ISO 11140-4:2001
(Main)Sterilization of health care products - Chemical indicators - Part 4: Class 2 indicators for steam penetration test packs
Sterilization of health care products - Chemical indicators - Part 4: Class 2 indicators for steam penetration test packs
Stérilisation des produits de santé — Indicateurs chimiques — Partie 4: Indicateurs de classe 2 pour paquets prépliés servant à l'essai de pénétration de la vapeur
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ISO 11140-4:2001 is a standard published by the International Organization for Standardization (ISO). Its full title is "Sterilization of health care products - Chemical indicators - Part 4: Class 2 indicators for steam penetration test packs". This standard covers: Sterilization of health care products - Chemical indicators - Part 4: Class 2 indicators for steam penetration test packs
Sterilization of health care products - Chemical indicators - Part 4: Class 2 indicators for steam penetration test packs
ISO 11140-4:2001 is classified under the following ICS (International Classification for Standards) categories: 11.080.01 - Sterilization and disinfection in general. The ICS classification helps identify the subject area and facilitates finding related standards.
ISO 11140-4:2001 has the following relationships with other standards: It is inter standard links to ISO/IEEE 11073-10407:2010, ISO 11140-4:2007. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 11140-4
First edition
2001-05-01
Sterilization of health care products —
Chemical indicators —
Part 4:
Class 2 indicators for steam penetration test
packs
Stérilisation des produits de santé — Indicateurs chimiques —
Partie 4: Indicateurs de classe 2 pour paquets prépliés servant à l'essai de
pénétration de la vapeur
Reference number
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ii ISO 2001 – All rights reserved
Contents Page
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 General requirements . 3
5 Indicator system format . 4
6 Performance requirements . 4
7 Packaging and labelling . 6
8 Quality assurance . 7
Annexes
A Determination of indicator strength during and after steam sterilization. 8
B Standard test cycles. 10
C Estimation of visual difference between colours of the substrate and of the changed or unchanged indicator
system by determination of relative reflectance density. 15
D Demonstration of uniform colour change on exposure to saturated steam. 18
E Determination of equivalence of the alternative indicator to the Bowie and Dick test. 19
F Determination of reproducibility of fail conditions created in a standard test pack by air injection, air leak and
retained air systems. 21
G Evaluation of indicator colour change on exposure to dry heat . 24
H Demonstration of shelf life of product. 25
I Accelerated ageing of test samples. 26
K Standard test pack . 30
L Air injection system . 31
Bibliography. 33
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ISO 2001 – All rights reserved iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO
member bodies). The work of preparing International Standards is normally carried out through ISO technical com-
mittees. Each member body interested in a subject for which a technical committee has been established has the
right to be represented on that committee. International organizations, governmental and non-governmental, in liai-
son with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission
(IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this part of ISO 11140 may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 11140-4 was prepared by Technical Committee ISO/TC 198, Sterilization of health care
products.
ISO 11140 consists of the following parts, under the general title Sterilization of health care products — Chemical
indicators:
— Part 1: General requirements
— Part 2: Test equipment and methods
— Part 3: Class 2 indicators for steam penetration test sheets
— Part 4: Class 2 indicators for steam penetration test packs
— Part 5: Class 2 indicators for air removal test sheets and packs
Annexes A,B,C,D, E, F,G,H,I,J, Kand Lforma normative part ofthis partof ISO 11140.
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iv ISO 2001 – All rights reserved
Introduction
The Bowie and Dick test was conceived as a test for successful air removal from high vacuum porous load
sterilizers [1]. A successful Bowie and Dick test indicates rapid and even penetration of steam into the test pack. The
presence of air within the pack, due either to an inefficient air removal stage, an air leak during this stage or non-con-
densable gases in the steam supply, are circumstances which can lead to failure of the test. The result of the test may
also be affected by other factors which inhibit steam penetration. The test does not necessarily demonstrate either
achievement of the required temperature or maintenance of that temperature for the required time to achieve
sterilization.
Failure of the Bowie and Dick test is not conclusive proof that the fault in the sterilizer is due to air retention, air leak-
age or non-condensable gases, and it may be necessary to investigate other causes of failure.
The Bowie and Dick test is a performance test for steam sterilizers for wrapped goods and porous loads. As such it
is performed during the demonstration of conformance of steam sterilizers to EN 285 and as a routine test of per-
formance in ISO 11134. The test procedure is described in EN 285.
