EN ISO 20789:2019
(Main)Anaesthetic and respiratory equipment - Passive humidifiers (ISO 20789:2018)
Anaesthetic and respiratory equipment - Passive humidifiers (ISO 20789:2018)
This document specifies requirements for so-called "cold bubble-through" or "cold pass-over" humidifying equipment, hereafter referred to as a passive humidifier. Figure 1 and Figure 2 illustrate these passive humidifiers.
Anästhesie- und Beatmungsgeräte - Passive Anfeuchter (ISO 20789:2018)
Dieses Dokument legt Anforderungen an sogenannte „Sprudelverdunster“ oder „Passover“-Geräte zur Anfeuchtung ohne Beheizung fest, nachfolgend als PASSIVE ANFEUCHTER bezeichnet. Bild 1 und Bild 2 stellen diese PASSIVEN ANFEUCHTER dar.
Matériel d'anesthésie et de réanimation respiratoire - Humidificateurs passifs (ISO 20789:2018)
Le présent document spécifie les exigences relatives aux équipements d'humidification dits à «barbotage à froid» ou «léchage à froid», ci-après désignés un humidificateur passif. La Figure 1 et la Figure 2 représentent ces humidificateurs passifs.
Anestezijska in dihalna oprema - Pasivni vlažilniki (ISO 20789:2018)
Ta dokument določa zahteve za tako imenovano vlažilno opremo, ki ustvarja vodne mehurčke (cold bubble-through) ali aerosol (cold pass-over) ter je v nadaljevanju imenovana pasivni vlažilnik. Sliki 1 in 2 prikazujeta te pasivne vlažilnike.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-november-2019
Anestezijska in dihalna oprema - Pasivni vlažilniki (ISO 20789:2018)
Anaesthetic and respiratory equipment - Passive humidifiers (ISO 20789:2018)
Anästhesie- und Beatmungsgeräte - Passive Anfeuchter (ISO 20789:2018)
Matériel d'anesthésie et de réanimation respiratoire - Humidificateurs passifs (ISO
20789:2018)
Ta slovenski standard je istoveten z: EN ISO 20789:2019
ICS:
11.040.10 Anestezijska, respiratorna in Anaesthetic, respiratory and
reanimacijska oprema reanimation equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EN ISO 20789
EUROPEAN STANDARD
NORME EUROPÉENNE
September 2019
EUROPÄISCHE NORM
ICS 11.040.10
English Version
Anaesthetic and respiratory equipment - Passive
humidifiers (ISO 20789:2018)
Matériel d'anesthésie et de réanimation respiratoire - Anästhesie- und Beatmungsgeräte - Passive Anfeuchter
Humidificateurs passifs (ISO 20789:2018) (ISO 20789:2018)
This European Standard was approved by CEN on 28 July 2019.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 20789:2019 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
European foreword
The text of ISO 20789:2018 has been prepared by Technical Committee ISO/TC 121 "Anaesthetic and
respiratory equipment” of the International Organization for Standardization (ISO) and has been taken
over as EN ISO 20789:2019 by Technical Committee CEN/TC 215 “Respiratory and anaesthetic
equipment” the secretariat of which is held by BSI.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by March 2020, and conflicting national standards shall
be withdrawn at the latest by March 2020.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 20789:2018 has been approved by CEN as EN ISO 20789:2019 without any modification.
