EN ISO 23500-2:2019

SLOVENSKI STANDARD
01-maj-2019
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SIST EN ISO 26722:2016
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Preparation and quality management of fluids for haemodialysis and related therapies -
Part 2: Water treatment equipment for haemodialysis applications and related therapies
(ISO 23500-2:2019)
Leitfaden für die Vorbereitung und das Qualitätsmanagement von Konzentraten für die
Hämodialyse und verwandte Therapien - Teil 2: Ausstattung zur Wasseraufbereitung zur
Verwendung in der Hämodialyse und in verwandten Therapien (ISO 23500-2:2019)
Préparation et management de la qualité des liquides d'hémodialyse et de thérapies
annexes - Partie 2: Équipement de traitement de l'eau pour des applications en
hémodialyse et aux thérapies apparentées (ISO 23500-2:2019)
Ta slovenski standard je istoveten z: EN ISO 23500-2:2019
ICS:
11.120.99 Drugi standardi v zvezi s Other standards related to
farmacijo pharmaceutics
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 23500-2
EUROPEAN STANDARD
NORME EUROPÉENNE
March 2019
EUROPÄISCHE NORM
ICS 11.040.40 Supersedes EN ISO 26722:2015
English Version
Preparation and quality management of fluids for
haemodialysis and related therapies - Part 2: Water
treatment equipment for haemodialysis applications and
related therapies (ISO 23500-2:2019)
Préparation et management de la qualité des liquides Leitfaden für die Vorbereitung und das
d'hémodialyse et de thérapies annexes - Partie 2: Qualitätsmanagement von Konzentraten für die
Équipement de traitement de l'eau pour des Hämodialyse und verwandte Therapien - Teil 2:
applications en hémodialyse et aux thérapies Ausstattung zur Wasseraufbereitung zur Verwendung
apparentées (ISO 23500-2:2019) in der Hämodialyse und in verwandten Therapien (ISO
23500-2:2019)
This European Standard was approved by CEN on 8 February 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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, 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 23500-2:2019 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 23500-2:2019) has been prepared by Technical Committee ISO/TC 150
"Implants for surgery" in collaboration with Technical Committee CEN/TC 205 “Non-active medical
devices” the secretariat of which is held by DIN.
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 September 2019, and conflicting national standards
shall be withdrawn at the latest by September 2019.
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.
This document supersedes EN ISO 26722:2015.
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, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 23500-2:2019 has been approved by CEN as EN ISO 23500-2:2019 without any
modification.
INTERNATIONAL ISO
STANDARD 23500-2
First edition
2019-02
Preparation and quality management
of fluids for haemodialysis and related
therapies —
Part 2:
Water treatment equipment for
haemodialysis applications and
related therapies
Préparation et management de la qualité des liquides d'hémodialyse
et de thérapies annexes —
Partie 2: Équipement de traitement de l'eau pour des applications en
hémodialyse et aux thérapies apparentées
Reference number
ISO 23500-2:2019(E)
©
ISO 2019
ISO 23500-2:2019(E)
© ISO 2019
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.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved

ISO 23500-2:2019(E)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
1.1 General . 1
1.2 Inclusions . 1
1.3 Exclusions . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Requirements . 2
4.1 Dialysis water quality requirements . 2
4.1.1 General. 2
4.1.2 Chemical contaminant requirements . 2
4.1.3 Organic Carbon, pesticides and other chemicals . 3
4.1.4 Microbiology of dialysis water . 3
4.2 Water treatment equipment requirements . 4
4.2.1 General. 4
4.2.2 Backflow prevention device . 5
4.2.3 Tempering valves . 5
4.2.4 Sediment filters . 5
4.2.5 Cartridge filters . 5
4.2.6 Softeners . 5
4.2.7 Anion exchange resin tank . 5
4.2.8 Carbon media . 5
4.2.9 Chemical injection systems . 7
4.2.10 Reverse osmosis . 7
4.2.11 Deionization . 8
4.2.12 Bacteria and endotoxin retentive filters . 8
4.2.13 Storage and distribution of dialysis water . 8
5 Testing .10
5.1 Conformity with dialysis water quality requirements .10
5.1.1 General.10
5.1.2 Microbiology of dialysis water .10
5.1.3 Maximum level of chemical contaminants .11
5.2 Conformity with water treatment equipment requirements .12
5.2.1 General.12
5.2.2 Backflow prevention devices .13
5.2.3 Tempering valves .13
5.2.4 Sediment filters .13
5.2.5 Cartridge filters .13
5.2.6 Softeners .13
5.2.7 Anion exchange resin tanks .13
5.2.8 Carbon media .13
5.2.9 Chemical injection systems .14
5.2.10 Reverse osmosis .14
5.2.11 Deionization .14
5.2.12 Endotoxin retentive filters .14
