EN 858-2:2003

SLOVENSKI STANDARD
01-oktober-2003
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Separator systems for light liquids (e.g. oil and petrol) - Part 2: Selection of nominal size,
installation, operation and maintenance
Abscheideranlagen für Leichtflüssigkeiten (z.B. Öl und Benzin) - Teil 2: Wahl der
Nenngröße, Einbau, Betrieb und Wartung
Installations de séparation de liquides légers (p.e. hydrocarbures) - Partie 2: Choix des
tailles nominales, installation, service et entretien
Ta slovenski standard je istoveten z: EN 858-2:2003
ICS:
13.060.99 Drugi standardi v zvezi s Other standards related to
kakovostjo vode water quality
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 858-2
NORME EUROPÉENNE
EUROPÄISCHE NORM
January 2003
ICS 13.060.30
English version
Separator systems for light liquids (e.g. oil and petrol) - Part 2:
Selection of nominal size, installation, operation and
maintenance
Installations de séparation de liquides légers (par exemple Abscheideranlagen für Leichtflüssigkeiten (z.B. Öl und
hydrocarbures) - Partie 2: Choix des tailles nominales, Benzin) - Teil 2: Wahl der Nenngröße, Einbau, Betrieb und
installation, service et entretien Wartung
This European Standard was approved by CEN on 29 September 2001.
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
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
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 858-2:2003 E
worldwide for CEN national Members.

Contents
page
Foreword.3
1 Scope .3
2 Normative references .3
3 Terms and definitions.4
4 Determination of type and size of separator systems .4
4.1 General.4
4.2 Components of separator systems, their combination and application.4
4.2.1 General.4
4.2.2 Bypass separators.4
4.2.3 Classes of separators.5
4.3 Sizing of separators.5
4.3.1 General.5
4.3.2 Factors .5
4.3.3 Combined drainage of rainwater and wastewater.6
4.3.4 Wastewater .6
4.3.5 Rainwater flow rate .8
4.3.6 Spillages .8
4.3.7 Quantity of light liquid.8
4.3.8 Special cases.9
4.4 Sludge traps .9
5 Installation .9
5.1 Limitations.9
5.2 Retention of light liquid.10
5.3 Automatic warning devices and electrical devices.10
5.4 Drainage to and from separator systems.10
5.5 Place of installation .10
5.6 Protection against escape of light liquids.10
5.7 Connection to the drainage system.12
6 Operation, inspection and maintenance .12
Annex A (informative)  Density factor f for particular light liquids and combination of components.14
d
Annex B (informative) Configuration and application of separator systems.17
Bibliography .20
Foreword
This European Standard (EN 858-2:2003) has been prepared by Technical Committee CEN/TC 165 "Wastewater
engineering", 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 July 2003, and conflicting national standards shall be withdrawn at the latest by
July 2003.
It is the second part of a two part standard for separator systems for light liquids. Part 1 gives principles of design,
performance and testing, marking and quality control of separator systems for light liquids.
When pollution control requires the treatment of pollutants other than light liquids, additional measures can be
necessary.
The annexes A and B are informative.
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.
1 Scope
This European Standard applies to separator systems used to separate hydrocarbons of mineral origin from
wastewater. It does not apply to grease and oils of vegetable or animal origin nor to separation of emulsions or
solutions.
This European Standard provides guidance on the selection of nominal sizes, as well as the installation operation
and maintenance of light liquid separators manufactured in accordance with EN 858-1. It also gives advice on the
suitability of cleansing agents if they are discharged to a separator.
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 752-2, Drain and sewer systems outside buildings — Part 2: Performance requirements.
EN 752-4, Drain and sewer systems outside buildings — Part 4: Hydraulic design and environmental consideration.
EN 858-1:2002, Separator systems for light liquids (e.g. oil and petrol) — Part 1: Principles of design, performance
and testing, marking and quality control.
3 Terms and definitions
For the purposes of this European Standard, the terms and definitions given in EN 858-1 as well as the following
term and definition apply.
3.1
cleansing agent
chemical substance which, when combined with light liquids, initially forms an emulsion during cleaning process
that rapidly breaks down in the separator
4 Determination of type and size of separator systems
4.1 General
Separator systems are used in a wide variety of situations to fulfil a number of different requirements. It is important
to establish why a separator system is needed and what specific function it is expected to fulfil before selecting the
appropriate size and type of installation.
Generally, separator systems are installed for one or more of the following reasons:
a) to treat waste water (trade effluent) from industrial processes, vehicle washing, cleansing of oil covered parts
or other sources, e.g. petrol station forecourts;
b) to treat oil contaminated rainwater (run-off) from impervious areas, e.g. car parks, roads, factory yard areas;
c) to retain any spillage of light liquid and to protect the surrounding area.
Where there is no specific sizing method given by a regulatory authority the following guidance on sizing of the
separator system shall be used:
4.2 Components of separator systems, their combination and application
4.2.1 General
The component parts of separator systems complying with EN 858-1 are listed in Table 1.
Table 1 — Components of separator systems
Components Code letter
Sludge trap S
Separator Class II II, II b (for bypass separators)
Separator Class I I, I b (for bypass separators)
Sampling shaft P
Annex B gives guidance on the selection of components to suit particular applications.
4.2.2 Bypass separators
Bypass separators include a device to allow a flow in excess of the maximum permissible flow to bypass the
separator.
Bypass separators are not suitable for category a) uses (see 4.1). They shall be used only in locations where it is
unlikely that there will be significant hydrocarbon contamination during times of heavy rainfall.
Separator systems shall not surcharge or cause surcharging upstream when subject to their maximum design flow.
4.2.3 Classes of separators
Classes of separators (class I and II) are defined in EN 858-1:2002, clause 4.
Class I separators provide a higher degree of separation than class II separators (see Table B.2 for applications).
4.3 Sizing of separators
4.3.1 General
The sizing of light liquid separators shall be based on the nature and flow rate of the liquids to be treated and will
need to take account of:
 maximum flow rate of rain water;
 maximum flow rate of waste water (trade effluent);
 density of the light liquid;
 presence of substances that may impede separation (e.g. detergents).
The sizing does not take into account special operational conditions (see 4.3.8).
The size of the separator shall be calculated from the following formula:
NS = (Q + f ⋅ Q ) f (1)
r x s d
where
NS is the nominal size of the separator;
is the maximum flow rate of rainwater, in l/s;
Q
r
Q is the maximum flow rate of wastewater, in l/s;
s
f is the density factor for the relevant light liquid;
d
f is the impediment factor depending on the nature of the discharge.
x
4.3.2 Factors
4.3.2.1 Impediment factor f
x
The impediment factor f allows for unfavourable separating conditions, e.g. where detergents are present in the
x
wastewater. The minimum recommended impediment factors are listed in Table 2.
Table 2 — Minimum impediment factors f
x
f
Discharge type in accordance with 4.1
x
a) 2
not relevant as Q = 0 (only rainwater)
b)
s
c) 1
4.3.2.2 Density factor f
d
The density factor f allows for differing densities of light liquids when using different combinations of system
d
components. Additional information is given in annex A.
Table 3 — Density factors f
d
Density up to 0,85 over 0,85 up to 0,90 over 0,90 up to 0,95
g/cm³
Density factor f
Combination
d
S-II-P 1 2 3
a a a
S-I-P
1 1,5 2
b b b
S-II-I-P
1 1 1
a
For class I separators operating by gravity only, use f for class II separator.
d
b
For class I and class II separators.
4.3.2.3 Cleansing agents
Cleansing agent manufacturers shall submit a declaration stating that the product is free from organically co
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