A test pack for the Bowie and Dick test consists of two components:
a) a small standardized test load and
b) a chemical indicator system to detect the presence of steam (see ISO 11140-3 and ISO 11140-4).
The Bowie and Dick test as originally described [1] utilized huckaback towels as the material for the test load. The
test described in EN 285 uses cotton sheets for this purpose.
Indicators intended as an alternative to the Bowie and Dick Test use different materials for the test load and employ
indicator systems specifically formulated for use with the defined test load. This part of ISO 11140 specifies the per-
formance of the indicator system in combination with the test load with which it is intended to be used. The test load
may be presented with the indicator system already incorporated and intended for single-use, or it may be intended
for multiple use with a new indicator system to be inserted prior to each use.
The indicator for which the performance is specified in this part of ISO 11140 is intended to indicate when steam pen-
etration has been inadequate. The performance of the indicator specified in this part of ISO 11140 should be equiv-
alent, but not necessarily identical, to the performance obtained in a Bowie and Dick test as described in EN 285.
Equivalence should be regarded as providing a similar response to steam penetration with any differences being pre-
dictable and such that the necessary level of assurance of satisfactory steam penetration is provided. An indicator
meeting this specification is not intended to identify which of the potential causes of poor steam penetration was re-
sponsible for the failure indicated by the test.
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ISO 2001 – All rights reserved v
INTERNATIONAL STANDARD ISO 11140-4:2001(E)
Sterilization of health care products — Chemical indicators —
Part 4:
Class 2 indicators for steam penetration test packs
1 Scope
This part of ISO 11140 specifies the performance requirements for a Class 2 indicator to be used as an alternative to
the Bowie and Dick test for steam sterilizers for wrapped health care goods (instruments, etc. and porous loads).
An indicator complying with this part of ISO 11140 incorporates a specified material which is used as a test load. This
test load may, or may not, be re-usable. This part of ISO 11140 does not specify requirements for the test load, but
specifies the performance of the indicator system in combination with the test load with which it is intended to be
used. The indicator specified in this part of ISO 11140 is intended to identify poor steam penetration but does not in-
dicate necessarily the cause of this poor steam penetration.
This part of ISO 11140 does not include test methods to establish the suitability of these indicators for use in steriliz-
ers in which the air removal stage does not include evacuation below atmospheric pressure.
NOTE The Bowie and Dick Test is performed to demonstrate conformance of a steam sterilizer for wrapped health care goods to
EN 285 and may be used as a routine test of performance of such a sterilizer (see ISO 11134). The test procedure is described in
EN 285.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this part of ISO 11140. For dated references, subsequent amendments to, or revisions of, any of these publications
do not apply. However, parties to agreements based on this part of ISO 11140 are encouraged to investigate the
possibility of applying the most recent editions of the normative documents indicated below. For undated references,
the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of cur-
rently valid International Standards.
ISO 5-1, Photography — Density measurements — Part 1: Terms, symbols and notations.
ISO 5-3, Photography — Density measurements — Part 3: Spectral conditions.
ISO 5-4:1995, Photography — Density measurements — Part 4: Geometric conditions for reflection density.
ISO 187, Paper, board and pulps — Standard atmosphere for conditioning and testing and procedure for monitoring
the atmosphere and conditioning of samples.
ISO 2248, Packaging — Complete, filled transport packages — Vertical impact test by dropping.
ISO 9001:1994, Quality systems — Model for quality assurance in design, development, production, installation and
servicing.
ISO 10012-1, Quality assurance requirements for measuring equipment — Part 1: Metrological confirmation system
for measuring equipment.
ISO 11140-1:1995, Sterilization of health care products — Chemical indicators — Part 1: General requirements.
IEC 60584-2:1982 + A1:1989, Thermocouples — Part 2: Tolerances.
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ISO 2001 – All rights reserved 1
IEC 60751:1983 + A1:1986, Industrial platinum resistance thermometer sensors.
EN 285:1996, Sterilization — Steam sterilizers — Large sterilizers.
3 Terms and definitions
For the purposes of this part of ISO 11140, the following terms and definitions apply.
3.1
air pocket
concentration of residual, induced or injected air or non-condensable gases in the standard test pack
3.2
chamber reference temperature
temperature measured at a defined reference point within the steam exposure apparatus
NOTE The defined reference point is usually located in the chamber drain or active chamber discharge.