5.2.13 Storage and distribution of dialysis water .14
6 Labelling .15
6.1 General .15
6.2 Device markings .15
6.3 Product literature .15
Annex A (informative) Rationale for the development and provisions of this document .18
ISO 23500-2:2019(E)
Annex B (informative) .29
Bibliography .32
iv © ISO 2019 – All rights reserved

ISO 23500-2:2019(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 (see 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 (see 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 of 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
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso
.org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 150, Implants for surgery, Subcommittee
SC 2, Cardiovascular implants and extracorporeal systems.
This first edition cancels and replaces ISO 26722:2014, which has been technically revised. The main
changes compared to the previous edition are as follows:
— The document forms part of a revised and renumbered series dealing with the preparation and
quality management of fluids for haemodialysis and related therapies. The series comprise
ISO 23500-1 (previously ISO 23500), ISO 23500-2, (previously ISO 26722), ISO 23500-3, (previously
ISO 13959), ISO 23500-4, (previously ISO 13958), and ISO 23500-5, (previously ISO 11663).
A list of all parts in the ISO 23500 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www. iso. org/members. html.
ISO 23500-2:2019(E)
Introduction
This document reflects the conscientious efforts of concerned physicians, clinical engineers, nurses,
dialysis technicians, and dialysis patients, in consultation with device manufacturers and regulatory
authority representatives, to develop an International Standard for performance levels that could be
reasonably achieved at the time of publication. The term “consensus,” as applied to the development
of voluntary medical device documents, does not imply unanimity of opinion, but rather reflects the
compromise necessary in some instances when a variety of interests should be merged.
This document applies to individual water treatment devices and to water treatment systems
assembled from one or more of these devices. In the first instance, this document is directed at the
individual or company that specifies the complete water treatment system and, second, at the supplier
who assembles and installs the system. Since systems can be assembled from a number of individual
water treatment devices, the provisions of this document are also directed at the manufacturers
of these devices, provided that the manufacturer indicates that the device is intended for use in
haemodialysis applications. This document is written principally to address water treatment systems
for dialysis facilities treating multiple patients. However, many of its provisions apply equally to water
treatment systems used in applications where a single patient is treated, such as in a home dialysis or
acute hospital dialysis setting. Specifically, requirements for the chemical and microbiological quality
of water are considered to apply in all settings, regardless of whether a single patient or many patients
are being treated.
Increasingly, self-contained, integrated systems designed and validated to produce water and dialysis
fluid are becoming available and used clinically. The provisions included in this document apply to
systems assembled from individual components. Consequently, some of the provisions in ISO 23500-1
and ISO 23500-2 might not apply to integrated systems, however such systems are required to comply
with ISO 23500-3, ISO 23500-4, and ISO 23500-5. In order to ensure conformity when using such
systems, the user shall follow the manufacturer's instructions regarding the operation, testing, and
maintenance of such systems in order to ensure that the system is being operated under the validated
conditions.
This document helps protect haemodialysis patients from adverse effects arising from known chemical
and microbial contaminants found in water supplies. However, dialysis and patient safety is ultimately
dependent on the quality of the dialysis fluid. Since the manufacturer or supplier of water treatment
equipment does not have control over the dialysis fluid, any reference to dialysis fluid in this document
is for clarification only and not a requirement of the manufacturer. The responsibility for assuring that
the dialysis fluid is not contaminated, mismatched, or otherwise damaging to the patient rests with the
clinical professionals caring for the patient under the supervision of the medical director. Requirements
and recommendations on the preparation and handling of water and dialysis fluid in a dialysis facility
are provided in ISO 23500-5. The rationale for the development of this document is given in Annex A.
