SIST EN 13079:2026

Devices to prevent pollution by backflow of potable water - Air gap with injector - Family A - Type D

This document specifies the characteristics and the requirements of air gap with injector Family A, Type D for nominal flow velocity not exceeding 3 m/s. Air gaps are devices for protection of potable water in water installations from pollution by backflow. This document is applicable to air gaps in factory-assembled products and to constructed air gaps in situ and specifies requirements and methods to verify and ensure compliance with this document during normal working use.
The fluid in the receiving vessel is assumed to have similar properties to the water supply. Where this is not the case, additional care or tests can be required to verify the efficacy of the solution in practical use.
The AD device is intended to be used in potable water installations according to EN 806 (all parts).

Sicherungseinrichtungen zum Schutz des Trinkwassers gegen Verschmutzung durch Rückfließen - Freier Auslauf mit Injektor - Familie A - Typ D

Dieses Dokument legt die Eigenschaften und Anforderungen für freie Ausläufe mit Injektor, Familie A, Typ D, für Nenn-Fließgeschwindigkeiten bis 3 m/s fest. Freie Ausläufe sind Sicherungseinrichtungen zum Schutz des Trinkwassers vor Verunreinigungen durch Rückfließen in Trinkwasser-Installationen. Dieses Dokument ist anwendbar für freie Ausläufe von werkseitig hergestellten Bauteilen sowie für vor Ort gebaute freie Ausläufe und legt Anforderungen und Verfahren fest, um im üblichen Betrieb eine Übereinstimmung mit diesem Dokument zu überprüfen und sicherzustellen.
Es wird angenommen, dass die Flüssigkeit in dem versorgten Behälter ähnliche Eigenschaften wie die Wasserversorgung aufweist. Ist dies nicht der Fall, können besondere Sorgfalt oder zusätzliche Prüfungen erforderlich sein, um die Wirksamkeit der Lösung im praktischen Einsatz sicherzustellen.
Die AD-Einrichtung ist für die Verwendung in Trinkwasser-Installationen nach EN 806 (alle Teile) bestimmt.

Dispositifs de protection contre la pollution de l'eau potable par retour - Surverse par injecteur - Famille A - Type D

Le présent document spécifie les caractéristiques et les exigences relatives aux surverses par injecteur de la Famille A, Type D, pour des débits nominaux n’excédant pas une vitesse de 3 m/s. Les surverses sont des dispositifs destinés à protéger l’eau potable des installations d’eau contre la pollution par retour. Le présent document s’applique à la fois aux surverses faisant partie de produits manufacturés en usine et à celles réalisées sur site. Il spécifie les exigences et les méthodes permettant de vérifier et d’assurer la conformité au présent document dans des conditions de service normales.
Le fluide dans le réceptacle est supposé posséder des propriétés similaires à celui du système de distribution d’eau. Lorsque ce n’est pas le cas, il peut être nécessaire de redoubler d’attention ou de mener des essais supplémentaires afin de vérifier l’efficacité de la solution en pratique.
Le dispositif AD est destiné à être utilisé dans des installations d’eau potable conformément à l’EN 806 (toutes les parties).

Naprave za preprečevanje onesnaženja pitne vode s povratnim tokom - Zračna reža z injektorjem - Družina A - Tip D

General Information

• Status: Published
• Public Enquiry End Date: 30-May-2024
• Publication Date: 17-Nov-2025
• ICS: 13.060.20 - Drinking water
• ICS: 23.060.99 - Other valves
• ICS: 91.140.60 - Water supply systems
• Technical Committee: IOVO - Water supply and waste water engineering
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 14-Nov-2025
• Due Date: 19-Jan-2026
• Completion Date: 18-Nov-2025
• Directive: 305/2011 - Regulation (eu) No 305/2011 of the European Parliament and of the Council of 9 march 2011 laying down harmonised conditions for the marketing of construction products and repealing council directive 89/106/eec
• Ref Project: EN 13079:2025 - Devices to prevent pollution by backflow of potable water - Air gap with injector - Family A - Type D

Relations

• Revises: SIST EN 13079:2004 - Devices to prevent pollution by backflow of potable water - Air gap with injector - Family A - Type D
• Effective Date: 28-Jan-2023

Overview

EN 13079:2025 - Devices to prevent pollution by backflow of potable water - Air gap with injector - Family A - Type D - is a CEN standard that specifies design, testing and verification requirements for air gaps with injector (Family A, Type D) used to protect potable water installations from backflow contamination. The standard applies to factory‑assembled units and to air gaps constructed in situ, for nominal flow velocities not exceeding 3 m/s. It is intended for use in installations conforming to EN 806 (all parts).

