Cleaning equipment for air and other gases — Terminology

ISO 29464:2011 establishes a terminology for the air filtration industry and comprises terms and definitions together with, in some cases, symbols and units. ISO 29464:2011 is applicable to both particulate and gas phase air filters and cleaners used for the general ventilation of inhabited enclosed spaces. Air inlet filters for static or seaborne rotary machines are included. ISO 29464:2011 does not apply to cabin filters for road vehicles or air inlet filters for mobile internal combustion engines, for which separate arrangements exist. Dust separators for the purpose of air pollution control are also excluded.

Séparateurs aérauliques — Terminologie

General Information

Status
Withdrawn
Publication Date
24-Aug-2011
Withdrawal Date
24-Aug-2011
Current Stage
9599 - Withdrawal of International Standard
Start Date
28-Aug-2017
Completion Date
28-Aug-2017
Ref Project

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INTERNATIONAL ISO
STANDARD 29464
First edition
2011-09-01
Cleaning equipment for air and other
gases — Terminology
Séparateurs aérauliques — Terminologie
Reference number
ISO 29464:2011(E)
ISO 2011
---------------------- Page: 1 ----------------------
ISO 29464:2011(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2011

The reproduction of the terms and definitions contained in this International Standard is permitted in teaching manuals, instruction

booklets, technical publications and journals for strictly educational or implementation purposes. The conditions for such reproduction are:

that no modifications are made to the terms and definitions; that such reproduction is not permitted for dictionaries or similar publications

offered for sale; and that this International Standard is referenced as the source document.

With the sole exceptions noted above, no other part of this publication may be reproduced or utilized in any form or by any means,

electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or

ISO's member body in the country of the requester.
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Published in Switzerland
ii © ISO 2011 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 29464:2011(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies

(ISO member bodies). The work of preparing International Standards is normally carried out through ISO

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, governmental and

non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the

International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. Draft International Standards

adopted by the technical committees are circulated to the member bodies for voting. Publication as an

International Standard requires approval by at least 75 % of the member bodies casting a vote.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent

rights. ISO shall not be held responsible for identifying any or all such patent rights.

ISO 29464 was prepared by Technical Committee ISO/TC 142, Cleaning equipment for air and other gases.

This first edition of ISO 29464 cancels and replaces ISO 3649:1980, which has been technically revised.

© ISO 2011 – All rights reserved iii
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INTERNATIONAL STANDARD ISO 29464:2011(E)
Cleaning equipment for air and other gases — Terminology
1 Scope

This International Standard establishes a terminology for the air filtration industry and comprises terms and

definitions together with, in some cases, symbols and units.

This International Standard is applicable to both particulate and gas phase air filters and cleaners used for the

general ventilation of inhabited enclosed spaces. Air inlet filters for static or seaborne rotary machines are

included.

It does not apply to cabin filters for road vehicles or air inlet filters for mobile internal combustion engines, for

which separate arrangements exist. Dust separators for the purpose of air pollution control are also excluded.

2 Normative references

The following referenced documents are indispensable for the application 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.

ISO 29463-1, High-efficiency filters and filter media for removing particles in air — Part 1: Classification,

performance testing and marking
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1 Particulate filters
3.1.1
aerosol
system of solid or liquid particles suspended in gas

NOTE In general, one divides the atmospheric aerosol into three size categories: the ultrafine range x  0,1 µm, the fine

range 0,1 µm  x  1 µm and the coarse range x  1 µm, whereby x is the particle diameter.

