prEN 14367
(Main)Non controllable backflow preventer with different pressure zones - Family C, type A
- Abstract
This document specifies the:
— field of application:
— The dimensional, the physicochemical, the design, the hydraulic, the mechanical and the acoustic characteristics of non-controllable backflow preventer with different pressure zones, family C, type A, nominal sizes DN 6 to DN 25, nominal pressure PN 10.
It is applicable to:
— Family C, type A, class “a” for general use: devices of class “a” can be capable of working:
— at any pressure up to 1 MPa (10 bar);
— with any pressure variation up to 1 MPa (10 bar);
— at a supply temperature limit of 65 °C and 90 °C for 1 h;
— Family C, type A, class “b” for specific use: devices of class “b” shall be capable of working:
— at any downstream pressure up to 0,3 MPa (3 bar);
— with any downstream pressure variation up to 0,3 MPa (3 bar); at a supply temperature limit of 65 °C and 90 °C for 1 h;
Class “b” devices can capable of operating: at any downstream pressure up to 300 kPa (3 bar), with any downstream pressure variation up to 300 kPa (3 bar) at a supply temperature limit of 65 °C and 90 °C for 1 h. Class “b” devices with specific hydraulic and non-acoustic requirements and are intended to equip filling devices physically integrated into a single-function (heating) or dual-function (heating and domestic hot water) boiler.
It specifies also:
— test methods and requirements for verifying these characteristics;
— marking;
— presentation and the delivery.
- Status
- Not Published
- Publication Date
- 29-Mar-2027
- Technical Committee
- CEN/TC 164 - Water supply
- Current Stage
- 4060 - Closure of enquiry - Enquiry
- Start Date
- 01-Oct-2026
- Due Date
- 10-Mar-2026
- Completion Date
- 01-Oct-2026
prEN 14367 is a draft European Standard from CEN for non controllable backflow preventer with different pressure zones - Family C, type A. It specifies the design, materials, test methods, marking and delivery requirements for DN 6 to DN 25 devices with PN 10, including class a for general use and class b for specific use in sealed heating system filling applications. It is aimed at people who need to specify, make, test, buy or approve these backflow protection devices for water supply installations.
What does prEN 14367 specify?
prEN 14367 specifies the characteristics and verification methods for family C, type A non controllable backflow preventers. The document covers dimensional, physicochemical, design, hydraulic, mechanical and acoustic requirements, together with marking, technical documentation and presentation at delivery.
The scope is limited to devices for water supply systems in nominal sizes DN 6 to DN 25 with nominal pressure PN 10. It distinguishes two application classes:
- class a for general use
- class b for specific use at filling points of domestic sealed heating systems, including devices physically integrated into single-function or dual-function boilers
How the document is organized
| Clause or annex | What it covers |
|---|---|
| 1 | Scope |
| 2 | Normative references |
| 3 | Terms and definitions |
| 4 | Nominal size (denomination) |
| 5 | Designation |
| 6 | Symbolization |
| 7 | Physico-chemical characteristics |
| 8 | Design |
| 9 | Characteristics and test methods |
| 10 | Marking and technical documents |
| 11 | Presentation at delivery |
| Annex A | Complementary test methods for CA class b with a plastic body |
| Annex B | Order of tests |
What are the key requirements of prEN 14367?
prEN 14367 sets out a complete product and test framework, not just a single functional check. In practice, a compliant device must be built from suitable materials, have the right connection and discharge arrangement, and pass the mechanical, tightness, hydraulic, compatibility and acoustic tests that apply to its class.
Size, designation and symbolization
Clause 4 links the nominal size to the flow-rate-related denomination for class a devices, while class b devices all have to meet the same performance requirements as DN 6. Clause 5 then defines the designation string, which combines family, type, class, denomination where applicable, connection type, body material, surface finish, acoustic group for class a, and the reference to the standard. This matters because procurement and documentation need a precise way to identify exactly which variant is being supplied.
Clause 6 provides the graphic symbol for class a and class b devices. That helps designers, drawings and installation documents show the device clearly and consistently.
Materials and construction
Clause 7 requires materials and coatings to be suitable for contact with drinking water and not to contaminate it or change its quality, appearance, smell or taste. The manufacturer has to state the nature of the materials and coatings in a technical document, and materials with insufficient corrosion resistance need additional protection.
