ISO 8573-1:1991
(Main)Compressed air for general use — Part 1: Contaminants and quality classes
Compressed air for general use — Part 1: Contaminants and quality classes
Air comprimé pour usage général — Partie 1: Polluants et classes de qualité
Komprimiran zrak za splošno uporabo - 1. del: Zamazanost in kakovostni razredi
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IS0
INTERNATIONAL
STANDARD
8573-l
First edition
1991-12-15
Compressed air for general use -
Part 1:
Contaminants and quality classes
Air cornprim pour usage g&M-al -
Partie I: Polluants et classes de qualit
-__I__
--
Reference number
____~ --- - -- IS0 8573-l : 1991 (E)
---------------------- Page: 1 ----------------------
IS0 85734:1991(E)
Contents
Page
Scope . . . . . . . . . . . . . . . . . . . . . . .
Definitions . . . . . . . . . . . . . . . .
Units . . . . . . . . . . . . . . . . . . . . . . .
The compressed-air system
......................... 3
Contaminants .
............ .................................... 6
Compressed-air quality classes
Annex
8
,.,.
A Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
0 IS0 1991 '
All rights reserved. No part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanicat, including photocopying and microfilm, without
permission in writing from the publisher.
tnternationat Organization for Standardtzatton
Case Postate 56 l CH-1211 Gen&ve 20 l Switzerland
Printed in Switzerland
ii
---------------------- Page: 2 ----------------------
IS0 85734:1991(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work
of preparing International Standards is normally carried out through IS0
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, govern-
mental and non-governmental, in liaison with ISO, also take part in the
work. IS0 collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an lnter-
national Standard requires approval by at least 75 % of the member
bodies casting a vote.
International Standard IS0 8573-l was prepared by Technical Committee
ISO/TC 118, Compressors, pneumatic tools and pneumatic machines,
Sub-Committee SC 4, Quality of compressed air.
IS0 8573 consists of the following parts, under the general title Com-
pressed air for general use:
- Part I: Contaminants and quality classes
-- Part 2: Test methods
Annex A of this part of IS0 8573 is for information only.
---------------------- Page: 3 ----------------------
IS0 85734:1991(E)
Introduction
It is not possible using most test methods to measure the full flow area
of a compressed-air stream and therefore it is necessary to take sam-
ples of the air. This method of testing has a major drawback in that oil,
for example, is not evenly distributed over the flow area.
Measurements should preferably be carried out at the actual operating
pressure and temperature of a compressor as otherwise the balance
between contaminants in liquid, aerosol or gaseous form will be altered.
Liquid oil and free water in particular tend to cling to pipe and tube walls
where they form a film or thin rivulets.
The content of water, oil and particles in compressed air varies owing
to sudden changes in the intake air, to the wear of components as well
as to changes in flow, pressure, temperature and ambient conditions.
Therefore the quality classes of a compressed-air system have to be
based on the mean value of a number of measurements carried out over
a specified period of time.
Recommended methods for measuring the oil content of compressed
air will be given in IS0 8573-2.
iv
---------------------- Page: 4 ----------------------
INTERNATIONAL STANDARD
IS0 8573-l :1991 (E)
Compressed air for general use -
Part 1:
Contaminants and quality classes
2.6 Brownian movement: Random movement of
1 Scope
small particles suspended in a fluid.
This part of IS0 8573 specifies quality classes of in-
2.7 coalescence: Action by which liquid particles in
dustrial compressed air for general use (e.g. for
suspension unite to form larger particles.
workshops, the construction industry, pneumatic
transport, etc.) without consideration of the quality
of the air when it is discharged from the
2.8 compression drying: Drying of air by com-
compressor. The quality class of compressed air for
pressing it to a higher pressure, cooling it and ex-
a particular application has to be based on the mean
tracting the water condensed, and finally expanding
value of several measurements carried out over a
it to the required pressure.
specific period of time and under defined operating
conditions.
2.9 contaminant: Any material or combination of
materials (solid, liquid or gaseous) which adversely
This part of IS0 8573 is not applicable to com-
affects the system or the operator.
pressed air for direct breathing and for medical use.
2.10 dewpoint: Temperature at which vapour be-
gins to condense.