Since the chemical and microbiological content of the water produced need to meet the requirements of
ISO 23500-3, the maximum allowable levels of contaminants are listed in Annex B (Tables B.1 and B.2).
The values shown include the anticipated uncertainty associated with the analytical methodologies
listed in Table B.3.
vi © ISO 2019 – All rights reserved

INTERNATIONAL STANDARD ISO 23500-2:2019(E)
Preparation and quality management of fluids for
haemodialysis and related therapies —
Part 2:
Water treatment equipment for haemodialysis
applications and related therapies
1 Scope
1.1 General
This document is addressed to the manufacturer and/or supplier of water treatment systems and/or
devices used for the express purpose of providing water for haemodialysis or related therapies.
1.2 Inclusions
This document covers devices used to treat potable water intended for use in the delivery of
haemodialysis and related therapies, including water used for:
a) the preparation of concentrates from powder or other highly concentrated media at a dialysis
facility;
b) the preparation of dialysis fluid, including dialysis fluid that can be used for the preparation of
substitution fluid;
c) the reprocessing of dialysers intended for single use where permitted for multiple uses,
d) the reprocessing of dialysers not specifically marked as intended for single use.
This document includes all devices, piping and fittings between the point at which potable water is
delivered to the water treatment system, and the point of use of the dialysis water. Examples of the
devices are water purification devices, online water quality monitors (such as conductivity monitors),
and piping systems for the distribution of dialysis water.
1.3 Exclusions
This document excludes dialysis fluid supply systems that proportion water and concentrates to
produce dialysis fluid, sorbent dialysis fluid regeneration systems that regenerate and recirculate
small volumes of the dialysis fluid, dialysis concentrates, haemodiafiltration systems, haemofiltration
systems, systems that process dialysers for multiple uses, and peritoneal dialysis systems. Some of these
devices, such as dialysis fluid delivery systems and concentrates, are addressed in other documents
such as ISO 23500-4 and ISO 23500-5,
This document also excludes the on-going surveillance of the purity of water used for dialysis fluid,
concentrate preparation, or dialyser reprocessing which is addressed in ISO 23500-1.
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.
ISO 23500-2:2019(E)
ISO 23500-1:2019, Preparation and quality management of fluids for haemodialysis and related
therapies — Part 1: General requirements
ISO 23500-3:2019, Preparation and quality management of fluids for haemodialysis and related
therapies — Part 3: Water for haemodialysis and related therapies
IEC 60601-1-8, Medical electrical equipment — Part 1-8: General requirements for basic safety and
essential performance — Collateral standard: General requirements, tests and guidance for alarm systems
in medical electrical equipment and medical electrical systems
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 23500-1 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1
microfilter
filter designed to remove particles down to 0,1 µm in size
Note 1 to entry: Microfilters have an absolute size cut-off and are available in both dead-end and cross-flow
configurations. Some microfilters can reduce the concentration of endotoxins by adsorption.
4 Requirements
4.1 Dialysis water quality requirements
4.1.1 General
The requirements contained in this document apply to the dialysis water as it enters the equipment
used to prepare concentrates from powder or other concentrated media at a dialysis facility, to prepare
dialysis fluid, or to reprocess dialysers. As such, these requirements apply to the water treatment system
as a whole and not to each of the individual devices that make up the system. However, collectively, the
individual devices shall produce dialysis water that, at a minimum, meets the requirements of the clause.
4.1.2 Chemical contaminant requirements
Dialysis water used to prepare dialysis fluid or concentrates from powder at a dialysis facility, or to
reprocess dialysers for multiple uses, shall not contain chemical contaminants at concentrations in
excess of those in ISO 23500-3:2019, Tables 1 and 2 (reproduced as Tables B.1 and B.2). The manufacturer
or supplier of a complete water treatment system shall recommend a system capable of meeting the
requirements of this clause based on the analysis of the feed water. The system design should reflect
possible seasonal variations in feed water quality. The manufacturer or supplier of a complete water
treatment and distribution system shall demonstrate that the complete water treatment, storage, and
distribution system is capable of meeting the requirements of this document at the time of installation.