For copper alloys, where dezincification-resistant material is required, the product has to meet the stated resistance limit and be tested to EN ISO 6509-1. If required by national rules, the product is marked DR. In practice, this is the part readers use to check whether the body material is acceptable for potable-water use and local market rules.
Design rules that affect safety and serviceability
Clause 8 requires the device function to depend only on water pressure, with fixed, non-adjustable spring settings. If the internal parts can be accessed for inspection or repair, they must go back in only one way, so reversal or interchange is not possible.
For class a devices, any strainer has to be upstream of the upstream non-return system and easy to remove for cleaning. For class b devices, the complete device is not meant to be removable for maintenance of the individual parts. That affects how the product is serviced and how installers should plan replacement versus repair.
Relief valve and discharge arrangement
Clause 8 also sets requirements for the relief valve. The control has to be of positive safety, meaning failure or leakage leaves the relief open. The discharge outlet needs an air break to drain, and class a devices have to meet the dimensional requirements of EN 1717 for that air break.
Class b devices have additional discharge features, including at least two air inlet openings and a relief device arrangement that does not obstruct those openings. In practical terms, this is about avoiding unsafe backflow paths while still allowing the device to discharge freely.
Test program and performance checks
Clause 9 makes the device undergo tests as installed according to the manufacturer’s technical documents. The standard also fixes the default test conditions and measuring accuracy, so the results are comparable between laboratories.
The test programme covers:
- body strength under pressure
- torque and bending checks on union fittings and body tightness
- endurance
- downstream and upstream check-valve tightness
- closing pressure of the downstream check valve
- vacuum behavior
- pressure loss versus flow rate
- relief-valve opening and closing behavior
- relief flow rate
- compatibility with potassium permanganate and sodium hypochlorite disinfection treatments
- acoustic testing for class a devices
This matters because compliance depends on the whole performance package, not only on whether the device resists pressure.
Marking, documents and delivery
Clause 10 requires permanent, visible marking on the casing or on a fixed plate, including identification, flow direction, family/type/class, DN where applicable, PN, maximum operating temperature, acoustic group where applicable, traceability, and the standard reference. Clause 11 requires protection against damage and contamination from manufacture up to installation. For users, this is what supports traceability, correct installation and clean delivery.
What terms does prEN 14367 define?
- Non controllable backflow preventer with different pressure zones - Family C - Type A (CA) - A device with upstream, vented intermediate and downstream zones that disconnects by venting when the pressure difference falls below the stated threshold, without control means.
- Class a - The general-use version of the device, intended to work at any pressure up to the stated limit and with the full range of pressure variations in the scope.
- Class b - The specific-use version for filling points in domestic sealed heating systems, with tighter hydraulic conditions and no acoustic requirement.
- Specific use - The use of the backflow protection device at the filling point of domestic sealed heating systems, which applies only to class b.
- Nominal size (DN) - The denomination used to identify the device size and its performance class.
- Nominal pressure (PN) - The pressure rating used for the device design and test basis.
- Acoustic group - The noise classification used for class a devices after acoustic testing.
- Air break to drain - The discharge arrangement that maintains an air gap between the waste drain and the collected discharged water.
Who uses prEN 14367?
Manufacturers of backflow protection devices use prEN 14367 to design the product, choose materials, set up the relief valve and prepare the marking and technical documents. Test laboratories use it to run the mechanical, hydraulic, tightness, endurance and acoustic checks.
It is also used by:
- plumbing and water-supply engineers who specify backflow protection in installations
- boiler and heating equipment manufacturers, especially for class b integrated applications
- quality and conformity-assessment teams checking product evidence and test reports
- buyers and technical approvers who need to match a device to a specific installation or market requirement
What changed in prEN 14367 from the previous edition?
prEN 14367:2026 will supersede EN 14367:2005. The foreword states these significant technical changes:
- the scope was updated
- an accuracy chapter was added
- the testing and requirements system was revised
- Annex B was deleted and replaced by a new order-of-tests annex
- all figures were updated
- the text was editorially revised
Which standards are used with prEN 14367?
