YY/T 0681.18-2020 PDF in English
YY/T 0681.18-2020 (YY/T0681.18-2020, YYT 0681.18-2020, YYT0681.18-2020)
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Test methods for sterile medical device package--Part 18: Nondestructive detection of leaks in packages by vacuum decay method
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Standards related to (historical): YY/T 0681.18-2020
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YY/T 0681.18-2020: PDF in English (YYT 0681.18-2020) YY/T 0681.18-2020
YY
PHARMACEUTICAL INDUSTRY STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
ICS 11.080.40
C 31
Test methods for sterile medical device package - Part 18:
Nondestructive detection of leaks in packages by vacuum
decay method
装泄露
ISSUED ON: MARCH 31, 2020
IMPLEMENTED ON: APRIL 01, 2021
Issued by: National Medical Products Administration
Table of Contents
Foreword ... 3
Introduction ... 5
1 Scope ... 7
2 Normative references ... 7
3 Terms and definitions ... 7
4 Overview ... 9
5 Significance and application ... 10
6 Instruments ... 10
7 Danger (source) ... 13
8 Instrument preparation ... 13
9 Calibration and standardization ... 14
10 Programs ... 14
11 Reports ... 15
Appendix A (Normative) Vacuum decay leak test theory ... 17
Appendix B (Normative) Determination of critical test parameters and verification of
test sensitivity ... 21
Appendix C (Informative) Precision and bias ... 23
References ... 31
Test methods for sterile medical device package - Part 18:
Nondestructive detection of leaks in packages by vacuum
decay method
1 Scope
This Part of YY/T 0681 specifies the test method for the non-destructive detection of
the leakage of the packaging system of sterile medical devices, by the vacuum decay
method.
This Part applies to rigid and semi-rigid trays without lids, trays or cups with porous
barrier covers, nonporous rigid packaging, nonporous flexible packaging.
2 Normative references
The following documents are essential to the application of this document. For the dated
documents, only the versions with the dates indicated are applicable to this document;
for the undated documents, only the latest version (including all the amendments) is
applicable to this standard.
GB/T 19633.1 Packaging for terminally sterilized medical devices - Part 1:
Requirements for materials, sterile barrier systems and packaging systems
3 Terms and definitions
The following terms and definitions apply to this document.
3.1
Baseline vacuum decay
The degree of change in vacuum within the test chamber over time, as evidenced by
non-leaking control packages.
3.2
Control, non-leaking packages
Defective packaging, which is properly sealed or closed, in accordance with the
manufacturer's specifications.
airflow rate into a test chamber, to verify instrument sensitivity. Airflow meters
should be calibrated to a suitable standard. The operating range of the airflow meter
should be such that the desired sensitivity limit for the intended leak test is obtained.
4 Overview
4.1 Place the test package in the test chamber, to apply vacuum. The test chamber is
isolated from the vacuum source; the pressure sensor (absolute pressure or gauge
pressure) is used alone or in combination with another differential pressure sensor, to
monitor the vacuum degree in the test chamber and the change of vacuum over time.
Vacuum decay, or pressure rise in the test chamber, is caused by the gas in the headspace
of the package being drawn out of the package through any leaks, as well as background
noise. Vacuum decay can also be caused by volatilization of liquid, within the package
that partially or completely enters the leak path. For this case, vacuum decay can only
occur, when the test pressure in the test chamber is lower than the vapor pressure of the
liquid.
4.2 For the tray or cup with the porous barrier cover material, the leakage located on
the tray or holder cup body, as well as the joint between the cover material and the tray,
can be tested. Leaks in the porous lid itself cannot be detected. When testing this type
of packaging, take measures to physically cover or block the surface of the porous
barrier material, to prevent the escape of packaging gases through the porous lid. This
may require some sample preparation, depending on the method of occlusion required,
BUT must be non-destructive and non-invasive. Vacuum decay in packages, which have
a porous barrier lid material, may include background noise from the gas, between the
lidding material and shielding surface, OR from lateral airflow through the porous
barrier material itself at the lid/tray's seal junction.
4.3 The sensitivity of the test depends on the design of the package under test, the
sensitivity of the sensor, the design of the test chamber, the design of the test system,
the critical test parameters of time and pressure. The choice of test system and leak test
parameters for any given product packaging system must be based on the contents of
the package (liquid/solid with large/small headspace gas) and the nature of the package
(soft or rigid, porous or nonporous). When the instrument has a more sensitive pressure
sensor AND the void volume in the test chamber is the smallest, the test system has the
potential to detect the smallest leak. Extended test times can detect smaller gas leaks.
Minimizing background noise pressure fluctuations also improves test sensitivity. For
packaging with a porous barrier lid material, occluder technology can minimize
background noise. For flexible packaging or semi-rigid packaging, the expansion of the
packaging can be limited to reduce noise, by rationally designing the test chamber.