3.1.2
monodisperse aerosol

aerosol, the width of whose distribution function, described by the geometric standard deviation g, is less

than 1,15 µm
3.1.3
polydisperse aerosol

aerosol, the width of whose distribution function, described by the geometric standard deviation g, exceeds

1,5 µm
3.1.4
quasi-monodisperse aerosol

aerosol, the width of whose distribution function, described by the geometric standard deviation g, lies

between 1,15 µm and 1,5 µm
© ISO 2011 – All rights reserved 1
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ISO 29464:2011(E)
3.1.5
test aerosol

aerosol used for determining filter performance and for calibrating particle measurement devices

3.1.6
agglomerate
collection of solid particles adhering to each other
3.1.7
agglomeration
action leading to the formation of agglomerates
3.1.8
agglutination

action of joining, by impact, solid particles coated with a thin adhesive layer or of trapping solid particles by

impact on a surface coated with adhesive
3.1.9
aggregate

relatively stable assembly of dry particles, formed under the influence of physical forces

3.1.10
filter media area
area of media contained in the filter
3.1.11
effective filter media area

area of the media contained in the filter (without adhesive spaces or ligament) and passed by air during

operation
3.1.12
exposed filter area
exp
area of filter medium in a filter effective for particle capture
3.1.13
nominal filter face area
nff

frontal face area of the filter including the header frame which determines the nominal filter face velocity

3.1.14
arrestance

measure of the ability of a filter to remove a standard test dust from the air passing through it, under given

operating conditions
NOTE This measure is expressed as a weight percentage.
3.1.15
average arrestance

ratio of the total amount of loading dust retained by the filter to the total amount of dust fed up to final test

pressure differential
3.1.16
initial arrestance
value of arrestance determined after the first loading cycle in a filter test
NOTE 1 For example, in EN 14799 procedure for the first 30 g of test dust.
2 © ISO 2011 – All rights reserved
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ISO 29464:2011(E)
NOTE 2 This measure is expressed as a weight percentage.
3.1.17
ash
solid residue of effectively complete combustion
3.1.18
fly ash
ash entrained by combustion gases
3.1.19
dust holding capacity
DHC
amount of loading dust retained by the filter up to final pressure differential
3.1.20
capture

extraction of particles, liquid particles or gases, close to their sources for purposes of collection or sampling

3.1.21
classification

allocation of filters into groups and classes according to relevant aspects of their filtration performance

3.1.22
cleaning (after clogging)
removal of the deposit of solid or liquid particles which has produced clogging
3.1.23
clogging

deposition, progressive or otherwise, of solid or liquid particles on or within a filter medium, causing the flow to

be obstructed
3.1.24
coalescence
action by which liquid particles in suspension unite to form larger particles
3.1.25
concentration
content

quantity of a solid, liquid or gaseous material expressed as a proportion of another material in which it is

contained in the form of a mixture, a suspension or a solution
3.1.26
correlation ratio of sampling points

downstream particle concentration divided by the upstream particle concentration (measured without filter)

3.1.27
particle counter

device for detecting and counting numbers of discrete airborne particles present in a sample of air

3.1.28
condensation particle counter
CPC

type of optical particle counter (3.1.29) in which very fine airborne particles are enlarged by condensation to

a size which may readily be counted by other particle counting methods

NOTE 1 It can provide data on particle numbers but not the original size distribution.

NOTE 2 The ISO committee dealing with CPC is TC 24/SC 4.
© ISO 2011 – All rights reserved 3
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ISO 29464:2011(E)
3.1.29
optical particle counter
OPC

particle counter which functions by illuminating airborne particles in a sample flow of air, converting the

scattered light impulses to electrical impulse data capable of analysis to provide data on particle population

and size distribution
NOTE See ISO 21501-4.
3.1.30
border zone error

with an optical limitation of the measuring volume or by means of the Gaussian distribution of the light

intensity in the laser beam, the particles passing the border of the sensing zone are less illuminated than the

ones passing the centre of the sensing zone

NOTE 1 The border zone error is device- and particle-size-dependent and has a direct effect on the size resolution.

NOTE 2 Due to the border zone error, the particle size is underestimated.
NOTE 3 The larger the particle to be measured, the larger the border zone error.
3.1.31
sizing accuracy
(x)
(x) determined by the function:
xx
measured reference
(x)100
reference
3.1.32
sizing resolution
R(x)

indicates which particle sizes can be differentiated by a particle measuring instrument

NOTE The sizing accuracy can be evaluated for any particle size as follows:
()xx ()
measured reference
Rx( )100, geometric standard deviation
reference
3.1.33
lower size limit

smallest particle diameter with a counting efficiency of 0,5  0,15 (50 %  15 %)

3.1.34
upper size limit
largest particle diameter with a counting efficiency of 0,5  0,15 (50 %  15 %)
3.1.35
sampling flow rate
volumetric flow rate through the instrument

NOTE Any error in the volume flow will affect the reported particle number concentration.

