ASTMF2338[1]

Designation: F 2338 – 05 Standard Test Method for Nondestructive Detection of Leaks in Packages by Vacuum Decay Method1 This standard is issued under the fixed designation F 2338; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (e) indicates an editorial change since the last revision or reapproval. 1. Scope 1.1 Test Packages—Packages that can be nondestructively evaluated by this test method include: 1.1.1 Rigid and semi-rigid non-lidded trays. 1.1.2 Trays or cups sealed with porous barrier lidding material. 1.1.3 Rigid, nonporous packages. 1.1.4 Flexible, nonporous packages (see 1.2.4). 1.2 Leaks Detected—This test method is capable of detect- ing package leaks using an absolute or differential pressure transducer leak detector. The sensitivity of a test is a function of the sensitivity of the transducer, the package design, the design of the package test fixture, and critical test parameters of time and pressure. Types and sizes of leaks that may be detected for various package systems, as well as test sensitivi- ties are described below. These data are based on precision and bias confirmation studies. 1.2.1 Trays or Cups (Non-lidded)—Hole or crack defects in the wall of the tray/cup of at least 50 µm in diameter can be detected at a Target Vacuum of 4·104 Pa (400 mbar) using an absolute pressure transducer test instrument. 1.2.2 Trays Sealed with Porous Barrier Lidding Material— Hole or crack defects in the wall of the tray/cup of at least 100 µm in diameter can be detected. Channel defects in the seal area (made using wires of 125 µm in diameter) can be detected. Severe seal bonding defects in both continuous adhesive and dot matrix adhesive package systems can be detected. Slightly incomplete dot matrix adhesive bonding defects can also be detected. All porous barrier lidding material packages were tested at a Target Vacuum of 4·104 Pa (400 mbar) using an absolute pressure transducer test instrument. Using a calibrated volumetric airflow meter, the sensitivity of the test for porous lidded packages is shown to be approximately 10-2 Pa·m3·s-1. 1.2.3 Rigid, Nonporous Packages—Hole defects of at least 5 µm in diameter can be detected. All rigid, nonporous packages were tested at a target vacuum of 5·104 Pa (500 mbar) using a differential pressure transducer test instrument. Using a calibrated volumetric airflow meter, the sensitivity of the test for rigid, nonporous packages is shown to be approximately 10-4 Pa·m3·s-1. 1.2.4 Flexible, Nonporous Packages—Such packages may also be tested by the vacuum decay method using either an absolute or differential pressure tranducer test instrument. The instrument should be selected based on the leak test sensitivity desired. Sensitivity data for flexible packages were not in- cluded in the precision and bias studies, although the use of vacuum decay for testing such packages is well known. 1.3 Test Results—The test results are qualitative (Accept/ Reject). Acceptance criteria for test results are established from quantitative baseline vacuum decay measurements obtained from control, non-leaking packages. 1.4 Standard Value Units—The values used in this test method are stated in SI units and are to be regarded as standard units. Values in parentheses are for information only. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appro- priate safety and health practices and determine the applica- bility of regulatory limitations prior to use. 2. Referenced Documents 2.1 ASTM Standards: 2 D 996 Terminology of Packaging and Distribution Environ- ments E 691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method F 17 Terminology Relating to Flexible Barrier Materials F 1327 Terminology Relating to Barrier Materials for Medi- cal Packaging 3. Terminology 3.1 Definitions—For definitions used in this test method, see Terminologies D 996, F 17, and F 1327. 1 This test method is under the jurisdiction of ASTM Committee F02 on Flexible Barrier Materials and is the direct responsibility of Subcommittee F02.40 on Package Integrity. Current edition approved April 1, 2005. Published April 2005. Originally approved in 2003. Last previous edition approved in 2004 as F 2338 – 04. 2 For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards volume information, refer to the standard’s Document Summary page on the ASTM website. 1 Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States. Copyright by ASTM Int'l (all rights reserved); Reproduction authorized per License Agreement with Oliver Pace (); Fri May 5 08:38:39 EDT 2006 3.2 Definitions of Terms Specific to This Standard: 3.2.1 baseline vacuum decay, n—the extent of vacuum change within the test chamber over time demonstrated by a control, non-leaking package. 3.2.2 control, non-leaking packages, n—packages without defects and properly sealed or closed according to manufac- turer’s specifications. 