INTERNATIONAL ISO
STANDARD 20789
First edition
2018-07
Anaesthetic and respiratory
equipment — Passive humidifiers
Matériel d'anesthésie et de réanimation respiratoire —
Humidificateurs passifs
Reference number
ISO 20789:2018(E)
©
ISO 2018
ISO 20789:2018(E)
© ISO 2018
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
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Published in Switzerland
ii © ISO 2018 – All rights reserved
ISO 20789:2018(E)
Contents Page
Foreword .v
Introduction .vi
1 * Scope . 1
2 Normative references . 2
3 Terms and definitions . 3
4 General requirements for testing . 5
4.1 Water level . 5
4.2 Passive humidifier test conditions . 6
4.3 * Gas flowrate and leakage specifications. 6
4.4 * Passive humidifier testing errors . 6
5 General requirements . 6
5.1 Mechanical basic safety for all passive humidifiers . 6
5.1.1 General. 6
5.1.2 * Requirements for instability from unwanted lateral movement . 6
5.1.3 * Requirements for audible acoustic energy . 7
5.1.4 * Overflow . 8
5.1.5 * Overpressure requirement . 8
5.2 Compatibility requirement . 9
5.3 General requirements for mechanical strength . 9
6 Identification, marking and accompanying documentation .10
6.1 Legibility and durability of markings .10
6.1.1 Legibility .10
6.1.2 Durability .10
6.2 Markings on the outside of the passive humidifier or its parts .10
6.2.1 Identification .10
6.2.2 Additional requirements .11
6.2.3 Requirements for physiological effects .12
6.2.4 Requirements for packaging .12
6.2.5 Symbols .12
6.3 Units of measurement . .12
6.4 Instructions for use .12
6.4.1 Identification .12
6.4.2 General requirements .13
6.4.3 * Requirements for warnings and safety notices .14
6.4.4 Requirements for installation .14
6.4.5 Requirements for start-up procedure .14
6.4.6 * Requirements for operating instructions .14
6.4.7 Requirements for cleaning, disinfection, and sterilization.16
6.4.8 Requirements for maintenance .16
6.4.9 Requirements for accessories, supplementary equipment and used material .16
6.4.10 Unique version identifier .16
6.5 Technical description .17
7 * Humidification output.17
8 Systems requirements .17
9 Specific single fault conditions .18
10 * Cleaning and disinfection .18
10.1 General .18
10.2 Home healthcare environment .18
11 * Breathing system connectors and ports .18
11.1 General .18
ISO 20789:2018(E)
11.2 Outlet connector .19
11.2.1 Directly connected to the supply source .19
11.2.2 Indirectly connected to the supply source .19
11.3 Flow-direction-sensitive components .19
11.4 * Accessory port .19
11.5 Monitoring probe port . .20
11.6 Oxygen inlet port .20
11.6.1 Directly connected to the supply source .20
11.6.2 Indirectly connected to the supply source .20
11.7 Air inlet port .20
11.7.1 Directly connected to the supply source .20
11.7.2 Indirectly connected to the supply source .20
11.8 Filling port .20
12 * Requirements for the breathing system and accessories .21
12.1 General .21
12.2 Accompanying documentation .21
12.3 Breathing tubes .21
12.4 Liquid container level .21
12.5 Filling cap.21
13 Compatibility with substances .22
14 * Biocompatibility .22
15 * Requirements for fire prevention .22
16 Usability .23
Annex A (informative) Rationale and guidance .25
Annex B (informative) Symbols on marking.33
Annex C (normative) Determination of humidification output .35
Annex D (informative) Reference to the essential principles .39
Annex E (informative) Terminology — Alphabetized index of defined terms .41
Bibliography .43
iv © ISO 2018 – All rights reserved
ISO 20789:2018(E)
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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2. www .iso .org/directives
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received. www .iso .org/patents
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the WTO
principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary
information
This document was prepared by Technical Committee ISO/TC 121, Anaesthetic and respiratory
equipment, Subcommittee SC 3, Lung ventilators and related equipment.
ISO 20789:2018(E)
Introduction
This document specifies requirements for so called “cold bubble-through or cold pass-over” respiratory
tract passive humidifiers intended for use on patients in home care and in healthcare facilities.
Passive humidifiers are used to raise the water content of gases delivered to patients. Gases available
for medical use do not contain sufficient moisture and can damage or irritate the respiratory tract or
desiccate secretions of patients whose upper airways have been bypassed. Inadequate humidity at the
patient-connection port can cause drying of the upper airway, or desiccation of tracheo-bronchial
secretions in the tracheal or tracheostomy tube, which can cause narrowing or even obstruction of the
1)
[1][2]
airway .
Passive humidifiers rely on moisture being transferred from a liquid reservoir to the gas at room
temperature, without heating of either the humidification chamber or breathing tubes, to increase
the water content of gases delivered to patients. Hence, such respiratory tract passive humidifiers
have a lower mg/l output than active humidifiers. Refer to ISO 80601-2-74 for basic safety and
essential performance of active humidifiers.
Since the safe use of a passive humidifier depends on the interaction of the passive humidifier
with its accessories, this document sets total system performance requirements up to the patient-
connection port. These requirements are applicable to accessories such as breathing tubes.
