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The committee responsible for this document is ISO/TC 142, Cleaning equipment for air and other gases.

This first edition of ISO 16890-1, together with ISO 16890-2, ISO 16890-3 and ISO 16890-4, cancels and replaces ISO/TS 21220:2009, which has been technically revised.

ISO 16890 consists of the following parts, under the general title Air filters for general ventilation:

• — Part 1: Technical specifications, requirements and classification system based upon particulate matter efficiency (ePM)
• — Part 2: Measurement of fractional efficiency and air flow resistance
• — Part 3: Determination of the gravimetric efficiency and the air flow resistance versus the mass of test dust captured
• — Part 4: Conditioning method to determine the minimum fractional test efficiency

Introduction

The effects of particulate matter (PM) on human health have been extensively studied in the past decades. The results are that fine dust can be a serious health hazard, contributing to or even causing respiratory and cardiovascular diseases. Different classes of particulate matter can be defined according to the particle size range. The most important ones are PM₁₀, PM_2,5 and PM₁. The U.S. Environmental Protection Agency (EPA), the World Health Organization (WHO) and the European Union define PM₁₀ as particulate matter which passes through a size-selective inlet with a 50 % efficiency cut-off at 10 µm aerodynamic diameter. PM_2,5 and PM₁ are similarly defined. However, this definition is not precise if there is no further characterization of the sampling method and the sampling inlet with a clearly defined separation curve. In Europe, the reference method for the sampling and measurement of PM₁₀ is described in EN 12341. The measurement principle is based on the collection on a filter of the PM₁₀ fraction of ambient particulate matter and the gravimetric mass determination (see EU Council Directive 1999/30/EC of 22 April 1999).

As the precise definition of PM₁₀, PM_2,5 and PM₁ is quite complex and not simple to measure, public authorities, like the U.S. EPA or the German Federal Environmental Agency (Umweltbundesamt), increasingly use in their publications the more simple denotation of PM₁₀ as being the particle size fraction less or equal to 10 µm. Since this deviation to the above mentioned complex “official” definition does not have a significant impact on a filter element’s particle removal efficiency, the ISO 16890 series refers to this simplified definition of PM₁₀, PM_2,5 and PM₁.

Particulate matter in the context of the ISO 16890 series describes a size fraction of the natural aerosol (liquid and solid particles) suspended in ambient air. The symbol ePM_x describes the efficiency of an air cleaning device to particles with an optical diameter between 0,3 µm and x µm. The following particle size ranges are used in the ISO 16890 series for the listed efficiency values.

Table 1 — Optical particle diameter size ranges for the definition of the efficiencies, ePM_x

Air filters for general ventilation are widely used in heating, ventilation and air-conditioning applications of buildings. In this application, air filters significantly influence the indoor air quality and, hence, the health of people, by reducing the concentration of particulate matter. To enable design engineers and maintenance personnel to choose the correct filter types, there is an interest from international trade and manufacturing for a well-defined, common method of testing and classifying air filters according to their particle efficiencies, especially with respect to the removal of particulate matter. Current regional standards are applying totally different testing and classification methods, which do not allow any comparison with each other, and thus hinder global trade with common products. Additionally, the current industry standards have known limitations by generating results which often are far away from filter performance in service, i.e. overstating the particle removal efficiency of many products. With this new ISO 16890 series, a completely new approach for a classification system is adopted, which gives better and more meaningful results compared to the existing standards.

The ISO 16890 series describes the equipment, materials, technical specifications, requirements, qualifications and procedures to produce the laboratory performance data and efficiency classification based upon the measured fractional efficiency converted into a particulate matter efficiency (ePM) reporting system.

Air filter elements according to the ISO 16890 series are evaluated in the laboratory by their ability to remove aerosol particulate expressed as the efficiency values ePM₁, ePM_2,5 and ePM₁₀. The air filter elements can then be classified according to the procedures defined in this part of ISO 16890. The particulate removal efficiency of the filter element is measured as a function of the particle size in the range of 0,3 µm to 10 µm of the unloaded and unconditioned filter element as per the procedures defined in ISO 16890-2. After the initial particulate removal efficiency testing, the air filter element is conditioned according to the procedures defined in ISO 16890-4 and the particulate removal efficiency is repeated on the conditioned filter element. This is done to provide information about the intensity of any electrostatic removal mechanism which may or may not be present with the filter element for test. The average efficiency of the filter is determined by calculating the mean between the initial efficiency and the conditioned efficiency for each size range. The average efficiency is used to calculate the ePM_x efficiencies by weighting these values to the standardized and normalized particle size distribution of the related ambient aerosol fraction. When comparing filters tested in accordance with the ISO 16890 series, the fractional efficiency values shall always be compared among the same ePM_x class (ex. ePM₁ of filter A with ePM₁ of filter B). The test dust capacity and the initial arrestance of a filter element are determined as per the test procedures defined in ISO 16890-3.

1   Scope

This part of ISO 16890 establishes an efficiency classification system of air filters for general ventilation based upon particulate matter (PM). It also provides an overview of the test procedures, and specifies general requirements for assessing and marking the filters, as well as for documenting the test results. It is intended for use in conjunction with ISO 16890-2, ISO 16890-3 and ISO 16890-4.