| Standard | What it contributes |
|---|---|
| EN 1717 | General backflow-protection terminology and the framework for protection of potable water |
| EN 1254 (all parts) | Copper and copper alloy plumbing fittings used for connections |
| EN 1267 | Water-based flow-resistance test method and related hydraulic test rig basis |
| EN ISO 228-1 | Pipe thread dimensions, tolerances and designation |
| EN ISO 3822-1:1999 | Laboratory measurement of noise emission |
| EN ISO 3822-3:2018 | Mounting and operating conditions for in-line valves and appliances in acoustic tests |
| EN ISO 6509-1 | Test method for dezincification resistance of brass |
| EN 13959 | Certified check valve EB referenced in the closing-pressure verification |
| EN ISO 5167-1 | Pressure-differential flow measurement principles used in the hydraulic test rig |
| ISO 7-1 | Pipe thread dimensions, tolerances and designation for pressure-tight joints |
| ISO 965-1 | Metric screw thread tolerances, used for M10 × 1 connections |
What does the prEN 14367 document contain?
The document contains design principles, symbols, connection rules and a large set of test figures and procedures. The figures show the device principle and the rigs used for torque, bending, endurance, tightness, vacuum, pressure-loss, relief-valve and acoustic testing.
Its tables provide the practical data used in testing and classification, including nominal-size-related flow values, torque and bending requirements, endurance flow rates, hydraulic pressure-loss limits, relief-flow limits and acoustic group limits. Annex A adds extra test methods for CA class b devices with a plastic body, while Annex B sets out the order of tests so laboratories can plan samples and test sequence correctly.
Relations
- Revises
EN 14367:2005 - Non controllable backflow preventer with different pressure zones - Family C, type A - Effective Date
- 19-Jan-2023
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Frequently Asked Questions
prEN 14367 is a draft published by the European Committee for Standardization (CEN). Its full title is "Non controllable backflow preventer with different pressure zones - Family C, type A". This standard covers: This document specifies the: — field of application: — The dimensional, the physicochemical, the design, the hydraulic, the mechanical and the acoustic characteristics of non-controllable backflow preventer with different pressure zones, family C, type A, nominal sizes DN 6 to DN 25, nominal pressure PN 10. It is applicable to: — Family C, type A, class “a” for general use: devices of class “a” can be capable of working: — at any pressure up to 1 MPa (10 bar); — with any pressure variation up to 1 MPa (10 bar); — at a supply temperature limit of 65 °C and 90 °C for 1 h; — Family C, type A, class “b” for specific use: devices of class “b” shall be capable of working: — at any downstream pressure up to 0,3 MPa (3 bar); — with any downstream pressure variation up to 0,3 MPa (3 bar); at a supply temperature limit of 65 °C and 90 °C for 1 h; Class “b” devices can capable of operating: at any downstream pressure up to 300 kPa (3 bar), with any downstream pressure variation up to 300 kPa (3 bar) at a supply temperature limit of 65 °C and 90 °C for 1 h. Class “b” devices with specific hydraulic and non-acoustic requirements and are intended to equip filling devices physically integrated into a single-function (heating) or dual-function (heating and domestic hot water) boiler. It specifies also: — test methods and requirements for verifying these characteristics; — marking; — presentation and the delivery.
This document specifies the: — field of application: — The dimensional, the physicochemical, the design, the hydraulic, the mechanical and the acoustic characteristics of non-controllable backflow preventer with different pressure zones, family C, type A, nominal sizes DN 6 to DN 25, nominal pressure PN 10. It is applicable to: — Family C, type A, class “a” for general use: devices of class “a” can be capable of working: — at any pressure up to 1 MPa (10 bar); — with any pressure variation up to 1 MPa (10 bar); — at a supply temperature limit of 65 °C and 90 °C for 1 h; — Family C, type A, class “b” for specific use: devices of class “b” shall be capable of working: — at any downstream pressure up to 0,3 MPa (3 bar); — with any downstream pressure variation up to 0,3 MPa (3 bar); at a supply temperature limit of 65 °C and 90 °C for 1 h; Class “b” devices can capable of operating: at any downstream pressure up to 300 kPa (3 bar), with any downstream pressure variation up to 300 kPa (3 bar) at a supply temperature limit of 65 °C and 90 °C for 1 h. Class “b” devices with specific hydraulic and non-acoustic requirements and are intended to equip filling devices physically integrated into a single-function (heating) or dual-function (heating and domestic hot water) boiler. It specifies also: — test methods and requirements for verifying these characteristics; — marking; — presentation and the delivery.
