ISO 27427:2009

INTERNATIONAL ISO
STANDARD 27427
First edition
2009-05-01
Anaesthetic and respiratory equipment —
Nebulizing systems and components
Matériel d'anesthésie et de réanimation respiratoire — Systèmes de
nébulisation et ses composants

Reference number
©
ISO 2009
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ii © ISO 2009 – All rights reserved

Contents Page
Foreword. iv
Introduction . v
1 *Scope. 1
2 Normative references . 1
3 Terms and definitions. 3
4 General requirements and requirements for test . 4
4.1 Risk management . 4
4.2 *Test methods and alternatives. 4
4.3 Electrical safety. 5
4.4 Mechanical safety . 5
4.5 Pneumatic safety . 5
4.6 Protection against inadvertent adjustments.5
4.7 Protection against infection . 5
5 Marking and instructions for use. 5
5.1 Marking . 5
5.2 Symbols . 6
5.3 Instructions for use . 6
6 Construction requirements. 8
6.1 Materials . 8
6.2 Connectors . 9
6.3 Rotary controls . 12
7 Cleaning, sterilization and disinfection. 12
8 Biocompatibility. 12
Annex A (informative) Rationale . 13
Annex B (normative) Diameters of respirable fraction particles. 15
Annex C (normative) Test methods for aerosol output and aerosol output rate . 16
Annex D (normative) Test methods for particle sizing. 20
Annex E (informative) Test apparatus for leak test . 26
Annex F (informative) Hazard identification for risk assessment . 27
Annex G (informative) Taxonomy of general purpose nebulizers . 34
Annex H (informative) Environmental aspects. 36
Annex AA (informative) Conformance to essential principles . 37
Bibliography . 41

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 committees. 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 liaison 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 2.
The main task of technical committees is to prepare International Standards. 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 document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 27427 was prepared by Technical Committee ISO/TC 121, Anaesthetic and respiratory equipment,
Subcommittee SC 2, Tracheal tubes and other equipment.

iv © ISO 2009 – All rights reserved

Introduction
Nebulizers are widely used to deliver drugs, in an aerosol form, to humans through the respiratory system.
These drugs may be in the form of a solution, suspension or emulsion. Aerosol inhalation is the preferred
route of administration of some drugs. Some drugs are intended for treatment of systemic disease and other
drugs are intended to treat respiratory diseases. To achieve the intended treatment, aerosol particles may
need to be deposited in specific parts of the respiratory tract. Different size particles tend to deposit in different
parts of the respiratory system, therefore, the performance profile and the intended use of the nebulizer must
be defined by the manufacturer and specified in the accompanying documentation. Nebulizers are also used
for diagnostic purposes using radioisotopes, and for lung challenge tests and the delivery of vaccines.
This International Standard is based on the European Standard EN 13544-1:2007. This International Standard
was developed to cover “general purpose” nebulizers. It was specifically written to ensure that the results of
the various tests declared by the manufacturer were meaningful to the users and buyers of nebulizers.
The objectives of this International Standard are to ensure:
⎯ the suitability of the nebulizers for the intended use as disclosed by the manufacturer;
⎯ safety, particularly for electrically-powered nebulizers;
⎯ compatibility between the materials of the components and the dispensed liquid;
⎯ biocompatibility of the materials of the components that come into contact with the human body.
Important changes were made to the original EN standard in recognition of the advances in test devices such
as lasers and low-flow impactors that allow manufacturers to use different test methods, provided these
alternate methods are validated against the methods specified in this International Standard.
Terms defined in this document are set in bold type.
Throughout this International Standard, text for which a rationale is provided in Annex A is indicated by an
asterisk (*).
INTERNATIONAL STANDARD ISO 27427:2009(E)

