This standard specifies the testing methods for the thermal protection performance values (hereinafter referred to as "TPP") and thermal protection performance evaluation (hereinafter referred to as "TPE") of thermal protection materials, including principles, laboratory personnel health and safety, equipment and materials, preparation and humidity control of specimens, calibration and maintenance, testing steps, result calculation, etc.

This standard is applicable to the thermal protection performance testing of single-layer or multi-layer materials, and is applied to the evaluation of thermal protection materials for practitioners exposed to convective and radiative heat hazards. This standard is not applicable to the testing of non flame retardant and materials that are prone to melting or dripping at high temperatures

principle

Place the sample horizontally and expose it to a convective radiation combined heat source, with a total heat flux of (84 ± 2) kW/m2 [(2.00 ± 0.05) cal/cm2? s] Measure and record the temperature change of the sample over time using a copper calorimeter, and convert the temperature change into thermal energy transmitted through the sample based on the thermal performance parameters of copper, to obtain the heat transfer reaction curve of thermal energy over time. Two testing methods can be used to characterize the thermal protection performance of materials:

——The first testing method: The thermal protection performance value (TPP) of the sample is obtained by multiplying the time corresponding to the intersection point of the heat transfer reaction curve measured by the copper calorimeter and the Stoll curve with the total heat flux exposed to the material (i.e., cumulative energy).

——The second testing method: The thermal protection performance evaluation (TPE) of the sample is the product of the exposure time when the heat transfer reaction curve recorded by the copper calorimeter after removing the specified convective radiation heat is tangent (or approximately tangent) to the Stoll curve and the total heat flux.

Test steps

1、 Thermal Protection Performance Test (TPP)

1. The thermal protection performance value is the average of the test results of three samples.

2. Calibrate the heat source - Follow steps 8.1.2.2 to 8.1.2.5 to calibrate the heat source so that the total heat flux reaches (84 ± 2) kW/m2 [(2.00 ± 0.05) cal/cm2? s]， Record the total heat flux data. Then remove the sample holder, install the sample and sensor for testing. It is recommended to recalibrate the total heat flux after testing a total of 9 samples from 3 groups (calibration frequency can be increased).

3. The front of the sample faces the heat source, and a copper calorimeter sensor is placed on the back. The inner layer of the multi-layer sample is facing the sensor. Adding a distance frame between the sensor and the sample is considered non-contact testing, while not adding it is considered contact testing, which should be noted in the report. The 6.4mm thick spacer frame is only used for non-contact testing.

The use of multi-layer sample spacing frames - non-contact (with spacing frames) testing is commonly used to simulate the air layer between the inner layer of clothing and the wearer. In this testing method, it is not recommended to use non-contact (with spaced frames) testing for multi-layer specimens with a testing time exceeding 60 seconds.

4. Use insulation shields to isolate heat sources before testing. After removing the insulation cover, the sample is exposed to the center point above the heat source and data recording begins.

5. When the accumulated energy measured by the copper calorimeter (calculation method see 10.2) intersects with the Stoll curve, the test is terminated, the exposure time is recorded, and the sample is removed from the heat source. The Stoll curve calculation formula is shown in 10.1.

6. The thermal protection performance value is calculated by multiplying the exposure time by the calibrated total heat flux (formula see 10.3).

7. Record the phenomena observed during testing.

8. Cool the sample holder and sensor assembly to (28-33) ° C (simulating the temperature of human skin), and then proceed with testing the remaining samples according to steps 9.1.3-9.1.7. After completing three sample tests, take the average value and record it as the thermal protection performance value of the sample.

9. Remove test results that differ from the average by more than ± 10%, and re cut three additional samples for testing.

2、 Thermal Protection Performance Evaluation Test (TPE)

1. Generally, three sets of samples are required to complete the thermal protection performance evaluation. One set of samples determines the evaluation time, and the last two sets of samples serve as the validation of the evaluation time.

2. Calibrate the heat source according to step 9.1.2 and record the total heat flux value.

3. Test the sample using the thermal protection performance value method in steps 9.1.3-9.1.5 to obtain the maximum exposure time (tmax) of the sample

4. Divide the exposure time by 2 to obtain the exposure time (ttrail).

5. Enter the exposure time (ttrail) in the device software and prepare the equipment sample for testing.

6. When the exposure time (ttrail) is reached, the insulation cover is reset, the sample leaves the heat source, and the instrument still records data. During this process, the ambient temperature should not exceed 35 ° C.

If this requirement cannot be met, the sample rack can also be designed as a removable structure. After the insulation cover is reset, the "sample rack/sample/sensor" can be quickly manually removed from the heat source, but data should be continuously recorded.

7. The instrument should continuously collect data for at least 30 seconds after the sample is exposed to the heat source, in order to release the accumulated heat energy on the sample. When the heat transfer reaction curve measured on the sensor decreases, the data collection can be manually stopped. When the heat reaction curve does not decrease after 30 seconds, the collection time should be extended (not exceeding 120 seconds).

8. The thermal protection performance evaluation is determined by the following relationship between the heat transfer reaction curve measured by the sensor and the Stoll curve.

a) If the heat transfer reaction curve measured by the sensor exceeds the Stoll curve (i.e. beyond second degree burn) within 60 seconds (or 120 seconds), the exposure time ttrail needs to be reduced. Take the intermediate value from the previous lower exposure time (0s) to the current exposure time ttrail. Set this time and repeat steps 9.2.5~9.2.7 until the heat transfer reaction curve of the sample is tangent to the Stoll curve, or the difference between the current exposure time ttrail and the previous exposure time is no more than 0.5s. The thermal protection performance evaluation of this sample group is the product of the current exposure time ttrail and the calibrated total heat flux value.

g) If the heat transfer reaction curve measured by the sensor within 60 seconds (or 120 seconds) is much lower than the Stoll curve (i.e., the second degree burn was not expected), the exposure time ttrail needs to be increased. Take the midpoint between the current exposure time and the previous higher exposure time (gao exposure time is tmax in 9.2.3), set this time, and repeat steps 9.2.5 to 9.2.7. Until the heat transfer reaction curve of the sample is tangent to the Stoll curve, or the difference between the current exposure time ttrail and the previous exposure time is not greater than 0.5s, the thermal protection performance evaluation of this sample group is the product of the current exposure time ttrail and the calibrated total heat flux value..

9. Record the phenomena observed during testing.

10. The repeated verification of exposure time ttrail and thermal protection performance evaluation are the products of the verified exposure time ttrail and the calibrated total heat flux (formula 10.4). The average of the three values is taken as the average thermal protection performance evaluation.

11. Remove test results that differ from the average by more than ± 10%, and re cut and supplement the samples for testing.