UV-C devices -- Measurement of the output of a UV-C lamp

This document specifies the measurement of the output of a UV-C lamp, types of UV-C lamp, lamp ballast, and safety issues. It is applicable to the output measurement of linear UV-C disinfection lamps. This document specifies a measurement method for evaluating output power of UV-C lamps installed in heating, ventilation and air conditioning (HVAC) systems. The method includes the simulation measurement of UV-C output power of UV-C lamps under various temperatures and various air velocities, and under conditions that the axial direction of the lamp is parallel or perpendicular to the air flow direction. It can reliably evaluate and compare the UV-C output power of UV-C lamps in the ultraviolet germicidal irradiation (UVGI) device based on the testing results. If the microbial inactivation rate of a particular UVGI device equipped with the same type of UV-C lamp is known, the microbial inactivation rate of the UVGI device at various temperatures and at various air velocities can be evaluated.

Dispositifs UV-C -- Mesurage de la sortie d'une lampe UV-C

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Published
Publication Date
09-Jan-2020
Current Stage
6060 - International Standard published
Start Date
06-Nov-2019
Completion Date
10-Jan-2020
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INTERNATIONAL ISO
STANDARD 15727
First edition
2020-01
UV-C devices — Measurement of the
output of a UV-C lamp
Dispositifs UV-C — Mesurage de la sortie d'une lampe UV-C
Reference number
ISO 15727:2020(E)
ISO 2020
---------------------- Page: 1 ----------------------
ISO 15727:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

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Published in Switzerland
ii © ISO 2020 – All rights reserved
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ISO 15727:2020(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Types of UV-C lamps and ballasts ........................................................................................................................................................ 2

4.1 General ........................................................................................................................................................................................................... 2

4.2 Types of UV-C lamps ........................................................................................................................................................................... 2

4.2.1 General...................................................................................................................................................................................... 2

4.2.2 Linear UV-C lamps .......................................................................................................................................................... 3

4.3 Type of ballasts ....................................................................................................................................................................................... 3

4.3.1 General...................................................................................................................................................................................... 3

4.3.2 Magnetic ballasts ............................................................................................................................................................. 3

4.3.3 Electronic ballasts ........................................................................................................................................................... 4

5 Measurement of the output of a UV-C lamp .............................................................................................................................. 4

5.1 Measurement method classification .................................................................................................................................... 4

5.2 Measurement of the output of a UV-C lamp in a darkroom .............................................................................. 4

5.2.1 Instrument ............................................................................................................................................................................ 4

5.2.2 Calibration ............................................................................................................................................................................. 5

5.2.3 UV-C radiation power calculation ..................................................................................................................... 5

5.2.4 Necessary conditions ................................................................................................................................................... 6

5.2.5 Measurements .................................................................................................................................................................... 6

5.3 Measurement of the output of a UV-C lamp in a test chamber ...................................................................10

6 Safety issues ...........................................................................................................................................................................................................10

6.1 General ........................................................................................................................................................................................................10

6.2 Protective clothing and eyewear ..........................................................................................................................................10

6.3 UV-C photodegradation of organics ...................................................................................................................................10

6.4 Ozone production ..............................................................................................................................................................................10

6.5 UV-C internal and external leakage ....................................................................................................................................10

6.6 Mercury content of the UV-C lamp ......................................................................................................................................11

6.7 Personal protective equipment..............................................................................................................................................11

Annex A (informative) Suggested methods to minimize the effects of reflected UV-C ...................................12

Annex B (normative) Measurement of the output of a UV-C lamp in a test chamber......................................13

Bibliography .............................................................................................................................................................................................................................20

© ISO 2020 – All rights reserved iii
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ISO 15727:2020(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.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).

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. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso .org/

iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 142, Cleaning equipment for air and

other gases.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2020 – All rights reserved
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ISO 15727:2020(E)
Introduction

The First World Health Organization (WHO) Global Conference on Air Pollution and Health took place

at WHO headquarters in Geneva, Switzerland from 30 October to 1 November 2018. The conference

participants considered the scientific evidence on air pollution and health and emphasized: Air

pollution — both ambient and household — is estimated to cause 7 million deaths per year; 5,6 million

deaths are from noncommunicable diseases and 1,5 million from pneumonia. There is an urgent need

to scale up the global response to prevent diseases and deaths (available at http:// www .who .int/ phe/

news/ clean -air -for -health/ en/ ).