prEN 14367 is classified under the following ICS (International Classification for Standards) categories: 91.140.60 - Water supply systems. The ICS classification helps identify the subject area and facilitates finding related standards.
prEN 14367 has the following relationships with other standards: It is inter standard links to EN 14367:2005. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
prEN 14367 is associated with the following European legislation: EU Directives/Regulations: 305/2011. When a standard is cited in the Official Journal of the European Union, products manufactured in conformity with it benefit from a presumption of conformity with the essential requirements of the corresponding EU directive or regulation.
prEN 14367 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
SLOVENSKI STANDARD
01-september-2026
Sistemski ločevalnik z različnimi nenadzorovanimi območji tlaka - Družina C, tip A
Non controllable backflow preventer with different pressure zones - Family C, type A
Systemtrenner mit unterschiedlichen nicht kontrollierbaren Druckzonen - Familie C, Typ
A
Disconnecteur non contrôlable à zones de pression différentes - Famille C, type A
Ta slovenski standard je istoveten z: prEN 14367
ICS:
91.140.60 Sistemi za oskrbo z vodo Water supply systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
DRAFT
EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM
July 2026
ICS 91.140.60 Will supersede EN 14367:2005
English Version
Non controllable backflow preventer with different
pressure zones - Family C, type A
Disconnecteur non contrôlable à zones de pression Systemtrenner mit unterschiedlichen nicht
différentes - Famille C, type A kontrollierbaren Druckzonen - Familie C, Typ A
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 164.
If this draft becomes a European Standard, 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.
This draft European Standard was established by CEN 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, Türkiye and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.
Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 14367:2026 E
worldwide for CEN national Members.
Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Nominal size (denomination) . 8
4.1 Class a device . 8
4.2 Class b device . 8
5 Designation . 8
6 Symbolization . 9
7 Physico-chemical characteristics . 9
7.1 Materials . 9
7.2 Nature of the materials . 9
7.2.1 General. 9
7.2.2 Dezincification resistant copper alloy . 10
7.2.3 Nature of apparent surfaces . 10
7.2.4 Uncoated surface . 10
7.2.5 Surface with coating . 10
7.2.6 Detection of residual stress . 10
8 Design . 11
8.1 General. 11
8.2 Relief valve . 12
9 Characteristics and tests methods . 13
9.1 General. 13
9.2 Accuracy of measurements . 13
9.3 Accuracy of measuring instruments . 13
9.3.1 General. 13
9.4 End connections . 13
9.4.1 General. 13
9.4.2 Class a device . 13
9.4.3 Class b device . 14
9.5 Mechanical characteristics . 14
9.5.1 General. 14
9.5.2 Mechanical resistance of the body under pressure . 14
9.5.3 Torque test of union fittings of the device and bending strength – tightness of the
body . 14
9.5.4 Endurance . 15
9.6 Tightness characteristics . 18
9.6.1 Verification of the tightness of the downstream check valve (in the closing direction) . 18
9.6.2 Verification of the closing pressure of the downstream check valve and its tightness
(opening direction) . 19
9.6.3 Verification of the tightness of the upstream check valve at low pressure . 20
9.6.4 Verification of the tightness of the upstream check valve under vacuum . 20
9.7 Hydraulic characteristics . 22
9.7.1 Test rig — General circuit . 22
9.7.2 Verification of the pressure loss as a function of the flow rate . 24
9.7.3 Verification of the opening (disconnection) and closing (tightness) of the relief valve . 24
9.7.4 Verification of the relief flow rate . 25
9.8 Compatibility with the products used for disinfection of the networks . 26
9.8.1 Requirement . 26
9.8.2 Test method . 26
9.9 Acoustic tests . 27
9.9.1 General . 27
9.9.2 Procedure . 27
10 Marking and technical documents . 27
10.1 Marking . 27
10.2 Technical documents . 28
11 Presentation at delivery . 28
Annex A (normative) Complementary test methods on backflow preventers CA class b with a
plastic body . 30
Annex B (informative) Order of Tests . 33
Bibliography . 35
European foreword
This document (prEN 14367:2026) has been prepared by Technical Committee CEN/TC 164 “Water
supply”, the secretariat of which is held by AFNOR.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 14367:2005.