2 Definitions
2.10.1 atmospheric dewpoint: Dewpoint measured
For the purposes of this part of IS0 8573, the follow-
at atmospheric pressure.
ing definitions apply.
NOTE 1 The term atmospheric dewpoint should not be
used in connection with compressed-air drying.
2.1 abrasion: Surface wearing of material by
mechanical action between solids.
2.10.2 pressure dewpoint: Dewpoint at the actual
pressure of the compressed air (this pressure
2.2 absorption: Process of attraction of one sub-
should be stated).
stance into another, so that the absorbed substance
disappears physically.
2.11 diffusion: Movement of gas molecules or small
particles caused by a concentration gradient.
2.3 adsorption: Attraction and adhesion of gaseous
and liquid molecules to the surface of a solid.
2.12 direct interception: Filtration effect in which a
droplet or a solid particle collides with an element
2.4 aerosol: Suspension in a gaseous medium of
solid particles, liquid particles or solid and liquid of a filter medium (e.g. fibre or granule) which is in
its direct path or is captured by pores of diameter
particles having a negligible fall velocity (generally
smaller than the diameter of the droplet or particle.
less than 0,25 m/s
2.5 agglomerate: Group of two or more particles 2.13 effective particle diameter: Diameter of a cir-
combined, joined or formed into a cluster by any cle having an area equivalent to the smallest pro-
means. jected area of the particle.
---------------------- Page: 5 ----------------------
IS0 $573.I:1991 (E)
of 10 pm and greater is 75 times higher upstream
2.14 equivalent particle diameter: Diameter of a
spherical particle having an equivalent “behaviour” of the filter than downstream.
to that of the considered particle with regard to a
2.17.3 penetration P: Ratio of the downstream par-
given characteristic (e.g. projected area or diam-
ticle concentration to the upstream particle concen-
eter).
tration.
2.15 erosion: Wearing of material caused by the
2.18 inertial interception: Process in which a par-
mechanical action of a fluid system with or without
ticle impinges on a part of the filter owing to the
solid particles in suspension.
momentum of the particle.
2.16 filter: Apparatus for separation of contami-
2.19 particle: A small discrete mass of solid or liq-
nants from a fluid stream in which they are present.
uid matter.
2.17 filter rating: Parameter expressing a particular
2.20 relative vapour pressure cp: Ratio of the partial
characteristic of a filter. This parameter may be the
pressure of water vapour to its saturation pressure
filtration efficiency, the filtration ratio or the pen-
at the same temperature.
etration.
2.21 van der Waais’ forces: Attractive or repulsive
2.17.1 filtration efficiency E: The change in con-
forces between any pair of molecules, caused by the
centration across the filter divided by the upstream
electric fields of the electrons (negative) and nuclei
concentration. It may also be expressed as
(positive) of which molecules are built up.
E=l-P
2.22 vapour: Gas which is at a temperature below
its critical temperature and which therefore can be
where P is defined in 2.17.3.
liquefied by isothermal compression.
The filtration efficiency is usually expressed in per
cent.
3 Units
2.17.2 filtration ratio p: For each particle size class,
The SI units of pressure and of volume are the
the ratio of the number of particles upstream of the
Pascal and the cubic metre respectively. However!
filter to the number of particles downstream. It may
for compliance with current practice in the pneu-
also be expressed as
matic field, the non-preferred SI units bar’) for
pressure and litre*) for volume are used in this part
p = I/P
of IS0 8573. National standards organizations may
convert these units into pure SI units. In addition, the
where P is defined in 2.17.3.
non-preferred SI unit parts per million (ppm) is em-
ployed for concentration. A summary of the units
The particle size class is used as an index. For ex-
used in the pneumatic field is given in table 1.
ample, p10 = 75 means that the number of particles
Table I - Units for various contaminants
Pressure Particle or Vapour Relative Concentration
Content’)
dewpoint droplet size pressure vapour
Contaminant
lwm
“C mbar mg/m3 pressure (by mass) (by volume)
I’m
--
Sol ids:
X
size
X
content
---
Water:
i iquid X
vapour X X X X
Oil:
liquid X X X
vapour X X X
--
1) At 1 bar absolute pressure, + 20 “C and a relative vapour pressure of 0,6. It should be noted that at pressures above atmospheric,
the contaminant concentration is correspondingly higher.