3.1.36
calibration curve

graph depicting the relationship between scattered light intensity and particle size

NOTE For the clear particle size and quantity determination, an unambiguous, monotonically increasing calibration curve

offers advantages. This enables narrower size intervals to be chosen.
4 © ISO 2011 – All rights reserved
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ISO 29464:2011(E)
3.1.37
calibrate

to compare readings from the instrument to be calibrated with those from a reference device

3.1.38
calibration particle

mono-disperse spherical particle with a known mean particle size, e.g. polystyrene latex (PSL) particle, that is

traceable to an international standard of length, and where the standard uncertainty of the mean particle size

is equal to or less than  2,5 %

NOTE The refractive index of (PSL) calibration particles is close to 1,59 at a wavelength of 589 nm (sodium D line).

[ISO 21501-3:2007, definition 2.1]
3.1.39
reference device

primary device possessing accurately known parameters used as a standard for calibrating secondary devices

3.1.40
coagulation losses
particle losses due to collision and adhesion of particles

NOTE Coagulation affects the measured particle parameters as follows: the particle number concentration decreases,

the particle mass concentration remains the same and the particle size increases.

3.1.41
counting rate
number of counting events per unit time
3.1.42
zero count rate

number of counts registered per unit time by the particle counter when air, which is free of particles, is passed

through the measuring volume
3.1.43
cyclone

dust separator or droplet separator utilizing essentially the centrifugal force derived from the motion of the gas

3.1.44
DEHS
DiEthylHexylSebacate
liquid used for generating the DEHS test aerosol
3.1.45
equivalent diameter

diameter of a spherical particle which will give behaviour equivalent to that of the particle being examined

3.1.46
count median diameter of aerosol
number median diameter of aerosol
CMD
50th percentile of the number distribution of the aerosol

NOTE 50 % of the particles are smaller than the count median diameter and 50 % are larger than the count median

diameter.
© ISO 2011 – All rights reserved 5
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ISO 29464:2011(E)
3.1.47
count mean particle diameter
number mean particle diameter
geometric average of the lower and upper limit of the size range
3.1.48
dispersion

operation as a result of which solid particles or liquid particles are distributed in a fluid

NOTE Also applied to a two-phase system in which one phase, known as the “disperse phase”, is distributed throughout

the other, known as the “continuous medium”, e.g. DOP (Dioctyl phthalate) liquid, or liquids with similar physical

properties, are dispersed in air to generate a test aerosol.
3.1.49
downstream
area or region into which fluid flows on leaving the filter
3.1.50
droplet
liquid particle of small mass, capable of remaining in suspension in a gas

NOTE In some turbulent systems, for example clouds, its diameter can reach 200 µm.

3.1.51
dust
airborne solid particles which settle by gravity in calm conditions
3.1.52
test dust capacity
TDC
amount of loading dust held by the filter at final test pressure differential
3.1.53
dust control

whole of the processes for the separation of solid particles from a gas stream in which they are suspended

NOTE By extension this also includes the activities involved in the construction and commissioning of a dust separator.

3.1.54
loading dust

synthetic dust formulated specifically for determination of the test dust capacity and arrestance of air filters

NOTE A number of loading dusts are currently used, e.g. ISO fine test dust, ASHRAE dust and JIS-11.

