object to decrease. This cycle repeats itself to achieve the goal of cooling down.