IEC 61340-4-7:2010

IEC 61340-4-7
®
Edition 1.0 2010-01
INTERNATIONAL
STANDARD


Electrostatics –
Part 4-7: Standard test methods for specific applications – Ionization



IEC 61340-4-7:2010(E)

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IEC 61340-4-7
®
Edition 1.0 2010-01
INTERNATIONAL
STANDARD


Electrostatics –
Part 4-7: Standard test methods for specific applications – Ionization


INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
U
ICS 17.200.99; 29.020 ISBN 978-2-88910-504-5
® Registered trademark of the International Electrotechnical Commission

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– 2 – 61340-4-7 © IEC:2010(E)
CONTENTS
FOREWORD.3
INTRODUCTION.5
1 Scope.6
2 Normative references .6
3 Terms and definitions .7
4 Safety requirements .8
4.1 Personnel safety .8
4.2 Electrical .9
4.3 Ozone .9
4.4 Radioactive .9
4.5 X-ray .9
4.6 Installation .9
5 Test equipment.9
6 Specific requirements for equipment categories.10
6.1 Room ionization .11
6.2 Laminar flow hood ionization .11
6.3 Worksurface Ionization .12
6.4 Compressed gas ionizers – Guns and nozzles.12
Annex A (informative) Standard test method for the performance of ionizers.21
Annex B (normative) Method of measuring the capacitance of an isolated conductive
plate .27
Bibliography.30

Figure 1 – Charged plate monitor components .13
Figure 2– Charged plate detail.13
Figure 3 – Test locations for room ionization – AC grids and DC bar systems .14
Figure 4 – Test locations for room ionization – Single polarity emitter systems .14
Figure 5 – Test locations for room ionization – Dual DC line systems.15
Figure 6 – Test locations for room ionization – Pulsed DC emitter systems.15
Figure 7 – Test locations for vertical laminar flow hood – Top view .16
Figure 8 – Vertical laminar flow hood – Side view .16
Figure 9 – Test locations for horizontal laminar flow hood – Top view .17
Figure 10 – Horizontal laminar flow hood – Side view .17
Figure 11 – Test locations for benchtop ionizer – Top view .18
Figure 12 – Benchtop ionizer – Side view .18
Figure 13 – Test locations for overhead ionizer – Top view.19
Figure 14 – Overhead ionizer – Side view .19
Figure 15 – Test locations for compressed gas ionizer (gun or nozzle) – Side view.20

Table 1 – Test set-ups and test locations.10
Table B.1 – Example measurement data.28

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61340-4-7 © IEC:2010(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

ELECTROSTATICS –

Part 4-7: Standard test methods for specific applications –
Ionization


FOREWORD
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all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61340-4-7 has been prepared by IEC technical committee 101:
Electrostatics.
The text of this standard is based on ANSI/ESD STM3.1-2006. It was submitted to the
National Committees for voting under the Fast Track Procedure.
The text of this standard is also based on the following documents:
FDIS Report on voting
101/292/FDIS 101/299/RVD

Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

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A list of all parts in the IEC 61340 series, under the general title Electrostatics, can be found
on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

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61340-4-7 © IEC:2010(E) – 5 –
INTRODUCTION
Grounding is the primary method used to limit static charge fwhen protecting electrostatic
discharge-susceptible items in the work environment. However, grounding methods are not
effective in removing static charges from the surfaces of non-conductive (insulative) or
isolated conductive materials. Air ionization techniques may be employed to reduce these
charges as the active parameters in charge neutralization are the conductivities of the air for
each polarity. It would be appropriate to measure either the conductivities themselves or the
ion concentrations for each polarity as this would determine the ability of the ionized air to
neutralize a charge in a given location. Annex A provides information on performance of
ionizers.
In practice, these measurements are difficult to make. A more feasible way of evaluating the
ability of an ionizer to neutralize a static charge is to directly measure the rate of charge
decay. Charges to be neutralized may be located on insulators as well as on isolated
conductors. It is difficult to charge an insulator reliably and repeatably. Charge neutralization
is more easily evaluated by measuring the rate of decay of the voltage of an isolated
conductive plate. The measurement of this decay should not interfere with or change the
nature of the actual decay. Four practical methods of air ionization are addressed in this
standard test method:
a) radioactive emission;
b) high-voltage corona from a.c. electric fields;
c) high-voltage corona from d.c. electric fields;
d) soft X-ray emission.
This part of IEC 61340 provides test methods and procedures that can be used when
evaluating ionization equipment. The objective of the test methods is to generate meaningful,
reproducible data. The test methods are not meant to be a recommendation for any particular
ionizer configuration. The wide variety of ionizers, and the environments within which they are
used, will often require test methods different from those described in this part of IEC 61340.
Users of this standard should be prepared to adapt the test methods as required to produce
meaningful data in their own application of ionizers.
Similarly, the test conditions chosen in this part of IEC 61340 do not represent a
recommendation for acceptable ionizer performance. There is a wide range of item
sensitivities to static charge. There is also a wide range of environmental conditions affecting
the operation of ionizers. Performance specifications should be agreed upon between the
user and manufacturer of the ionizer in each application. Users of this standard test method
should be prepared to establish reasonable performance requirements for their own
application of ionizers.
Annex B has been provided in order to provide a method for measuring capacitance of the
charged plate.