1) 1 bar = 10’ Pa
2) 1 litre = 10v3 m”
2
---------------------- Page: 6 ----------------------
IS0 8573-I :1991 (E)
concentration of dust in the intake air and the
4 The compressed-air system
compressor technology.
4.1 A typical compressed-air generating system is
In addition to the dust load, the dust characteristics
shown in figure 1.
are also important. Dust is characterized not only
by its shape and size but also by its hardness.
4.2 The maintenance and operation of com-
Very generally, small dust particles will often form
pressors and their auxiliaries and prime movers
deposits, whereas particles larger than 5 pm will
shall be in accordance with the manufacturer’s in-
lead to erosion if the flow velocity is sufficiently high.
structions and specifications.
It should also be borne in mind that certain solids
4.3 The lubricant shall meet the specifications for
can have a catalytic effect and that corrosion can
the compressor.
occur owing to their chemical properties.
4.4 The compressor or the remote intake pipe
5.1.2 Measuring methods
should be located in an uncontaminated area, i.e. in
an area with the lowest possible contamination from
5.1.2.1 Particle size
engine exhaust, process discharge, etc. The intake
air should preferably be as cool and dry as possible.
The particle size of solid contaminants can be
measured using the following methods:
4.5 It is advisable to place a suitable filter in the
compressed-air pipeline as close as possible to the
cascade impactor, which can be operated at high
a)
point of use. Samples should whenever possible be
pressures and temperatures;
taken at the point of use.
particle counter, which employs microscopic
W
5 Contaminants
scanning in combination with retention on a
membrane of suitable pore size.
The three major contaminants in compressed air are
solids (dust), water and oil. These contaminants
5.1.2.2 Concentration
have an influence on each other (e.g. dust particles
agglomerate in the presence of oil or water to form
The concent ration of solid contaminants can be
larger particles, oil and water emulsify) and are
mea sured us ing the following methods:
sometimes deposited or condensed (e.g. oil vapour
or wate
...
SLOVENSKI STANDARD
SIST ISO 8573-1:1995
01-avgust-1995
Komprimiran zrak za splošno uporabo - 1. del: Zamazanost in kakovostni razredi
Compressed air for general use -- Part 1: Contaminants and quality classes
Air comprimé pour usage général -- Partie 1: Polluants et classes de qualité
Ta slovenski standard je istoveten z: ISO 8573-1:1991
ICS:
71.100.20 Industrijski plini Gases for industrial
application
SIST ISO 8573-1:1995 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST ISO 8573-1:1995
---------------------- Page: 2 ----------------------
SIST ISO 8573-1:1995
IS0
INTERNATIONAL
STANDARD
8573-l
First edition
1991-12-15
Compressed air for general use -
Part 1:
Contaminants and quality classes
Air cornprim pour usage g&M-al -
Partie I: Polluants et classes de qualit
-__I__
--
Reference number
____~ --- - -- IS0 8573-l : 1991 (E)
---------------------- Page: 3 ----------------------
SIST ISO 8573-1:1995
IS0 85734:1991(E)
Contents
Page
Scope . . . . . . . . . . . . . . . . . . . . . . .
Definitions . . . . . . . . . . . . . . . .
Units . . . . . . . . . . . . . . . . . . . . . . .
The compressed-air system
......................... 3
Contaminants .
............ .................................... 6
Compressed-air quality classes
Annex
8
,.,.
A Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
0 IS0 1991 '
All rights reserved. No part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanicat, including photocopying and microfilm, without
permission in writing from the publisher.
tnternationat Organization for Standardtzatton
Case Postate 56 l CH-1211 Gen&ve 20 l Switzerland
Printed in Switzerland
ii
---------------------- Page: 4 ----------------------
SIST ISO 8573-1:1995
IS0 85734:1991(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work
of preparing International Standards is normally carried out through IS0
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, govern-
mental and non-governmental, in liaison with ISO, also take part in the
work. IS0 collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an lnter-
national Standard requires approval by at least 75 % of the member
bodies casting a vote.
International Standard IS0 8573-l was prepared by Technical Committee
ISO/TC 118, Compressors, pneumatic tools and pneumatic machines,
Sub-Committee SC 4, Quality of compressed air.