Anaesthetic and respiratory equipment — Nebulizing systems
and components
1 *Scope
This International Standard specifies requirements for the safety, performance and testing for general purpose
nebulizing systems intended for continuous or breath-actuated delivery of liquids, in an aerosol form, to
humans through the respiratory system.
This International Standard includes gas-powered nebulizers which can be powered by, e.g., compressors,
pipeline systems, cylinders, etc., and electrically-powered nebulizers [e.g. spinning disc, ultrasonic,
vibrating mesh (active and passive) and capillary devices] or manually-powered nebulizers.
*This International Standard does not apply to devices intended for nasal deposition.
This International Standard does not apply to devices intended solely to provide humidification or hydration by
providing water in aerosol form.
*This International Standard does not apply to drug-specific nebulizers (e.g. metered dose inhalers, metered
liquid inhalers, dry powder inhalers and their components).
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 594-1, Conical fittings with a 6 % (Luer) taper for syringes, needles and certain other medical
equipment — Part 1: General requirements
ISO 594-2, Conical fittings with 6 % (Luer) taper for syringes, needles and certain other medical equipment —
Part 2: Lock fittings
ISO 5356-1, Anaesthetic and respiratory equipment — Conical connectors — Part 1: Cones and sockets
ISO 5356-2, Anaesthetic and respiratory equipment — Conical connectors — Part 2: Screw-threaded
weight-bearing connectors
ISO 5359, Low-pressure hose assemblies for use with medical gases
ISO 5361-1, Tracheal tubes — Part 1: General requirements
ISO 7000, Graphical symbols for use on equipment — Index and synopsis
ISO 7396-1, Medical gas pipeline systems — Part 1: Pipeline systems for compressed medical gases and
vacuum
ISO 9170-1, Terminal units for medical gas pipeline systems — Part 1: Terminal units for use with
compressed medical gases and vacuum
ISO 9276-2, Representation of results of particle size analysis — Part 2: Calculation of average particle
sizes/diameters and moments from particle size distributions
ISO 10524-1, Pressure regulators for use with medical gases — Part 1: Pressure regulators and pressure
regulators with flow-metering devices
ISO 10524-3, Pressure regulators for use with medical gases — Part 3: Pressure regulators integrated with
cylinder valves
ISO 10524-4, Pressure regulators for use with medical gases — Part 4: Low-pressure regulators
ISO 10993-1, Biological evaluation of medical devices — Part 1: Evaluation and testing
ISO 11135-1, Sterilization of health care products — Ethylene oxide — Part 1: Requirements for development,
validation and routine control of a sterilization process for medical devices
ISO 11137-1, Sterilization of health care products — Radiation — Part 1: Requirements for development,
validation and routine control of a sterilization process for medical devices
ISO 11137-2, Sterilization of health care products — Radiation — Part 2: Establishing the sterilization dose
ISO 11137-3, Sterilization of health care products — Radiation — Part 3: Guidance on dosimetric aspects
ISO 14971:2007, Medical devices — Application of risk management to medical devices
ISO 15001, Anaesthetic and respiratory equipment — Compatibility with oxygen
ISO 15002, Flow-metering devices for connection to terminal units of medical gas pipeline systems
ISO 15223, Medical devices — Symbols to be used with medical device labels, labelling and information to be
supplied
ISO 17665-1, Sterilization of health care products — Moist heat — Part 1: Requirements for the development,
validation and routine control of a sterilization process for medical devices
ISO 23328-1, Breathing system filters for anaesthetic and respiratory use — Part 1: Salt test method to
assess filtration performance
IEC 60601-1:2005, Medical electrical equipment — Part 1: General requirements for basic safety and
essential performance
IEC 60601-1-2, Medical electrical equipment — Part 1-2: General requirements for basic safety and essential
performance — Collateral standard: Electromagnetic compatibility — Requirements and tests
EN 13544-2, Respiratory therapy equipment — Part 2: Tubing and connectors
EN 556-1, Sterilization of medical devices — Requirements for medical devices to be designated
“STERILE” — Part 1: Requirements for terminally sterilized medical devices
ENV 737-6, Medical gas pipeline systems — Part 6: Dimensions and allocation of probes for terminal units for
compressed medical gases and vacuum
CGA V-5-2005, Diameter Index Safety System — Noninterchangeable Low Pressure Connectors for Medical
Gas Applications
2 © ISO 2009 – All rights reserved