3.2.3 flexible, nonporous packages, n—packages that sig- nificantly deflect when under vacuum, and are constructed of malleable, nonporous materials. Examples include pouches or bags made of polymeric, foil, or laminate films. 3.2.4 rigid, nonporous packages, n—packages that do not significantly deflect under vacuum and are constructed of solid, nonporous materials. For example, plastic bottles with screw- thread or snap-on closures are rigid, nonporous packages. 3.2.5 semi-rigid trays or cups, n—trays made of material that retain shape upon deflection. For example, thermoformed PETE or PETG trays are considered semi-rigid trays. 3.2.6 spotty or mottled seals, n—an incomplete adhesive bond made between a package tray or cup and porous lidding material that can be visibly identified by a distinctive pattern of dots, spotting or mottling on the tray sealing surface after the lid is removed. 3.2.7 volumetric airflow meter, n—a calibration tool that can be used to provide an artificial leak of known volumetric airflow rate into the test chamber for verification of instrument sensitivity. Airflow meters should be calibrated to NIST standards. The operational range of the meter should reflect the desired limit of sensitivity for the intended leak test. 3.3 Definitions of Test Cycle and Critical Parameters Terms—For terms and abbreviations relating to the test cycle and the critical parameters for establishing accept/reject limits, see Annex A1. 4. Summary of Test Method 4.1 The test package is placed in a test chamber to which vacuum is applied. The chamber is then isolated from the vacuum source and an absolute or differential vacuum trans- ducer is used to monitor the test chamber for both the level of vacuum, as well as the change in vacuum over time. Vacuum decay, or rise in chamber pressure, is a result of package headspace gas being drawn out of the package through any leaks present, plus background noise. Leak detection requires vacuum decay in excess of the background noise level. Background noise vacuum decay may result from package expansion when exposed to vacuum (flexible or semi-rigid packages), or from residual gases inherent in the test chamber or test system lines. 4.2 Porous barrier lidded tray or cup packages are tested for leaks located in the tray or cup, and at the lidding material/tray seal junction. Leaks in the porous lidding material itself cannot be detected. When testing such packages, steps are taken to physically mask or block the porous barrier surface to prevent the migration of package gas through the porous lid. These steps may require some sample preparation, depending on the masking approach required, but must be nondestructive and noninvasive. Vacuum decay from porous barrier lidded pack- ages may potentially include background noise from gas trapped between the lidding material and the masking surface, or from transverse gas flow through the porous barrier material itself at the lid/tray seal junction. 4.3 The sensitivity of a vacuum decay leak test is a function of several factors. Smaller leaks can be detected with more sensitive pressure transducers, and with longer test times. Also, pressure changes can be more readily detected with smaller void volumes between the test package and the test chamber, and with smaller test system line volumes. Steps to reduce background noise can also improve sensitivity. For example, for porous barrier lidded packages, more effective masking techniques will minimize background noise. NOTE 1—Further information on the “Leak Test Theory” may be found in Annex A1. 5. Significance and Use 5.1 Leaks in medical device, pharmaceutical and food packages may result in the ingress of unwanted gases (most commonly oxygen), harmful microbiological or particulate contaminants. Package leaks may appear as imperfections in the package components themselves or at the seal juncture between mated components. The ability to detect leaks is necessary to ensure consistency and integrity of packages. 5.2 After initial set-up and calibration, the operations of individual tests may be semi-automatic, automatic or manual. The test method permits the non-destructive detection of leaks not visibly detectable. The test method does not require the introduction of any extraneous materials or substances, such as dyes or gases. However, it is important to physically mask or block off any porous barrier surface of the package during the test to prevent a rapid loss of chamber vacuum resulting primarily from gas migration through the porous surface. Leak detection is based solely on the ability to detect the change in pressure inside the test chamber as a result of air egress from the properly masked package when challenged with vacuum conditions. 