ASTM F2391-05 Standard Test Method for Measuring Package and Seal Integrity Using Helium as a Tracer Gas

The standard “ASTM F2391-05 Standard test method for measuring package and seal integrity using helium as a tracer gas” developed by the American Society for Testing and Materials (ASTM) describes a test method that can be used to measure the overall package and seal barrier performance of various package types and package forms, as well as seal/closure types. The key elements of this method are:

• Helium (used as tracer gas)
• Helium leak detector (mass spectrometer)
• Package/product specific test fixtures

Most applications of helium leak detection are destructive, meaning that helium must be injected into the package after it has been sealed. The injection site must then be externally sealed or patched. Alternatively, if helium can be introduced into the headspace prior to sealing, the method can be non-destructive, as all that needs to be done is to detect helium escaping from the sealed package.

This standard includes two test methods: sniffer mode and vacuum mode. Sniffer mode is a valuable procedure for many applications, but has more variability depending on how the operator conducts the test. For example, whether the package is compressed or not, the effect of multiple small leaks compared to fewer large leaks, background helium concentration, package permeability, and the speed at which the scan is conducted. More testing is expected to quantify the variability of this procedure.

Procedure A: Sniffer mode, the package is externally scanned for helium escaping to the atmosphere or the fixture. Procedure B: Vacuum mode, the package containing helium is placed in a closed fixture. After vacuum is drawn, helium escaping into the closed fixture (capture volume) is detected. Often fixtures are custom made for the particular package being tested.

The sensitivity of the method depends on the detection of:

• Major leaks: 10^-2 Pa m³/s to 10^-5 Pa m³/s
• Medium leaks: 10^-5 Pa m³/s to 10^-7 Pa m³/s
• Fine leaks: 10^-7 Pa m³/s to 10^-9 Pa m³/s
• Ultra-fine leaks: 10^-9 Pa m³/s to 10^-11 Pa m³/s

The terms large, medium, fine and ultra fine are relative terms and do not imply that any leakage rate is acceptable. The individual application determines the level of integrity required. For many packaging applications, only large leaks are considered unacceptable and the ability to detect smaller leaks is unimportant. All leakage rates specified in this method are based on conversion of actual conditions (based on the partial pressure of helium) to one atmosphere pressure difference and standard temperature conditions.

This standard is applicable to any type of packaging, flexible, semi-rigid or rigid. The sensitivities reported in the supporting data for this method relate to the detectability of helium emitted from the sample and are not a function of the packaging form. The method is not applicable to breathable or porous packaging. The results obtained may be qualitative, semi-quantitative or quantitative, depending on the procedure used.

Test fixture design is not covered by this method, except that different designs will be needed for different applications (with different packaging types and package integrity requirements). Additionally, fixture selection and design is determined by where in the production process the testing will be performed, i.e., quality control and research results.

Both of these test procedures (sniffer mode or vacuum mode) require a measurable level of helium on the side of the package under test opposite the leak detector sensor (usually the interior of the package). If the package cannot or must not be helium sealed, the test fixture used for that test must provide helium entry at the appropriate location and time in the test cycle. The exception to this is a package with a major leak where a variation of the helium pressure backfill or soak technique is employed.

For the purposes of this standard, the terms and definitions in “ASTM D996-23 Standard terminology for packaging and distribution media,” “ASTM F17-17 Standard terminology for primary barrier packaging,” and “ASTM F1327-05 Standard terminology for barrier materials for medical packaging,” as well as the following definitions, apply:

• The actual helium leak rate, the measured helium leak rate signal level, is set to a driving force at a concentration of 101 percent at 1,0 KPa (100 atmosphere).
• Breathable/porous packaging is packaging that intentionally allows gases or vapors to flow freely, fully or partially, into and out of the package.
• Flexible packaging is packaging (usually bags, pouches, and sacks) made from materials that can be bent easily.
• Impermeable packaging is packaging made of materials (usually metal or glass) that prevent gases or vapors from flowing into or out of the package.
• The measured helium leak rate is the helium signal level obtained according to the actual helium concentration in the package.
• Degassing is the release of adsorbed, absorbed or physically trapped gas from the surface of a structure.
• The pass/fail criterion is the predetermined actual helium leak rate at which the tested package is deemed defective and therefore unacceptable.
• Semi-rigid packaging is packaging that is usually formed into blisters or trays to which the appropriate closure materials are applied as a closure medium (usually thermoformable or cold-formable materials).

Our organization has a strong staff that closely follows the developments in the world in the field of science and technology and constantly improves itself. Among the numerous test, measurement, analysis and evaluation studies provided for businesses in various sectors, there are also test services in accordance with the standard "ASTM F2391-05 Standard test method for measuring package and seal integrity using helium as a tracer gas".