Research shows that indoor air pollution can be 2 to 5 times greater than outdoor pollution and under

particular circumstances; it can be up to 100 times. Since people generally spend more than 80 % to

90 % of our time indoors, the quality of indoor air pollution is a key element to good health of people.

At the same time, indoor air pollution is one of 5 environmental risk factors to the public health. Under

most indoor environments, microbial suspension in the air is the chief culprit to transmitted diseases

and it is a factor that many people ignore because these organisms, whose body size is ranging from

several micrometres to more than 10 micrometres, are invisible to the naked eye.

In recent years, these germs bring much more intense effect, including frequent occurrences of sick

building syndrome, elevated nosocomial infection rate, rapid increase of air-conditioning energy

consumption (a microbe film a few millimetres thick accumulates on the air conditioner coil, reducing

the heat transfer efficiency of the air treatment unit), smelly air-conditioned rooms and resurgence

of tuberculosis. Many people have a drop in their own productivity and spend more on medical care

because headache, chest congestion, disturbance in respiration, neurasthenia, nausea and state of mind

are fidgety are the most common symptoms for people staying in the air-conditioned rooms. In addition,

people in air-conditioned rooms are more susceptible to the infection of ophthalmic and nasitis.

Meanwhile, clinical medical evidence suggests that various diseases, such as heart disease,

neurasthenia, memory decline and influenza, correlate with polluted indoor air. The improvement of

indoor air quality is desperately needed.

Ultraviolet air disinfection devices are invented in such circumstances. Most ultraviolet air disinfection

devices circulate the air indoors. With media filtration and a high-efficiency UV-C lamp, disinfection

devices have good effects of filtration of dust in air, meanwhile, it can kill germs and viruses directly

and cut the spread of disease. Disinfection devices application can reduce indoor air pollution, improve

indoor air quality and provide protection against pneumonia, influenza and other respiratory diseases.

© ISO 2020 – All rights reserved v
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INTERNATIONAL STANDARD ISO 15727:2020(E)
UV-C devices — Measurement of the output of a UV-C lamp
1 Scope

This document specifies the measurement of the output of a UV-C lamp, types of UV-C lamp, lamp

ballast, and safety issues.
It is applicable to the output measurement of linear UV-C disinfection lamps.

This document specifies a measurement method for evaluating output power of UV-C lamps installed

in heating, ventilation and air conditioning (HVAC) systems. The method includes the simulation

measurement of UV-C output power of UV-C lamps under various temperatures and various air

velocities, and under conditions that the axial direction of the lamp is parallel or perpendicular to

the air flow direction. It can reliably evaluate and compare the UV-C output power of UV-C lamps in

the ultraviolet germicidal irradiation (UVGI) device based on the testing results. If the microbial

inactivation rate of a particular UVGI device equipped with the same type of UV-C lamp is known, the

microbial inactivation rate of the UVGI device at various temperatures and at various air velocities can

be evaluated.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements 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 15858, UV-C Devices — Safety information — Permissible human exposure
ISO 29464:2017, Cleaning of air and other gases — Terminology

ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories

CIE S 017, International Lighting Vocabulary
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 29464, CIE S 017 and the

following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
ultraviolet radiation
UV radiation
wavelength of the electromagnetic spectrum of radiation from 10 nm to 400 nm

Note 1 to entry: The range between 100 nm and 400 nm is commonly subdivided into:

— UV-A: 315 nm to 400 nm;
— UV-B: 280 nm to 315 nm;
— UV-C (3.2): 200 nm to 280 nm;
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ISO 15727:2020(E)
— Vacuum UV: 100 nm to 200 nm.