IS0 8573 consists of the following parts, under the general title Com-
pressed air for general use:
- Part I: Contaminants and quality classes
-- Part 2: Test methods
Annex A of this part of IS0 8573 is for information only.
---------------------- Page: 5 ----------------------
SIST ISO 8573-1:1995
IS0 85734:1991(E)
Introduction
It is not possible using most test methods to measure the full flow area
of a compressed-air stream and therefore it is necessary to take sam-
ples of the air. This method of testing has a major drawback in that oil,
for example, is not evenly distributed over the flow area.
Measurements should preferably be carried out at the actual operating
pressure and temperature of a compressor as otherwise the balance
between contaminants in liquid, aerosol or gaseous form will be altered.
Liquid oil and free water in particular tend to cling to pipe and tube walls
where they form a film or thin rivulets.
The content of water, oil and particles in compressed air varies owing
to sudden changes in the intake air, to the wear of components as well
as to changes in flow, pressure, temperature and ambient conditions.
Therefore the quality classes of a compressed-air system have to be
based on the mean value of a number of measurements carried out over
a specified period of time.
Recommended methods for measuring the oil content of compressed
air will be given in IS0 8573-2.
iv
---------------------- Page: 6 ----------------------
SIST ISO 8573-1:1995
INTERNATIONAL STANDARD
IS0 8573-l :1991 (E)
Compressed air for general use -
Part 1:
Contaminants and quality classes
2.6 Brownian movement: Random movement of
1 Scope
small particles suspended in a fluid.
This part of IS0 8573 specifies quality classes of in-
2.7 coalescence: Action by which liquid particles in
dustrial compressed air for general use (e.g. for
suspension unite to form larger particles.
workshops, the construction industry, pneumatic
transport, etc.) without consideration of the quality
of the air when it is discharged from the
2.8 compression drying: Drying of air by com-
compressor. The quality class of compressed air for
pressing it to a higher pressure, cooling it and ex-
a particular application has to be based on the mean
tracting the water condensed, and finally expanding
value of several measurements carried out over a
it to the required pressure.
specific period of time and under defined operating
conditions.
2.9 contaminant: Any material or combination of
materials (solid, liquid or gaseous) which adversely
This part of IS0 8573 is not applicable to com-
affects the system or the operator.
pressed air for direct breathing and for medical use.
2.10 dewpoint: Temperature at which vapour be-
gins to condense.
2 Definitions
2.10.1 atmospheric dewpoint: Dewpoint measured
For the purposes of this part of IS0 8573, the follow-
at atmospheric pressure.
ing definitions apply.
NOTE 1 The term atmospheric dewpoint should not be
used in connection with compressed-air drying.
2.1 abrasion: Surface wearing of material by
mechanical action between solids.
2.10.2 pressure dewpoint: Dewpoint at the actual
pressure of the compressed air (this pressure
2.2 absorption: Process of attraction of one sub-
should be stated).
stance into another, so that the absorbed substance
disappears physically.
2.11 diffusion: Movement of gas molecules or small
particles caused by a concentration gradient.
2.3 adsorption: Attraction and adhesion of gaseous
and liquid molecules to the surface of a solid.
2.12 direct interception: Filtration effect in which a
droplet or a solid particle collides with an element
2.4 aerosol: Suspension in a gaseous medium of
solid particles, liquid particles or solid and liquid of a filter medium (e.g. fibre or granule) which is in
its direct path or is captured by pores of diameter
particles having a negligible fall velocity (generally
smaller than the diameter of the droplet or particle.
less than 0,25 m/s
2.5 agglomerate: Group of two or more particles 2.13 effective particle diameter: Diameter of a cir-
combined, joined or formed into a cluster by any cle having an area equivalent to the smallest pro-
means. jected area of the particle.
---------------------- Page: 7 ----------------------
SIST ISO 8573-1:1995
IS0 $573.I:1991 (E)
of 10 pm and greater is 75 times higher upstream
2.14 equivalent particle diameter: Diameter of a
spherical particle having an equivalent “behaviour” of the filter than downstream.
to that of the considered particle with regard to a
2.17.3 penetration P: Ratio of the downstream par-
given characteristic (e.g. projected area or diam-
ticle concentration to the upstream particle concen-
eter).
tration.