3.3
defined end-point
visible change occurring after exposure to the specified variable(s) at a level equal to or greater than that specified for
the indicator
3.4
dry saturated steam
steam with a dryness value between 0,9 and 1,0 and a non-condensable gas content of not more than 3,5 % (volume
fraction) when determined by the methods given in EN 285
3.5
exposure time
period for which the chamber reference temperature lies within the sterilization temperature band
3.6
graduated response
progressive visible change, occurring on exposure to one or more process variables, which allows assessment of the
level achieved
3.7
indicator
indicator system in the form in which it is intended to be used
3.8
indicator reagent
active ingredient or combination of ingredients before conversion into the indicator
[ISO 11140-1:1995, 3.4]
3.9
indicator system
combination of the indicator reagent and its substrate
3.10
pre-assembled pack
indicator in which the indicator system is incorporated into the test load during the manufacturing process and which
is supplied ready for use
3.11
reference fault period
period of 30 s commencing when the chamber reference temperature attains the set operating temperature
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3.12
sterilization temperature
minimum temperature of the sterilization temperature band
NOTE The use of the word “sterilization” within this and subsequent definitions is not intended to imply that sterilizing conditions
will take place under the test cycle conditions.
3.13
sterilization temperature band
range of temperatures from the sterilization temperature to the maximum allowable temperature which may prevail
throughout the load during the holding time
NOTE These temperatures are usually stated in whole degrees Celsius.
3.14
temperature depression
thermodynamic temperature difference in kelvin given by (chamber reference temperature, in degrees Celsius) mi-
nus (temperature in the standard test pack, in degrees Celsius)
3.15
test equilibration time
time elapsed after the chamber reference temperature attains the set operating temperature until the temperature
within the standard test pack is the same as the chamber reference temperature, within the limits of accuracy of the
temperature-measuring equipment
3.16
user-assembled pack
indicator in which the user combines the indicator system with the test load prior to use
4 General requirements
4.1 The requirements of ISO 11140-1 apply.
4.2 Test samples shall be conditioned in accordance with ISO 187 prior to testing for performance.
4.3 Compliance with the requirements of this part of ISO 11140 shall be determined by establishing conformity with
the requirements of clause 6.
4.4 The indicator shall have sufficient strength to withstand steam sterilization and subsequent handling.
Compliance shall be tested in accordance with annex A.
4.5 Test cycles for demonstrating compliance with the requirements of this part of ISO 11140 shall employ sub-at-
mospheric, trans-atmospheric and super-atmospheric air removal stages (see Table 1 and clauses B.1, B.2 and B.3
respectively in annex B) except when the indicator, or indicator system, is intended solely for use with one type of air
removal system, in which case only the specified air removal system needs to be used during compliance testing.
4.6 A thermometric recording instrument(s) shall be used in conjunction with temperature sensors to record the
temperatures measured in the locations specified in the tests described in this part of ISO 11140. The temperature-
measuring equipment used in all test methods for demonstrating compliance with this part of ISO 11140 shall meet
the following requirements.
a) Temperature sensors shall be either platinum resistance and comply with Class A of IEC 60751:1983 + A1:1986
or thermocouple and comply with one of the tables of tolerance class 1 of IEC 60584-2:1982 and A1:1989.
b) The performance characteristic of the temperature sensor shall not be affected by the environment in which it is
used, e.g. pressure, steam or vacuum.
c) The temperature sensors shall have a response time in water of 6 0,5 s.
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ISO 2001 – All rights reserved 3
d) The temperature measured by all temperature sensors when immersed in a temperature source at a temperature
known to within� 0,1 K, and within the sterilization temperature band, shall not differ by more than 0,5 K.
e) The recording instrument shall record the temperature from a minimum of 12 sensors. The sampling duration
shall not exceed 2,5 s. All data sampled shall be used for the interpretation of results.
� �
f) The scale range shall include 0 C to 150 C. For analog instruments, the minor mark interval shall not exceed
1 K, the resolution shall be not less than 0,5 K and the chart speed shall be not less than 15 mm/min. Digital in-
struments shall register and record in increments of not more than 0,1 K.
� �
g) The limit of error of the recording instrument between 0 C and 150 C (excluding temperature sensors) shall not
�
exceed 0,25 % when tested in an ambient temperature of (20� 3) C. The additional error due to change in
the environmental temperature shall not exceed 0,04 K/K.
h) Calibration shall be carried out using a working or reference standard which is traceable to a national standard or
a primary standard. The instrument shall have a valid test certificate.