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ELECTROSTATICS –

Part 4-7: Standard test methods for specific applications –
Ionization



1 Scope
This part of IEC 61340 provides test methods and procedures for evaluating and selecting air
ionization equipment and systems (ionizers).
This standard establishes measurement techniques, under specified conditions, to determine
offset voltage (ion balance) and discharge (charge neutralization) time for ionizers.
This standard does not include measurements of electromagnetic interference (EMI), or uses
of ionizers in connection with ordnance, flammables, explosive items or electrically initiated
explosive devices.
As contained in this standard, the test methods and test conditions may be used by
manufacturers of ionizers to provide performance data describing their products. Users of
ionizers are urged to modify the test methods and test conditions for their specific application
in order to qualify ionizers for use, or to make periodic verifications of ionizer performance
(refer to ESD SP3.3). The user will need to decide the extent of the data required for each
application.
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.
1
ESD ADV1.0, Glossary of terms
ESD SP3.3, Standard practice for protection of electrostatic discharge susceptible items –

1
Periodic verification of air ionizers
2
29 CFR 1910.1000, Ozone, (OSHA) Air contaminants
2
29 CFR 1910.95, (OSHA) Occupational noise exposure
2
29 CFR 1910.242 (b), (OSHA) Compressed air used for cleaning
2
10 CFR 20, (NRC) Standards for protection against radiation
2
21 CFR 1020, (FDA) Performance standards for ionizing radiation emitting products
___________
1
 ESD Association, 7900 Turin Road, Bldg. 3, Rome, NY 13440-2069, 315-339-6937, www.esda.org
2
 CFR (Code of Federal Regulations) U.S. Government printing office, 732 N. Capitol Street NW, Washington,
DC 20401, 866-512-1800, http://bookstore.gpo.gov

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61340-4-7 © IEC:2010(E) – 7 –
3 Terms and definitions
For the purposes of this document, the following terms and definitions, in addition to those
specified in the ESD association glossary of terms, shall apply.
3.1
air conductivity
ability of air to conduct (pass) an electric current under the influence of an electric field
3.2
air Ions
molecular clusters of about ten molecules (water, impurities, etc.) bound by polarization
forces to a singly charged oxygen or nitrogen molecule
3.3
charge decay
decrease and/or neutralization of a net electrostatic charge
3.4
charge induction
redistribution of charge in an isolated conductor when placed in an electric field (e.g. from a
charged body)
NOTE Momentary grounding of such a conductor would result in its gaining a net charge.
3.5
charged plate monitor
CPM
instrument used to measure the charge neutralization properties of ionization equipment
3.6
compressed gas ionizer
ionization devices that can be used to neutralize charged surfaces and/or remove surface
particles with pressurized gas
NOTE This type of ionizer may be used to ionize the gas within production equipment.
3.7
corona
production of positive and negative ions by a very localized high electric field
NOTE The field is normally established by applying a high voltage to a conductor in the shape of a sharp point or
wire.
3.8
decay rate
decrease of charge or voltage per unit time
3.9
discharge time
time necessary for a voltage (due to an electrostatic charge) to decay from an initial value to
some arbitrarily chosen final value
3.10
emitter
conducting sharp object, usually a needle or wire, which will cause a corona discharge when
kept at a high potential