2.15 erosion: Wearing of material caused by the
2.18 inertial interception: Process in which a par-
mechanical action of a fluid system with or without
ticle impinges on a part of the filter owing to the
solid particles in suspension.
momentum of the particle.
2.16 filter: Apparatus for separation of contami-
2.19 particle: A small discrete mass of solid or liq-
nants from a fluid stream in which they are present.
uid matter.
2.17 filter rating: Parameter expressing a particular
2.20 relative vapour pressure cp: Ratio of the partial
characteristic of a filter. This parameter may be the
pressure of water vapour to its saturation pressure
filtration efficiency, the filtration ratio or the pen-
at the same temperature.
etration.
2.21 van der Waais’ forces: Attractive or repulsive
2.17.1 filtration efficiency E: The change in con-
forces between any pair of molecules, caused by the
centration across the filter divided by the upstream
electric fields of the electrons (negative) and nuclei
concentration. It may also be expressed as
(positive) of which molecules are built up.
E=l-P
2.22 vapour: Gas which is at a temperature below
its critical temperature and which therefore can be
where P is defined in 2.17.3.
liquefied by isothermal compression.
The filtration efficiency is usually expressed in per
cent.
3 Units
2.17.2 filtration ratio p: For each particle size class,
The SI units of pressure and of volume are the
the ratio of the number of particles upstream of the
Pascal and the cubic metre respectively. However!
filter to the number of particles downstream. It may
for compliance with current practice in the pneu-
also be expressed as
matic field, the non-preferred SI units bar’) for
pressure and litre*) for volume are used in this part
p = I/P
of IS0 8573. National standards organizations may
convert these units into pure SI units. In addition, the
where P is defined in 2.17.3.
non-preferred SI unit parts per million (ppm) is em-
ployed for concentration. A summary of the units
The particle size class is used as an index. For ex-
used in the pneumatic field is given in table 1.
ample, p10 = 75 means that the number of particles
Table I - Units for various contaminants
Pressure Particle or Vapour Relative Concentration
Content’)
dewpoint droplet size pressure vapour
Contaminant
lwm
“C mbar mg/m3 pressure (by mass) (by volume)
I’m
--
Sol ids:
X
size
X
content
---
Water:
i iquid X
vapour X X X X
Oil:
liquid X X X
vapour X X X
--
1) At 1 bar absolute pressure, + 20 “C and a relative vapour pressure of 0,6. It should be noted that at pressures above atmospheric,
the contaminant concentration is correspondingly higher.
1) 1 bar = 10’ Pa
2) 1 litre = 10v3 m”
2
---------------------- Page: 8 ----------------------
SIST ISO 8573-1:1995
IS0 8573-I :1991 (E)
concentration of dust in the intake air and the
4 The compressed-air system
compressor technology.
4.1 A typical compressed-air generating system is
In addition to the dust load, the dust characteristics
shown in figure 1.
are also important. Dust is characterized not only
by its shape and size but also by its hardness.
4.2 The maintenance and operation of com-
Very generally, small dust particles will often form
pressors and their auxiliaries and prime movers
deposits, whereas particles larger than 5 pm will
shall be in accordance with the manufacturer’s in-
lead to erosion if the flow velocity is sufficiently high.
structions and specifications.
It should also be borne in mind that certain solids
4.3 The lubricant shall meet the specifications for
can have a catalytic effect and that corrosion can
the compressor.
occur owing to their chemical properties.
4.4 The compressor or the remote intake pipe
5.1.2 Measuring methods
should be located in an uncontaminated area, i.e. in
an area with the lowest possible contamination from
5.1.2.1 Particle size
engine exhaust, process discharge, etc. The intake
air should preferably be as cool and dry as possible.
The particle size of solid contaminants can be
measured using the following methods:
4.5 It is advisable to place a suitable filter in the
compressed-air pipeline as close as possible to the
cascade impactor, which can be operated at high
a)
point of use. Samples should whenever possible be
pressures and temperatures;
...
