Sealing tester measures the pressure resistance and leakage of composite film bags.

This article introduces how to use a seal tester to evaluate the pressure resistance and leakage performance of composite film bags. The test primarily involves applying controlled pressure inside the packaging and observing pressure changes or leakage to assess the quality of the seal. The instrument includes components such as pressure control, a sample chamber, and sensors. During testing, samples must be placed according to the steps, parameters must be set, and the pressure resistance test involves observing the burst pressure, while the leakage test focuses on the pressure stability or the presence of bubbles during the pressure-holding period. Key aspects include controlling parameters such as the pressure range, accuracy, and pressure-holding time. Proper operation and result analysis can help identify weak points in the seal, providing a basis for improving packaging.

Introduction

In the field of packaging materials, composite film bags are widely used due to their excellent barrier properties and mechanical strength. Its sealing integrity is directly related to the quality and safety of the contents. Pressure resistance and leakage testing of composite film bags through a sealing tester is a key means to evaluate their sealing performance. This article aims to systematically elaborate the principles, methods and related technical points of this test.

Test Principle:

The seal tester evaluates the strength and integrity of the seal by applying controlled pressure (positive or negative) to the inside of the package and monitoring pressure changes or observing leaks. The pressure resistance test examines the ability of the seal to resist internal pressure without breaking; Leak testing detects the presence of leak channels at specific pressures. For example, for rigid containers, the relationship between pressure and leakage rate can be approximated as:
Q= (ΔP·V) / (t·P_atm)
Among them,QIndicates the leakage rate, ΔPis the amount of pressure change,Vis the sample volume,tFor the test time,P_atmIt is the ambient atmospheric pressure. This model helps to understand the physical changes during testing.

Instrument composition

A typical seal tester consists of the following parts: a pressure control system to accurately generate and adjust the test pressure; Sample sealing chamber to hold the sample under test and create a confined space; sensors and data acquisition modules for real-time monitoring of pressure, time and other parameters; and a human-computer interface for setting test conditions and displaying results. These components work together to ensure accuracy and repeatability of tests.

Test methodology

The test typically follows the following steps: First, the composite bag sample is placed in the test chamber and properly sealed. Subsequently, the parameters are set according to the purpose of the test. For pressure resistance, the incremental pressure method is usually used until the sample breaks or reaches a predetermined upper limit, and the rupture pressure value at this time is recorded. For leakage testing, pressure is often held at the set pressure for a period of time, and whether there is a leak is determined by observing the pressure decay or using the immersion method to observe bubbles. Specific parameter settings need to refer to relevant technical standards.

Key parameters:

The reliability of test results depends on the proper control of several key parameters. The main parameters and their descriptions are shown in the table below:

Test pressure range	The safe pressure range that the instrument can apply should cover the pressure that the sample may actually be subjected to.
Pressure accuracy	The accuracy of instrument control and measurement pressure directly affects the judgment of the results.
Holding time	The duration of maintenance at the target pressure to fully assess the leakage.
Pressurization rate	The speed at which the pressure rises too quickly may cause the test results to deviate from the actual conditions of use.
Sample size adaptability	The capacity of the instrument chamber for samples of different sizes.

Analysis of results

The analysis of test results should be combined with the purpose of the test. In withstand pressure testing, higher rupture pressure usually indicates better seal strength. In the leakage test, if the pressure is stable or there are no visible bubbles during the packing period, it is judged to be leak-free. Any abnormal drop in pressure or bubble generation point should be recorded where it occurs and the pressure value should be recorded, which can help locate seal weaknesses and guide production process improvement.

Notes:

In order to ensure the effectiveness of the test, it should be noted that the sample should be adjusted in the specified temperature and humidity environment; Place the sample to ensure that the seal is fully positioned in the test area and not distorted; Before testing, the sealing of the instrument pipeline should be checked; Composite film bags of different materials and structures may need to adjust the test parameters; Operators should be properly trained to understand standard processes.

Summary

It is a direct and effective method to evaluate the seal quality of composite film bags by using a seal tester to test the pressure resistance and leakage. Through standardized testing processes and strict parameter control, quantitative and qualitative data reflecting the sealing performance of packaging can be obtained, and technical support can be provided for packaging design, material selection and production process control, thereby helping to ensure the reliability of packaging.

References

1. Introduction: Refers to the relevant industry overview of the general testing requirements for the tightness of packaging materials.
2. Test Principles: References to model descriptions of gas pressure and leakage in fundamental physics.
3. Test method part: It integrates a number of domestic and foreign technical standards and methods for flexible packaging sealing performance testing.
4. Key parameters: summarize and sort out according to the technical specifications of common seal testers.