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3.11
horizontal laminar flow
non-turbulent airflow in a horizontal direction
3.12
ion balance
(see offset voltage)
3.13
ionizer
device that is designed to generate positive and/or negative air ions
3.14
isolated conductor
non-grounded conductor
3.15
laminar flow hood ionization
these devices or systems provide local area ionization coverage in vertical or horizontal
laminar flow hoods or benches
3.16
offset voltage
observed voltage on the isolated conductive plate of a charged plate monitor (CPM) that has
been placed in an ionized environment
3.17
peak offset voltage
for pulsed ionizers, the maximum value of the offset voltage for each polarity, as the ionizer
cycles between positive and negative ion outputs
3.18
room ionization
ionization systems that provide large area coverage with air ions
3.19
worksurface ionization (formerly tabletop ionization)
ionization devices or systems used to control static charges at a workstation
NOTE This type includes benchtop ionizers, overhead worksurface ionizers and laminar flow hood ionizers.
3.20
vertical laminar flow
non-turbulent airflow in a vertical direction
4 Safety requirements
In addition to the safety issues mentioned in this clause, there may be local, state, national
and international safety standards or regulations that affect the operation of ionizers. Users of
this standard test method should determine if such requirements will apply to their installation
of ionizers.
4.1 Personnel safety
4.1.1 The procedures and equipment described in this part of IEC 61340 may expose
personnel to hazardous electrical conditions. Users of this standard, therefore, are
responsible for selecting equipment that complies with applicable laws, regulatory codes and

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61340-4-7 © IEC:2010(E) – 9 –
both external and internal policy. Users are also cautioned that this standard cannot replace
or supersede any requirements for personnel safety.
Ground fault circuit interrupters (GFCI) and other safety protection should be considered
wherever personnel may come into contact with electrical sources.
Electrical hazard reduction practices should be exercised and proper grounding instructions
for the equipment must be followed.
4.2 Electrical
In the case of high-voltage ionizers with exposed emitters, the corona points or wires should
be peak current limited to applicable safety requirements for the installation.
4.3 Ozone
The OSHA limit, as defined by 29 CFR 1910.1000, shall not be exceeded. If ozone-sensitive
components are in the vicinity of an ionizer, the manufacturer should provide information
and/or evaluation suggestions for the situation.
4.4 Radioactive
The manufacturer is required to obtain a license from the Nuclear Regulatory Commission
(NRC) or the NRC agreement state in which the equipment is manufactured. The
manufacturer and user shall meet all requirements of 10 CFR 20 and any other applicable
government regulations.
4.5 X-ray
The manufacturer and user shall meet all requirements of 21 CFR 1020 and any other
applicable government regulations. Typically, state and local government agencies will require
the device to be registered at its use location. X-ray devices should be installed in such a way
that prevents accidental exposure to personnel. Typically this will include some type of
enclosure for the X-ray device and electrical interlocking to turn the X-ray device off when the
enclosure is opened.
4.6 Installation
Installation should conform to applicable electrical, mechanical and safety codes, as well as
individual facility standards. Some equipment, such as compressed gas guns and nozzles
may have to meet other requirements such as 29 CFR 1910.95 for noise exposure and
29 CFR 1910.242 for personnel safety with compressed gas devices. Installation techniques
should also be applicable to the particular environment in which the ionizer is to be installed
(e.g., cleanrooms).
5 Test equipment
5.1 The instrument recommended in this standard to make performance measurements on
air ionization equipment is the CPM (refer to Figure 1). The conductive plate shall be 15 cm
by 15 cm (6“ by 6“) with a minimum capacitance of 15 pF when mounted in the test fixture
without electrical hook-ups. The total capacitance of the test circuit, with plate, shall be 20 pF
± 2 pF (refer to Annex B). The instrument recommended by this standard test method may
also be used for the periodic verification of air ionizers (refer to ESD SP3.3).
5.2 There shall be no objects, grounded or otherwise, closer than dimension "A" of the
conductive plate except the supporting insulators or plate voltage contacts, as shown in
Figure 2 (refer to Annex B).