— Scope was updated
— Accuracy chapter was added
— The whole systematic of testing and requirements was revised
— Annex B was deleted and replaced by a new one with order of tests
— All figures were updated
— Editorially revised
Introduction
In respect of potential adverse effects on the quality of water intended for human consumption, caused
by the product covered by this document:
a) This document provides no information as to whether the product might be used without
restriction in any of the Member States of the EU or EFTA.
b) while awaiting the adoption of verifiable European criteria, existing national regulations concerning
the use and/or the characteristics of this product remain in force.
1 Scope
This document specifies the:
— field of application:
— The dimensional, the physicochemical, the design, the hydraulic, the mechanical and the acoustic
characteristics of non-controllable backflow preventer with different pressure zones, family C,
type A, nominal sizes DN 6 to DN 25, nominal pressure PN 10.
It is applicable to:
— Family C, type A, class “a” for general use: devices of class “a” can be capable of working:
— at any pressure up to 1 MPa (10 bar);
— with any pressure variation up to 1 MPa (10 bar);
— at a supply temperature limit of 65 °C and 90 °C for 1 h;
— Family C, type A, class “b” for specific use: devices of class “b” shall be capable of working:
— at any downstream pressure up to 0,3 MPa (3 bar);
— with any downstream pressure variation up to 0,3 MPa (3 bar); at a supply temperature limit of
65 °C and 90 °C for 1 h;
Class “b” devices can capable of operating: at any downstream pressure up to 300 kPa (3 bar), with any
downstream pressure variation up to 300 kPa (3 bar) at a supply temperature limit of 65 °C and 90 °C
for 1 h. Class “b” devices with specific hydraulic and non-acoustic requirements and are intended to
equip filling devices physically integrated into a single-function (heating) or dual-function (heating and
domestic hot water) boiler.
It specifies also:
— test methods and requirements for verifying these characteristics;
— marking;
— presentation and the delivery.
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.
EN 1254 (all parts), Copper and copper alloys — Plumbing fittings
EN 1267, Industrial Valves — Test of flow resistance using water as test fluid
EN 1717, Protection against pollution of water intended for human consumption in potable water
installations and general requirements for devices to prevent pollution by backflow
EN ISO 228-1, Pipe threads where pressure-tight joints are not made on the threads — Part 1: Dimensions,
tolerances and designation (ISO 228-1)
EN ISO 3822-1:1999, Acoustics — Laboratory tests on noise emission from appliances and equipment used
in water supply installations — Part 1: Method of measurement (ISO 3822-1:1999)
EN ISO 3822-3:2018, Acoustics — Laboratory tests on noise emission from appliances and equipment used
in water supply installations — Part 3: Mounting and operating conditions for in line valves and
appliances(ISO 3822-3:2018)
EN ISO 6509-1, Corrosion of metals and alloys — Determination of dezincification resistance of brass
(ISO 6509-1:1981)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 1717 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp/
— IEC Electropedia: available at https://www.electropedia.org/
3.1
non controllable backflow preventer with different pressure zones — Family C — Type A
the specific characteristics of this device called “CA”, are as follows:
The device is divided into three zones:
— one upstream zone p ;
— one intermediate zone (p not measurable) vented to the atmosphere;
i
— one downstream zone p .
The device provides disconnection by venting the intermediate pressure zone to the atmosphere when
the difference of pressure between the intermediate zone and the upstream zone is less than 10 % of
the upstream pressure (p – p < 10 % p )
i 1 1
It ensures a discharge (backflow rate) through the intermediate zone, at least equal to the given
discharge flow rate
Means for the control of the protection device are not included
Key
p
1 Upstream zone
p
2 Intermediate zone
i
p
3 Downstream zone
4 Strainer (optional)
Figure 1 — Design principle
For the purposes of this document “Non controllable backflow preventer with different pressure
zones — Family C — Type A” is hereafter referred to as “device”.
3.2
specific use
use of the backflow protection device at the filling point of domestic sealed heating systems, class b only
4 Nominal size (denomination)
4.1 Class a device
The nominal size shall be in accordance with the flow rate in the Table 3.
4.2 Class b device
All Class b devices shall comply with the same performances requirements as a DN 6.
5 Designation
A non-controllable backflow preventer with different pressure zones family C, type A is designated by:
— family, its type and class;
— denomination (see Table 3) except class b device;
— connection type;
— material of its body;
— surface finish (possible coating);
— acoustic group except class b device;
— reference to the present standard.