5 Indicator system format
5.1 When the indicator system is one in which the indicator reagent is distributed on a substrate, it shall meet the
following requirements.
a) The indicator reagent shall be distributed to cover not less than 30 % of the surface area of the substrate. The
distance between adjacent areas of indicator reagent shall not exceed 20 mm.
The pattern of indicator reagent distribution should permit clear interpretation of the colour change.
b) The substrate shall have a colour which is uniform to visual observation.
c) The indicator system shall have a difference in relative reflectance density of not less than 0,3 between the colour
of the substrate and either the changed indicator or unchanged indicator as specified by the manufacturer.
Compliance shall be tested in accordance with annex C.
5.2 When the indicator system depends on migration of the indicator reagent to demonstrate change, the pattern of
indicator reagent distribution before and after use shall permit clear interpretation of the result.
5.3 When the indicator system is intended for use with a user-assembled pack, the indicator system shall permit
writing in permanent ink to be made legibly on both processed and unprocessed materials. Those markings made
before processing shall remain legible after processing.
5.4 When the indicator system is provided by the manufacturer already incorporated into the test load, the material
of either the indicator or the indicator system, as appropriate, shall permit writing to be made after processing.
6 Performance requirements
6.1 The indicator, when tested in combination with the test load specified by the manufacturer, shall show a uniform
� �
colour change complying with 5.1 c) after exposure to dry saturated steam at 134 C for 3,5 min, or at 121 C for
15 min
or at any other time/temperature combination specified by the manufacturer when the temperature tolerance
� �
+1,5
�
shall be C and the time tolerance shall be�5s.
Compliance shall be tested in accordance with annex D using the steam exposure apparatus. The steam exposure
apparatus shall be operated with the standard test cycles described in annex B as shown in Table 1.
Indicators intended for use only with specific air removal cycles shall be tested with those specific cycles only (see
ISO 11140-1).
�
NOTE Indicators intended to be used over a wide range of sterilization temperatures, e.g. both for cycles operating at 121 C
�
and for those operating at 134 C, may not give the same depth or intensity of colour change at both temperatures. This should
be regarded as in compliance if:
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4 ISO 2001 – All rights reserved
a) all other performance characteristics required by this part of ISO 11140 are met and
b) the nature of the colour change is unambiguously defined in the instructions for use (see ISO 11140-1).
6.2 The indicator shall show no colour change, an incomplete, or an uneven colour change when exposed to a test
cycle previously demonstrated to produce a reference fault condition, whether the system used to produce the fault
depends on air retention, air leak or air injection. The test cycles used to generate the reference fault conditions shall
�
be as shown in Table 1. The chamber reference temperatures and holding times shall include 134 C for 3,5 min, or
�
121 C for 15 min or other time/temperature combination specified by the manufacturer (see 6.1) when the tem-
� �
+1,5 �
perature tolerance shall be C and the time tolerance shall be�5s.
Compliance shall be tested in accordance with annex E.
Compliance of the fault condition reproducibility shall be demonstrated in accordance with annex F.
Table1 —Schedule of test cyclesto beused
Standard test cycle of annex B
Test condition
B.1 B.2 B.3
“Pass” cycle (see 6.1)
“Fail” cycle — modified air removal stage (see 6.2) �
“Fail” cycle — induced leak (see 6.2)��
“Fail” cycle — air injection (see 6.2)�
= test required;
� = test not required.
�
6.3 The indicator system shall show no discernible colour change after exposure to dry heat at (140� 2) C for
not less than 30 min.
With some indicators the indicator system may show a slight colour change after exposure to dry heat; this shall be
acceptable if the change that occurs is slight or markedly different from that brought about by exposure to steam in
accordance with 6.1 and within the limits specified by the manufacturer.
Compliance shall be tested in accordance with annex G.
�
6.4 Indicators intended for use only with a sterilization temperature 121 C shall be tested by exposure to dry heat
� �
at (130� 2) C for not less than 45 min if the indicator will not withstand heating to 140 C.
Compliance shall be tested in accordance with annex G.
6.5 Indicator systems intended for use with re-usable user-assembled packs shall not visibly transfer indicator rea-
gent to the material of the test load during processing. Pre-assembled packs and indicator systems intended for use
with single-use user-assembled packs shall not transfer indicator reagent to the material of the test load during
processing to an extent which impairs the utility of the product.