3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
aerosol
suspension of particles in gas
NOTE 1 Particles can be liquid or solid.
NOTE 2 The gas can be the driving gas or ambient air.
3.2
aerosol output
amount of aerosol delivered to the patient by the nebulizing system for the given fill volume
3.3
aerosol output rate
amount of aerosol delivered to the patient by the nebulizing system per unit of time
3.4
breath-actuated nebulizing system
nebulizer triggered by a respiratory parameter
NOTE Examples of this classification are to be found in Annex G.
3.5
continuous nebulizing system
nebulizer in which aerosol is delivered continuously over multiple inhalation/exhalation breathing cycles or
over long periods
3.6
electrically-powered nebulizer
nebulizer that operates by means of electrical power
NOTE Electrically-powered nebulizer includes ultrasonic, vibrating mesh and capillary-type devices
3.7
gas-powered nebulizer
nebulizer in which the aerosol is generated by compressed gas
3.8
liquid container
part of the nebulizer that contains the liquid for nebulization
3.9
manually-powered nebulizer
nebulizer that operates by means of human power
3.10
mass median aerodynamic diameter
MMAD
maximum particle size at which 50 % of the aerosol output is delivered to the respiratory tract
3.11
maximum fill volume
maximum volume of liquid, expressed in millilitres, in the liquid container when the nebulizer is filled to its
maximum filling level
3.12
nebulizer
device that converts a liquid to an aerosol of a controlled particulate size range
3.13
nebulizing system
device, including the nebulizer and all other components, required to make the aerosol available for
inhalation
3.14
respirable fraction
amount of drug (in micrograms) contained in particles with sizes less than 5 µm
3.15
respirable range
aerosol particle sizes from 0,5 µm to 5,0 µm
3.16
validation
confirmation through the provision of objective evidence that the requirements for a specific intended use or
application have been fulfilled
NOTE 1 The term “validated” is used to designate the corresponding status.
NOTE 2 The use conditions for validation can be real or simulated.
4 General requirements and requirements for test
4.1 Risk management
Nebulizing systems and nebulizers shall, when transported, stored, installed, operated in normal use and
maintained according to the instructions of the manufacturer, cause no safety hazard which could be
reasonably foreseen using risk management procedures in accordance with ISO 14971 and which is
connected with their intended application, in normal and in single fault condition.
NOTE A situation in which a fault is not detected is considered a normal condition. Fault conditions/hazardous
situations may remain undetected over a period of time and, as a consequence, may lead to an unacceptable risk. In that
case, a subsequent detected fault condition needs to be considered as a single fault condition. Specific risk control
measures need to be determined within the risk management process to deal with such situations.
4.2 *Test methods and alternatives
4.2.1 Test methods for aerosol output, aerosol output rate and particle sizing
The type test methods for aerosol output, aerosol output rate and particle sizing are specified in Annexes C
and D.
4.2.2 Alternative test methods
The manufacturer may use type-test methods for aerosol output, aerosol output rate and particle sizing
different from those specified in Annexes C and D.
Alternative test methods shall be validated against the test methods in Annexes C and D to demonstrate
equivalency.
Demonstration of equivalency shall be included in the technical documentation of the manufacturer.
Evidence shall be provided upon request, e.g. to regulatory authorities.
4 © ISO 2009 – All rights reserved