[SOURCE: ISO 29464:2017, 3.6.18, modified — "UVA", "UVB" and "UVC" have been changed to "UV-A",

"UV-B" and "UV-C".]
3.2
ultraviolet C
UV-C
ultraviolet radiation (3.1) from 200 nm to 280 nm
3.3
UV-C disinfection

disinfection method that uses ultraviolet radiation (3.1) with a wavelength between 200 nm and 280 nm

to kill microorganisms

Note 1 to entry: UV-C (3.2) radiation attacks the vital DNA of the bacteria directly. The bacteria lose their

reproductive capability and are destroyed.
3.4
UV-C irradiance
power passing through a unit area perpendicular to the direction of propagation

Note 1 to entry: UV-C (3.2) irradiance is typically reported in watt per square metre (W/m ). It is also usually

2 2
reported in mW/cm or uW/cm .
3.5
low pressure UV-C lamp

discharge lamp of the mercury vapour type, without a coating of phosphors, in which the partial

pressure of the vapour does not exceed 100 Pa during operation and which mainly produces ultraviolet

radiation of 253,7 nm
3.6
UV-C radiation conversion efficiency

ability of a UV-C (3.2) lamp to convert electrical power into UV-C radiation power

Note 1 to entry: The ratio is the UV-C radiation power accounting for the electrical power of the UV-C lamp. The

UV-C conversion efficiency of a low pressure UV-C lamp (3.5) at 253,7 nm is between 25 % and 45 %. The UV-C

conversion efficiency should be not less than 30 % in an air disinfection field under all circumstances due to

energy consumption of the system.
3.7
UV-C radiometer

instrument used to measure UV-C (3.2) radiometric quantities, particularly UV-C irradiance (3.4) or fluence

[SOURCE: ISO 29464:2017, 3.6.15]
4 Types of UV-C lamps and ballasts
4.1 General

Ballasts shall comply with requirements for starting parameters and operating parameters of UV-C

lamps. Lamps bases of UV-C lamps and cables between UV-C lamps and ballasts shall comply with

performance and safety requirements.
4.2 Types of UV-C lamps
4.2.1 General

UV-C lamps are divided into medium pressure UV-C lamps and low pressure UV-C lamps; air disinfection

devices usually use low pressure UV-C lamps. The low pressure UV-C lamps are made of liquid mercury

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ISO 15727:2020(E)

or amalgam that controls mercury vapour pressure in the UV-C lamp to provide mercury atoms required

for discharge. Mercury atoms produce 253,7 nm UV-C photons through electron bombardment. Figure 1

shows the spectrum of low pressure UV-C lamps.
Key
X wavelength (nm)
Y relative radiation ratio at various wavelengths (%)
Figure 1 — Low pressure mercury lamp spectrum
4.2.2 Linear UV-C lamps

The most common type of UV-C lamp, linear UV-C lamps can have any length or diameter and are

typically characterized by having connectors at both ends or having a connector at a single end,

requiring a compatible fixture, as shown in Figure 2 and Figure 3.
Figure 2 — Linear UV-C lamp with connectors at both ends
Figure 3 — Linear UV-C lamp with connector at a single end
4.3 Type of ballasts
4.3.1 General

The ballast provides the high initial voltage required to create the starting arc and then limits the

current to prevent the UV-C lamp from self-destructing. UV-C lamp ballast can be either magnetic or

electronic.
4.3.2 Magnetic ballasts

Magnetic ballasts are used to start the UV-C lamp and may be either standard electromagnetic or

energy-efficient electromagnetic. The ballast provides a time-delayed inductive kick with enough

voltage to ionize the gas mixture in the tube after which the current through the tube keeps the

filaments energized. The starter will cycle until the tube lights up. While the UV-C lamp is on, a preheat

ballast is just an inductor which at the main frequency (50 Hz or 60 Hz) has the appropriate impedance

to limit the current to the UV-C lamp to the proper value. Ballasts shall be fairly closely matched to the

UV-C lamp in terms of tube wattage, length, and diameter.
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ISO 15727:2020(E)
4.3.3 Electronic ballasts

Electronic ballasts are basically switching power supplies, which eliminate the large, heavy, 'iron'

ballast in favour of an integrated high frequency inverter/switcher. Current limiting is then done by a

very small inductor, which has sufficient impedance at the high frequency. Properly designed electronic

ballasts are relatively reliable, which depend on the ambient operating temperature, location with

respect to the heat produced by the UV-C lamp as well as other factors.
5 Measurement of the output of a UV-C lamp
5.1 Measurement method classification
There are two methods to measure the output of a UV-C lamp:

1. Measurement of the output of a UV-C lamp in a darkroom: Tests in laboratory (also known as static

darkroom test) are conducted to ensure the accuracy and consistency of the measured results;

2. Measurement of the output of a UV-C lamp in a test chamber: For industrial application, the tests

in a test chamber shall take account of the impact of environmental changes in field (such as

temperature change and air velocity change). This method is described in Annex B.