Release of trapped gas or trapped water vapor, in the test system or between package
components under test, may also contribute to background noise. This noise can be
distinguished from an actual leak, by extending the test time, to allow the vacuum to
return to the initial level, OR by extending the equilibration time.
Note: See Appendix A for more information on "Leak test theory". Examples of experimental
methods and test instruments, which are used to obtain precision and bias data, are given in
Appendix C and summarized in Table C.1.
5 Significance and application
5.1 Leaks in medical device packaging may result in the ingress of unwanted gases
(most commonly oxygen), harmful microorganisms, or particulate contaminants.
Package leaks may manifest as defects in the package components themselves or in the
sealed joints between package components. Ensuring the consistency and integrity of
packaging is an essential capability for leak detection.
5.2 After initial setup and calibration, a test operation can be semi-automatic, fully
automatic or manual. This test method is capable of non-destructively detecting leaks,
that are not apparent. The test method does not require the introduction of any foreign
materials or substances, such as dye solutions or gases. However, it shall be noted that
the surface of all porous materials needs to be physically blocked during the test, to
prevent the gas from passing through the porous surface and causing the vacuum in the
test chamber to drop rapidly. Because this test method is only based on the detection of
pressure changes in the test chamber, which are affected by the leakage of gas or steam
from the challenge package.
5.3 This test is a useful research tool, for optimizing package sealing parameters and
for comparative evaluation of various packages and materials. Because of its rapidity,
non-invasiveness, non-destructiveness, this test method is also suitable for installation
on the production line, or for 100% online testing of products, or for statistical sampling
testing.
5.4 For the vacuum decay test, leak test results exceeding allowable limits may be
indicated by an acoustic or optical signal response (or both).
6 Instruments
6.1 Vacuum decay leak detection instrument
The vacuum decay leak detection instrument consists of a test chamber, which is
connected to the vacuum decay test system, AND a volume flow meter.
6.2 Test chamber
The test chamber has a lower chamber for accommodating the test package AND an
upper chamber for closing the test chamber. Figure 1 shows a test chamber, which is
dedicated to testing packaging with a porous barrier lid. The test fixture is covered with
an elastic bladder, that is used to cover the package's porous barrier during testing.
Figures 2 and 3 illustrate the test chamber, which is used for testing nonporous rigid
Note: Different leak testing instruments, based on the type of packaging (e.g., rigid or non-rigid,
porous or non-porous) and the vacuum required for the test, may use different types of pressure
sensors or combinations thereof.
6.3.1 Comparison between absolute pressure sensor and gauge pressure sensor
All instruments include a transducer to monitor the test pressure throughout the test
cycle. Absolute pressure sensors are preferred over gage pressure sensors, when
accurate and true pressure readings are required (i.e., unaffected by changes in
atmospheric pressure due to climate or altitude). When performing liquid leakage tests
under high vacuum, an absolute pressure sensor is used.
6.3.2 Differential pressure sensor
Can be used as a second sensor, to measure the smallest detectable leaks on rigid/semi-
rigid non-porous packaging.
6.3.3 Vacuum source
Select the appropriate vacuum pump, based on the target vacuum level, which shall be
able to achieve the vacuum level, within the allocated time, under the given test
instrument system headspace conditions.
6.4 Cover or plug
During the test, the porous barrier closure package must be shrouded or plugged, to
minimize the escape of air in the package through the lid. Various occlusion techniques
can be used, including an elastic bladder on the upper test chamber (see Figure 1).
6.5 Volumetric airflow meter
An adjustable volume flow meter is placed in the test chamber tubing, to introduce
artificial leaks at different rates. An airflow meter is recommended, to verify the
sensitivity of the leak test.
7 Danger (source)
There is a possible pinch hazard, when the test chamber is closed (source).
8 Instrument preparation
Test instruments shall be powered on, warmed up, prepared, according to the
manufacturer's specifications. For instruments with self-contained air-driven vacuum
pumps, the required configuration for instrument operation includes a power supply in
accordance with the manufacturer's specifications and a source of dry, lubricant-free
compressed air. For instruments with an external vacuum pump, the configuration
required for instrument operation includes a power supply that complies with the
instrument and vacuum pump manufacturer's specifications.
9 Calibration and standardization
9.1 The instrument shall be calibrated, before being put into the test. Pressure
transducers, all available vacuum source gauges, adjustable volume flow meters shall
be calibrated, according to the manufacturer's recommended procedures and
maintenance schedules.
9.2 The instrumentation test system should be leak tested, to verify that it has a stable
baseline leak rate. In general, the test parameters are qualified, according to the system
qualification test procedure, which is recommended by the instrument manufacturer.
