Bsi bs en 13078 2003 (2008)

BRITISH STANDARD BS EN 13078 2003 Devices to prevent pollution by backflow of potable water — Air gap with submerged feed incorporating air inlet plus overflow — Family A, type C The European Standard[.]

Devices to prevent

pollution by backflow

of potable water — Air

gap with submerged

feed incorporating air

inlet plus overflow —

Family A, type C

The European Standard EN 13078:2003 has the status of a

British Standard

ICS 13.060.20; 23.060.99

Confirmed November 2008

This British Standard, was

published under the authority

of the Standards Policy and

Strategy Committee on

8 December 2003

© BSI 8 December 2003

ISBN 0 580 43024 3

National foreword

This British Standard is the official English language version of

EN 13078:2003

The UK participation in its preparation was entrusted by Technical Committee B/504, Water supply, to Subcommittee B/504/4, Backflow prevention devices, which has the responsibility to:

A list of organizations represented on this subcommittee can be obtained on request to its secretary

Cross-references

The British Standards which implement international or European

publications referred to in this document may be found in the BSI Catalogue

under the section entitled “International Standards Correspondence Index”, or

by using the “Search” facility of the BSI Electronic Catalogue or of British

Standards Online

This publication does not purport to include all the necessary provisions of a contract Users are responsible for its correct application

Compliance with a British Standard does not of itself confer immunity from legal obligations.

— aid enquirers to understand the text;

— present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the

UK interests informed;

— monitor related international and European developments and promulgate them in the UK

Summary of pages

This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 13 and a back cover

The BSI copyright notice displayed in this document indicates when the document was last issued

Amendments issued since publication

EUROPÄISCHE NORM November 2003

ICS 13.060.20; 23.060.99

English version

Devices to prevent pollution by backflow of potable water - Air

gap with submerged feed incorporating air inlet plus overflow

-Family A, type C

Dispositifs de protection contre la pollution de l'eau potable

par retour - Surverse avec alimentation immergée

incorporant une entrée d'air et un trop plein - Famille A,

type C

Sicherungseinrichtungen zum Schutz des Trinkwassers gegen Verschmutzung durch Rückfließen - Freier Auslauf mit belüftetem Tauchrohr und Überlauf - Familie A, Typ C

This European Standard was approved by CEN on 1 September 2003.

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 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 Management Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATION

C O M I T É E U R O P É E N D E N O R M A L I S A T I O N

E U R O P Ä I S C H E S K O M I T E E F Ü R N O R M U N G

Management Centre: rue de Stassart, 36 B-1050 Brussels

© 2003 CEN All rights of exploitation in any form and by any means reserved Ref No EN 13078:2003 E

Foreword 3

Introduction 4

1 Scope 5

2 Normative references 5

3 Terms and definitions 5

4 Symbolization 6

5 Designation 6

6 Materials 6

7 Requirements 7

7.1 General 7

7.2 Water inlet device 7

7.3 Overflow arrangement 7

7.4 Air gap (distance) 7

7.5 Verification of the air gap 8

7.6 Efficiency of the air inlet orifice 8

8 Marking (not required for site constructed products) 9

9 Technical documents 9

Annex A (normative) Vacuum test 11

A.1 General 11

A.2 Principle 11

A.3 Apparatus 11

A.4 Procedure 11

This document (EN 13078:2003) has been prepared by Technical Committee CEN/TC 164 “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 2004, and conflicting national standards shall be withdrawn at the latest by May 2004

Annex A is normative

According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland 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 standard:

a) this standard provides no information as to whether the product may be used without restriction in any of the Member State of the EU or EFTA;

b) it should be noted that, 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 European Standard specifies the characteristics and the requirements of air gaps with submerged feed incorporating air inlet and an overflow, Family A, type C Air gaps are devices for protection of potable water in water installations from pollution This standard applies to air gaps in factory assembled products and to constructed air gaps in situ and defines the physico-chemical characteristics of materials of construction used for the purpose and application to ensure compliance with this standard during normal working use

Annex A specifies the vacuum test

2 Normative references

This European Standard incorporates by dated or undated reference, provisions from other publications These normative references are cited at the appropriate places in the text, and the publications are listed hereafter For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision For undated references the latest edition of the publication referred to applies (including amendments)

EN 1717:2000, Protection against pollution of potable water in water installations and general requirements of devices to prevent pollution by backflow