5.2 Measurement of the output of a UV-C lamp in a darkroom
5.2.1 Instrument

The cosine correction for radiometers and spectroradiometers is critical to the proper measurement of

the UV-C irradiance. The cosine correction shall be confirmed by the following method for each UV-C

lamp and ballast combination so that the UV-C lamp measurements are consistent within and between

laboratories.

The minimum measurement distance needs to be determined for the given UV-C lamp and UV-C

radiometer in order to verify cosine response characteristics of the UV-C radiometer and reduce its

cosine correction error. The method is as follows:

a) Take readings of the UV-C radiometer for different distances (radiometer position perpendicular to

the UV-C lamp axis), see Figure 4;

b) Take several readings of the UV-C irradiance. For example, moving the radiometer from the closest

point to the most remote point and then back again;
c) Average the irradiance readings for each distance;

d) Calculate the output UV-C radiation power of the UV-C lamp from the measured irradiance using

Formula (1) for each distance;

e) Calculate the output UV-C radiation power of the UV-C lamp; plot the calculated UV-C power versus

the distance;

f) When the measurement distance is greater than the minimum distance D , the measured UV-C

min

irradiance is consistent with the UV-C output power through calculation as per Formula (1). The

UV-C output power of the UV-C lamp should become independent of the distance;
g) The measurement distance shall be greater than D .
min

The distance derived by this method is valid for the combination of specific UV-C lamp length and

specific individual radiometer.
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ISO 15727:2020(E)
5.2.2 Calibration

In order to ensure the accuracy and reliability of the data issued by the laboratory, the laboratory shall

meet the requirements of ISO/IEC 17025.
The following instruments shall be calibrated as per the standard method:
a) UV-C radiometer shall have valid and traceable calibration documents;

b) Calibration of the radiometer or the spectroradiometer shall comply with requirements of

ISO/IEC 17025;
c) Power analyser shall have valid and traceable calibration documents.
5.2.3 UV-C radiation power calculation
5.2.3.1 UV-C radiation power calculation schematic diagram
For the UV-C radiation power calculation schematic diagram, see Figure 4.
Key
A UV-C radiometer
L UV-C lamp length (m) from electrode tip to electrode tip

D distance (m) from the UV-C lamp centre to the UV-C radiometer (here D is not less than D , many testing data

min
indicate that D amounts to 2L, recommended D from 2L to 4L)
min

α half angle (rad) subtended by the UV-C lamp at the radiometer position; that is, tan α = L/(2D)

Figure 4 — Geometry of the measurement system
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ISO 15727:2020(E)
5.2.3.2 UV-C radiation power calculation

Based on the work of Keitz, the UV-C radiation power P of UV-C lamp shall be calculated from

Formula (1).
ED2π L
P= (1)
22αα+sin
where
P is UV-C radiation power of the UV-C lamp (W);
E is the measured irradiance (W/m );
D is the distance from UV-C lamp centre to the UV-C radiometer (m);
L is the UV-C lamp length from electrode tip to electrode tip (m);

α is the half angle subtended by the UV-C lamp at the radiometer position (rad), tan α = L/(2D).

This formula has been tested by comparing with goniometric measurements of the UV-C lamp output

and by comparing results from laboratories in different countries. The results are considered accurate

within 5 % and have shown good agreement among laboratories.

Formula (1) is applicable to the UV-C output power calculation of linear UV-C lamps; it is not applicable

to other types of UV-C lamps. For other types of ultraviolet lamps, it is necessary to correct the angle

radiation measurement or adopt the method of integrating spheres to measure and calculate UV-C

output power.
5.2.4 Necessary conditions
The following general conditions shall be fulfilled:

1. The measurements shall be conducted in still room air, not in a moving air stream;

2. The UV-C lamp orientation shall be horizontal;

3. Reflected light shall be avoided (e.g. through use of baffles, differential measurement with

beam stops);

4. The UV-C radiometer shall have an adequate cosine response for the UV-C lamp length and distance

used; this can require a distance D that is not less than 2L, measured from the UV-C lamp’s axis.