4.3 Electrical safety
A nebulizing system that utilizes electrical power shall meet the requirements given in IEC 60601-1, in
addition to the requirements given in this International Standard.
Check compliance by application of the tests of IEC 60601-1.
4.4 Mechanical safety
Nebulizing systems shall comply with Clause 9 of IEC 60601-1:2005.
Check compliance by inspection.
4.5 Pneumatic safety
If it is declared by the manufacturer that a nebulizer is intended to be connected directly to a pipeline system
complying with ISO 7396-1 or a pressure regulator complying with ISO 10524-1 or ISO 10524-3, the
nebulizer shall meet the requirements of this International Standard for a pneumatic power supply having a
range of 280 kPa (2,8 bar) to 600 kPa (6 bar) and shall not cause a safety hazard under single fault conditions
of the medical gas supply, i.e. up to 1 MPa (10 bar) inlet pressure.
4.6 Protection against inadvertent adjustments
Means of protection against inadvertent adjustment of controls which can create a hazardous output shall be
provided.
NOTE Mechanical control techniques such as locks, shielding, friction-loading and detents are considered suitable.
Pressure-sensitive finger pads, capacitive finger switches and microprocessor-oriented “soft” controls or a specific
sequence of key or switch operations are also considered suitable.
Check compliance by visual inspection following the instructions for use.
4.7 Protection against infection
All parts of the nebulizing system subject to contamination by exhaled gases and intended to be re-used by
different patients shall be disinfectable or sterilizable.
5 Marking and instructions for use
5.1 Marking
5.1.1 General
a) All flow-direction-sensitive components, breathing attachments or parts (e.g. face mask or mouth piece
one-way valve, etc.) shall be either clearly and durably marked with an arrow showing the direction of gas
flow if operator-detachable, manufactured to prevent incorrect assembly or permanently attached.
b) If gas-specific, the inlet and outlet shall be identified by clear and durable marking.
5.1.2 Marking of devices, labels and packaging
Devices, labels and/or packaging shall contain the following:
a) the name and address of the manufacturer;
b) device identification and content information;
c) an indication that the device is sterile, if appropriate;
d) device packaging and/or labelling to differentiate between the same or similar products, both sterile and
non-sterile, placed on the market by the same manufacturer;
e) the batch code, if appropriate;
f) the expiry date, if the device is sensitive to storage or shelf-life;
g) an indication that the device is for single use, if appropriate;
h) any special storage and/or handling conditions;
i) any warning and/or precaution to take, e.g. compatibility with the use of oxygen mixtures and compatibility
between oxygen and administered drugs;
j) the year of manufacture, except for those covered by f);
k) the recommended method(s) of cleaning and disinfection or sterilization, if appropriate;
l) for packages containing parts made of antistatic or conductive material, the word “ANTISTATIC” or
“CONDUCTIVE”, if appropriate;
m) the liquid container of the nebulizer shall be marked at the maximum fill volume level; this shall be
defined in the instruction for use (see 5.3.2 i).
5.1.3 Marking of controls and instruments
a) Gas supply pressures shall be displayed in kilopascals.
b) Pressures in breathing systems shall be displayed in pascals × 100.
c) Flows shall be displayed in litres per minute.
d) If supplied, air entrainment/oxygen dilution valves shall be marked in % O (oxygen).
5.2 Symbols
ISO 7000, ISO 15223 and Clause 6.4 of IEC 60601-1:2005 apply.
5.3 Instructions for use
5.3.1 *General
Nebulizers, nebulizing systems and parts thereof shall be accompanied by instructions for use which shall
include the information given in 5.3.2.
5.3.2 Disclosures
a) The purpose and the intended use of the device and parts thereof, including the power and/or control
devices.
b) The types of liquid (e.g. solution and/or suspension and/or emulsion) the device is designed to nebulize.
c) The distribution of particles, in terms of mass, within each of the following size ranges: % > 5 µm, % 2 µm
to 5 µm, % < 2 µm.
6 © ISO 2009 – All rights reserved