[3]
This document also constitutes a major technical revision of a portion of ISO 8185:2007 , which it
replaces in combination with ISO 80601-2-74. The most significant changes relative to ISO 8185:2007
for passive humidifiers are the following modifications:
— extending the scope to include the passive humidifier and its accessories, where the characteristics
of those accessories can affect the basic safety or essential performance of the passive
humidifier, and thus not only the passive humidifier itself;
— modification of the humidification test procedure and the disclosure of humidification performance;
and the following additions:
— requirements for mechanical strength (via IEC 60601-1-11);
— new symbols;
— requirements for a passive humidifier as a component of a system;
— requirements for cleaning and disinfection procedures;
— requirements for biocompatibility;
— requirements for fire prevention;
— requirements for usability.
Passive humidifiers are commonly used with air and air-oxygen mixtures and a passive humidifier
should be able to operate with these gases. Care should be taken if using other gas mixtures such as
helium/oxygen mixtures as their physical properties are different from those of air and oxygen.
In this document, the following print types are used:
— requirements and definitions: roman type;
— test specifications: italic type;
— informative material appearing outside of tables, such as notes, examples and references: in smaller
type. Normative text of tables is also in a smaller type;
1) Figures in square brackets refer to the Bibliography.
vi © ISO 2018 – All rights reserved
ISO 20789:2018(E)
— terms defined in Clause 3 of this document or as noted: small capitals.
In this document, the conjunctive “or” is used as an “inclusive or” so a statement is true if any
combination of the conditions is true.
The verbal forms used in this document conform to usage described in Annex H of the ISO/IEC
Directives, Part 2. For the purposes of this document, the auxiliary verb:
— “shall” means that compliance with a requirement or a test is mandatory for compliance with this
document;
— “should” means that compliance with a requirement or a test is recommended but is not mandatory
for compliance with this document;
— “may” is used to describe a permissible way to achieve compliance with a requirement or test.
An asterisk (*) as the first character of a title or at the beginning of a paragraph or table title indicates
that there is guidance or rationale related to that item in Annex A.
INTERNATIONAL STANDARD ISO 20789:2018(E)
Anaesthetic and respiratory equipment — Passive
humidifiers
1 * Scope
This document specifies requirements for so-called “cold bubble-through” or “cold pass-over”
humidifying equipment, hereafter referred to as a passive humidifier. Figure 1 and Figure 2 illustrate
these passive humidifiers.
NOTE 1 Passive humidifier humidification chambers are at room temperature so they have a lower
humidification output than active humidifiers.
Figure 1 — Cold pass-over passive humidifier
Figure 2 — Cold bubble-through passive humidifier
This document is also applicable to those accessories intended by their manufacturer to be
connected to a passive humidifier.
A passive humidifier integrated into another medical device is subject to the requirements of the
standard of the other medical device.
[4]
EXAMPLE 1 The requirements in ISO 80601-2-69 also apply to a passive humidifier integrated into an
oxygen concentrator.
[5]
EXAMPLE 2 The requirements in ISO 80601-2-70 also apply a passive humidifier integrated into sleep
apnoea therapy equipment.
ISO 20789:2018(E)
This document does not specify the requirements for active heated humidifiers, heated breathing
tubes, or active heat and moisture exchangers (HMEs), the requirements for which are given in
ISO 80601-2-74.
NOTE 2 ISO 5367 specifies other safety and performance requirements for breathing tubes.
This document is not applicable to a passive HME, which returns a portion of the expired moisture and
heat of the patient to the respiratory tract during inspiration without adding heat or moisture, the
[6] [7]
requirements for which are given in ISO 9360-1 and ISO 9360-2 .
This document is not applicable to nebulizers used for the delivery of liquids to patients, the
[8]
requirements for which are given in ISO 27427 .
This document is not applicable to equipment commonly referred to as “room humidifiers” or
humidifiers used in heating, ventilation and air conditioning systems, or humidifiers incorporated into
infant incubators.
An asterisk (*) as the first character of a title or at the beginning of a paragraph or table title indicates
that there is guidance or rationale related to that item in Annex A.
This document has been prepared to support the essential principles of safety and performance
of a passive humidifier and related accessories as medical devices in accordance with
ISO 16142-1:2016. Annex D maps the clauses and subclauses of this document with the essential
principles of ISO 16142-1:2016.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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.
NOTE 1 The way in which these referenced documents are cited in normative requirements determines the
extent (in whole or in part) to which they apply.
NOTE 2 Informative references are listed in the Bibliography.