NOTE 1 If the manufacturer or supplier does not install the water storage and distribution system, then the
responsibility of the manufacturer or supplier is limited to demonstrating that the water treatment system,
excluding the water storage and distribution system, meets the requirements of this document. If individual
devices of the water treatment system are provided by different manufacturers or suppliers, the person or
organization specifying the devices is responsible for demonstrating that the complete system meets the
requirements of this document at the time of installation.
For disposable water treatment and distribution systems that have been validated to produce dialysis
water meeting the quality requirements of this document for a specified time, surveillance of the
2 © ISO 2019 – All rights reserved

ISO 23500-2:2019(E)
incoming potable water is required to ensure that the input to the treatment system is in the range
for which the system has been validated. The manufacturer's recommendation for surveilling the
final dialysis water can be followed when the system is operated according to the manufacturer's
instructions. Alternatively, the quality of the dialysis water can be closely observed as outlined for non-
validated systems.
NOTE 2 Following the installation of a water treatment, storage, and distribution system, the user is
responsible for continued surveillance of the levels of chemical contaminants in the water and for complying
with the requirements of this document.
4.1.3 Organic Carbon, pesticides and other chemicals
The presence of organic compounds, such as pesticides, polycyclic aromatic hydrocarbons and other
chemicals such as pharmaceutical products and endocrine disruptors in respect of hemodialysis
patients are difficult to define. Consequences of exposure are probably of a long-term nature and it is
technically difficult and costly to measure these substances on a routine basis. Furthermore, there is
an absence of evidence of their widespread presence in water although it is recognized that inadvertent
discharges are possible. In view of this, it is not possible to currently define limits for their presence in
water used in the preparation of dialysis fluid.
Nanofiltration and reverse osmosis are capable of significant rejection of many such compounds.
Granular Activated Carbon (GAC) is also highly effective at removing majority of such compounds.
However, as Granular Activated Carbon is widely used in the removal of chlorine/chloramine, their use
in the removal of organic carbons, pesticides and other chemicals will be dependent upon the size of the
carbon filters and/or beds and users shall be aware of appropriate dimensioning since the majority of
carbon valences might be already occupied and not available for further removal activity.
4.1.4 Microbiology of dialysis water
Dialysis water used to prepare dialysis fluid or concentrates from powder at a dialysis facility, or to
reprocess dialysers for multiple uses, shall contain a total viable microbial count and endotoxin levels
as specified in ISO 23500-3.
The manufacturer or supplier of a complete water treatment and distribution system shall demonstrate
that the complete water treatment, storage, and distribution system meets the requirements of this
document, including those related to action levels at the time of installation.
NOTE 1 If the manufacturer or supplier does not install the water storage and distribution system, then the
responsibility of the manufacturer or supplier is limited to demonstrating that the water treatment system,
excluding the water storage and distribution system, meets the requirements of this document. If individual
devices of the water treatment system are provided by different manufacturers or suppliers, the person or
organization specifying the devices is responsible for demonstrating that the complete system meets the
requirements of this document at the time of installation.
For disposable water treatment systems validated by the manufacturer to produce dialysis water
meeting the quality requirements of this document for a specified time, surveillance of the incoming
feed water is required to ensure that the input to the treatment system is in the range for which the
system has been validated. The manufacturer's recommendations for surveilling the dialysis water can
be followed when the system is operated according to the manufacturer's instructions. Alternatively,
the quality of the dialysis water can be observed as outlined for non-validated systems.
NOTE 2 Following installation of a water treatment, storage, and distribution system, the user is responsible
for continued surveillance of the water bacteriology of the system and for complying with the requirements of
this document, including those requirements related to action levels.