d) The mass median aerodynamic diameter (MMAD) as derived from the particle size distribution curve
(see Figure D.2).
e) The respirable fraction performance of the nebulizer.
f) The aerosol output and aerosol output rate at the maximum fill volume under test conditions defined
in C.1.1. In addition, for gas-powered nebulizers, the aerosol output and aerosol output rate at the
minimum and maximum driving gas flows with the corresponding pressures under test conditions defined
in C.1 and C.2.
g) Disclosure of the residual volume (in millilitres), when tested in accordance with the test method
described in Annex C.
h) For a breath-actuated nebulizer, the method and relevant sensitivity.
i) A statement that using a solution, suspension or emulsion different from that recommended by the
manufacturer, in particular for a suspension and/or high viscosity solution, may alter the particle size
distribution curve, the mass median aerodynamic diameter, aerosol output and/or aerosol output
rate, which may be different from those disclosed by the manufacturer.
j) The recommended maximum fill volume.
k) The maximum A-weighted sound pressure level, as derived from the test method in 9.6.2.1 of
IEC 60601-1:2005.
l) If hand-held, an indication of the spatial orientation (e.g. vertical, horizontal, inverted) at which the
nebulizer continues to function as intended.
m) Whether the nebulizer is suitable for use in anaesthetic breathing systems or lung ventilator breathing
systems.
n) If applicable, the maximum temperature above ambient reached in the nebulizing chamber in all operating
conditions.
o) Interdependence of controls, if applicable.
p) The pressure and flow characteristics of any gas power outlet under the worst case conditions stated by
the manufacturer.
q) The specified range of flows required from any gas source, if applicable.
r) A statement of the composition and dryness specification for all gases to be supplied to the nebulizer, if
relevant.
s) Details of non-return valves and pressure-relief valves and their characteristics, if fitted.
t) The lifetime of the re-usable parts.
Check compliance by inspection.
5.3.3 Materials compatibility
a) A statement that the materials used for the components may not be compatible with solutions,
suspensions or emulsions different from those recommended by the manufacturer, in particular for
suspensions and high viscosity solutions.
b) A warning that oxygen or oxygen mixtures (O > 23 %) should not be used as driving gas, if applicable.
5.3.4 Driving gas supply
a) The recommended driving gas.
b) The minimum and maximum recommended driving gas pressures and flows.
5.3.5 Cleaning, disinfection and sterilization
The instructions for use shall contain information on the following:
a) Methods of cleaning, disinfection and/or sterilization prior to use.
b) The number of cycles of cleaning, disinfection and/or sterilizations the nebulizing system will withstand.
5.3.6 Dismantling and reassembling
The manufacturer shall recommend the following:
a) Procedures for reassembly, if applicable.
b) A functional test of operation to be carried out after re-assembly and before use.
5.3.7 Monitoring, alarm and protection devices
The instructions for use shall contain:
a) a description of the methods of verifying alarm functions;
b) details of any pressure-relief valves fitted.
5.3.8 Electromagnetic compatibility
If applicable, the instructions for use shall include a warning statement to the effect that the functioning of this
nebulizer may be affected by electromagnetic interference exceeding the levels specified in IEC 60601-1-2.
5.3.9 Device disposal
The instructions for use shall include information about any precautions to be taken if there is a specific
unusual risk associated with the disposal of a device.
5.3.10 Parts not integral to the nebulizing system
The instructions for use shall include:
a) a list of the parts that are not integral parts of the system and are necessary for correct use;
b) a statement that these parts shall comply with the relevant requirements of this International Standard.
6 Construction requirements
6.1 Materials
6.1.1 Materials for construction shall be compatible with the manufacturer's recommended gas(es) or gas
mixture(s) and, if applicable, in compliance with ISO 15001.
NOTE While intended to be used with drugs and cleaning agents, materials should be chosen to minimize risks due
to toxicity.
8 © ISO 2009 – All rights reserved

6.1.2 Nebulizer components that come into contact with cleaning agents, sterilants, medical gases and
medicaments recommended by the manufacturer shall not degrade, affect performance or present a hazard
for the nebulizer's intended use.
6.1.3 The recommended cleaning agents shall not affect the performance of the nebulizer.
6.1.4 Components that come into contact with the aerosol or the liquid to be nebulized shall not have any
lasting visible damage from the recommended cleaning or sterilizing agents.
Check compliance by inspection.
6.2 Connectors
6.2.1 Driving gas inlet connectors
The driving gas inlet connector of a nebulizing system shall be compatible with the gas delivery system to
which it is intended to be connected and shall be one of the following (see Figure 1).
a) the nut and nipple of a non-interchangeable screw-threaded (NIST) connector complying with ISO 5359;
b) the nut and nipple of a DISS connector complying with ISO 5359 (CGA V-5-2005 diameter index safety
system non-interchangeable connectors for medical gas applications);
c) a probe complying with ISO 9170-1, ENV 737-6 or the relevant national standard;
d) a threaded connector complying with EN 13544-2;
e) a nipple complying with EN 13544-2.
6.2.2 Nebulizer breathing system connectors
a) If conical, shall be 8,5 mm, 15 mm, or 22 mm size connectors complying with ISO 5356-1 or ISO 5356-2.
b) If proprietary, shall not engage with conical connectors complying with ISO 5356-1 or ISO 5356-2 unless
they comply with the engagement, disengagement and leakage requirements of ISO 5356-1 or
ISO 5356-2.
Key
1 terminal unit complying with ISO 9170-1 (on a pressure regulator or on an MGPS)
2 probe or DISS or NIST – ISO 9170-1, ENV 737-6, ISO 5359
3 threaded connector – EN 13544-2
4 nipple – EN 13544-2
5 hose – EN 13544-2
6 flowmeter – ISO 15002
7 nebulizer
8 pressure regulator – ISO 10524-4
9 compressor
a
To the patient.
Figure 1 — Examples of driving gas inlet connectors for nebulizer systems
10 © ISO 2009 – All rights reserved

