Positive pressure method seal tester evaluates packaging pressure resistance

This article introduces how the positive pressure method sealing tester evaluates the pressure resistance of packaging. The instrument simulates actual pressure conditions by injecting compressed air into the packaging and then monitors pressure changes to detect any leaks. The article explains that its working principle is based on pressure decay detection and lists several testing modes, such as inflation release, pressure holding, burst, and creep tests. Key performance parameters include pressure control accuracy and sensor resolution, and standardized testing procedures are crucial for result reliability. Test data can be used to compare packaging materials, monitor production processes, and provide a basis for transportation safety.

Introduction

In packaging quality control for various types of products, it is crucial to evaluate the ability of packages to resist internal or external pressure differences during storage and transportation. As a widely used testing equipment, the positive pressure seal tester scientifically evaluates the pressure resistance and overall sealing integrity of the package by applying controllable positive air pressure to the inside of the package to simulate the actual pressure conditions. This method is suitable for packaging inspection in various fields such as food, daily chemicals, electronic components and industrial products.

How it works:

The basic principle of the positive pressure seal tester is pressure decay detection. The instrument places the package under test in a specific test chamber or directly connects it, and fills the inside of the package with clean compressed air through an air source, so that its internal pressure rises steadily to a preset value. During the packing phase, the instrument continuously monitors changes in the pressure inside the package. If there is a leak in the package, there will be an observable attenuation of the internal pressure. By monitoring the rate of change in pressure over time, the sealing performance of packaging can be quantitatively evaluated. Its basic relationship can be expressed as:

ΔP/Δt = k · Q_leak

where ΔP/Δt is the pressure change per unit time, k is the constant related to the test gas and volume, Q_leakIt is the equivalent leakage rate. The faster the pressure decays, the worse the sealing of the package.

Main test modes

Depending on the purpose of the test and the type of packaging, positive pressure seal testers typically offer the following main test modes:

Expansion release test	Suitable for flexible packaging. The package expands under pressure, and after releasing the pressure, observe whether it returns to its original state to determine whether there is a leak.
Packing Pressure	Fill the package to the target value and hold it for a period of time, directly monitoring whether the pressure drops.
Rupture test	Continuous pressurization until the package ruptures, the rupture pressure value is recorded, and the compressive ultimate strength of the package is evaluated.
Creep test	At constant pressure, the expansion changes of the packaging volume are monitored to evaluate the deformation characteristics of the material under continuous pressure.

Key performance parameters

The performance of the instrument directly affects the accuracy and repeatability of the test results. Here are a few key parameters:

Pressure control range and accuracy	It determines the range of pressure scenarios that can be simulated by the instrument and the fineness of control.
Pressure sensor resolution	Affects the sensitivity to detect small leaks.
Test chamber volume with adapters	It needs to be adapted to different sizes and shapes of packaging to ensure versatility of testing.
Data sampling rate	High-frequency sampling captures pressure transients more accurately.

Testing process essentials

A standardized testing process is the basis for reliable data. The general process includes: sample preparation, instrument calibration, parameter setting, sample installation, testing execution, data logging and analysis of results. Special attention should be paid to ensuring that the sample is stable under standard temperature and humidity conditions before testing, and setting reasonable pressure thresholds, holding time and other judgment criteria according to relevant product standards or internal specifications.

Analysis and application of results

Test results are usually presented in the form of pass/fail, or specific leak rate, rupture pressure values. This data can be used to: compare the advantages and disadvantages of different packaging materials or processes; Monitor the process stability of the production line; Provide compressive data support for packaging design; Verify that the packaging meets transportation safety requirements. Trend analysis of test data with historical data or standard limits can effectively warn of potential quality risks.

Summary

The positive pressure seal tester provides a quantitative evaluation method for the pressure resistance and sealing performance of packaging. By understanding its principles, reasonably selecting test modes and standardizing operations, users can obtain highly repeatable and comparable test data, thereby providing a solid technical basis for improving packaging quality and reducing circulation loss. In practical applications, it is recommended to formulate targeted test plans based on the characteristics of specific products and the circulation environment.

References

1. General technical conditions for packaging and transportation safety testing, compilation of domestic general packaging standards.
2. Analysis of the Principle of Leak Detection by Pressure Decay Method, Proceedings of the International Society for Non-Destructive Testing.
3. Physical and mechanical properties test methods for flexible packaging, industry technical manuals.
4. Review of seal testing instrument technology, Journal of Metrology and Testing Technology.