ISO 23500-2:2019(E)
4.2 Water treatment equipment requirements
4.2.1 General
4.2.1.1 Water treatment system
The supplier of the feed water or the supplier of the water treatment system or a laboratory specified
by the user shall perform chemical analyses on feed water to determine the compatibility of the
system with the feed water and the suitability of the system for providing dialysis water meeting the
requirements of 4.1.2. The result of the chemical analyses shall be available to the user in charge of
dialysis. In the case of an individual device, the person incorporating the device into the water treatment
system is responsible for ensuring that incorporation of the device does not compromise the ability of
the overall system to deliver dialysis water capable of meeting the requirements of 4.1.2 and 4.1.4.
The water treatment and distribution system should include appropriate pressure gauges, flow meters,
sample ports, and other ancillary equipment necessary to allow surveillance of the performance of
individual system devices and the system as a whole.
Valves can be included in the water treatment system to allow individual devices to be bypassed when
there is device failure or to facilitate replacement of a device. If it is possible to bypass a device of the
water treatment system, then the manufacturer or installer of that component shall inform the user of
the risks associated with bypassing that device and the need for clearly defining the responsibility for
operating the bypass. Where such valves are installed, however, a means should be included to minimize
the likelihood that the device will be inadvertently bypassed during normal operation of the system.
Operating controls shall be positioned so as to minimize inadvertent resetting.
Electrical circuits shall be separate from hydraulic circuits and adequately protected from fluid leaks.
4.2.1.2 Materials compatibility
Materials that are in contact with dialysis water (including materials used in piping, storage, and
distribution systems) shall not interact chemically or physically with that water so as to adversely affect
its purity or quality. Water-contacting surfaces shall be fabricated from non-reactive materials (e.g.
plastics) or appropriate stainless steel. The use of materials known to cause toxicity in haemodialysis,
such as copper, brass, galvanized metal, or aluminium, are specifically prohibited at any point beyond
the water treatment device used to remove contaminating metal ions, most commonly a reverse
osmosis system or a deionizer. The materials of any water treatment devices (including piping, storage,
and distribution systems) shall be compatible with the means used to disinfect those devices. Chemicals
infused into the water in the pre-treatment section, such as chlorine, acid, flocculants, and complexing
agents, shall be adequately removed from dialysis water before they reach any point of use. Monitors or
specific test procedures to verify removal of additives shall be provided.
4.2.1.3 Regenerated or reconstituted devices
All devices that are regenerated or reconstituted at a site remote from the dialysis facility, such as
deionizers, shall be disinfected at the time of regeneration or reconstitution, so that contaminated
water is not reintroduced into the system after regeneration or reconstitution. Separate processes shall
be used to ensure no intermixing of devices or their component parts between devices returned from
medical or potable water users and devices returned from non-potable water users.
4.2.1.4 Disinfection protection
When the manufacturer recommends chemical disinfectants [see 6.3 x)], means shall be provided to
restore the equipment and the system in which it is installed, to a safe condition relative to residual
disinfectant prior to the dialysis water being used for dialysis applications. When recommending
chemical disinfectants, the manufacturer shall also recommend methods for testing for residual
levels of the disinfectants. When disinfection is accomplished automatically by chemical disinfectant,
4 © ISO 2019 – All rights reserved

ISO 23500-2:2019(E)
including ozone, or by high temperature procedures, activation of the disinfection system shall result in
activation of a warning system and measures to prevent patient exposure to an unsafe condition.
If sodium hypochlorite (bleach) is used for cleaning or disinfecting the internal pathways of dialysis
equipment, including but not limited to water treatment loops, concentrate containers, mixers,
and delivery systems, the post rinse water residual level of free chlorine shall be as specified by the
manufacturer’s instructions.
4.2.2 Backflow prevention device
A backflow prevention device to isolate the water treatment system from the potable water supply
according to local plumbing codes should be fitted to all water treatment systems.
4.2.3 Tempering valves
Tempering valves, if used, shall be sized to accommodate the anticipated range of flow rates of hot and
cold water. They shall be fitted with a mechanism to prevent backflow of water into the hot and cold
water lines and with a means to measure the outlet water temperature.
