Oct 27 , 2021
High and low temperature testing machine acceptance methods and acceptance criteria
High and low temperature testing machine is in a kind of high temperature, low temperature (alternating) cycle changes in the case, test the material product performance indicators of the testing equipment, is widely used in electronic and electrical, automotive motorcycle, aerospace, ships and weapons, colleges and universities, scientific research units and other industries, it and constant temperature and humidity test chamber work in a different way, it is possible to do a one-time high temperature, low temperature and the temperature required to do the Time set within the parameters of the instrument, the test chamber will follow the set to go program, high and low temperature testing machine is to do a fixed temperature, so that the test effect is closer to the natural climate, simulating a more severe high and low temperature test chamber natural climate, so that the reliability of the samples tested higher, and constant temperature and humidity test chamber is based on the test method and industry standards can be divided into alternating test, constant temperature test, two test methods are in High and low temperature testing machine on the basis of the upgrade to expand.
The high and low-temperature testing machine acceptance criteria.
the main test instruments and devices:
Anemometer: induction should be no less than 0.05m / s anemometer
Thermometer: using platinum resistance, thermocouple or other similar temperature sensor composition and meet the following requirements of the temperature measurement system: sensor time constant: 20S ~ 40S; temperature measurement system extended uncertainty (K = 2): not more than 0.4 ℃
Surface thermometer: using platinum resistance or other similar sensors and meet the following requirements of the measurement system: sensor time constant: 20S ~ 40S; temperature measurement system of the extended uncertainty (K = 2): not more than 1.0 ℃
The test is carried out under no-load conditions
Cooling rate test, the ambient temperature should not be higher than 25 ℃, cold power temperature should not be higher than 30 ℃
Second, the accepted method of a high and low-temperature test machine
1. The location and number of test points
In the test chamber studio content set out on the top, middle, and bottom three horizontal test surfaces, referred to as the top, middle and bottom layer, the distance between the top layer and the top surface of the studio is 1/10 of the studio height, the middle layer through the geometric center of the studio, the bottom layer in the zui low layer above the sample frame 10mm.
Test points are located on three test surfaces, the central test point is located in the geometric center of the studio, the rest of the test points to the studio wall distance of 1/10 of the respective side length, but the studio volume is not greater than 1 cubic meter of the test chamber, the distance is not less than 50mm
The relationship between the number of test points and the size of the studio volume: the studio volume is not greater than 2 cubic meters, the test points for 9; studio volume greater than 2 cubic meters, the test points for 15; when the studio volume is greater than 50 cubic meters, the number of temperature test points can be increased appropriately
In the test chamber temperature adjustable range, select the highest nominal temperature and the lowest nominal temperature
Make the test chamber run according to the procedure of low temperature first and then high temperature, the temperature at the center of the workspace to reach the test temperature and stable 2H, the first minute in 30 minutes to test the temperature of all test points 1 time, a total of 30 times
3、Data processing and test results
The measured temperature data, according to the correction value of the test instrument to correct
4、Remove suspicious data
Calculate the average temperature of the measured values for each point 30 times for the data measured in the constant temperature phase
Calculate the temperature gradient: the average value of temperature large value minus the average value of temperature small value
Calculate the temperature fluctuation, temperature deviation
The difference between the set value of the test chamber control instrument and the center test value should meet the requirements of the allowable deviation.
The temperature difference between the inner wall of the studio and the working space test method
1, test point placement location and number
In the center of the workspace and the center of a temperature sensor, the geometric center of each of the six inner walls of the studio and a surface temperature sensor
If there are lead holes or other devices in the center of the inner wall of the studio, the distance between the test point and the hole wall or other devices should not be less than 100mm
In the test chamber temperature adjustable range, choose the high nominal temperature and low nominal temperature for the test temperature
In the workspace geometric center point of the temperature di once to reach the test temperature and stable 2H, every 2 minutes to test the temperature value of all test points once, a total of 5 times
3、Calculation and evaluation of test results
Will test the temperature value according to the correction value of the test instrument correction
Calculate the arithmetic mean of the temperature of each test point separately
Calculate the percentage of the difference between the studio wall and the thermodynamic temperature of the studio
4、Raising and cooling rate test method
The test point is the geometric center of the workspace
In the test chamber temperature adjustable range, select the lowest nominal temperature for the lowest specified temperature, the highest nominal temperature for the highest specified temperature
Turn on the cold source, so that the test chamber from room temperature down to the lowest specified temperature, stabilize 2H, adjust to the highest specified temperature, test the test chamber temperature from 10% of the temperature range to 90% of the time; make the test chamber at the highest specified temperature, stabilize 2H, then adjust to the lowest specified temperature, test the test chamber temperature from 90% of the temperature range down to 10% of the time.