Compliance shall be demonstrated by visual examination after testing in accordance with the requirements of 6.1
and annex D.
6.6 The indicator shall comply with the requirements of this part of ISO 11140 for the duration of the shelf life
specified by the manufacturer.
If any change in the indicator occurs during ageing, it shall be different to the change on exposure to dry saturated
steam (as described in 6.1) and have either inactivated the indicator system so that no further change can take place
or not affected the performance of the indicator system with respect to the requirements of 6.1 and 6.2.
Compliance shall be tested in accordance with annex H or by performance testing after accelerated ageing in ac-
cordance with annex I.
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ISO 2001 – All rights reserved 5
7 Packaging and labelling
7.1 Each indicator, or indicator system, shall be marked with
a) the sterilization temperature(s) at which the product is designed to be used,
b) a unique code from which the manufacturing history can be traced,
c) the expiry date under the specified storage conditions,
d) at least the information summarized in Figure 1. Adjacent to each heading there shall be a clear space not less
than 5mm� 20 mm for the user to enter the required information at the time of use, or, if the size of the indicator
system does not permit this, each indicator or indicator system shall be supplied with means of retaining the in-
dicator or indicator system as a permanent record which shall be printed with the information given in Figure 1.
The means of retention shall permit writing in permanent ink to be made in association with the indicator.
NOTE This is an example of a suitable format. Other formats and/or text can be used.
Figure 1 — Provision for recording information to be provided on or with each indicator
7.2 When the indicator is supplied assembled, i.e. with the indicator system within the test load, the exterior of the
test load shall be marked with the sterilization temperature(s) at which the product is suitable for use, the manufac-
turer’s name, batch number and date of manufacture. In addition, either a means of uniquely identifying the individual
indicator or an area on the outside of the test load onto which the operator can write the number of the machine
tested and the date shall be provided.
When a manufacturer provides similar products which are intended only for specific sterilization cycles, the product
shall include identification sufficient to enable the user to determine, from the instructions for use, any restrictions on
the use of the product. The identification shall be on the indicator or indicator system and, if not visible to the user
before use, shall also be on the outside of the test load.
7.3 The transport package shall be such that the product can be removed easily. The package shall protect the
product to the extent necessary to ensure that the indicator retains its performance throughout the stated shelf-life
when stored and transported in accordance with the manufacturer's instructions.
The manufacturer shall retain documentary evidence demonstrating compliance.
7.4 The outside of each package shall be marked with the sterilization temperature(s) at which the product is suit-
able for use.
7.5 The information supplied by the manufacturer (see 5.6 of ISO 11140-1:1995) shall include sufficient instruc-
tions on the use of the indicator to enable correct interpretation of the test results.
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7.6 When requested by the purchaser, the manufacturer shall supply a certificate of conformity to the requirements
of this part of ISO 11140 for each batch of product supplied.
8 Quality assurance
8.1 The manufacturer's quality system shall ensure that an acceptable quality level (AQL) of 1,0 or less is main-
tained for performance requirements given in clause 6 of this part of ISO 11140. Other statistical control systems
which provide equivalent or better assurance of consistent product quality also shall be acceptable.
NOTE The AQL is the maximum number of defects per hundred units that, for the purposes of sampling inspection, can be con-
sidered satisfactory as a process average.
8.2 Suitable records shall be maintained to ensure that, if necessary, faulty batches can be recalled from use.
8.3 The manufacturing and distribution records shall be retained for a period of five years, or twice the declared
shelf-life of the product, whichever is greater. These records shall be maintained in accordance with the requirements
of 4.16 of ISO 9001:1994.
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ISO 2001 – All rights reserved 7
Annex A
(normative)
Determination of indicator strength during and after steam sterilization
A.1 Apparatus
A.1.1 Steam exposure apparatus, complying with annex J.
A.2 Procedure
A.2.1 Expose the indicator to three successive test cycles at the stated sterilization temperature of the indicator or
indicator system. The indicator shall be tested using both the standard test cycles specified in B.1 and B.2 (see 4.5)
unless the indicator is intended for use with only one type of air removal stage, in which case the appropriate test cy-
cle shall be used. The rate of pressure change of evacuation during the air removal pulse and during the drying stage
−1
shall be not less than 400 kPa� min .
