Guidelines for Air Emission Regulation
8. Measurement of emissions from installations causing air-polluting
8.1 Introduction
The objective of this chapter is to provide guidelines on how to carry out measurements of emissions into air. It will describe methods of sampling and analysis, and set up guidelines on the design of sample-extraction sites, and on the measurement report.
8.2 List of recommended methods from the Danish Environmental Protection Agency
The Danish EPA reference laboratory for measurement of emissions into air [hereafter referred to as "the reference laboratory"] has published (at the end of 2000) a list of recommended methods regarding performance monitoring, AMS, and random testing. The list also includes method sheets with standard operating procedures for a number of common emission parameters (substances), as well as a method sheet for planning and reporting emission measurements.
The list of recommended methods is available on the reference laboratory website72, where the full text in the method sheets can be seen and downloaded.
8.2.1 List of recommended methods, performance monitoring, and random testing
The recommended methods are listed in table 11. It is recommended to use these methods for performance monitoring and random testing. In special cases, it may be appropriate to apply modifications to these methods, or to use other methods of measurement than those recommended. In such cases, the choice of method should be justifiable and approved by the supervisory authority before measurement is carried out. If in doubt, please contact the reference laboratory.
8.2.2 List of recommended methods from the Danish Environmental Protection Agency
8.2.2.1 Performance monitoring and random testing
Table 11 features a list of recommended methods for parameters73, based on the national and international standards available.
Table 11.
Recommended methods for measurement of air pollution from installations (emission):
Methods for performance monitoring and random testing
8.2.3 List of methods, AMS
Use of the methods of measurement listed in table 12 below is recommended in connection with AMS. In special cases, it may be appropriate to apply modifications to these methods, or to use other methods of measurement than those recommended here. In such cases, the choice of method should be well founded and approved by the supervisory authority before measurement is carried out.
8.2.3.1 Measurement of installation
Generally speaking, these standards do not include measurement ranges. Instead, the requirements are related to measurement ranges and/or concentrations measured.
Table 12.
Recommended methods for measurement of air pollution from installations (emission):
Methods for installation measurement using Automatic Measuring Systems (AMS)
8.2.3.2 Design of sampling site
For the purposes of these Guidelines, "sampling site" means the area of space required for a sampling location, i.e. the area where sampling equipment is placed, and from where sampling technicians are able to handle and operate such equipment.
Note that all access to sampling sites must be entirely safe and in accordance with current regulations issued by the Danish Working Environment Authority.
It is necessary to distinguish between designs of sampling sites at large-scale installations, where measurement is carried out regularly, and small installations, such as outlets, where only very few measurements may be called for. This makes it unfeasible to establish definite guidelines. The following, however, gives some recommendations which should be observed at large-scale installations where repeated measurements are called for, and where measurement is carried out at heights greater than 6 m above ground level:
Sampling sites should
 | be 3-5 mē in size (the exact size of the sampling platform depends on the type of measuring equipment used), |
| be able to support a point load of at least 400 kg, |
| have handrails built with kickboard approximately 0.25 m in height and two rails at heights of approximately 0.5 m and 1.2 m, |
| be situated in a manner ensuring that the railings do not obstruct access to sampling apparatus, |
| include stairs or a fixed ladder leading to the sampling site. Where the stairs or ladder meet the sampling site, the railings must have gates that close automatically or a similar safety device, |
| feature 230V electric connections, |
| have a pulley or similar device to lift equipment, |
| have good lighting and ventilation, |
| include protection against severe weather, |
| have a non-skid surface. |
The conditions regarding safety at sampling sites are regulated by the Danish Working Environment Authority. This means that no terms should be included in environmental approvals for these facilities.
8.2.3.3 Design of sampling location
For the purposes of these Guidelines, "sampling location" means the point where emission measurement is carried out within a given duct. Sampling locations in stacks or ventilation ducts are typically made accessible by means of nozzles for securing exhaust probes
The location of such sampling locations and the number of sampling ports in a certain duct are very significant for the quality of the measurement results.
8.2.3.3.1 Particle measurements and volume-flow measurements
As gas velocities, particle concentrations, and distributions of particle sizes may vary within a given duct cross-section, sampling locations should be designed to facilitate extraction of representative samples in the gas flow. This is ensured by creating opportunities for traversing across the entire duct cross section, by inducing good gas mixture (i.e. avoiding layering), and by creating uniform flow conditions throughout the entire cross section.