Iso
NORME
8573-l
INTERNATIONALE
Premkre édition
19914245
Air comprimé pour usage général -
Partie 1:
Polluants et classes de qualité
Compressed air for general use -
Part 1: Contaminants and quality classes
Numéro de référence
ISO 8573-l : 1991 (F)
---------------------- Page: 1 ----------------------
ISO 857391:1991 (F)
Sommaire
Page
1
Domaine d’application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1
Définitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . .-. 2
Unités
Circuit d’air comprimé . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Polluants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*. 3
Classes de qualité d’air comprimé . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Annexe
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
A Bibliographie
0 ISO 1991
Droits de reproduction réservés. Aucune partie de cette publication ne peut être repro-
duite ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou
mécanique, y compris la photocopie et les microfilms, sans l’accord écrit de l’éditeur.
Organisation Internationale de normalisation
Case Postale 56 l CH-121 1 Genève 20 l Suisse
Imprimé en Suisse
ii
---------------------- Page: 2 ----------------------
ISO 8573-l :1991 (F)
Avant-propos
L’ISO (Organisation internationale de normalisation) est une fédération
mondiale d’organismes nationaux de normalisation (comités membres
de I’ISO). L’élaboration des Normes internationales est en général
confiee aux comités techniques de I’ISO. Chaque comité membre inte-
ressé par une étude a le droit de faire partie du comité technique créé
à cet effet. Les organisations internationales, gouvernementales et non
gouvernementales, en liaison avec I’ISO participent également aux tra-
vaux. L’ISO collabore étroitement avec la Commission électrotechnique
internationale (CEI) en ce qui concerne la normalisation électrotech-
nique.
Les projets de Normes internationales adoptés par les comités techni-
ques sont soumis aux comités membres pour vote. Leur publication
comme Normes internationales requiert l’approbation de 75 % au moins
des comités membres votants.
La Norme internationale ISO 8573-l a été elaborée par le comité tech-
nique ISO/TC 118, Compresseurs, outils et machines pneumatiques,
sous-comité SC 4, Qualité de l’air comprimé.
L’ISO 8573 comprend les parties suivantes, présentées sous le titre gé-
néral Air comprimé pour usage général:
- Partie 1: Polluants et classes de qualité
- Partie 2: Méthodes d’essai
L’annexe A de la présente partie de I’ISO 8573 est donnée uniquement
à titre d’information.
. . .
III
---------------------- Page: 3 ----------------------
ISO 85734:1991(F)
Introduction
Étant donné qu’en employant la plupart des méthodes d’essai, il n’est
pas possible de mesurer le débit total d’air comprimé, il est nécessaire
de prélever des échantillons d’air. La présente méthode d’essai pose
un problème important, car I’huile, par exemple, n’est pas uniformé-
ment répartie dans la veine.
Les mesures doivent de préférence être effectuées à la température et
à la pression de fonctionnement du compresseur, autrement l’équilibre
entre les différentes phases liquide, aérosol ou gazeuse peut être mo-
difié.
t l’eau adh èrent partiellement aux parois de
L’huile en phase liquide
la tuyauterie et forment u film ou de minces traînées.
La concentration massique de l’eau, de I’huile et des particules dans
l’air comprimé varie en raison des variations brusques de débit d’air,
de l’usure des éléments, ainsi que des modifications de débit, de pres-
sion, de température et de conditions ambiantes.
II faut donc que la spécifïcation des classes de qualité d’un circuit d’air
comprimé se fonde sur la moyenne d’un certain nombre de mesurages
effectués sur une période de temps définie.
Les méthodes de mesurage de la concentration d’huile dans l’air com-
primé seront données dans I’ISO 8573-2.
---------------------- Page: 4 ----------------------
ISO 85734:1991(F)
NORME INTERNATIONALE
Air comprimé pour usage général -
Partie 1:
Polluants et classes de qualité
2.6 mouvement brownien: Mouvement aléatoire de
1 Domaine d’application
très petites particules en suspension dans un fluide.
La présente partie de I’ISO 8573 prescrit les classes
de qualité de l’air comprimé industriel d’usage gé-
2.7 coalescence: Processus dans lequel les parti-
néral (par exemple pour les usines, les travaux pu- cules liquides en suspension se groupent pour for-
blics, le transport pneumatique, etc.) sans présumer mer des particules de plus gros volume.
de la qualité de l’air à la sortie du compresseur. La
classe de qualité de l’air comprimé pour un do-
2.8 séchage par compression: Séchage de l’air par
maine d’application doit représenter la valeur
compression à une pression supérieure, refroidis-
moyenne de plusieurs mesurages effectués sur une
sement, extraction de l’eau condensée et finalement
période de temps et dans des conditions de fonc-
décompression jusqu’à la pression requise.
tionnement données.