Key
1 ISO conical connectors – ISO 5356-1
2 aerosol mask, vented
3 tracheal tube connector – ISO 5361-1
4 mouthpiece
5 nebulizer
6 tee piece
7 ventilator breathing circuit
8 ventilator
a
To the patient.
Figure 2 — Examples of breathing system connectors for nebulizer systems
6.2.3 Nebulizer outlet connector
The outlet connector of the nebulizer:
a) if intended to be connected to a breathing system or breathing tube, shall be a 22 mm connector
complying with ISO 5356-1;
b) proprietary nebulizer connectors shall not be compatible with conical connectors complying with
ISO 5356-1 or Luer connectors complying with ISO 594-1 and ISO 594-2.
6.2.4 Flow-direction-sensitive connectors
Any flow-direction-sensitive, operator-detachable component shall be designed so that it cannot be fitted in
such a way as to present a hazard to the patient.
6.2.5 Small-bore nebulizer connector
Any small-bore connector of the nebulizing system shall not be compatible with 6 % conical (Luer)
connectors as defined in ISO 594-1 and ISO 594-2.
6.3 Rotary controls
The manufacturer should ensure consistency regarding direction of movement of rotary controls of the
equipment.
7 Cleaning, sterilization and disinfection
a) If provided sterile, the nebulizing system and components shall have been sterilized using an
appropriate, validated method described in: ISO 11135-1, ISO 11137-1, ISO 11137-2, ISO 11137-3,
ISO 17665-1, EN 556-1.
b) Evidence about the method(s) to ensure the intended level of cleanliness of the nebulizing system
components during production and supply shall be given by the manufacturer upon request.
c) Nebulizing systems and components intended for re-use shall be constructed so as to enable
dismantling for cleaning and disinfection or sterilization.
d) The relevant performance tests such as aerosol output, aerosol output rate and particle size testing
shall be repeated after the given number of cleaning and/or sterilization cycles to validate the nebulizer
performance.
8 Biocompatibility
a) Parts of the nebulizing system intended to come into contact with biological tissues, cells, body fluids or
breathing gases shall be assessed and documented according to the guidance and principles given in
ISO 10993-1.
b) All parts of the nebulizer shall be designed and manufactured to minimize health risks due to substances
leached from the device during use.
c) Nebulizing systems shall be free of volatile organic compounds and particulate matter throughout the
operating life of the equipment.
d) Nebulizing systems shall comply with volatile organic compounds and particulate matter testing, if
required by regional or national competent authorities.
Check compliance by inspection of the relevant validation reports. Subclause 11.7 of IEC 60601-1:2005
applies.
12 © ISO 2009 – All rights reserved