8.2.3.4 Location of sampling location
Cross sections for measurement should be placed at a right angle to the gas flow. Where possible, sampling locations should be located in vertical ducts. Horizontal ducts should be rectangular. There should be a straight section M1 without obstacles before the sampling
location. For circular ducts, the length of M1 should be at least 5 x D, and
for rectangular ducts, M1 should be at least 2.5 x (H + W). At existing
installations, a shorter straight section is acceptable if the number of sampling points
is increased, see section 8.2.3.6.
D = inside diameter of a circular duct. H = inside height of a rectangular duct. W = inside width of a rectangular duct.
There should be a straight section M2 without obstacles after the sampling
location. For circular ducts, the length of M2 should be at least 1 x D, and
for rectangular ducts, M2 should be at least 0.5 x (H + W). (At existing
installations, a shorter straight section is acceptable if the number of sampling points
is increased, see section 8.2.3.6. There should be a straight section M2 after the sampling location and before
the opening of the outlet of at least 5 x D or 2.5 x (H + W) in length. If the gases in a duct rotate, a flow straightening device should be fitted before the
entrance of the straight section of the duct. Sampling locations should be located in a manner ensuring that they do not interfere
with AMS measurements or reference measurements.
If the measurement technician considers that a given sampling location has not been designed in accordance with current regulations, and that this fact entails greater uncertainty as to measurement results, the relevant installation and supervisory authorities should be notified before measurement commences.
8.2.3.5 Number and design of sampling ports
General instructions:
| The sockets used must be 4" BSP sockets with an internal thread. Deviations may be made from the 4" dimension, if duct dimensions or duct parameters so dictate. Such deviations should always be discussed with an accredited laboratory. |
| Socket depth should be between 30 and 70 mm. |
| There should be at least 1.5 m of open space in front of each sampling port to facilitate insertion and removal of sampling apparatus (probes, etc.) from the duct. If the diameter of a given duct (height/width) is greater than 1 metre, the area of free space in front of each sampling port should extend to a distance equal to the duct diameter + 0.5 metres outside each sampling port. |
| Where measurement must be carried out for several parameters at the same time, extra sampling ports should be fitted, particularly if the parameters to be measured include particles or metals. |
| All sampling ports are fitted with plugs. It must be possible to remove such plugs without difficulty. |
| Ducts with thick walls (e.g. insulation) should be fitted with an opening to the outside of the duct itself (where the sampling ports are located). Such an opening should be rectangular, with inside measurements of 100 x 500 mm, or should be dimensioned in consultation with an accredited laboratory. |
Circular ducts:
| Two sampling ports should be placed 90° apart. |
| Where D + P is greater than 3 m, a total of 4 sampling ports should be placed at relative angles of 90° to each other. D = internal diameter and P = port depth. |
See also figure 7.
Rectangular ducts:
| The sampling ports should be fitted on one of the vertical sides of the duct, so that the required number of sampling points can be distributed evenly across the cross section. |
| Thus the number of sampling ports depends on the number of sampling points and the dimensions of the duct. See section 8.2.3.6 for details concerning the number of sampling points. |
See also figure 8.
8.2.3.6 Number of sampling points
The number of sampling points in a cross section is based on the area of the cross section, as well as on the length of the straight duct sections before and after sampling locations.
The required number of sampling points in both circular and rectangular cross sections must be calculated as illustrated in the following diagram:
Figure 6
Number of sampling points in cross sections
In circular cross sections, the number of sampling points should be divisible by four. The sampling points should be distributed symmetrically along two diameters placed at right angles to each other.
For short, straight duct sections, the number of sampling points should be registered for both M1 and M2. The highest number of sampling points should then be selected.
Example 1
Table 13.
Location of sampling points in a circular cross section
|
Sampling point along cross section |
Number of sample points in a circular cross section |
||||||
|
2 |
4 |
6 |
8 |
10 |
12 |
14 |
|
|
1 |
85 |
93 |
96 |
97 |
97 |
98 |
98 |
|
2 |
15 |
75 |
85 |
90 |
92 |
93 |
94 |
|
3 |
25 |
70 |
81 |
85 |
88 |
90 |
|
|
4 |
7 |
30 |
68 |
77 |
82 |
85 |
|
|
5 |
15 |
32 |
66 |
75 |
80 |
||
|
6 |
4 |
19 |
34 |
64 |
73 |
||
|
7 |
10 |
23 |
36 |
63 |
|||
|
8 |
3 |
15 |
25 |
37 |
|||
|
9 |
8 |
18 |
27 |
||||
|
10 |
3 |
12 |
20 |
||||
|
11 |
7 |
15 |
|||||
|
12 |
2 |
10 |
|||||
|
13 |
6 |
||||||
|
14 |
|
|
|
|
|
|
2 |
A circular cross section has a D = 1,000 mm. M1 is greater than or equals 5 x D and M2 is greater than or equals 1 x D. According to the diagram, there should be 11 sampling points. The number of sampling points should, however, be divisible by four. This means that a total of 12 sampling points should be chosen instead. |
This table illustrates the position of sampling points within a circular cross section. The table indicates the distances from the inside duct wall to the various sampling points. These distances are given as percentages of the duct diameter D.