La présente partie de I’ISO 8573 ne s’applique pas
2.9 polluant: Toute matière ou combinaison de
à l’air comprimé respiratoire ou pour usage médi-
matières solides, liquides ou gazeuses qui influe
cal.
défavorablement sur un système ou sur l’opérateur.
2.10 point de rosée: Température à partir de la-
2 Définitions
quelle la vapeur d’eau commence à se condenser.
Pour les besoins de la présente partie de I’ISO 8573,
2.10.1 point de rosée atmosphérique: Point de ro-
les définitions suivantes s’appliquent.
sée mesuré à la pression atmosphérique.
2.1 abrasion: Usure superficielle de la matière par
Le terme ((point de rosée atmosphérique~~ ne
NOTE 1
action mécanique entre deux solides.
devrait pas être utilisé avec le séchage de l’air comprimé.
2.2 absorption: Processus d’attraction d’une sub-
2.10.2 point de rosée sous pression: Point de rosée
stance dans une autre de telle manière que la sub-
à la pression réelle de l’air comprimé (cette pres-
stance absorbée disparaît physiquement.
sion doit être indiquée).
2.3 adsorption: Attraction et rétention de molécules
diffusion: Mouvement de molécules ou de pe-
2.11
gazeuses et liquides à la surface d’un solide.
tites particules de gaz dû à une variation de
concentration.
2.4 aérosol: Suspension dans un milieu gazeux de
particules solides, de particules liquides ou de par-
ticules solides et liquides ayant une vitesse de chute
interception directe: Effet de filtration résultant
2.12
négligeable (généralement inférieure à 0,25 m/s).
de la rencontre d’une gouttelette ou d’une particule
avec un élément de médium filtrant (fibres ou
2.5 agglomérat: Groupe de deux ou plusieurs par- grains) placé sur son chemin direct, ou de sa cap- ’
ticules associées, jointes ou groupées par un moyen ture par des pores de diamètre inférieur au diamé-
quelconque. tre de la gouttelette ou de la particule.
1
---------------------- Page: 5 ----------------------
ISO 85734:1991(F)
2.‘T3 diamètre effectif de particule: Diamètre d’un ticules de 10 prn et plus est 75 fois plus élevé en
cercle de surface équivalente à la plus petite sur- amont du filtre qu’en aval.
face projetée de la particule.
2.17.3 pénétration, P: Rapport de la concentration
2.14 diamètre équivalent de particule: Diamètre
de particules aval à la concentration de particules
d’une particule sphérique ayant un amont.
(comportement,, équivalent à celui de la particule
considérée par rapport à une caractéristique don-
2.18 interception par inertie: Processus dans lequel
née (par exemple surface projetée ou diamètre).
une particule s’agglomère dans une partie du filtre
sous l’effet de sa propre quantité de mouvement.
2.15 érosion: Usure de la matière due à l’action
mécanique d’une veine fluide contenant ou non des
2.19 particule: Petite masse discrète de matière li-
particules solides en suspension.
quide ou solide.
2.16 filtre: Appareil pour séparer des polluants
2.20 pression de vapeur relative, cp: Rapport de la
d’une veine fluide où ils sont en suspension.
pression partielle de la vapeur d’eau à sa pression
de saturation à la même température.
pouvoir de filtration: Paramètre exprimant une
2.17
caractéristique particulière d’un filtre. Ce paramètre
2.21 forces de van der Waal: Forces d’attraction ou
peut être l’efficacité de filtration, le rapport de fil-
de répulsion entre toute paire de molécules dues
tration ou la pénétration.
aux champs électriques des électrons (négatifs) et
du noyau (positif) dont est constituée chaque molé-
2.17.1 efficacité de filtration, J!? Changement de
cule.
concentration au travers du filtre, divisé par la
concentration amont. Elle peut être exprimée
2.22 vapeur: Gaz à une température inférieure à
comme
sa température critique et qui peut donc être liquéfié
par compression isotherme.
E=V-P
où P est défini en 2.17.3.
3 Unités
L’efficacité de filtration est généralement exprimée
en pourcentage.