Key topics and technical requirements

• Device components: upstream injector orifice, air break to drain (or discharge to atmosphere), downstream receiving orifice, and receiving vessel (vented to atmosphere).
• Materials: all materials in contact with drinking water must present no health risk and must be compatible with the water and other fluids they may contact.
• Air gap distance (A): horizontal measurement from the injector terminal to the receiving orifice or anti‑splashing plate. Minimum values depend on injector diameter D:
  • D > 10.0 mm → A = 2D
  • D 3.5–10.0 mm → A = 20 mm
  • D 2.5–3.4 mm → A = 15 mm
  • D 0–2.4 mm → A = 10 mm
• Flow calculation and testing: incoming flow Q can be calculated by Q = 0.14 · D (l/min). If Q cannot be achieved, a dynamic pressure of 1 MPa (10 bar) is applied at the inlet for testing.
• Performance and tolerances: flow/pressure tolerance ±2%; temperature ±5 °C for cold water; measuring instruments error limit ±2%.
• Drainage and vents: intermediate zone must drain the maximum incoming flow without rise to feed orifice; atmospheric vents (if used) must be at least 4 mm in all directions.
• Design options: optional anti‑splashing plate and warning pipe; standard includes a validation/verification procedure and revised minimum gap dimensions compared to the 2003 version.

Applications

• Backflow prevention in building water supply systems (residential, commercial and some industrial processes) where an injector‑type air gap is suitable.
• Protection of potable water in installations covered by EN 806 (installation design, operation and maintenance).
• Use in both new installations and retrofit solutions where an air break to atmosphere and receiving vessel arrangement is required.

Who should use this standard

• Water system designers and consulting engineers
• Plumbing product manufacturers and installers
• Building services and facilities managers
• Test laboratories performing backflow and air‑gap validation

Related standards

• EN 806 (all parts) - specifications for installations inside buildings conveying water for human consumption
• EN 1717 - protection against pollution of potable water and general requirements for backflow prevention devices

Keywords: EN 13079:2025, air gap with injector, backflow prevention, potable water, Family A Type D, EN 806, receiving vessel, anti‑splashing plate.

Standards Content (Sample)

SLOVENSKI STANDARD
01-januar-2026
Naprave za preprečevanje onesnaženja pitne vode s povratnim tokom - Zračna
reža z injektorjem - Družina A - Tip D
Devices to prevent pollution by backflow of potable water - Air gap with injector - Family
A - Type D
Sicherungseinrichtungen zum Schutz des Trinkwassers gegen Verschmutzung durch
Rückfließen - Freier Auslauf mit Injektor - Familie A - Typ D
Dispositifs de protection contre la pollution de l'eau potable par retour - Surverse par
injecteur - Famille A - Type D
Ta slovenski standard je istoveten z: EN 13079:2025
ICS:
13.060.20 Pitna voda Drinking water
23.060.99 Drugi ventili Other valves
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.

EN 13079
EUROPEAN STANDARD
NORME EUROPÉENNE
November 2025
EUROPÄISCHE NORM
ICS 13.060.20; 91.140.60 Supersedes EN 13079:2003
English Version
Devices to prevent pollution by backflow of potable water
- Air gap with injector - Family A - Type D
Dispositifs de protection contre la pollution de l'eau Sicherungseinrichtungen zum Schutz des Trinkwassers
potable par retour - Surverse par injecteur - Famille A - gegen Verschmutzung durch Rückfließen - Freier
Type D Auslauf mit Injektor - Familie A - Typ D
This European Standard was approved by CEN on 18 May 2025.