5.2.5 Measurements
5.2.5.1 Basic wiring diagram for electrical parameters measurements

Figure 5 is the basic wiring diagram for electrical parameters measurement of the UV-C lamp system;

the UV-C lamp as showed operates with the preheated electronic ballast, while other types of ballast

shall refer to the wiring diagram supplied by the manufacturer.
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ISO 15727:2020(E)
Key
1 UV-C lamp
2 electronic ballast
3 equivalent resistance of the filament
V voltmeter, used to measure input electric voltage of the UV-C lamp
Pe power meter, used to measure input electric power of the UV-C lamp
A ampere meter, used to measure input electric current of the UV-C lamp
Figure 5 — Basic wiring diagram for electrical parameters measurements
5.2.5.2 Typical test chamber

The UV-C lamp output shall be measured after a UV-C lamp 100 h burn-in period. The UV-C lamp output

shall be based on a UV-C lamp operating under air conditions, in which the UV-C lamp has reached

a maximum output and then decreases to a steady state, indicating that the UV-C lamp has passed

through an optimum into an overheated condition. This will generate a UV-C irradiance curve as a

function of time, which will illustrate the maximum and steady state output values. Figure 6 shows a

typical test chamber (typically called a darkroom), in which the UV-C lamp is mounted about 1 m off the

floor and the UV-C radiometer is mounted at the same height as the UV-C lamp.
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ISO 15727:2020(E)
Dimensions in metres
Key
A black curtains
B slotted divider
C UV-C lamp
D wall
E UV-C radiometer
Figure 6 — Top view of a typical test chamber
5.2.5.3 Measurement procedure
The measurement procedure is as follows:

1. Record or monitor the ambient temperature (±1 °C tolerance); preferably, the ambient temperature

can adjust within the range of the actual UV-C lamp operating temperature, so that the data of

irradiance vs. time can be tested;
2. Determine that the distances for radiometer readings are valid;

3. Start recording the readings (UV-C irradiance, electrical measurements, etc.) after the UV-C lamp is

turned on;

4. The sampling rate shall match the rate of changing of the UV-C irradiance readings;

5. One reading every 10 s is often sufficient to mark the maximum;

6. Record the irradiance until a steady state is achieved; record the steady state value of the

irradiance;
7. Record the ambient temperature again;
8. Calculate the output UV-C radiation power of the UV-C lamp using Formula (1);

9. Calculate the output UV-C radiation conversion efficiency of the UV-C lamp using Formula (2).

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ISO 15727:2020(E)
ŋ = (2)
where
ŋ is the UV-C radiation conversion efficiency of the UV-C lamp (%);
P is the UV-C radiation power of the UV-C lamp (W);
P is the input power of the UV-C lamp (W), see Figure 5.
5.2.5.4 Cautions

Reflected light during the measurement of the UV-C radiation shall be avoided. Specific measures to

avoid the reflected light are as follows:
1. Use non-reflecting materials for walls, floor, and baffles;

2. Be aware that the UV-C reflectance can be different from reflectance in the visible range. Wood and

black cloth have very low UV-C reflectance;

3. Test: to check the amount of reflected light, compare the UV-C radiometer signal to that measured

when direct irradiation is blocked out. Report the corrected result.

More information about methods and requirements for reducing reflected light are provided in Annex A.

5.2.5.5 UV-C lamp and ballast efficiency

UV-C lamp radiation power is generally compared with the electrical (line) power consumed in order

to calculate the efficiency of the UV-C lamp/ballast system. It is recommended that the input power

to the ballast be accurately measured as true root mean square (RMS), so that the efficiency can be

calculated. This electrical power measurement shall be done accurately.
5.2.5.6 Measurement report
The measurement report shall include:

1. full and detailed information about the UV-C lamp (e.g., manufacturer, identification etc.);

2. full and detailed information about the ballast (e.g., manufacturer, identification etc.);

3. UV-C lamp orientation during testing (horizontal required);

4. active arc length L (between the ends of the filaments for a linear UV-C lamp);

5. measurement of the distance D from the UV-C lamp centre (with tolerance) to the calibration plane

of the radiometer;
6. laboratory room temperature (°C);
7. sensor and ra
...

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