ISO 3744:2010, Acoustics — Determination of sound power levels and sound energy levels of noise sources
using sound pressure — Engineering methods for an essentially free field over a reflecting plane
ISO 4135:2001, Anaesthetic and respiratory equipment — Vocabulary
ISO 5356-1:2015, Anaesthetic and respiratory equipment — Conical connectors — Part 1: Cones and sockets
ISO 5367:2014, Anaesthetic and respiratory equipment — Breathing sets and connectors
ISO 7396-1:2016, Medical gas pipeline systems — Part 1: Pipeline systems for compressed medical gases
and vacuum
ISO 10993-1:2009, Biological evaluation of medical devices — Part 1: Evaluation and testing within a risk
management process
ISO 13485:2016, Medical devices — Quality management systems — Requirements for regulatory purposes
EN 13544-2:2002+AMD1: 2009, Respiratory therapy equipment — Part 2: Tubing and connectors
ISO 14937:2009, Sterilization of health care products — General requirements for characterization
of a sterilizing agent and the development, validation and routine control of a sterilization process for
medical devices
ISO 14971:2007, Medical devices — Application of risk management to medical devices
2 © ISO 2018 – All rights reserved
ISO 20789:2018(E)
ISO 15223-1:2016, Medical devices — Symbols to be used with medical device labels, labelling and
information to be supplied — Part 1: General requirements
ISO 16142-1:2016, Medical devices — Recognized essential principles of safety and performance of medical
devices — Part 1: General essential principles and additional specific essential principles for all non-IVD
medical devices and guidance on the selection of standards
ISO 17664:2017, Processing of health care products — Information to be provided by the medical device
manufacturer for the processing of medical devices
ISO 18562-1:2017, Biocompatibility evaluation of breathing gas pathways in healthcare applications —
Part 1: Evaluation and testing within a risk management process
ISO 23328-2:2002, Breathing system filters for anaesthetic and respiratory use — Part 2: Non-
filtration aspects
IEC 60601-1:2005+AMD1: 2012, Medical electrical equipment — Part 1: General requirements for basic
safety and essential performance
IEC 60601-1-11:2015, Medical electrical equipment — Part 1-11: General requirements for basic safety and
essential performance — Collateral standard: Requirements for medical electrical equipment and medical
electrical systems used in the home healthcare environment
IEC 61672-1:2013, Electroacoustics — Sound level meters — Part 1: Specifications
IEC 62366-1:2015, Medical devices — Part 1: Application of usability engineering to medical devices
ISO 80369-1:2010, Small-bore connectors for liquids and gases in healthcare applications — Part 1: General
requirements
ISO 80601-2-12:2011, Medical electrical equipment — Part 2-12: Particular requirements for basic safety
and essential performance of critical care ventilators
ISO 80601-2-74:2017, Medical electrical equipment — Part 2-74: Particular requirements for basic safety
and essential performance of respiratory humidifying equipment
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 4135:2001, ISO 7396-1:2016,
ISO 13485:2016, ISO 14971:2007, ISO 16142-1:2016, ISO 17664:2017, ISO 18562-1:2017,
ISO 23328-2:2002, IEC 60601-1:2005+AMD1: 2012, IEC 60601-1-11:2015, IEC 62366-1:2015, ISO 80601-2-
12:2011, ISO 80601-2-74:2017 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http: //www .electropedia .org/
— ISO Online browsing platform: available at https: //www .iso .org/obp
NOTE For convenience, the sources of all defined terms used in this document are given in Annex E.
3.1
accompanying documentation
materials accompanying a medical device and containing information for the user or those accountable
for the installation, use and maintenance of the medical device, particularly regarding safe use
Note 1 to entry: The accompanying documentation can consist of the instructions for use, technical description,
installation manual, quick reference guide, etc.
Note 2 to entry: Accompanying documentation is not necessarily a written or printed document but could
involve auditory, visual or tactile materials and multiple media types.
ISO 20789:2018(E)
Note 3 to entry: Medical devices that can be used safely without instructions for use are exempted from having
instructions for use by some authorities with jurisdiction.
[SOURCE: IEC 62366-1:2015, 3.2]
3.2
basic safety
freedom from unacceptable risk directly caused by physical hazards when the medical device is used
under normal condition and single fault condition
[SOURCE: IEC 60601-1:2005, 3.10, modified: replaced “me equipment” with “the medical device”]
3.3
clearly legible
capable of being read by a person with normal vision
Note 1 to entry: See the test in 6.1.1.
