About Constant Temperature and Humidity Test Chamber

In today's advanced device testing industry, constant temperature and humidity test chambers play a key testing role in various industry fields. This article delves into the basic aspects of constant temperature and humidity test chambers: their definition, size selection and basic factors for maintenance.

Introduction

Main Content

Constant Temperature and Humidity Test Chamber for Industrial Applications.

Constant temperature and humidity chamber for the industry large parts, semi-finished products, finished products of the temperature and humidity environment test, such as: computer terminals, automotive parts. Constant temperature and humidity chamber is mainly composed of control panel, switchboard, humidification library board, blower, heater, humidifier, freezer combination.

Volume size of the constant temperature and humidity box

When choosing the size of the cabinet, we usually need to consider two aspects. The first is the location of the laboratory. In this regard, we need to consider the relationship between the size of the cabinet and the size of the laboratory. The capacity of the cabinet Whether it can enter the laboratory and whether it can be placed in the laboratory. The second is how much space is required for the experimental sample. In this regard, we need to consider the volume of the inner tank of the box. Now the minimum constant temperature and humidity box is 50L, and the maximum can be 1000L. It can even be used in several cubic laboratories, so Don't worry about not having the right size, just be sure to get the size you want.

Standards to specify the working room size

The national standard has the following provisions: When the product under test (component, assembly, part or complete machine) is placed in an environmental test chamber for testing, in order to ensure that the environment around the product under test can meet the environmental test conditions specified in the test specifications, the test chamber The following regulations should be followed between the working dimensions and the outer dimensions of the tested product:

a. The volume of the product under test (W×D×H) shall not exceed (20~35)% of the effective working space of the test chamber (20% is recommended). For products that generate heat during the test, it is recommended to use no more than 10%.

b. The ratio of the windward cross-sectional area of the product being tested to the total area of the test chamber working room on this cross-section shall not be greater than (35-50)% (35% is recommended).

c. The distance between the outer surface of the tested product and the wall of the test chamber. The distance should be kept at least 100~150mm (150mm is recommended). The above three provisions are actually interdependent and unified. Taking a 1 cubic meter cube box as an example, the area ratio is 1: (0.35~0.5), which is equivalent to a volume ratio of 1: (0.207~0.354). A distance of 100 to 150 mm from the box wall is equivalent to a volume ratio of 1: (0.343 to 0.512).

To summarize the above three regulations, the working room volume of the climate environment test chamber should be at least 3 to 5 times the outer volume of the product being tested.

Frequently Asked Questions

Question 1: Users who use the constant temperature and humidity test chamber for the first time may encounter this situation. During the test, the humidity suddenly displays 100%, but they don’t know what the cause is?

Step 1: Check whether the wet ball gauze is hanging on the humidity sensor. The sensor close to the sink is the humidity sensor. The gauze should be hung on the humidity sensor and wrap the temperature sensing part of the sensor. A few customers often hang the gauze in the wrong position and above the temperature sensor, causing machine failure. Therefore, please identify it carefully. The top one is the temperature probe, and the bottom one near the sink is the humidity probe.

Step 2: If the hanging method is correct and the humidity still displays 100%, please check whether the wet ball gauze has turned yellow, or if it has been used for too long, too many minerals have accumulated on the gauze, causing the water absorption performance of the wet ball gauze to decrease and it cannot absorb water. water, which will make the detected humidity inaccurate and create the illusion of high humidity; if so, please replace the wet ball gauze. If not, you need to check that there is no water in the wet ball sink or the water level is low. The gauze cannot absorb water. Key inspections The following parts:

a. Check whether there is water in the water level box next to the sink. If not, the float may be damaged.

b. The electromagnetic pump is damaged. Use the voltage range of a multimeter to measure its resistance. If it is open circuit, it is damaged.

c. The gap replenishment timer is damaged and cannot replenish water normally.