The test method described in this part of ISO 16890 is applicable for air flow rates between 0,25 m³/s (900 m³/h, 530 ft³/min) and 1,5 m³/s (5 400 m³/h, 3 178 ft³/min), referring to a test rig with a nominal face area of 610 mm × 610 mm (24 inch × 24 inch).

ISO 16890 (all parts) refers to particulate air filter elements for general ventilation having an ePM₁ efficiency less than or equal to 99 % when tested according to the procedures defined within ISO 16890-1, ISO 16890-2, ISO 16890-3 and ISO 16890-4. Air filter elements with a higher initial efficiency are evaluated by other applicable test methods (see ISO 29463-1, ISO 29463-2, ISO 29463-3, ISO 29463-4 and ISO 29463-5).

Filter elements used in portable room-air cleaners are excluded from the scope of this part of ISO 16890.

The performance results obtained in accordance with ISO 16890 (all parts) cannot by themselves be quantitatively applied to predict performance in service with regard to efficiency and lifetime. Other factors influencing performance to be taken into account are described in Annex A.

2   Normative references

The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

• ISO 15957, Test dusts for evaluating air cleaning equipment
• ISO 16890-2, Air filter for general ventilation — Part 2: Measurement of fractional efficiency and air flow resistance
• ISO 16890-3, Air filter for general ventilation — Part 3: Determination of the gravimetric efficiency and the air flow resistance versus the mass of test dust captured
• ISO 16890-4, Air filter for general ventilation — Part 4: Conditioning method to determine the minimum fractional test efficiency
• ISO 29464:2011, Cleaning equipment for air and other gases — Terminology

3   Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 29464 and the following apply.

3.1   Arrestance and efficiency

3.1.1
arrestance
gravimetric efficiency

A
measure of the ability of a filter to remove mass of a standard test dust from the air passing through it, under given operating conditions
Note 1 to entry: This measure is expressed as a weight percentage.

3.1.2
initial arrestance
initial gravimetric efficiency
A_i
ratio of the mass of a standard test dust retained by the filter to the mass of dust fed after the first loading cycle in a filter test
Note 1 to entry: This measure is expressed as a weight percentage.

3.1.3
average arrestance
average gravimetric efficiency
A_m
ratio of the total mass of a standard test dust retained by the filter to the total mass of dust fed up to final test pressure differential

3.1.4
efficiency
fraction or percentage of a challenge contaminant that is removed by a filter

3.1.5
fractional efficiency
ability of an air cleaning device to remove particles of a specific size or size range
Note 1 to entry: The efficiency plotted as a function of particle size (3.7.1) gives the particle size efficiency spectrum.
[SOURCE: ISO 29464:2011, 3.1.61]

3.1.6
particulate matter efficiency
ePM_x
efficiency (3.1.4) of an air cleaning device to reduce the mass concentration of particles with an optical diameter between 0,3 µm and x µm

3.2
filter element
structure made of the filtering material, its supports and its interfaces with the filter housing

3.3
group designation
designation of a group of filters fulfilling certain requirements in the filter classification
Note 1 to entry: This part of ISO 16890 defines four groups of filters. Group designations are “ISO coarse”, “ISO ePM10”, “ISO ePM2,5” and “ISO ePM1” as defined in Table 4.

3.4   Air flow rates

3.4.1
air flow rate
q_V
volume of air passing through the filter per unit time
[SOURCE: ISO 29464:2011, 3.2.38]

3.4.2
nominal air flow rate
q_V,nom
air flow rate (3.4.1) specified by the manufacturer

3.4.3
test air flow rate
q_Vt
air flow rate (3.4.1) used for testing

3.5   Particulate matter

3.5.1
particulate matter
PM
solid and/or liquid particles suspended in ambient air

3.5.2
particulate matter PM₁₀
particulate matter (3.5.1) which passes through a size-selective inlet with a 50 % efficiency cut-off at 10 μm aerodynamic diameter

3.5.3
particulate matter PM_2,5
particulate matter (3.5.1) which passes through a size-selective inlet with a 50 % efficiency cut-off at 2,5 μm aerodynamic diameter

3.5.4
particulate matter PM₁
particulate matter (3.5.1) which passes through a size-selective inlet with a 50 % efficiency cut-off at 1 μm aerodynamic diameter

3.6
particle counter
device for detecting and counting numbers of discrete airborne particles present in a sample of air
[SOURCE: ISO 29464:2011, 3.27]

3.7   Particle size and diameter

3.7.1
particle size
particle diameter
geometric diameter (equivalent spherical, optical or aerodynamic, depending on context) of the particles of an aerosol
[SOURCE: ISO 29464:2011, 3.1.126]

3.7.2
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
[SOURCE: ISO 29464:2011, 3.1.128]

3.8
resistance to air flow
pressure differential
difference in pressure between two points in an airflow system at specified conditions, especially when measured across the filter element (3.2)

3.9
test dust capacity
amount of a standard test dust held by the filter at final test pressure differential

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