[SOURCE: IEC 60601-1:2005+A1: 2012, 3.15, modified: replaced “7.1.2” with “6.1.1”]
3.4
expected service life
time period specified by the manufacturer during which the medical device or accessory is expected
to remain safe for use
Note 1 to entry: Maintenance can be necessary during the expected service life.
[SOURCE: IEC 60601-1:2005+AMD1: 2012, 3.28, modified: replaced “me equipment or me system” with
“the medical device or accessory” and deleted parenthetical]
3.5
flow-direction-sensitive component
component or accessory through which gas flow must be in one direction only for proper functioning
or patient safety
[SOURCE: ISO 4135:2001, 3.1.7, modified: added “or accessory”]
3.6
humidification chamber
part of the passive humidifier in which vaporization or nebulization takes place
3.7
humidification output
total mass of water vapour per unit volume of gas at the patient-connection port
Note 1 to entry: Humidification output shall be expressed under body temperature and pressure,
saturated (btps) conditions.
Note 2 to entry: Physiology lung volumes and flows are standardized to barometric pressure at sea level, body
temperature, and saturated with water vapour (btps).
3.8
liquid container
part of the passive humidifier which holds the liquid
Note 1 to entry: The liquid container can be accessible to the breathing gas.
Note 2 to entry: The liquid container can also be part of the humidification chamber.
Note 3 to entry: The liquid container can be detachable for filling.
4 © ISO 2018 – All rights reserved
ISO 20789:2018(E)
3.9
liquid reservoir
part of the passive humidifier which replenishes the liquid container
3.10
maximum limited pressure
P
LIM max
highest airway pressure during normal use under normal condition or single fault condition
3.11
passive humidifier
bubble–through or pass-over medical device that creates vapour or droplets from water at room
temperature to moisten the inspired gas
Note 1 to entry: Passive humidifier humidification chambers are at room temperature so they have a lower
humidification output than an active humidifier.
Note 2 to entry: Passive humidifiers do not use heat to increase the temperature of either the humidification
chamber or the breathing tubes.
Note 3 to entry: Figure 1 and Figure 2 illustrate passive humidifiers.
3.12
patient-connection port
port at the patient end of the breathing tubes intended for connection to an airway device
EXAMPLE A tracheal tube, tracheostomy tube, face mask and supralaryngeal airway are all airway devices.
3.13
protection device
part or function of medical device or accessory that, without intervention by the user, protects the
patient from hazardous output due to incorrect delivery of energy or substances
[SOURCE: ISO 80601-2-12:2011, 203.3.220, modified: replaced “me equipment” with “medical device
or accessory” and “operator” with “user”]
3.14
relative humidity
water vapour pressure, expressed as a percentage of the saturation vapour pressure, at a particular
temperature
3.15
single fault condition
condition of medical device in which a single means for reducing a risk is defective or a single
abnormal condition is present
[SOURCE: IEC 60601-1:2005, 3.116, modified: “me equipment” was replaced by “medical device”]
4 General requirements for testing
4.1 Water level
Unless otherwise specified, the liquid container and liquid reservoir shall be filled to maximum
capacity, as indicated in the instructions for use, at the beginning of a test with distilled water at the
ambient test temperature.
ISO 20789:2018(E)
4.2 Passive humidifier test conditions
a) For testing, the passive humidifier
1) shall be connected to gas supplies as specified for normal use,
2) except that industrial-grade oxygen and air may be substituted for the equivalent medical gas,
as appropriate, unless otherwise stated.
b) When using substitute gases, care should be taken to ensure that the test gases are oil-free and
appropriately dry.
The moisture content of all gas supplies shall be less than 1 mg/l.
4.3 * Gas flowrate and leakage specifications
In this document, requirements for the flowrate, volume and leakage are expressed at standard
temperature and pressure, dry (stpd), except for those associated with the breathing system,
which are expressed at body temperature and pressure, saturated (btps).
NOTE 1 For the purposes of this standard, stpd is 101,325 kPa at an operating temperature of 20 °C.
NOTE 2 For the purposes of this standard, btps is local atmospheric pressure and a relative humidity of
100 % at an operating temperature of 37 °C.
Correct all test measurements to stpd or btps, as appropriate.
4.4 * Passive humidifier testing errors
a) For the purposes of this document, declared tolerances shall be adjusted by the measurement
uncertainty.
b) The manufacturer shall disclose the measurement uncertainty or each disclosed tolerance in the
technical description.