9.3 Critical test parameters shall be set for each package/test fixture combination.
Parameters will vary, depending on the test package geometry and the inherent air
permeability of any porous material surface. A small number of non-leaking control
packages or a simulated non-leaking package shall be used, to select critical parameter
settings.
Note: See Chapter 4 and Appendix A for critical test parameters.
9.4 Critical test parameters shall be optimized, using a larger number of non-leaking
control package samples. Control packages are fabricated from materials of the same
design as the test units.
9.5 Determine the sensitivity of the optimized leak test, using the non-leaking control
test pack and a calibrated volumetric flow meter.
9.6 Identify the ability of the optimized test to reliably distinguish between known leak-
free and defective packages.
9.7 The test system baseline identification (see 9.2) and test sensitivity verification (see
9.5) shall be carried out regularly, at least once or several times a day, preferably before
the start of each shift.
10 Programs
10.1 Select and install a test chamber which is suitable for the size of the package to be
tested. Make any necessary adjustments to the test chamber, to ensure that the lid of the
test chamber (upper chamber) is sufficiently airtight to the lower packaging chamber
(lower chamber), when the test chamber is in the closed position.
10.2 Verify the attainable pressure level at the air source. Check the performance of the
vacuum source.
Appendix A
(Normative)
Vacuum decay leak test theory
A.1 The vacuum decay leak test is performed by exposing the package under test to an
external vacuum. The pressure differential applied to the package causes the air to
escape, through the leak path in the package. If the package contains a liquid, the
vacuum below the vapor pressure of the liquid will also volatilize the liquid in or near
the leak path. During a test cycle, one or more pressure transducers monitor the pressure
rise in the test chamber, as a result of migration of headspace gas and/or volatile liquid
in the package through leaks in the package plus background noise. Leak detection
requires vacuum decay over background noise. Background noise decay may be caused
by expansion of the package when exposed to vacuum or the presence of traces of gas
or water vapor in the test chamber or in the test system tubing. The background noise
can be minimized by improving the design of the test chamber, adjusting the pressure
or time parameters, or exposing the test chamber to vacuum for a period of time, before
the test sample is loaded into the test chamber.
A.2 The packaging containing the porous barrier lid material can physically cover or
block the surface of the porous barrier of the package, so that the amount of air released
through the porous barrier material is minimized before testing. Defects in the gas
barrier lid cannot be detected, but defects in the seal area or the tray itself can be
detected. Vacuum decay from gas barrier lid material packaging may include
background noise from gas between the lid material and the closure surface, or lateral
airflow through the seal joint between lid material and tray.
A.3 A typical test cycle is to first place the test package into the test chamber and cover
or block any porous barrier packaging surface. Vacuum the closed test chamber. At the
end of a predetermined time period, bring it to the initial target vacuum; isolate the test
chamber from the vacuum source. After a short equilibration period, the vacuum in the
test chamber is monitored, for a predetermined test time. For many packages, it may
take only a few seconds, from the time the test chamber is closed to the completion of
the test cycle. Various critical test parameters, such as test cycle time, pressure, leak test
acceptance criteria, are described below. Figure A.1 shows a typical test cycle, that is
expected with various leak test failure modes.
Note: The terms of critical test parameters used in the following clauses may be different from
those used by leak manufacturers, BUT the definitions remain consistent.
test cycle. The test vacuum is expressed in the pressure unit mbar or Pa. Some devices
use vacuum (negative pressure) to represent the test vacuum, whilst others use absolute
pressure to represent the test vacuum. Both are as shown in Figure A.1.
A.3.5 Vacuuming time and reference vacuuming time
The reference vacuuming time is the allocated time, to reach the target vacuum; the
actual time necessary to reach the target vacuum is the vacuuming time. Both the
vacuuming time and the reference vacuuming time are expressed in seconds. If the
programmed test cycle is to monitor vacuum rise (or absolute pressure drop) during this
period, THEN, use the reference vacuum setting and reference vacuuming time
specifications.
A.3.6 Equilibration time
The equilibration time is immediately after the vacuuming time. The equilibration time
(indicated by s) is to stabilize the pressure fluctuation in the test chamber AND take
into account the escape of gas in the gap around the package (for example, from around
the screw cap). Typical equilibration times are a few seconds, but can be very short (<
1 s) when rapid pressure rises (i.e., loss of vacuum) as liquids evaporate from the leak
space need to be examined.
A.3.7 Test time
The test time (indicated by s) immediately follows the equilibration time, during which
the test vacuum is continuously monitored for evidence of package leakage. The same
pressure sensor is used to measure the vacuuming time, equilibration time, test time.