The rate of pressure change shall be determined as follows (see Figure A.1):
p = 0,125 (7p +p ) (A.1)
3 1 2
p = 0,5 (p +p ) (A.2)
4 1 2
p (p −p )
3 4
= (A.3)
t (t −t )
4 3
where
p
is the maximum absolute pressure attained during the last air removal pulse and the operating stage, in kilo-
pascals;
p is the minimum absolute pressure attained during the last air removal pulse (prior to the admission of steam
to the operating pressure required for the chamber reference temperature to attain the sterilization tem-
perature) and the drying stage, in kilopascals;
p is thepressurecalculatedfrom(A.1),inkilopascals;
p is thepressurecalculatedfrom(A.2),inkilopascals;
t is the time atp , in minutes;
3 3
t is the time atp , in minutes;
4 4
p
is the rate of pressure change, in kilopascals per minute.
t
A.2.2 Remove the pre-assembled or user-assembled indicator from the exposure apparatus and examine the indi-
cator for visible damage, including for example opening or distortion of seals. Record the result.
A.2.3 If the indicator has remained intact, perform a drop test in accordance with ISO 2248 from a height of 1m
onto a firm horizontal surface. Record the result.
NOTE Concrete or terrazzo surfaces are suitable.
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8 ISO 2001 – All rights reserved
Figure A.1 — Determination of the rate of pressure change
A.2.4 Carry out this test with three samples for each of three separate production batches.
NOTE All nine samples can be processed simultaneously.
A.2.5 Damage occurring during the drop test which can be demonstrated as not impairing the interpretation of the
indicator in normal use nor, for re-usable test loads, the subsequent re-use of the test load shall not constitute a
failure.
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ISO 2001 – All rights reserved 9
Annex B
(normative)
Standard test cycles
B.1 General
Each of the test cycles described within this annex consists of three principal stages: air removal, exposure time
(equivalent to the sterilization stage) and evacuation stage. The temperatures attained during the air removal stage
and the duration of the air removal stage can have a significant effect on indicator performance. The cycles described
are not intended to imitate any of the many cycles which are commercially available. They are intended to provide an
overall range of effects within which most commercially available cycles will occur.
B.2 Cycle 1: Air removal by sub-atmospheric pulsing
The standard test cycle for sub-atmospheric air removal shall consist of the following steps:
a) evacuation of the chamber to 5,0 kPa;
97,0 kPa
b) steam admission to ;
c) repetition of steps a) and b) for a further three times;
d) if air injection is being used, it shall take place and be completed during steam admission to the exposure time at
a pressure between 75 kPa and 105 kPa (indicated with an arrow on Figure B.1);
e) steam admission to set operating pressure (see specific requirements for steam admission stage in B.5);
f) exposure time;
g) evacuation to 5,0 kPa;
h) air admission.
NOTE The actual pressures achieved at the set points will be determined by the tolerance permitted for the steam exposure ap-
paratus (see annex J).
Key
1 Set operating pressure
2 Air injection
Figure B.1 — Standard test cycle — Sub-atmospheric air removal
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10 ISO 2001 – All rights reserved
B.3 Cycle 2: Air removal by trans-atmospheric pulsing
The standard test cycle for air removal by trans-atmospheric pulsing shall consist of the following steps:
a) evacuation of the chamber to 5,0 kPa;
b) steam admission to 150 kPa;
c) evacuation of the chamber to 50 kPa;
d) repetition of steps b) and c) for a further three times;
e) steam admission to (set operating pressure minus 10,0 kPa);
f) evacuation of chamber to 110 kPa to 120 kPa;
g) repetition of steps e) and f) for one further time;
h) if air injection is being used, it shall take place during steam admission to the exposure time at a pressure be-
tween 120 kPa and 130 kPa (indicated with an arrow in Figure B.2);
i) steam admission to set operating pressure (see specific requirements for steam admission stage in B.5).
j) exposure time;
k) evacuation to 5,0 kPa;
l) air admission.
NOTE The actual pressures achieved at the set points will be determined by the tolerance permitted for the steam exposure ap-
paratus (see annex J).