5.3 This test is a useful research tool for optimization of package sealing parameters and for comparative evaluation of various packages and materials. This test method is also applicable to production settings as it is rapid, non-invasive and non-destructive, making it useful for either 100 % on-line testing or to perform tests on a statistical sampling from the production operation. 5.4 Leak test results that exceed the permissible limits for the vacuum decay test are indicated by audible or visual signal responses, or both. 6. Apparatus 6.1 Vacuum Decay Leak Detection Apparatus—All vacuum decay test systems include a test chamber with a lower compartment (lower tooling) designed to nest the test package, and an upper lid (top tooling) for closing the test chamber. Fig. 1 illustrates a test chamber designed for testing packages with porous barrier lidding material. The test fixture upper lid consists of a flexible bladder to mask the package’s porous barrier during the test cycle. Fig. 2 illustrates a test chamber designed for testing rigid, nonporous packages. In this case, there is no flexible bladder. For both test chamber designs, the test chamber is connected to the vacuum decay test system. This system includes a vacuum source for establishing vacuum F 2338 – 05 2 Copyright by ASTM Int'l (all rights reserved); Reproduction authorized per License Agreement with Oliver Pace (); Fri May 5 08:38:39 EDT 2006 within the chamber at the beginning of the test cycle, and an absolute or differential pressure transducer for monitoring the level of vacuum as well as the pressure change as a function of time during the test cycle. A calibrated volumetric airflow meter may be placed in-line with the test system for verifying the sensitivity of a leak test. 6.2 Tray Nest or Lower Tooling—The bottom half of the test chamber is dimensionally designed to closely nest the test package, while still allowing for easy gas flow around the test package. Without ready gas flow around the package, leakage sites can be blocked. Conversely, the larger the gap between the test chamber and the test package, the less sensitive the leak test, as vacuum decay from package leakage will be minimized in a larger net test chamber volume. 6.3 Upper Lid or Upper Tooling—The upper lid is designed to tightly seal the closed test chamber during the vacuum cycle. 6.4 Mask or Block—The porous barrier lidding material of packages must be masked or blocked during testing to mini- mize egress of air from the package through the lidding. Various masking techniques may be used, including a test chamber designed with a flexible bladder in the upper tooling (refer to Fig. 1). 6.5 Volumetric Airflow Meter—An adjustable volumetric airflow meter is placed in-line with the test chamber to introduce an artificial leak of variable size. It is recommended that an airflow meter be used to verify the sensitivity of the leak test parameters. NOTE 2—Refer to Annex A2 for further information about the use of a volumetric airflow meter for verifying leak test sensitivity. 7. Hazards 7.1 As the test chamber is closed, it may present pinch-point hazards. 8. Preparation of Apparatus 8.1 The test apparatus must be started, warmed-up, and made ready according to the manufacturer’s specifications. Utilities required for instrument operation include electrical power and a supply of dry, non-lubricated compressed air, according to manufacturer’s specifications. 9. Calibration and Standardization 9.1 Before test measurements are made, the apparatus must be calibrated. The pressure transducers, the vacuum source pressure gage, and the adjustable volumetric airflow meter must all be calibrated according to the manufacturer’s recom- mended procedures and maintenance schedule. 9.2 Critical test parameter settings must be established for each package/test fixture combination. Parameters will vary based on the test package geometry and any porous barrier surface’s inherent porosity. NOTE 3—Refer to Section 4 and Annex A1 for a description of critical test parameters. FIG. 1 Schematic of Fixture and Porous Barrier Lidded Test Package F 2338 – 05 3 Copyright by ASTM Int'l (all rights reserved); Reproduction authorized per License Agreement with Oliver Pace (); Fri May 5 08:38:39 EDT 2006 9.3 A sample population of control non-leaking packages must be used for selecting and optimizing critical test param- eters. Control packages are to be made from the same materials and according to the same design as the test units. NOTE 4—Refer to Annex A2 for information on critical test parameter selection. 9.4 After critical test parameters have been selected, qualify the ability of the test to reliably differentiate between known non-leaking and defective packages. 9.5 Determine the sensitivity of the test using control non-leaking test packages and a calibrated volumetric airflow meter. NOTE 5—Refer to Annex A2 for information about test sensitivity verification procedures. 