3.1.55
efficiency
fraction of contaminant entering the filter which is retained
3.1.56
average efficiency

value of efficiency which results from averaging the efficiencies determined over a number of discrete intervals

up to the final pressure differential
6 © ISO 2011 – All rights reserved
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ISO 29464:2011(E)
3.1.57
collection efficiency

ratio of the quantity of particles retained by a separator to the quantity entering it with regard to filters, dust

separators and droplet separators
NOTE It is generally expressed as a percentage.
3.1.58
conditioned efficiency

efficiency of the conditioned filter media operating at an average media velocity corresponding to the test air

flow rate in the filter
3.1.59
counting efficiency

ratio, expressed as a percentage, of detected number concentration of particles divided by the actual number

concentration of particles in a given size or range of sizes
3.1.60
dust loaded efficiency

efficiency of the filter operating at test flow rate and after dust loadings up to final test pressure differential

3.1.61
fractional efficiency

ability of an air cleaning device to remove particles of a specific size or size range

NOTE The efficiency plotted as a function of particle size gives the particle size efficiency spectrum.

3.1.62
initial efficiency
efficiency of the air cleaning device operating at the test air flow rate
NOTE Expressed in % for each selected size of particle.
3.1.63
integral efficiency

efficiency, averaged over the whole superficial face area of a filter under given operating conditions

3.1.64
local filter efficiency
local

efficiency at a specific point of a filter element under given operating conditions

3.1.65
minimum filter efficiency
min
minimum value of the filter efficiency curve under given operating conditions
3.1.66
effluent
fluid discharged from a given source into the external environment

NOTE This is a general term describing any fluid discharged from a given source. In this context the discharged fluid

may be liquid or gaseous and may contain associated liquid and/or particulate contaminants.

3.1.67
filter element
filtering material in a preformed shape being a part of a complete filter
© ISO 2011 – All rights reserved 7
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ISO 29464:2011(E)
3.1.68
elutriation

method of separating a mixture of particles according to their settling velocities within a fluid

3.1.69
coincidence error

error which occurs because at a given time more than one particle is contained in the measurement volume of

a particle counter

NOTE The coincidence error leads to a measured number concentration which is too low and a value for the particle

diameter which is too high.
3.1.70
air filter

apparatus for separating solid or liquid particles or gaseous contaminants from a gas stream

NOTE The apparatus is generally formed of a layer or layers of porous, fibrous or granular material.

3.1.71
brush filter
air filter in which the medium consists of a screen of intermeshing brushes
3.1.72
cartridge filter
compact filter often of cylindrical design
3.1.73
cellular filter

replaceable filter insert which is or may be installed in a multiple bank or wall structure

NOTE Examples of these are HEPA filters, rigid bags and panels.
3.1.74
ceramic filter
filter with a medium consisting of ceramic fibres or sintered porous ceramic
3.1.75
charged filter
filter in which the medium is electrostatically charged or polarized
3.1.76
filter class
range of filtration performances clearly defined by lower and upper limit values
3.1.77
cleanable filter

filter designed to enable the removal of collected dust by application of an appropriate technique

NOTE The removal of collected dust is usually partial.
3.1.78
disposable filter
filter which is not intended to be cleaned or regenerated for re-use
3.1.79
effective filtering area
area of filter medium in the filter which collects dust
3.1.80
electret filter
filter with an electrostatically charged medium
8 © ISO 2011 – All rights reserved
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ISO 29464:2011(E)
3.1.81
efficient particulate air filter
EPA filter

filter with performance complying with requirements of filter class ISO 15 – ISO 30 as per ISO 29463-1

3.1.82
fabric filter

filter medium manufactured either from woven or non-woven textile or a combination of both

NOTE The term is most often applied to dust collectors. In these devices the filtering is effectively carried out by a bed of

deposited dust, the textile providing a supporting substrate.
3.1.83
filter face area
frontal face area of the filter including the header frame
3.1.84
filter face velocity
air flow rate divided by the filter face area
3.1.85
fibrous filter

filter comprising a medium consisting of a mass of fibres, including fine and very fine fibres

NOTE 1 The efficiency of these filters is derived from the presence of very fine fibres which are supported by coarser

fibres in a relatively open structure.
NOTE 2 Fibrous filters are usually disposable.
3.1.86
final filter

air filter used to collect the loading dust passing through or shedding from the filter under test

3.1.87
group of filters
filters of more than one adjacent class within a performance spectrum
3.1.88
HEPA filter

filters with performance complying with requirements of filter class ISO 35 - ISO 45 as per ISO 29463-1