Key
1 Set operating pressure
2 Set operating pressure minus 10 kPa
3 Air injection
Figure B.2 — Standard test cycle — Trans-atmospheric air removal
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ISO 2001 – All rights reserved 11
B.4 Cycle 3: Air removal by super-atmospheric pulsing
The standard test cycle for air removal by super-atmospheric pulsing shall consist of the following steps:
a) evacuation of the chamber to 5,0 kPa;
b) steam admission to 95 kPa;
c) evacuation of the chamber to 5,0 kPa;
d) repetition of steps b) and c);
e) steam admission to (set operating pressure minus 20,0 kPa);
f) evacuation of the chamber to 105 kPa to 120 kPa;
g) repetition of steps e) and f) for a further two times;
h) if air injection is being used, it shall take place during steam admission to the exposure time at a pressure be-
tween 120 kPa and 130 kPa (indicated with an arrow in Figure B.3);
i) steam admission to set operating pressure (see specific requirements for steam admission stage in B.5);
j) exposure time;
k) evacuation to 5,0 kPa;
l) air admission.
Key
1 Set operating pressure
2 Set operating pressure minus 20 kPa
3 Air injection
Figure B.3 — Standard test cycle — Super-atmospheric air removal
B.5 Acceptance limits during steam admission
B.5.1 The rate of pressure rise during steam admission to set operating pressure over the range 100 kPa or lowest
pressure at the bottom of the last super-atmospheric pulse to the set operating pressure of the exposure time shall
−1 −1
be between 100 kPa� min and 250 kPa� min as indicated in Figure B.4.
B.5.2 Select the operating temperature of the exposure time such that it corresponds to the temperature as stated
for the indicator. Set the operating pressure such that it corresponds to a saturated steam temperature of (selected
�
operating temperature, in degrees Celsius + 0,2 C).
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12 ISO 2001 – All rights reserved
B.5.3 The integral [Integrated Come-up Exposure (ICE)] between the chamber reference temperature when the
chamber reaches 100 kPa or at the bottom of the last super-atmospheric pulse, whichever is the greater, and the set
temperature during the steam admission period, bounded by the chamber reference temperature on the graph, shall
not exceed
T � (12�T =6)
R R
�
whereT is the set temperature in degrees Celsius minus 100 C.
R
EXAMPLE
�
at a set temperature 134 C the integral shall not exceed [34 (12� 34)=6]= 2 312 s�K, or
�
at a set temperature 121 C the integral shall not exceed [21 (12� 21)=6]= 882 s�K.
NOTE These limits are intended to ensure that steam admission does not contribute to excessive exposure of the indicator to
untypical conditions.
Key
(p −p )
R 0
1 Maximum rate of pressure rise during steam admission
t
1min
2Rateofpressurerise
(p −p )
R 0
3 Minimum rate of pressure rise during steam admission
t
1max
4 Integrated Come-up Exposure: Area bounded byT and the curve traced byT over the timet tot
0 C 0 1
p is the pressure of saturated steam, corresponding to the set operating temperature, in kilopascals;
R
p is the pressure of saturated steam, corresponding to the temperatureT , in kilopascals
0 0
Figure B.4 — Steam admission
ICE shall be calculated using the equation:
t
X
ICE = (T −T )� dt
1 0
t
where
T is the chamber reference temperature at timet, in degrees Celsius;
�
T is 100 C or the lowest temperature of the last positive pulse, in degrees Celsius;
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ISO 2001 – All rights reserved 13
dt is 1s;
t is the time at which chamber reference temperature attainsT , in seconds;
0 0
t is the time aftert at which the chamber reference temperature (T ) attains set operating temperature (T )
1 0 C R
�
e.g. 134 C, in seconds;
T is the chamber reference temperature, in degrees Celsius;
C
T is the set operating temperature of the exposure time, in degrees Celsius.
R
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14 ISO 2001 – All rights reserved
Annex C
(normative)
Estimation of visual difference between colours of the substrate and of the
changed or unchanged indicator system by determination of relative
reflectance density
C.1 Principle
The relative reflectance density, as defined in ISO 5-1, of the changed indicator and the substrate shall be deter-
mined in accordance with the methods given below which are based on ISO 5-3 and ISO 5-4, to which reference
shall also be made.
Relative reflectance density,D , is calculated as follows
Rf
D =−log R
(C.1)
Rf 10 f
R = = (C.2)
f c ce
where
is the reflected flux from the indicator;
c
is the reflected flux from the substrate.
ce
To completely define a type of density spectrally, it is necessary to specify the light source, optics and spectral re-
sponse of the measuring system.
C.2 Apparatus
C.2.1 Steam exposure apparatus, complying with annex J.
C.2.2 Illuminant.
D
The relative spectral power distribution of the incident flux shall conform to CIE standard illuminant .