EN 837-1, Pressure gauges – Part 1: Bourdon tube pressure gauges – Dimensions, metrology, requirements and testing

3 Terms and definitions

For the purposes of this European Standard, the terms and definitions given in EN 1717:2000, and the following apply

3.1

air gap with submerged feed incorporating air inlet plus overflow Family A, type C

"A C" air gap is a permanent and vertical distance between the lowest point of the air inlet orifice in the feed pipe and the critical water level at which the container overflows

NOTE See Figure 1 for the design principle

Figure 1 — Design principle 3.2

spillover level

level at which water will start to overflow the receiving vessel with all outlets closed

3.3

critical water level

physical or piezometric level of the liquid reached in any part of the appliance 2 s after closing the water inlet starting from maximum fault level

3.4

dimension h

height between the spillover level and the critical level

3.5

maximum level

highest water level H reached above the spillover level under positive pressure fault conditions with all outlets closed

3.6

splashing

when contamination from microbiological or viral elements is likely to occur and when maintaining the maximum flow rate at the normal operational level, will contact be observed between the air inlet orifice and the liquid in the receiving vessel due to the splashing, foaming or turbulence, the air gap will be increased to a point where no contact is observed

3.7

diameter of feed pipe (bore D )

diameter D is the maximum internal diameter found within the last metre of the supply pipe or the DN of the inlet connection

NOTE The dimension is in millimetres

4 Symbolization

The graphic representation of the air gap with submerged feed incorporating air inlet plus overflow Family A, type C

is as follows (see Figure 2)

Figure 2 — Graphic symbol

5 Designation

An air gap with submerged feed incorporating air inlet plus overflow Family A, type C is designated by:

 name;

 family and its type;

 denomination (see 3.7 DN or D);

 reference to this standard

EXAMPLE Air gap, EN 13078, Family A, type C, DN 15

6 Materials

The manufacturer shall state the type of materials chosen in his technical and commercial documents

The materials used in water installations, including the materials of protection units in contact with drinking water, shall satisfy the European Standards and national acceptance criteria and/or national restrictions for use currently

in force in EU and EFTA

They shall be compatible among themselves, with the water supplied and with the fluids or substances that can come into contact with them

There are no special requirements concerning the materials used downstream of the atmospheric outlet opening provided they do not have any harmful effect on the upstream part

7 Requirements

7.1 General

The protection assembly comprises four parts integral with one another:

 water inlet device;

 receiving vessel (container);

 air inlet orifice;

 overflow

7.2 Water inlet device

Every float-operated valve or other device, which controls the inflow of water to receiving vessel, shall be securely and rigidly fixed to that vessel

Every feed pipe supplying water to such a valve or other device shall be fixed in its position to prevent it from moving or buckling

The air inlet orifice shall not come into contact in any way with a product from downstream; it shall always be above the maximum level H

Adjustable or dismantle able joints to submerged supply pipes to the inlet device are not permitted below the critical level Submerged supply pipes shall be made from corrosion resistant materials and be pressure tested as part of the inlet device

7.3 Overflow arrangement

The overflow arrangements shall not be less than 19 mm internal diameter

The overflow arrangements shall include an air break prior to a connection to drain An air break to drain shall comply with the requirements of EN 1717, excluding WCs

7.4 Air gap (distance)

7.4.1 Single supply

For air gaps Family A, type C the critical water level shall be established and the air gap distance A measured from the lowest point of the air inlet orifice to the critical water level and shall also satisfy the vacuum test in annex A (see Figure A.1) The distance A is ≥ 20 mm for valves not exceeding G½, ≥ 25 mm for valves exceeding G½ but not exceeding G¾ and 2 D for valves exceeding G¾

The distance h is determined by measurement of the depth of water above the spillover level of the overflow 2 s

the overflow) based on a velocity of 3 m/s, or the maximum recommended flow rate for manufactured appliances when the flow rate is higher than Q

7.4.2 Multiple supplies

In the case of multiple feed pipes to a single vessel having an overflow, the distance of the air gaps for the potable water supply shall be dimension A above the critical water level The critical water level (3.3) shall be determined 2

s after stopping the inflow with all feed pipes discharging at an individual inflow calculated at Q = 0,14D2 If the flow rate Q cannot be achieved, apply a dynamic pressure of 1 MPa (10 bar) on all inlets No feed orifice shall be less than distance A above the critical water level