3.1.89
filter insert

replaceable part of a filter which contains the filter medium but which can only operate mounted inside a frame

3.1.90
filter medium
material used for filtering
NOTE The part of a filter on or within which the particles are retained.
3.1.91
metal filter

filter with a medium consisting of metal mesh(es), fibres or sintered porous metal

3.1.92
filter pack
filtering material in a preformed shape being a part of a complete filter
© ISO 2011 – All rights reserved 9
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ISO 29464:2011(E)
3.1.93
panel filter
shallow parallel-faced filter element or cell
3.1.94
particulate air filter
filter designed to remove suspended particles from air flowing through it
3.1.95
pocket filter
bag filter
filter in which the medium is formed into pockets or bags
3.1.96
renewable media filter
filter in which the medium can be replaced
3.1.97
roll filter
filter incorporating a means for advancing new medium
NOTE For example, from a roll.
3.1.98
self-cleaning filter
filters having an inbuilt mechanism for removing collected contaminants
3.1.99
filter type
designation of the structure and test regime of a filter
3.1.100
ULPA filter

filters with performance complying with requirements of filter class ISO 55 - ISO 75 as per ISO 29463-1

3.1.101
nominal air volume flow rate
v,nom
air volume flow rate specified by the manufacturer
3.1.102
rated flow

gas flow rate through a separator, either as stated by the manufacturer for defined conditions of use, or as

agreed between the interested parties for a particular installation
3.1.103
sampling volume flow rate

representative partial flow rate used for the determination of airborne particle characteristics

3.1.104
service flow
gas flow rate through a separator under given service conditions
3.1.105
test flow
gas flow rate through a separator during a rig test or a site test

NOTE This flow, which can differ from the rated flow, shall be specified or, failing this, agreed between the interested

parties.
10 © ISO 2011 – All rights reserved
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ISO 29464:2011(E)
3.1.106
test volume flow rate
volumetric air flow rate used for testing
3.1.107
header frame

integral rigid frame of a filter enabling it to be fastened and sealed against the holding frame

3.1.108
holding frame

rigid structural frame, part of an air handling system into which filters are fastened and sealed

3.1.109
fume

aerosol of solid particles, usually from metallurgical processes, generated by condensation from the gaseous

state generally after volatilization from melted substances and often accompanied by chemical reactions such

as oxidation

NOTE In popular usage, this is referred to as gaseous effluent, often unpleasant and malodorous, which may arise from

chemical processes.
3.1.110
grit
airborne solid particles in the atmosphere or flues
NOTE In the UK, of size greater than 75 µm [see “dust” (3.1.51)].
3.1.111
hood
inlet device for extraction system
3.1.112
housing
device used to hold filter
3.1.113
impact

collision of two particles with each other, or of a particle with a solid or liquid surface

3.1.114
impaction

inertial separation due to mass and velocity of a particle causing divergence from the airflow stream lines onto

individual filter fibres
3.1.115
KCl

solid potassium chloride particles generated from an aqueous solution and used as test aerosol

3.1.116
porous layer

permeable layer of solid material in any form having interstices of small size, generally known as “pores”

3.1.117
leak
point in a filter at which the local penetration exceeds a given value
3.1.118
mist
suspension of droplets in a gas
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ISO 29464:2011(E)
3.1.119
neutralization

action of bringing the aerosol to a Boltzmann charge equilibrium distribution with bipolar ions

NOTE This process is more often described as “discharging”.
3.1.120
particle
small discrete mass of solid or liquid matter
3.1.121
particle bounce
behaviour of particles that impinge on the filter without being retained
3.1.122
mean particle diameter
geometric mean of the upper and lower border diameters in a size range
3.1.123
particle number
number of particles present in a defined group
3.1.124
particle number concentration
number of particles per unit of volume of air
3.1.125
particle production rate
number of particles produced per unit of time by an aerosol generator
3.1.126
particle size

geometric diameter (equivalent spherical, optical or aerodynamic, depending on context) of the particles of an

aerosol
3.1.127
particle size analysis
technique used to measure the size distribution of an assembly of particles
3.1.128
particle size distribution

presentation, in the form of tables of numbers or of graphs, of the experimental results obtained using a

method or an apparatus capable of measuring the equivalent diameter of particles in a sample or capable of

giving the proportion of particles for which the equivalent diameter lies between defined limits