Check compliance by inspection of the instructions for use and the technical description.
5 General requirements
5.1 Mechanical basic safety for all passive humidifiers
5.1.1 General
A passive humidifier shall be free of rough surfaces, sharp corners and edges that can cause injury
or damage.
Check compliance by inspection.
5.1.2 * Requirements for instability from unwanted lateral movement
a) A transit-operable passive humidifier shall include a means by which the passive humidifier
can be easily attached to prevent unwanted movement during transport while in use.
b) The means shall allow the passive humidifier to withstand accelerations or decelerations of 1,0 g
longitudinal (forward, backward), 1,0 g transverse (left, right) for at least 5 s each.
EXAMPLES Means to be physically restrained during transport in a personal vehicle, in an ambulance or on a
wheelchair.
Check compliance by functional testing.
6 © ISO 2018 – All rights reserved
ISO 20789:2018(E)
5.1.3 * Requirements for audible acoustic energy
The A-weighted sound pressure level emitted by the passive humidifier shall be less than 50 dB as
determined by the following test method.
Check compliance with the following test.
a) Place the passive humidifier on a sound-reflecting plane, fill the liquid container to the least favourable
level and attach the least favourable set of accessories from those indicated in the instructions for use.
b) Configure the test lung with the compliance and resistance components whose values are indicated in
Table 1.
— Connect the patient-connection port to the test lung.
— Connect a ventilator or other appropriate flow source to the input of the passive humidifier.
NOTE The ventilator or other appropriate flow source is being used as a driving source for the
passive humidifier.
— Acoustically isolate the test lung and ventilator or other appropriate flow source by a suitable
means so that any noise caused by the test lung and ventilator does not interfere with the sound
measurement of the passive humidifier.
c) If the flow source is a ventilator, set the ventilator to volume control mode that generates ventilation as
indicated in Table 1. Otherwise, configure the flow source to the worst-case flow.
Table 1 — Test conditions for acoustic tests
Test condition
Adjustable parameter For a passive humidifier intended to provide an inspired volume
V ≥ 300 ml 300 ml ≥ V ≥ 50 ml V ≤ 50 ml
del del del
a
Delivered volume, V 500 ml 150 ml 30 ml
del
−1 −1 −1
Ventilatory frequency, f 10 min 20 min 30 min
I:E ratio 1:2 1:2 1:2
PEEP 5 hPa 5 hPa 5 hPa
b[9][10][11] −1 −1 −1
Resistance, R 5 hPa(l/s) ± 10 % 20 hPa(l/s) ± 10 % 50 hPa(l/s) ± 10 %
b −1 −1 −1
Isothermal Compliance, C 50 ml hPa ± 5 % 20 ml hPa ± 5 % 1 ml hPa ± 5 %
a
V is measured by means of a pressure sensor on the test lung, where V = C × P , and
del T max
V is the volume delivered to the test lung
t
C is the Isothermal Compliance of the test lung
P is the maximum pressure measured in the test lung
max
b
The accuracy for C and R applies over the ranges of the measured parameters.
d) Using the microphone of a sound level meter complying with the requirements of type 1 instruments
specified in IEC 61672-1:2013, measure the sound pressure levels at 10 positions in a hemisphere with a
radius from the geometric centre of the passive humidifier as specified in ISO 3744:2010, 7.2.
e) Calculate the A-weighted sound pressure level averaged over the measurement surface according to
ISO 3744:2010, 8.1.
f) Confirm that the A-weighted background level of extraneous noise is at least 6 dB below that measured
during the test.
g) Take measurements using the frequency-weighting characteristic A and the time-weighting
characteristic F on the sound level meter in a free field over a reflecting plane as specified in
ISO 3744:2010. Average the values in accordance with ISO 3744:2010, 8.1.
ISO 20789:2018(E)
h) Ensure that the measured sound pressure level is less than 50 dB.
5.1.4 * Overflow
a) In normal condition and single fault condition, a passive humidifier shall be so constructed
that the following hazardous situations shall not occur:
1) the volume of liquid exiting the humidification chamber outlet and the patient-connection
port exceeding:
i) 1,0 ml in 1 min or 2,0 ml in 1 h when intended for use with patients weighing less than
5 kg; and
ii) 5 ml in 1 min or 20 ml in 1 h for all other patients.
b) When a passive humidif
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