Annex A
(informative)
Rationale
General
This annex provides a concise rationale for the important requirements of this International Standard and is
intended for use for those who are familiar with the subject of this International Standard but who have not
participated in its development. An understanding of the reasons for the main requirements is considered
essential for its proper application. Furthermore, as clinical practices and technologies change, it is believed
that a rationale for the present requirements will facilitate any revisions of this International Standard
necessitated by those developments.
The clauses in this annex have been so numbered to correspond to the clauses in this International Standard
to which they refer. The numbering is, therefore, not consecutive.
A.1 Scope
The essence of this International Standard is to describe the characteristics and requirements of a general
purpose nebulizer that can be used with a variety of medicinal substances. It is expected that the selection of
the nebulizer be based on the requirements and characteristics developed in this International Standard and
declared in the manufacturer's instructions for use.
Nasal deposition devices are also excluded, as they are not considered general purpose nebulizers.
There may be times when a device falls under the scope of either ISO 27427 or ISO 20072. The committee
envisions that the intended use of the product and the risk assessment of the device will derive which
standard the manufacturer chooses to qualify the device.
A.4.2 Test methods and alternatives
Various methods are in use for presenting the particle size distribution of nebulizers [see Annex B
(normative)].
A.5.3.1 General
The respirable fraction, as defined in 3.14, is an important parameter because, along with the aerosol output,
it gives a single physical characteristic that allows the comparison of the performance of nebulizing systems.
A.C.2.2 Test principles
A treatment session using a nebulizer requires the patient to breathe in and out of the nebulizer for a
duration of between approximately 5 min to 15 min (depending on the medication used) while the nebulizer is
running. During this time, the nebulizer is continuously producing aerosol. When the patient inhales aerosol,
it is taken up in the lungs. However, when the patient exhales, some aerosol is driven out of the nebulizer
and lost. Thus, only a certain fraction of aerosol produced by the nebulizer can be taken up by the patient.
The test described in this section collects the amount of aerosol exiting at the nebulizer mouthpiece while the
nebulizer is subjected to a simulated breathing pattern.
A.C.2.3 Test equipment
A sine pump is used when determining aerosol output from a nebulizer in order to reasonably estimate the
mass of aerosolized active pharmaceutical ingredient provided at the exit of the nebulizer system under
simulated conditions of breathing.
A.C.2.4 g) Test method
Measurements of mass (weight) rather than volume alone correct for evaporative losses.
A.D.2 Test principle
A continuous suction pump is used for nebulized aerosol size testing as impactors for performing these
measurements operate at a constant “inhalation” flow rate in order to reasonably estimate aerosol size.
14 © ISO 2009 – All rights reserved

Annex B
(normative)
Diameters of respirable fraction particles
In general, it is considered that aerosol particles with an aerodynamic diameter of:
⎯ > 5 µm will result in deposition in the upper airways;
⎯ 2 µm to 5 µm will result in deposition in the lower airway;
⎯ 0,5 µm to 2 µm will result in deposition in the alveoli.
Aerosol particle sizing can be defined in terms of Mass Median Aerodynamic Diameter (MMAD) and
Geometric Standard Deviation (GSD). These values can be interpolated from the cumulative particle size
distribution curve as follows.
MMAD – Note the particle size at which the line crosses the 50 % mark.
GSD – This should be calculated only if the particle size distribution curve is reasonably straight between
10 % and 90 %, showing that the aerosol is log-normally distributed. Where a straight line is a good fit to the
data, the calculation of GSD is performed by noting the particle size X at which the line crosses the 84,13 %
mark and the particle size Y at which the line crosses the 15,87 % mark.
0,5
Then the GSD = (X/Y) .
Methods of deriving information from data that are based on interpolation from a graph are inevitably subject
to some degree of approximation.
Rigorous mathematical methods of analysis are described in ISO 9276-2. These methods are readily
performed by computer, including the generation of the particle size distribution graph.
Annex C
(normative)
Test methods for aerosol output and aerosol output rate
C.1 Aerosol output
C.1.1 Test conditions and test equipment
The ambient conditions shall be:
⎯ temperature: (23 ± 2) °C;
⎯ relative humidity: 45 % to 75 %;
⎯ pressure: from 86,0 kPa to 106,0 kPa.
For the test equipment, please refer to C.2.3.
C.1.2 Test principle
The nebulizer under test is connected to the same equipment as in C.2.3, filled with albuterol 1 % (10 mg/ml)
(M/V), which is equivalent to albuterol sulfate 1,2 % (M/V) and operated until nebulization ceases. A
quantitative chemical analysis is then applied and the output is expressed as millilitres of albuterol 1 % (M/V).
C.1.3 Test equipment
For the test equipment, please refer to C.2.3.
C.1.4 Test method
Use the test method described in C.2.4, but continue until nebulization ceases. If necessary, interrupt the test
and replace the filter before saturation occurs.
The aerosol output shall be taken:
⎯ for gas-powered nebulizers 1 min after the beginning of sputtering, or
⎯ for electronic nebulizers at the end of the operation.
C.1.5 Test results
The test results shall include:
⎯ for gas-powered nebulizers, the test gas employed;
⎯ the fill volumes and flow rates used;
⎯ the aerosol output expressed as millilitres of albuterol 1 % (M/V) solution.
16 © ISO 2009 – All rights reserved