9.6 Test qualification (see 9.4) and test sensitivity verifica- tion (see 9.5) are to be conducted frequently, typically at least one or more times a day, preferably at the beginning of every shift. 10. Procedure 10.1 Select and install the appropriately sized test chamber for the package to be tested. Make any necessary adjustments to the chamber to ensure a sufficiently tight seal of the chamber lid (upper tooling) to the lower chamber package nest (lower tooling) when the test chamber is in the closed position. FIG. 2 Schematic of Fixture and Rigid, Nonporous Test Package F 2338 – 05 4 Copyright by ASTM Int'l (all rights reserved); Reproduction authorized per License Agreement with Oliver Pace (); Fri May 5 08:38:39 EDT 2006 10.2 Verify the pressure level available at the supply source. Check the functionality of the vacuum source. 10.3 Program the test instrument with all necessary test parameters and accept/reject criteria. 10.4 Place the assembled package into the lower tooling nest and close the test chamber. Take appropriate steps to mask or block any porous barrier surface of the package. NOTE 6—Inspect and clean the masking or blocking surface according to a regularly established routine according to the instrument manufac- turer’s recommended procedures to ensure effective masking of the porous barrier surface. 10.5 Start the test. 10.6 Note the pass or fail indicator or other means of detecting vacuum decay and document results. Identify and set aside any failed package for further evaluation. 10.7 Select another package and repeat the testing process. 11. Report 11.1 For each package tested, report the values for the following critical test parameters as well as package test results: 11.1.1 Reserve Vacuum (VRes), 11.1.2 Target or Test Vacuum (Vac), 11.1.3 Reference Vacuum (VRef), 11.1.4 Reference Fill Time (TfillRef), 11.1.5 Equalization Time (Tequal), 11.1.6 Vacuum Decay Test Time (Ttest), 11.1.7 Reference Vacuum Decay Rate Accept/Reject Limit (dP/dt Ref), and 11.1.8 Accept/Reject Test Results. NOTE 7—Refer to Annex A1 for definitions of critical test parameters. 12. Precision and Bias 12.1 Nonlidded and Porous Barrier Lidded Trays—An interlaboratory study was run in accordance with Practice E 691 using an absolute pressure decay instrument.3 Three laboratories ran the study, each using a separate instrument. Each laboratory performed three replicate tests on each test sample. Test sample populations consisted of non-lidded semi- rigid (PETE) thermoformed trays, and trays sealed with vari- ous porous barrier lidding materials. The same test samples were tested at each laboratory.4 Test results are qualitative in nature (Pass or Fail). Operators selected test critical parameters for each sample population; therefore test results reflect opera- tor, laboratory and instrument variability. 12.1.1 Nonlidded Trays—As summarized in Table 1, two populations of non-lidded trays representing two tray sizes were tested. Defective samples contained a single hole in the tray wall of either 50 µm or 100 µm in diameter. Two of the five larger trays, each with a 50 µm hole, repeatedly failed to be detected at more than one test site, while the other three trays were consistently identified as leaking. At the completion of the study the two suspect trays were independently reexamined for the presence and size of the holes. It was determined that the holes could no longer be located and it was hypothesized that they had become clogged. Eliminating the two suspect trays, results demonstrate the ability of the test method to identify defective trays with holes $50 µm, when using a Target Vacuum (Vac) of 4·104 Pa (400 mbar). 12.1.2 Porous Barrier Lidded Trays—As per the results outlined in Table 2, two populations of porous barrier lidded tray packages were tested, representing two package sizes, all sealed with one type of coated porous barrier lidding material. Defective samples included packages with a single hole in the tray wall (50 µm or 100 µm in diameter), and packages with a single seal channel defect created using a wire of either 75 µm, 100 µm, or 125 µm in diameter (0.003, 0.004, and 0.005 in., respectively). An independent laboratory microscopically veri- fied tray hole sizes, however seal channel sizes could not be reliably verified. Results demonstrate the ability of the test method to identify defective packages sealed with porous barrier lidding material. Defects consistently identified include tray holes of at least 100 µm in diameter, and channel defects created using a 125 µm wire, when using a Target Vacuum of 4·104 Pa (400 mbar). 12.1.3 Porous Barrier Lidded Trays with Various Adhesive Bonding Systems—Table 3 documents test results using two populations of tray packages wi