ISO 15714:2019
(Main)Method of evaluating the UV dose to airborne microorganisms transiting in-duct ultraviolet germicidal irradiation devices
Method of evaluating the UV dose to airborne microorganisms transiting in-duct ultraviolet germicidal irradiation devices
This document describes a method in laboratory to assess the performance of ultraviolet germicidal irradiation (UVGI) devices which will be mounted in-duct in heating, ventilating and air-conditioning (HVAC) systems. The method includes the detailed requirements for test rig, microorganisms, procedures, data calculation and result report to determine the UV dose to model microorganisms by an UVGI device at several airflow rates. By the testing results, the capacity of in-duct UVGI devices for air disinfection can be evaluated and compared reliably. If the susceptibility constant of a given microorganism is known, the inactivation rate of that micro-organism by the tested UVGI devices can be further calculated.
Méthode d'évaluation de la dose d'UV pour les microorganismes en suspension dans l'air transitant par des dispositifs d'irradiation germicide aux ultraviolets raccordés
General Information
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 15714
First edition
2019-07
Method of evaluating the UV dose to
airborne microorganisms transiting
in-duct ultraviolet germicidal
irradiation devices
Méthode d'évaluation de la dose d'UV pour les microorganismes
en suspension dans l'air transitant par des dispositifs d'irradiation
germicide aux ultraviolets raccordés
Reference number
©
ISO 2019
© ISO 2019
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ii © ISO 2019 – All rights reserved
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, symbols and abbreviated terms . 1
3.1 Terms and definitions . 1
3.2 Symbols and abbreviated terms. 3
3.2.1 Symbols . 3
3.2.2 Abbreviated terms . 3
4 Configuration of the test rig . 4
5 Test rig qualification . 5
6 Preparation of test microorganisms . 5
6.1 Test microorganisms . 5
6.1.1 Serratia marcescens . 5
6.1.2 Bacillus subtilis . 5
6.1.3 Cladosporium sphaerospermum . 5
6.2 Preparation of microbial suspensions . 6
6.2.1 Acquisition of pure culture of test microorganisms . 6
6.2.2 Cultivation and dispersion of the test microorganism . 6
6.2.3 Dilution of the microbial suspensions . 6
7 Testing procedure for an in-duct UVGI device . 6
7.1 Determination of airflow rate, temperature and humidity . 6
7.2 Production of the airborne test microorganism . 6
7.3 Measurement of the test microorganism concentration without and with UV irradiation . 7
7.3.1 Sampling procedure . 7
7.3.2 Test microorganism sampling methods . . 7
7.3.3 Test microorganism culture and enumeration . 7
7.4 Repeating the tests at other flow rates . 7
7.5 Determination of the UV susceptibility of the test microorganism . 7
8 Safety and environmental considerations . 7
9 Calculation, evaluation and reporting . 8
9.1 Determination of the inactivation rate of the test microorganism . 8
9.2 Determination of the UV dose of the UVGI device . 8
9.3 Evaluation of the UVGI capacity . 8
9.4 Results reporting . 8
Annex A (informative) Recipe of culture medium for the test microorganism .9
Annex B (informative) Method for determining the UV dose-response curve and
susceptibility constant of a test microorganism in air .10
Annex C (informative) Susceptibility constants of some typical microorganisms in air
by the literature .13
Bibliography .16
Foreword
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This document was prepared by Technical Committee ISO/TC 142, Cleaning equipment for air and
other gases.
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iv © ISO 2019 – All rights reserved
Introduction
Airborne microorganisms including some pathogens in indoor air may cause different types of
diseases or adverse health effects on humans. Among different air disinfection techniques, ultraviolet
germicidal irradiation (UVGI) has been used for several decades to effectively inactivate the airborne
microorganisms in indoor air and thereby prevent the transmission of a variety of airborne infections.
In-duct UVGI device is a primary form of air disinfection method by UV lamps mounted in heating,
ventilation and air-conditioning (HVAC) systems to irradiate the microorganisms in air with high
intensities. However, other than the power supply, there is no standard or index available to characterize
or understand the performance of the UVGI products made by different manufacturers. In addition,
effective parameters derived from a standard method are lacking to predict the performance of the
UVGI device on microorganism inactivation in a real HVAC system.
As microorganisms in air are irradiated by UV-C light emitted by an in-duct UVGI device, the
inactivation rate of a specific microorganism primarily depends on the UV dose given by the device
and the susceptibility of that microorganism. If the UV dose under a specific condition is known, the
inactivation capacity and disinfection performance of the UVGI devices can be compared. Furthermore,
the inactivation rate for specific microorganism can be calculated with its susceptibility data known.
Therefore, the development of a standard method to evaluate the UV dose of the in-duct UVGI device is
very useful and necessary.
INTERNATIONAL STANDARD ISO 15714:2019(E)
Method of evaluating the UV dose to airborne
microorganisms transiting in-duct ultraviolet germicidal
irradiation devices
1 Scope
This document describes a method in laboratory to assess the performance of ultraviolet germicidal
irradiation (UVGI) devices which will be mounted in-duct in heating, ventilating and air-conditioning
(HVAC) systems.
The method includes the detailed requirements for test rig, microorganisms, procedures, data
calculation and result report to determine the UV dose to model microorganisms by an UVGI device at
several airflow rates. By the testing results, the capacity of in-duct UVGI devices for air disinfection can
be evaluated and compared reliably.
If the susceptibility constant of a given microorganism is known, the inactivation rate of that micro-
organism by the tested UVGI devices can be further calculated.
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
3 Terms, definitions, symbols and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at http: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1.1
airborne microorganism
microbial particle with an aerodynamic diameter up to 100 μm suspended in air
Note 1 to entry: Airborne microorganism includes bacterium, fungus, their spore or virus.
3.1.2
pathogen
infectious agent that causes diseases in its host
Note 1 to entry: Pathogen includes some virus, bacterium, prion, fungus, viroid, or parasite.
3.1.3
test microorganism
microbial surrogate representing the typical pathogen (3.1.2)
Note 1 to entry: Test microorganism is chosen to be safer than the real pathogen in order to prevent the infection
of testers or analysts.
3.1.4
air disinfection
process that can remove, inactivate or destroy the airborne microorganisms (3.1.1), especially pathogen
(3.1.2) in air
3.1.5
ultraviolet germicidal irradiation
UVGI
method for disinfection of air, water
...
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