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, Türkiye 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
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 13079:2025 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Designation . 6
5 Symbolization . 6
6 Materials . 6
7 Requirements . 7
7.1 General. 7
7.2 Characteristics and tests . 7
7.2.1 General. 7
7.2.2 General tolerances and measurements . 7
7.2.3 Accuracy of measuring instruments . 7
7.2.4 Measurements . 7
7.3 Upstream feed orifice . 7
7.4 Downstream receiving orifice . 7
7.5 Receiving vessel. 8
7.6 Discharge from the intermediate zone . 8
7.7 Air gap (Distance “A”) . 8
7.7.1 General. 8
7.7.2 Single supply to a single receiving vessel . 10
7.7.3 Multiple supplies to a single receiving vessel . 10
7.8 Verification . 10
8 Marking . 12
9 Technical documents . 12

European foreword
This document (EN 13079:2025) has been prepared by Technical Committee CEN/TC164 “Water
supply”, the secretariat of which is held by AFNOR.
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 May 2026, and conflicting national standards shall be
withdrawn at the latest by May 2026.
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 13079:2003.
— terms and definitions have been adjusted;
— Clause 7.7, Air gap was revised by reducing the minimum size of the air gap;
— added an optional anti-splashing plate;
— validation procedure has been introduced;
— Figure 3 was divided in 2 figures and revised;
— the entire standard was revised editorially.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organisations 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, Türkiye and the United
Kingdom.
Introduction
In respect of potential adverse effects on the quality of water intended for human consumption, caused
by the product covered by this document, it provides no information as to whether the product may be
used without restriction in any of the Member State of the EU or EFTA.
NOTE Attention is drawn to existing national regulations concerning the use and/or the characteristics of this
product that can apply.
1 Scope
This document specifies the characteristics and the requirements of air gap with injector Family A,
Type D for nominal flow velocity not exceeding 3 m/s. Air gaps are devices for protection of potable water
in water installations from pollution by backflow. This document is applicable to air gaps in factory-
assembled products and to constructed air gaps in situ and specifies requirements and methods to verify
and ensure compliance with this document during normal working use.
The fluid in the receiving vessel is assumed to have similar properties to the water supply. Where this is
not the case, additional care or tests can be required to verify the efficacy of the solution in practical use.
The AD device is intended to be used in potable water installations according to EN 806 (all parts).
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 806-1, Specifications for installations inside buildings conveying water for human consumption —
Part 1: General
EN 806-5:2012, Specifications for installations inside buildings conveying water for human consumption —
Part 5: Operation and maintenance
EN 1717, Protection against pollution of potable water in water installations and general requirements of
devices to prevent pollution by backflow
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 806-1 and 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
air gap with injector Family A, Type D
permanent and horizontal distance between the upstream injector orifice and the downstream receiving
orifice, having an air break to drain and a receiving vessel
Note 1 to entry: See Figure 1 for the design principle.

Figure 1 — Design principle
3.2
upstream feed orifice
D
internal diameter size of the upstream injector orifice (or calculated from the equivalent cross-sectional
area)
3.3
downstream receiving orifice
pipework that receives the water directed across the full air gap from the upstream injector orifice and
discharges the water into the receiving vessel
3.4
receiving vessel
vessel that the downstream receiving orifice pipework discharges into and then supplies the downstream
pipework to process
Note 1 to entry: The receiving vessel is vented to atmosphere.
3.5
maximum incoming flow rate
maximum total flow rate determined by the sum of the individual flow rates of each inlet orifice for
multiple inlets
4 Designation
An air gap with injector Family A — Type D is designated by:
— name;
— reference to this document EN 13079;
— family and type;
— maximum operating flow rate (Q).
EXAMPLE Air gap, EN 13079, Family A — Type D, 14 l/min.
5 Symbolization
The graphic representation of the air gap with injector Family A — Type D is as follows (see Figure 2).

Figure 2 — Graphic symbol
6 Materials
All materials coming i
...