NOTE This is regarded as equivalent to “Daylight – cloudy northern sky”.
C.2.3 Photoelectric reflectance photometer, giving within 0,3 % an indicated reading proportional to the inten-
sity of light reflected from the surface under test. The instrument shall have the following characteristics.
a) Optical geometry
Optical geometry shall conform to the requirements of ISO 5-4; this includes illumination of the specimen at an-
� � � �
gles between 40 and 50 , viewed along the normal (0 ) with an angle of acceptance (observer angle) of 10 .
The dimensions of the measurement aperture of the instrument shall permit the measurement aperture to be en-
tirely filled with substrate or indicator reagent.
To minimize measurement errors, the optical system should be equipped with a polarizing filter if the surface to
be measured is highly reflecting, e. g. a plastics coated surface.
b) Spectral response
For the visual reflectance density, the combined spectral sensitivity of the receiver and spectral characteristics of
the components on the efflux section of the measuring instrument shall match the spectral luminance efficiency
in photopic vision, designatedV . The product ofV and the reflection densitometer illuminanceS , wave-
() () A
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ISO 2001 – All rights reserved 15
length by wavelength, defines the spectral products required of the measuring instrument in order to provide
comparison of visual densities. The spectral product of the measuring instrument shall be within� 20 % of the
values given in Table C.1.
The logarithms of the products are given in Table C.1.
NOTE These conditions assume that there is no fluorescence in the optical elements of the instrument or the sample.
c) Calibration
NOTE Reflectance density is determined using a perfectly-reflecting and perfectly-diffusing material as a reference
standard. Such a material does not exist, but the response that would theoretically be obtained from such a material can be
compared with a suitable secondary reference standard, e. g. compressed barium sulfate, enamelled metal plaques which
can then be used to calibrate the densitometer.
The measuring instrument shall be calibrated against reference samples previously calibrated by a National Ref-
erence Laboratory.
The instrument shall indicate values within�3% of the calibrated values of the reference samples.
d) Background
While readings of the reflectance density of the substrate and the indicator are being made the sample shall be
in contact with a backing material which is spectrally non-selective and diffuse-reflecting and which has an ISO
reflection density greater than 1,50 (see annex A of ISO 5-4:1995).
C.3 Sample conditioning
�
Samples shall be conditioned to, and in equilibrium with, (23� 2) C and (50� 5) % relative humidity when
tested.
Standardized conditions are recommended because some materials change density with variations in temperature
and relative humidity.
C.4 Test procedure
Expose the indicator system within the indicator to a cycle of the steam exposure apparatus at the specified
operating temperature for the indicator, to produce a uniform colour change in the indicator reagent in accordance
with 6.1.
Determine the relative reflectance density of the indicator reagent on the substrate by using the substrate as the ref-
erence reflectance.
Carry out this measurement on three samples for each of three batches of the indicator system and on aged samples
(see annex H and annex I) in accordance with 6.6.
C.5 Test report
The test report shall contain at least the following information:
a) name and address of the indicator manufacturer;
b) batch numbers of the individual batches of indicator tested;
c) make, model and serial number of the test instrument;
d) calibration details traceable to a national standards authority;
e) temperature chart records of the steam exposure to which the indicators were exposed;
f) mean and range of the relative reflectance density measurements;
g) date of test;
h) identification of the test operator.
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16 ISO 2001 – All rights reserved
Table C.1 — Values of spectral product required of the reflectance photometer at the given values
of wavelength and illuminance
Wavelength Reflection densitometer illuminance Visual density spectral product
nm S v
A
340 4
350 5
360 6
370 8
380 10
390 12
400 15 < 1 000
410 18 1 322
420 21 1 914
430 25 2 447
440 29 2 811
450 33 3 090
460 38 3 346
470 43 3 582
480 48 3 818
490 54 4 041
500 60 4 276
510 66 4 513
520 72 4 702
530 79 4 825
540 86 4 905
550 93 4 957
560 100 4 989
570 107 5 000
580 114 4 989
590 122 4 956
600 129 4 902
610 136 4 827
620 144 4 731
630 151 4 593
640 158 4 433
650 165 4 238
660 172 4 013
670 179 3 749
680 185 3 490
690 192 3 188
700 198 2 901
710 204 2 622
720 210 2 334
730 216 2 041
740 222 1 732
750 227 1 431
760 232 1 146
770 237 < 1 000
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ISO 2001 – All rights reserved 17
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