During the test time, another differential pressure sensor with greater sensitivity can
also be used, to detect the pressure change caused by the smallest leak.
A.3.8 Reference vacuum
The reference vacuum is defined as the vacuum, that must be maintained in the test
chamber after reaching the target vacuum and throughout the equilibration time and test
time. The reference vacuum is a vacuum, which is slightly lower than the target vacuum
or test vacuum, expressed in mbar or Pa. When absolute pressure is used, the reference
vacuum is slightly higher than the target vacuum or test vacuum.
A.3.9 Reference vacuum decay
The reference vacuum decay is defined as the maximum allowable vacuum drop (or
rise in absolute pressure), over the test time. The reference vacuum decay can be
expressed in the pressure unit Pa or in the pressure change unit (Pa/s).
A.4 When one of the following situations occurs, the test package is identified as
rejection (“failure”):
Appendix B
(Normative)
Determination of critical test parameters and verification of test sensitivity
B.1 Procedures for determining critical test parameters
B.1.1 General
The critical test parameters (vacuum purge before test, vacuuming time, equilibration
time, test time) of each cycle time, the establishment of each pressure (reserve vacuum,
target vacuum and reference vacuum), vacuum decay (reference vacuum decay) require
support by knowledge and experience in packaging for testing. It is recommended that
the user of the instrument consult the instrument operation manual for more detailed
information. B.1.2 ~ B.1.6 describe methods that can be used to establish critical
parameters for leak testing.
B.1.2 Determination of target vacuum and (reference) vacuuming time
In order to determine the test vacuum (high enough to detect significant package leaks,
without causing a breach of the package seal) and the time period required to achieve
this typical vacuum level (evacuation time), a group of leak-free control packages are
exposed to various vacuum levels for 1 s or longer vacuuming times of a few seconds.
Once the target vacuum is selected, a reserve vacuum slightly higher than the target
vacuum is selected, in order to ensure that the target vacuum continues to apply to the
non-defective control packages. When testing the leakage of a package with headspace
gas, the target vacuum can be set, within the pressure (absolute pressure) range from
+2.5 × 104 Pa (+250 mbar) to +5 × 104 Pa (+500 mbar). When the leaks are partially or
completely blocked by liquid, in order to ensure that the liquid evaporates, a higher
target vacuum condition of 0 Pa (0 mbar) to +100 Pa (+1 mbar) is required.
B.1.3 Determination of equilibration time
When testing against control leak-free packages, choose the equilibration time, by
observing how long it takes for the test vacuum to stabilize. When testing for leaks, the
equilibration time shall be very short (typically < 1 s), so that the rapid pressure rise
due to liquid volatilization can be measured, before the headspace of the system reaches
the saturated partial pressure (the point at which no pressure rise occurs).
B.1.4 Determination of test time
When testing defective packages, or when testing leak-free control packages and
introducing a small calibrated airflow rate into the test chamber, select the test time, by
observing the time it takes for a significant increase in test chamber pressure to occur.
B.1.5 Determination of critical parameters of reference vacuum and reference
vacuum decay
Observe and test the vacuum, through a group of control packages, to select the critical
parameters of each vacuum decay. These baseline vacuum decay data are used to select
critical parameters for the reference vacuum and reference vacuum decay.
B.1.6 Determination of vacuum purging time before test
When testing the leak-free control package and comparing it with the package with the
smallest defect, the vacuum purge time before the test is selected, by continuously
changing the vacuum purge time and observing the vacuum decay data obtained
subsequently. Optimizing the vacuum purge time before testing will ensure that the
vacuum decay results for the control packages are consistently significantly lower than
the vacuum decay results for the defective packages.
B.1.7 Test qualification
After identifying the critical test parameters, it is important to verify the ability of the
test to successfully identify defective packages. Successful defect detection is related
to critical test parameters as well as the configuration of the test chamber. Successful
testing is also related to the location and type of defects on the package. For example,
when closed inside the test chamber, the leak may be blocked by the product or be
pinched or covered (see Chapters 4 and 6 for details).
B.2 Sensitivity verification
B.2.1 Test sensitivity is verified during the test cycle, by introducing a known volume
of air flow rate into the test system containing leak-free packaging. Sensitivity is
defined as the minimum airflow rate, that triggers a "rejection" or "failure" result. The
critical test parameters, which are selected for different types of packaging/test chamber
combinations, have different sensitivities.
B.2.2 Another method, that is, to determine the sensitivity according to the nature and
size of the packaging defect, that can be reliably detected, may be the ideal method for
determining the sensitivity. The reliability of this method depends on the quality of
defect sample preparation, whilst it is often difficult to prepare and maintain accurate
defects. Testing both defective and non-defective packages, which are filled with liquid,
requires verification of the leak test's ability to identify liquid leaks.
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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