EXAMPLE
Examples for a designation:
class a:
— Non controllable backflow preventer with different pressure zones, EN 14367, family C, type
A, class a, DN 20, G3/4 × G3/4, bronze, I,
class b:
— Non controllable backflow preventer with different pressure zones, EN 14367, family C, type
A, class b, M10 × 1, brass,
6 Symbolization
The graphic representation of the non-controllable backflow preventer with different pressure zones —
family C, type A is as follows:
a) Class a b) Class b
Figure 2 — Graphic symbol
7 Physico-chemical characteristics
7.1 Materials
The selection of materials is the responsibility of the manufacturer, provided they satisfy the following
requirements:
a) materials and coatings shall not contaminate the potable water;
b) in a technical document, the nature of the materials and coatings used shall be stated;
c) materials with inadequate corrosion resistance shall have additional protection;
d) the materials used shall be suitable for the temperatures specified in the tests in this document;
e) the materials, and in particular copper alloys, for which recommendations or international
standards exist, shall comply with the relevant European standards.
7.2 Nature of the materials
7.2.1 General
All materials coming into contact with water intended for human consumption shall present no health
risk nor cause any change to the water in terms of quality, appearance, smell or taste.
NOTE While awaiting the adoption of verifiable European criteria for testing materials in contact with water
intended for human consumption, existing national regulations concerning the use and/or the characteristics of
these products remain in force.
7.2.2 Dezincification resistant copper alloy
Copper-zinc alloys containing more than 15 % zinc are subject to dezincification when submitted to
water capable of dezincification. In the countries where the use of products made of dezincification
resistant materials is required, the materials used shall guarantee a dezincification depth less than
200 µm in any direction. For this purpose, materials shall be tested in accordance with EN ISO 6509-1
and the product shall be marked in compliance with the indications according to Clause 10.
7.2.3 Nature of apparent surfaces
Depending on the materials of the disconnectors, the outer and inner surfaces may or may not have a
coating. This coating shall not disturb the functional characteristics of the device.
7.2.4 Uncoated surface
The finish of surfaces should be free from appearance defects such as:
— Gales
— Cracks
— sand inclusions,
— machining “fire”,
— blows, tool bites
— scratches, etc. .
No disturb the functional characteristics of the device.
7.2.5 Surface with coating
It is strongly recommended not to use a so-called “decorative” coating for this type of product (Ni, Ni-
Cr .). Any use shall be justified by the holder.
Coated surfaces shall meet the requirements of article 5 of EN 248:2002.
7.2.6 Detection of residual stress
7.2.6.1 General
This test shall be performed for bodies made out of brass materials and with female threads according
to EN 10226-1 and compression ends according to EN 1254-2.
7.2.6.2 Test
This test is based on ISO 6957. Its purpose is to verify the resistance to cracking under stress corrosion
in ammonia medium (as described in 7.2.6.3, b)).
The test entails exposing test specimens consisting of the assembled device in an atmosphere loaded
with ammonia vapour.
7.2.6.3 Test method (Procedure)
The paragraph below details ISO 6957.
Test solution:
a) Use solutions of analysis quality and of distilled water.
b) Solution of ammonia at 20 % (in weight).
c) The pH of the test solution shall be adjusted to 9,5 by using hydrochloric acid.
d) The test temperature shall be (23 ± 2) °C with a measurement uncertainty of ± 1 K.
Test specimen:
e) The test specimen consists of three samples of a single assembled product. The test specimen shall
be inserted into the test enclosure under no stress.
7.2.6.4 Instructions
a) Rinse the test specimens with a clean non-chlorinated solvent (for example, ethanol).
b) Let it dry in the air.
c) Insert the test specimens into the test enclosure along with the ammonia solution. The volume of
the container made of glass (e.g. desiccator) shall be minimum (10 ± 1) l.
d) The volume of the solution inserted shall be (200 ± 10) ml per 3 l of total volume of the container
(e.g. for a 10 l container it means (667 ± 33) ml).
e) Place the test specimens in the container in such a way that they will not touch each other and that
they will not be in contact with the solution.
(+2)
After an exposure of 24 h, remove the test specimens and rinse them.
(−0)
7.2.6.5 Requirements
After the test, the devices shall be inspected visually for stress corrosion cracking. No cracking shall
occur on any component.