4.2.4 Sediment filters
Sediment filters should have an opaque housing or other means to inhibit proliferation of algae. Filters
should be fitted with pressure gauges on the inlet and outlet water lines to measure the pressure drop,
ΔP, across the filter.
NOTE Sediment filters are also known as multimedia or sand filters.
4.2.5 Cartridge filters
Cartridge filters should have an opaque housing or other means to inhibit proliferation of algae. Filters
should be fitted with pressure gauges on the inlet and outlet water lines to measure the pressure drop,
ΔP, across the filter.
4.2.6 Softeners
Water softeners should be fitted with a mechanism to prevent water containing the high concentrations
of sodium chloride used during regeneration from entering the product water line during regeneration.
Automatic regeneration can be performed on a volume schedule or on a time schedule. For softeners that
are regenerated automatically on a time schedule, the face of the timers used to control the regeneration
cycle should be visible to the user. Operating controls shall be positioned so as to minimize inadvertent
resetting.
4.2.7 Anion exchange resin tank
Anion exchange resin, sometimes referred to as an organic scavenger, can remove organic matter and
other contaminants from the source water and protect carbon media from fouling, which can shorten
its effective life for chlorine/chloramine removal. If an organic scavenger is installed to protect the
carbon media, the scavenger should be installed upstream of the carbon beds. Anion exchange resins
can also be used to remove contaminants that might otherwise foul the reverse osmosis membrane.
4.2.8 Carbon media
Carbon is used to remove small organic compounds, chlorine, and chloramine. At least one carbon bed
or filter should be installed even if the water supply is from a well and no chlorine is present. Carbon
removes organic contaminants from ground water, including solvents, pesticides, industrial wastes,
and substances leaking from underground storage tanks. If chlorine is not present in the water, the
carbon should be changed on a routine schedule. When carbon is used for the removal of chloramine, it
ISO 23500-2:2019(E)
shall be adapted specifically to the maximum anticipated water flow rate of the system and the level of
chloramine in the feed water.
Due to the risk of harm to a patient in the event of total chlorine breakthrough or organic contamination,
the system shall be designed to prevent patient exposure to unsafe product water in the event of a
single point failure. Protective measures can be incorporated into the system design through several
means including:
— the use of two carbon beds in series with off-line sampling of product water from the first bed in
each series (see off-line testing in ISO 23500-1:2019, 7.3.5). Each of the carbon beds shall have an
EBCT of at least 5 min at the maximum product water flow rate (a total EBCT of at least 10 min);
— the use of redundant means of chloramines removal with off-line sampling of product water after
the primary device (see off-line testing in ISO 23500-1:2019, 7.3.5). Possible alternatives include a
granular activated carbon bed followed by a dense carbon block or two carbon block filters in series;
— the use of carbon systems used to prepare water for portable dialysis systems are exempt from
the requirement for the second carbon and a 10 min EBCT, provided there is a redundant means
of chloramine removal with off-line sampling after the primary device (see off-line testing in
ISO 23500-1:2019, 7.3.5);
— the use of batch systems used to prepare water for portable dialysis systems are exempt from the
requirement for the second carbon and a 10 min EBCT, provided there is a redundant means of
chloramine removal with off-line sampling after batch production (see chlorine test methods in
ISO 23500-1:2019, 7.3.5);
— the use of carbon media with duration or process volume limitation in conjunction with online
surveillance of the product water and diversion of the product water to drain or a blocking valve
with system shutdown, should the total chlorine level in the product water exceed 0,1 mg/l (see
online testing in ISO 23500-1:2019, 7.3.5). Periodic testing of the online monitor and the frequency
of the testing is specified per the system manufacturer’s instructions. If an online monitor failure
occurs, manual testing can be implemented to observe for chlorine and chloramines for 72 h similar
to dual carbon designs as in ISO 23500-1:2019, B.2.5.
To avoid overly large beds, carbon beds are sometimes arranged as parallel sets, each set consisting
of two beds in series. The beds are equally sized and water flows in parallel through each set. In this
situation, each bed shall have a minimum EBCT of 5 min at the maximum flow rate through the bed.
When parallel sets of beds are used, the
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