Les unités SI de pression et de volume sont le
pascal et le mètre cube respectivement. Toutefois,
2.17.2 rapport de filtration, /?: Pour chaque classe
conformément à la pratique usuelle en matière d’air
de taille de particules, rapport du nombre de parti-
comprimé, les unités SI non préférentielles sont uti-
cules en amont d’un filtre au nombre de particules
lisées dans la présente partie de I’ISO 8573, et no-
en aval du filtre. II peut être exprimé comme
tamment, pour la pression, le bar’) et pour le
volume, le litre *! Les organisations nationales de
p = l/P
normalisation peuvent convertir ces unités en unités
SI préférentielles. En outre, l’unité SI non préféren-,
où P est défini en 2.17.3.
tielle partie par million (ppm) est utilisée pour la
taille de particules est notée en in dite, concentration. Un résumé des unités utilisées dans
La classe de
le domaine d’air comprimé est donné au tableau 1.
r exemple 10 = 75 signifie que le nomb re de par-
Pa P
1) 1 bar = 105 Pa
2) 1 litre=10-3m3
2
---------------------- Page: 6 ----------------------
ISO 8573-1:1991(F)
Tableau 1 - Unité pour les divers polluants
Point de Taille des Concentration
Pression
rosée particules ou Concentration Pression
de
massiquel)
Polluant sous gouttelettes de vapeur
PPm
vapeur
pression (granulométrie) relative
OC mbar mg/m3 (en masse) (en volume)
Crm
Solides:
taille, X
concentration
X
massique
Eau:
liquide,
X
vapeur X
I
Huile:
X X
liquide, X
X X X
vapeur
1) À une pression absolue de 1 bar, une température de + 20 “C et une pression de vapeur relative de 0,6. II convient
de tenir compte du fait qu’aux pressions supérieures à la pression atmosphérique, la concentration relative des pol-
luants sera plus forte.
de procédé, etc. L’air d’entrée doit être aussi frais
1 Circuit d’air comprimé
et sec que possible.
4.1 Un circuit d’air comprimé type est montré à la
4.5 II est recommandé de placer un filtre approprié
figure 1.
dans la tuyauterie d’air comprimé, aussi près que
possible du poste d’utilisation. Les échantillons doi-
4.2 Le fonctionnement et l’entretien des compres-
vent, si possible, être prélevés au poste d’utilisation.
seurs et de leurs moteurs et accessoires doivent
être conformes aux instructions et spécifications du
constructeur.
5 Polluants
4.3 Le lubrifiant du compresseur doit être
Les trois polluants principaux dans l’air comprimé
conforme aux spécifications.
sont les solides (poussières), l’eau et I’huile. Ces
polluants ont une influence mutuelle (par exemple,
les poussières s’agglomèrent en grosses particules
4.4 Le compresseur, ou l’entrée de sa tuyauterie
en présence d’huile ou d’eau, I’huile et l’eau
d’aspiration quand elle est distincte, doivent être
situés dans un endroit propre, c’est-à-dire dans un s’émulsionnent). Ils se déposent ou se condensent
aussi parfois (par exemple vapeur d’huile ou d’eau)
endroit avec le minimum de pollution provenant de
dans le réseau de tuyauterie.
l’échappement du moteur, de l’évacuation des gaz
---------------------- Page: 7 ----------------------
60 8573~1:1991 (F)
I
Filtre’)
Moteur électrique
I
-0
Refroidisseur
Compresseur
Purgeur d’eau
Réservoir sous pression
Sécheurl)
Bac
---
r - Vanne d’isolement
I
I
I
Soupape de sûreté
l-
Air
b
1) Suivant le type d’application, il est possible de trouver des sécheurs ou des filtres en amont du réservoir pour sécher l’air à emmagasiner.
NOTE - Les symboles utilisés, à l’exception du symbole pour l’air, sont en conformité avec US0 1219-l. Le symbole pour
l’air est en conformité avec I’ISO 7000.
Figure 1 - Circuit d’air comprimé type
---------------------- Page: 8 ----------------------
ISO 85734:1991(F)
a) méthodes gravimétriques qui peuvent aussi être
5.1 Solides
utilisées à des pressions élevées;
5.1 .l Généralités
b) compteurs de particules et photomètres à di
...
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