8 Design
8.1 General
a) Only the pressure of the water (upstream and/or downstream): shall have an effect of the function
of components of the device.
b) The settings of the springs shall be fixed and not adjustable.
c) As regards devices designed in such a way that the access to the internal parts is possible (for
inspection, repair or replacement), these components shall be able to be refitted at their initial place
without ambiguity (impossibility of reversal, interchange of obturators, diaphragms, springs, …). A
visible mark is not sufficient.
d) For the non-controllable backflow preventer with different pressure zones – Family C-Type
A-Class a: If the device includes a strainer:
— it located upstream of the upstream non-return system (see the Figure 1);
— it shall be easily removable for cleaning.
e) For the non-controllable backflow preventer with different pressure zones – Family C-Type
A-Class b: The complete device shall not be removable for maintenance service of the single parts of
Cab.
8.2 Relief valve
If the relief valve system operates by means of pilot tube then the cross section of the pilot tube shall be
2 2
equal to or greater than 45 mm for devices DN > 15 or 12,5 mm for devices DN ≤ 15 no dimension
being less than 4 mm.
The water passage through the discharge orifice shall have a cross-section of minimal 12,5 mm .
The smallest dimension used to calculate this cross-section shall not be inferior to 4 mm for non-
moving part.
The control of the relief valve shall be of positive safety, i.e. in case of rupture or leakage, the relief shall
be open.
This will be checked by examination of the behaviour of the device, after dismantling the control system
of the relief valve (diaphragm, piston seal …).
An air break to drain shall be placed at the discharge outlet. An air gap shall exist between any waste
drain and any means to collect the discharged water (floor, tundish, curb, sink …).
The device shall be capable, by design, evacuating the full relief flow rate as defined in 9.6.4 without
spilling to the outside of the air break to drain.
Class a device shall be equipped with:
The air break to drain shall meet the dimensional requirements of EN 1717.
This air break to drain shall be:
— either directly incorporated into the device;
— or factory fitted;
— or supplied with the device.
In the last two cases, the relief valve outlet of the device shall permit neither fitting of a standardized
threaded pipe, nor the connection by the inside of a standardized pipe or shape, be it by glue, welding or
interlocking.
Class b device shall be equipped with:
— At least two air inlets openings with each a minimum cross-section of 12,5 mm upstream of the
relief piping shall be incorporated.
The smallest dimension used to calculate this cross-section shall not be less than 4 mm.
— A relief device capable of mounting a standardized or flexible tube without disturbing the operation
of the discharge device system and without obstructing, even partially, the air inlet ports.
Characteristics and test methods General.
Performance tests shall be carried out on the device as installed in accordance with the manufacturer’s
technical documents.
9 Characteristics and tests methods
9.1 General
The performance tests shall be carried out on the device as installed in accordance with the
manufacturer’s technical documents.
If not specified, all tests shall be carried out with water at room temperature.
The examples illustrated in the figures are for illustrative purposes only. Laboratory equipment shall be
designed to ensure that the device can be tested in accordance with the requirement (e.g sensors
instead of column).
9.2 Accuracy of measurements
In the absence of any particular specifications:
— flow rate and pressure: ±2 % of the value specified;
— temperature: cold water ± 5 K of the value specified;
hot water ± 2 K of the value specified;
+10
— time:
% of the value specified;
— other values: ±5 % of the value specified.
9.3 Accuracy of measuring instruments
9.3.1 General
All the measuring instruments shall have a measurement accuracy of ± 2 % of the measured value,
except for temperature measurement accuracy shall be ± 1 K.
9.4 End connections
9.4.1 General
The connection shall be demountable without any damage to the piping and in accordance with
relevant European Standards e.g. EN 1254-20, EN ISO 228-1 and ISO 10226-1.
EXAMPLE Coupling nut, union.
9.4.2 Class a device
The threaded ends of the body of the device shall have a sufficient joint span to ensure a good seal
under stress and to prevent deterioration of the seals joints.
Connections which allow the device to be dismantled without deterioration of the pipe shall be supplied
with the device.
The interlocking of the pipe shall in no case be able to disturb the operation of the device (tube stop, .).
The dimension of threaded connections on the pipeline shall comply with the dimensional
specifications of standard EN 1254-20, EN I
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