The GB T 17794-2021 standard for flexible foam rubber and plastic insulation products issued by the National Standardization Technical Committee of China is the standard on the dimensional change rate of flexible foam rubber insulation products. The main purpose of this standard is to stipulate the detection method of the dimensional change rate of flexible foam rubber insulation products under certain conditions to ensure their stability and reliability in practical applications. In this article, we will introduce in detail the specific detection method of the dimensional change rate in the GB T 17794-2021 standard.
First of all, the dimensional change rate refers to the percentage of dimensional change that occurs under certain conditions for flexible foam rubber and plastic insulation products. This variation can be caused by factors such as temperature, humidity, pressure, etc., so the detection of the dimensional change rate is essential to evaluate the performance of the product. The GB T 17794-2021 standard specifies two methods for detecting the rate of change of dimensions, namely the linear rate of change and the rate of change of volume dimensions.
1.Detection method of linear dimensional rate of change:
The linear dimensional rate of change is the percentage change in the length of the article in a certain direction. The steps to detect the linear dimensional rate of change are as follows:
1.1. Prepare samples: Randomly select representative samples from mass-produced flexible foam rubber and plastic insulation products.
1.2 Stable conditions: The sample is left under the environmental conditions specified by the standard for a period of time to ensure that it reaches a stable state.
1.3 Measure Dimensions: Using the appropriate measuring tools, measure the initial length of the sample in the direction of interest.
1.4 Applied stress: According to the conditions specified in the standard, a specified stress is applied to the sample, which can be tensile, compressive or bending stress.
1.5. Hold Stress: Hold for a certain amount of time under the specified stress conditions to ensure that the sample is fully affected by the stress.
1.6 Remeasure the size: After holding the stress, remeasure the length of the sample in the direction of interest.
1.7. Calculate the linear dimensional change rate: Calculate the linear dimensional change rate according to the measured initial length and the length after stress.
2.Detection method of volume size change rate:
The volume size change rate refers to the comprehensive embodiment of the length change of the product in the three orthogonal directions. The steps to detect the rate of change of volume size are as follows:
2.1 Prepare samples: As with the detection of linear dimensional rate of change, a representative sample is randomly selected from the mass-produced sample.
2.2 Stable conditions: The sample is left under the environmental conditions specified by the standard for a period of time to ensure that it reaches a stable state.
2.3 Measuring Dimensions: Using the appropriate measuring tools, measure the initial length of the sample in three orthogonal directions.
2.4 Applied stress: According to the conditions specified in the standard, a specified stress is applied to the sample, which can be tensile, compressive or bending stress.
2.5. Hold Stress: Hold for a certain amount of time under the specified stress conditions to ensure that the sample is fully affected by the stress.
2.6 Remeasure Dimensions: After holding stress, remeasure the length of the sample in three orthogonal directions.
2.7. Calculate the rate of change of volume size: Calculate the rate of change of volume size according to the measured initial length and the length after stress.
Through the above steps, the linear dimensional change rate and volume size change rate of flexible foam rubber and plastic insulation products under specified conditions can be obtained. These data are of guiding significance for the design, production and use of products, and help to ensure their good stability and reliability in practical applications. When conducting testing, it is necessary to strictly follow the conditions and methods specified in the standard to ensure the accuracy and comparability of the test results.