C.2 Aerosol output rate
C.2.1 Test conditions
Ambient conditions as given in C.1.1.
C.2.2 *Test principles
The nebulizer is filled with a solution of known concentration of albuterol, connected to a sine pump (to
simulate respiratory flow) and operated for a known time, during which the aerosol is collected on a filter. The
amount of albuterol on the filter is then quantified by chemical analysis.
This figure, divided by the time of the test, provides the aerosol output rate.
C.2.3 Test equipment
The test equipment (see the schematic diagram given in Figure C.1) shall comprise:
⎯ a filter holder;
⎯ a sine pump, which creates a cycle of: frequency, f, = 15 breaths/min; I/E ratio = 1/1; tidal volume (V )
t
= 500 ml measured at the output of the filter;
⎯ solution of albuterol 1 % (M/V) concentration;
⎯ a breathing system filter complying with ISO 23328-1 with a filtration efficiency > 98 % of particles less
than 10 µm.
1)
NOTE Suitable filters are high-efficiency polypropylene filters (product K248 of 3M) .
⎯ a dead space of the equipment 10 % or less of the tidal volume (between the patient interface and the
filtering surface);
⎯ for gas-powered nebulizers, a driving gas of medical air unless the nebulizer is exclusively designed to
be powered by a compressor at ambient conditions described in C.1.1, as defined in ISO 7396-1;
⎯ a means of extracting albuterol from filters and other components and quantitative analysis apparatus
calibrated in 1 % albuterol (M/V) to an accuracy of ± 5 % of reading.
The aerosol and aerosol output test for a pneumatic nebulizer shall be driven by the gas and at the flow
rate recommended by the manufacturer.

1) This information is given for the convenience of users of this International Standard and does not constitute an
endorsement by ISO of the product named.
Key
1 nebulizer system filled with 1 % albuterol solution (see note)
2 connection to the patient interface
3 dismountable connectors
4 patient interface
5 dead space
6 collection filter
7 sine pump
a
Recommended driving gas inlet.
NOTE The recommended delivery system can terminate e.g. in a mouthpiece or facemask. The dismountable
connector (3) at the inlet to the filter holder should provide a matching adaptor to make a leak-free joint.
Figure C.1 — Schematic diagram showing the equipment for testing
the aerosol output and aerosol output rate
C.2.4 Test method
a) Stabilize all parts of the nebulizer system, fluids and test equipment at the ambient conditions as
described in C.1.1 before use.
b) Perform a series of tests with the nebulizer filled with albuterol (1 %) (M/V) solution to the fill volume of
2 ml or to the fill volume recommended by the manufacturer.
c) By means of dismountable connectors, connect the outlet of the nebulizing system to the filter and its
holder, and the latter to the sine pump, as shown in Figure C.1.
d) Switch on the pump and, 10 s later, the nebulizer.
e) Run the nebulizer for (60 ± 1) s, switch off the nebulizer and, 5 s later, the pump.
f) Dismantle the filter, the filter holder and the dismountable connectors from the outlet of the nebulizing
system to the filter holder.
g) *Extract and measure the mass of albuterol in the components downstream of the outlet of the nebulizer,
including the filter.
18 © ISO 2009 – All rights reserved

C.2.5 Test results
The test results shall include:
a) for a gas-powered nebulizer, the test gas employed;
b) the filling volume and flow rate used;
c
...