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5.3 The isolated conductive plate, when charged to the desired test voltage, shall not
discharge more than 10 % of the test voltage within 5 min, in the absence of ionization.
5.4 The voltage on the plate shall be monitored in such a way that the system conforms to
5.1, 5.2 and 5.3. The response time of the monitoring device shall be sufficient to accurately
measure changing plate voltages.
5.5 The voltage source used to charge the plate should be current limited so as to meet
the requirements of 4.1.
6 Specific requirements for equipment categories
For the types of ionization equipment listed in 6.1, 6.2, 6.3 and 6.4, the following specific
requirements apply:
a) Discharge time test – The conductive plate of the test fixture shall be charged to an initial
test voltage and allowed to discharge to 10 % of the initial test voltage. The time required
shall be monitored and recorded for both polarities of initial charge. This time is referred to
as the discharge time (refer to 5.1 and Figure 1).
b) Offset voltage test – The conductive plate shall be momentarily grounded to remove any
residual charges and to verify zero of the monitoring device. The plate is then monitored
within the ionized environment, per the procedure described for each equipment category.
The resulting observed voltage is referred to as the offset voltage.
c) Locations – The discharge time and offset voltage should be measured for each test
location described in the test location figures (see Table 1).
d) Same conditions – Discharge time and offset voltage shall be measured under the same
conditions without any equipment adjustments. If ionizers from different categories are to
be compared, the same test voltages shall be used for all tests.
e) Peak offset voltage – In the case of pulsed ionizers, offset voltage should be measured
and reported in peak values using the test equipment described in 5.1.
f) Other parameters – Application specific parameters such as humidity, temperature, air
velocity, etc., should be recorded.
Table 1 – Test set-ups and test locations
Offset voltage
Equipment Figure Number of test Charged plate
measurement
category references locations initial voltage
time interval
Room ionization
Grids, AC 3 2 (1 to 5) min 1 000
Bars, pulsed and DC 3 2 (1 to 5) min 1 000
Single polarity emitter 4 3 (1 to 5) min 1 000
Dual DC Line 5 3 (1 to 5) min 1 000
Pulsed DC emitter 6 2 (1 to 5) min 1 000
Laminar flow hood
Vertical 7 and 8 8 (1 to 5) min 1 000
Horizontal 9 and 10 6 (1 to 5) min 1 000
Worksurface ionization
Benchtop 11 and 12 12 (1 to 5) min 1 000
Overhead 13 and 14 12 (1 to 5) min 1 000
Compressed gas ionization
Guns and nozzles 15 1 10 s to 1 min 1 000

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61340-4-7 © IEC:2010(E) – 11 –
6.1 Room ionization
6.1.1 The area around the charged plate monitor should be cleared for a horizontal distance
of 60“ in all directions. The ionization system should be operated for a minimum of 30 min to
stabilize conditions in the test area.
6.1.2 During the test, the test technician should be grounded and stand outside the 60“
cleared area.
6.1.3 Discharge time from a 1 000 V initial voltage to a 100 V final voltage shall be
measured for both positive (+) and negative (-) polarities.
6.1.4 The air velocity at the test location should be recorded.
6.1.5 Measurements should be taken with the charged plate monitor at a distance of 60“
from the ionizer under test. Since installed ionizer heights may vary, a consistent
measurement height should be selected for the evaluation of different systems. This height
and the ionizer mounting height shall be recorded in the test results.
6.1.6 The minimum number of test locations is determined by the type of system. (See
Table 1 and refer to Figures 3 through 6.)
6.1.7 Discharge time as described in Clause 6, point a), should be measured at each test
location.
6.1.8 Offset voltage as described in Clause 6, points b) and e) should be determined at
each test location. Offset voltage shall be measured after a period of at least 1 mkin to allow
the reading to stabilize (5 min maximum).
6.2 Laminar flow hood ionization
6.2.1 The test should be performed on a surface that does not contain obstructions to
airflow. Unless otherwise specified, the test surface should be static dissipative or conductive
and properly grounded.
6.2.2 The test technician should be properly grounded.
6.2.3 Discharge time from a 1 000 V initial voltage to a 100 V final voltage shall be
measured for both positive (+) and negative (-) polarities.
6.2.4 The air velocity at test location TP4, as shown in Figures 7 or 9, should be recorded.
6.2.5 For a vertical laminar flow hood, the test set-up is shown in Figures 7 and 8. Data
should be taken at test positions TP1 through TP8 as shown in Figure 7.
6.2.6 For a horizontal laminar flow hood, the test set-up is shown in Figures 9 and 10. Data
should be taken at test positions TP1 through TP6 as shown in Figure 9.
6.2.7 Discharge time as described in Clause 6, point a), should be measured at each test
location.
6.2.8 Offset voltage as described in Clause 6, points b) and e) should be determined at
each test location. Offset voltage shall be measured after a period of at least 1 min, or as
necessary to allow the reading to stabilize (5 min maximum).

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6.3 Worksurface Ionization
6.3.1 The test should be performed on a surface that does not contain obstructions to
airflow. Unless otherwise specified the test surface should be static dissipative or conductive
and properly grounded.
6.
...