Step 3: There is still a problem with the controller setting. A few customers have a misunderstanding about the use of constant temperature and humidity test chambers. They often set the humidity at low temperatures and set the humidity at high temperatures of 120 degrees Celsius. This situation will also cause control instrument misalignment and instability. Low-temperature machines cannot control humidity and are prone to freezing; high-temperature machines evaporate too quickly, and it is also very difficult to set the humidity of the machine. Therefore, customers are requested to read the instructions carefully and operate the machine in a standardized manner to extend the service life of the equipment.

Question 2: What should I do if the constant temperature and humidity test chamber is out of service for a long time?

If the constant temperature and humidity test chamber needs to be stopped for a period of time due to special circumstances, some protective measures should be taken. The specific methods are as follows:

(1) When the constant temperature and humidity test chamber is out of use, the items in the box should be taken out, the power plug should be unplugged, and the inside and outside of the test chamber should be cleaned.

(2) Use paper strips between the door seal and the box to prevent the door seal from adhering to the box; if it is not going to be used for a long time, you can also apply some talcum powder on the door seal.

(3) The constant temperature and humidity test chamber after deactivation must also be placed in a dry and ventilated place to avoid direct sunlight. The test chamber should be kept stable after the position is moved.

(4) The indoor air has a certain humidity, so do not cover the test box with a plastic bag. Tin moisture will not easily escape if it enters, causing corrosion of metal parts and damaging the performance of electrical components.

(5) The freezing temperature of Freon used for refrigeration in the constant temperature and humidity test chamber is very low, so there is no need to worry about it freezing and placing the test chamber in a higher temperature place.

(6) If possible, it is best to turn on the power once a month, so that the compressor can run normally for half an hour to an hour and then turn off.

Question 3: Correct placement of wet ball gauze in constant temperature and humidity test chamber

When conducting hygrothermal tests, wet ball gauze plays an important role in sensing humidity in the constant temperature and humidity test chamber. Therefore, the correct placement and maintenance of wet ball gauze must follow certain specifications and steps:

1. Take out the wet ball gauze from the packaging box and cut it about 10cm;

2. Put the lower end of the wet ball gauze into the sink and soak it (it is easier to sense the humidity), and hang it to dry or put it on the humidity sensor.

Maintenance and inspection of wet ball gauze in constant temperature and humidity test chamber: The upper end of the wet ball gauze must be hung on the wet ball sensor, and the lower end must be placed in the wet ball gauze sink so that it can easily absorb the moisture in the sink and get soaked. If the wet ball gauze is installed elsewhere, the humidity sensor will not be able to sense the humidity, leading to the illusion that the humidity is 100%, the humidity cannot be reduced, or the humidity cannot be controlled at all. When doing a humidity test, you must check whether the wet ball gauze is hung properly. If it has been hung up, please check whether the gauze is moist. If it is dried out or has poor water absorption, please replace the wet ball gauze in time.

Maintenance of constant temperature and humidity test chamber

In order to ensure the safe and trouble-free operation of the constant temperature and humidity test chamber, regular inspection and maintenance can not only solve problems in time but also keep the system in the best working condition. Therefore, we should remind our customers that after the constant temperature and humidity test chamber is used for a certain period, a certain amount of dust will accumulate inside, which will affect the life of the high and low temperature test chamber.

One: The condenser should be maintained regularly every month. The dust attached to the condenser heat distribution net should be absorbed by the vacuum cleaner or the dust should be removed by high-pressure air spraying.

Two: when the surface of the test cloth is not clean or hard, or after the temperature control, continue to do the temperature wet bulb control must be replaced. The test cloth should be replaced every three months.

Three: constant temperature and humidity test chamber humidification boiler water storage should be replaced once a month, to ensure clean water, humidification tank should be cleaned once a month, to ensure smooth water flow, prevent water blockage humidification system, affect the machine humidity test results.

Four: It is best to open the outer cover of the constant temperature and humidity test chamber regularly by the maintenance engineer or under the guidance of the engineer to dust the interior. It should be corrected regularly during maintenance.

Conclusion

Constant temperature and humidity test chambers are suitable for temperature and humidity environmental testing of various finished products in industry. This article introduces constant temperature and humidity test chambers, how to choose the size, and maintenance matters. Let more people know about constant temperature and humidity test chambers.