Views: 238 Author: Wendy Publish Time: 2023-08-03 Origin: Site
The working area, adjusting tools, supporting tools, and control system normally make up the temperature test chamber. The heater, evaporator, air supply device, and auxiliary equipment main room refrigeration unit are all parts of the regulating system. The control system consists of a temperature regulator, a program setter, a safety warning device, and others.
The heater operates by heating resistance wire or an electric heating tube with electricity. In addition to providing natural heating for high-temperature drying ovens without heat-dissipating samples, the heater is typically fitted with an air supply system for forced air circulation. The primary air supply mode is upper side supply and lower side return or full orifice top supply and lower side return, which is crucial for maintaining the test chamber's overall uniformity.
The majority of refrigeration techniques use mechanical refrigeration; refrigerators can be partially or completely closed, and cooling circuits can be either water- or air-cooled. The majority of refrigerants used nowadays are environmentally safe, and the circuit can operate continuously for a very long time using a capillary or electronic expansion valve as a throttling mechanism.
The display part has also been upgraded from the previous digital display mode to the LCD touch screen mode, which is clear, beautiful, and more convenient for operation. The control system now generally adopts PID mode, allowing the heating power to be automatically adjusted and controlled with the deviation between the actual temperature and the set temperature, realizing stepless adjustment and small temperature fluctuation. Additionally, the equipment's insulation layer is made of glass wool or polyurethane foam, both of which have low heat conductivity and high temperature resistance. For highly accurate temperature detection, thermistor, platinum resistance, and thermocouple are all used.
The test scope must be needed to match the test scope of potential product failure, meaning that the high temperature box, low temperature box, or cold and hot impact box must satisfy the severe temperature conditions mentioned in the test criteria.
The rule that the sample volume cannot exceed 1/5 of the test chamber's working volume must be followed when choosing the test chamber.
Forced air circulation or non-forced air circulation mode is chosen in accordance with the sample's heat dissipation in order to ensure the test area's temperature uniformity. The test findings are significantly impacted by the variation in equipment temperature distribution. The test findings for various positions will differ greatly when larger samples are used or when many samples are evaluated simultaneously. As a result, the machinery with the best temperature consistency ought to be chosen.
The sample temperature can be measured using either an upwind sensor or a downwind sensor. According to the needs of the test, the position and control method of the temperature control sensor can be chosen, and the proper equipment should be chosen.
The heating or cooling system of the apparatus must not have an impact on the sample in order to prevent it from absorbing or emitting heat as a result of heat radiation or heat conduction in the test region.
Both recording and viewing are simple. During the cycle test, instruments such as an automatic counter, indication light, recording equipment, automatic shutdown, and others should be placed.
The sample holder can be placed or suspended to make placing samples easier, and changes in high and low temperatures won't affect the sample holder's mechanical qualities.
To connect the test power supply to the equipment workshop, drill leading holes.
For the safety of test employees and to prevent sample damage, preventative measures must be used. For instance, it has a window for observation, lights, and alarms for phase failure, a lack of water, an overheated environment, and operator safety.
Whether the ability to monitor remotely is required.
During the bulk sample test, the temperature and humidity deviation will be visible in the updraft and downdraft, thus the sample position needs to be carefully evaluated. The test chamber's working area should have it as close to the center as possible. The samples should not contact or overlap, and space should be allowed between them to allow air to circulate. It should also be made sure that the sample is simple to move during the test and simple to replace during the test.
Verify whether odorous compounds and volatile substances like gas and oil are present in the test area. Such chemicals' test findings must be verified in advance.
Be sure to check the test sample's temperature in the testing environment.
The test environment temperature and the equipment's power supply should fluctuate as little as possible in order to maintain a constant temperature in the test zone. This will prevent the test sample from producing heat radiation or absorbing heat, which would cause a change in the test zone's temperature.
Taking the test sample out of the temperature test chamber too soon may put undue stress on it and could give unexpected findings. The test sample must therefore be chilled to room temperature before being removed.
To guarantee that the test sample and the installation and support frame are in an adiabatic state, the thermal conductivity of the installation and support frame of the test sample should be low.
The test requester, designer, and tester all contribute to determining the test content for various goods. A technical test chamber specification framework has been designed from the perspective of delivering a test chamber in line with the test, allowing the test chamber supplier to give the precise equipment requirements. It is very simple to use current equipment and buy new equipment because every type of test chamber that can replicate the testing environment typically has a measurement system. Simple test chambers can also be made by hand, but it's important to take into account elements like cost, test findings' dependability, level of precision in control, and safety during continuous operation.