3.1.129
most penetrating particle size
MPPS
mpps

particle size at which the minimum of the particle size efficiency curve occurs under test conditions

12 © ISO 2011 – All rights reserved
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ISO 29464:2011(E)
3.1.130
penetration

ratio of particle concentration detected downstream versus the particle concentration upstream

NOTE In some industries, the reciprocal of the penetration is known as the “decontamination factor” (DF).

3.1.131
pollutant
contaminant
undesirable solid, liquid or gaseous matter in a gaseous or liquid medium
3.1.132
pollution
contamination

introduction of pollutants into a liquid or gaseous medium, or any undesirable modification of the composition

of a liquid or gaseous medium
3.1.133
precipitation

operation in which particles are separated from a gas stream in which they are suspended

NOTE For example, by the action of an electrical field or a thermal gradient.
3.1.134
electrostatic precipitator

device in which particles become charged and are precipitated on the collecting surface

NOTE Also referred to as electrostatic collector, electrical separator or electrostatic separator.

3.1.135
burst pressure

value of differential pressure across a filter, above which damage/destruction of the filter media or the

structure occurs
3.1.136
differential pressure
difference in absolute (static) pressure between two points in a system
3.1.137
mean differential pressure
arithmetical mean value of the measured number of differential pressures
3.1.138
final differential pressure

differential pressure up to which the filtration performance is measured for classification purposes

3.1.139
recommended final differential pressure
pfr

maximum operating differential pressure of the filter as recommended by the manufacturer

3.1.140
initial differential pressure
differential pressure of the clean filter operating at its test air flow rate
© ISO 2011 – All rights reserved 13
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ISO 29464:2011(E)
3.1.141
purification
total or partial removal of unwanted constituents from a gaseous medium
3.1.142
re-entrainment
release to the air flow of particles previously collected on the filter
3.1.143
sampling duration

time period during which the particles in the sample are counted upstream and downstream

3.1.144
isokinetic sampling

technique for air sampling such that the probe inlet air velocity is the same as the velocity of the air

surrounding the sampling point
3.1.145
scan test

test procedure by which local efficiency or penetration values are determined by sampling filtered air at the

downstream filter face according to a specified grid pattern
3.1.146
sedimentation

separation of particles from the fluid in which they are suspended, by the action of gravity

3.1.147
separator

apparatus for separating solid or liquid particles or gases from a gaseous stream in which they are suspended

or mixed
3.1.148
droplet separator
apparatus for separating suspended liquid particles from a gas stream
3.1.149
dust separator
apparatus for separating suspended solid particles from a gas stream
3.1.150
shedding

release to the air flow of particles due to particle bounce and re-entrainment effects and to the release of

fibres or particulate matter from the filter or filtering material
3.1.151
smoke
visible aerosol resulting from combustion
3.1.152
soot
deposits of agglomerated carbonaceous particles formed by incomplete combustion
3.1.153
suspension

two-phase system in which one phase, the disperse phase, is distributed throughout the other, known as the

continuous phase
14 © ISO 2011 – All rights reserved
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ISO 29464:2011(E)
3.1.154
transmission

ratio of the quantity of particles leaving a filter, dust separator or a droplet separator, to the quantity entering it

3.1.155
upstream

region in a process system traversed by a flowing fluid before it enters that part of the process under

consideration

NOTE The part of the process under consideration in the context of this International Standard will normally be a filter.

3.1.156
filter face velocity
average velocity of the air through the filter face area
3.1.157
filter medium face velocity

volume flow rate divided by the effective filter medium area of the filter element

3.1.158
washer

dust separator, droplet separator or gas purifier that depends on a liquid acting as a collecting medium for its

operation
3.2 Gas phase filters
3.2.1
absorption

transport and dissolution of a sorbate into an absorbent to form a homogeneous mixture having the

characteristics of a solution
3.2.2
activated alu
...

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