For calculating air gap A, use:

∑

2 D

7.4.3 Backflow/Backpressure

If the receiving vessel can be subject to positive pressure backflow, it is important that the inlet orifice is positioned

so that the ascending/returning backflow fluid cannot contaminate it

When the air gap is part of an installation which can generate positive pressure backflow it is essential that a means of limiting the flow rate to a rate which shall not compromise the overflow arrangement is incorporated, i.e non-return valve fitted upstream of the pressurisation unit

Potable water inlets shall terminate at a higher level than non-potable inlets and never closer than 2 D measured horizontally and vertically downward

7.5 Verification of the air gap

Verification can be achieved by test

a) Procedure for verification by test (see 7.4.1 and 7.4.2):

 Close all outlets (except the overflow);

 Identify D' ;

 Calculate Q ;

 Apply flow rate Q and maintain maximum water level;

 Note contact with inlet device(s) air inlet orifice during filling and at maximum level;

 Stop flow rate Q ;

 After 2 s establish distance h ;

 Measure air gap between distance h and lowest point of the air inlet orifice

b) Requirements:

 No contact between the downstream fluid and the air inlet orifice

 The measured air gap shall meet the requirements of dimension A (see 7.4)

7.6 Efficiency of the air inlet orifice

a) Procedure for vacuum test is specified in annex A;

b) Requirement.

There shall be no backflow

8 Marking (not required for site constructed products)

Each appliance incorporating an air gap with submerged feed incorporating air inlet plus overflow Family A, type C shall be clearly and permanently marked and accessibly visible

Marking shall indicate:

a) Manufacturer’s brand or logo;

b) letter indicating family and type of air gap;

c) denomination (DN or D);

d) reference to this European Standard

Following information to be given where possible:

e) reference (type or model, etc.);

f) serial number

9 Technical documents

The manufacturer’s documentation shall include the appropriate installation requirements to ensure that the air gap

is not compromised, including positive pressure backflow

Key

A Air gap (distance)

D Internal diameter of feed pipe (bore)

H Maximum level

1 Feed pipe

2 Feed orifice

3 Receiving vessel

4 Spillover level

5 Air inlet

6 Critical level (distance h)

7 Air break to drain

Figure 3 — Air gap with submerged feed incorporating air inlet plus overflow Family A, type C

Annex A

(normative)

Vacuum test

A.1 General

The test is used to verify the efficacy of the air gap orifice of Family A, type C air gaps

A.2 Principle

Under a vacuum test observation of the transparent tube or water trap for no visible evidence of backflow of water

A.3 Apparatus

NOTE Examples shown in the Figures are for guidance only Laboratory equipment should be designed to ensure that the device could be tested in accordance with the specified requirements

A.3.1 General

The test apparatus shall be arranged and constructed as shown in Figure A.1 so that the absolute pressure measured near the device under test on its supply side remains less than 0,05 MPa (0,5 bar) for at least 5 s NOTE These conditions indicate the existence of choking airflow Details of the components are given in A.3.2 to A.3.5

A.3.2 Vacuum vessel and connecting pipe, of sufficient strength to support a total vacuum safety The vacuum

vessel shall be provided with a drain cock to remove any water drawn into the vessel during the test

NOTE Recommended capacities of the vacuum vessel are given in Table A.1

A.3.3 Vacuum device, capable of reducing the absolute pressure within the vacuum vessel to 20 kPa

(200 mbar) (-80 kPa (-800 mbar) gauge pressure)

A.3.4 Pipes and fittings, of nominal size not less than the bore of the orifice at the lowest part of the inlet of feed

part of the device under test The connecting pipe shall be of transparent material or alternatively a transparent water trap shall be employed

Any valve fitted in the test pipe shall be a full-way valve offering an unimpeded flow path

Connections to the vacuum vessel shall not unduly impede the fluid flow and shall have a low loss pipe

A.3.5 Vacuum gauges, 100 kPa (1 bar) to 0 kPa (0 bar) (0 kPa (0 bar) to 100 kPa (1 bar) gauge pressure)

complying with EN 837-1, class 1 The gauge connection shall be made in such a way that it does not disturb the flow in the pipework

A.4 Procedure

Remove or render inoperative any upstream additional backflow prevention devices

Connect the fitting to be tested to the test apparatus