Figure 7
Example of sampling point location in a circular cross section
Example 2
In a rectangular cross section at an existing installation, H = 1,100 mm and W = 700 mm. The straight sections without any disruptions of flow are short, M1 = 2.5 x D and M2 = 0.6 x D. The theoretical diameter D = 0.5 x (1,100 + 700) = 900. According to the diagram, there should be 17 sampling points. A total of 3 x 6 = 18 sampling points should then be selected. The rule for circular ducts and rectangular ducts is that figures should then be rounded up. |
Figure 8
Example of the distribution of 12 sampling points in a rectangular cross section
8.2.3.7 Sampling gaseous air pollutants
When sampling gaseous air pollution, in principle the samples should be taken at a sufficient number of points within the cross section to arrive at a representative volume of the average concentration. Under good flow conditions, where it is estimated that concentrations are not layered in the cross section, sampling may be carried out from a single point.
In general, the requirements on measurement-position design outlined in section 8.2.3.5 also apply to measurements of gas. In certain situations, such as when measuring in circular ventilation ducts, it may be sufficient to have access to the duct via two 1" BSP sockets placed 90° apart. If an installation wishes to deviate from the requirements on the design of sampling locations, as specified in section 8.2.3.5, this should be approved by the supervisory authorities and an accredited laboratory.
8.2.3.8 Ducts less than 300 mm in diameter
Special rules on the measurement of particles and volume flow apply to circular ducts with a diameter of less than 300 mm (0.5 x (H + W) <300 mm for rectangular ducts). If the requirements concerning distance, as specified in section 8.2.3.6, are complied with, particle measurements may be carried out isokinectically at a single point in the middle of the duct. Measurements of volume flow are traversed as usual. However, no measurements should be carried out at points situated less than 30 mm from the duct walls.
It may be helpful to select smaller sockets for smaller ducts. If an installation wishes to deviate from the requirements on socket dimensions, etc., as specified in section 8.2.3.5, this should first be approved by the supervisory authorities and an accredited laboratory.
8.2.4 Performance monitoring and random testing
Performance monitoring or random testing should be reported in the form of an accredited measurement report. Such reports must, as a minimum, meet the requirements laid down in DS/EN 45 001 or EN/ISO 17025, as stipulated in each accreditation.
The following points should be included in a measurement report:
| the name and address of the test laboratory, the site tested, and the person or enterprise requesting the test, |
| unambiguous identification of the report (e.g. through a serial number) and each page therein, and indication of the total number of pages, |
| a description and identification of the test subject (outlet or stack), |
| date and time of sampling, |
| identification of test/sample specification (reference) or a description of the sample method or procedure used, |
| a description of the sample-extraction procedures, |
| any deviation from, addition to, or omissions regarding test specifications, as well as any other information of importance regarding a specific sample/test, |
| identification of any non-standard test/sample method used, including deviations from recommended methods, |
| measurements, surveys, and results, supported as necessary by tables, diagrams, drawings and photographs, and by records of all errors identified, |
| a statement regarding measurement uncertainties, |
| signature and job title or similar identification of the person(s) assuming technical responsibility for the test report, as well as the date of issue of the report, |
| a statement that the sample results apply only to the sample subjects, |
| a statement that the report may not be reproduced, except in its entirety, without written permission from the test laboratory. |
All quantitative results must include statements regarding calculated or estimated uncertainty. This means that the total uncertainty for a given measurement must be calculated or estimated and included in the report. In addition to the uncertainty associated with the measurement method used, other factors include the design of sampling locations, the measurement process, and the composition of the gas may affect the total uncertainty involved.
A measurement report must include a description (sketch) of the design of the relevant sampling location, including information on duct dimensioning and orientation, the length of straight sections before and after the sampling location, and the number of sampling ports and their relative positions. All matters that influence measurement uncertainty must be described.
The measurement report must include a measure for the level and type of production during the control period. For example, this may concern "energy" and the type of coal involved, or the number of objects painted, their surface, and the type of coating used. For certain types of production plants, it may be sufficient to state whether production is rated as "normal" or "maximum".
| 72 | http://www.dk-teknik.dk/ref-lab/ref-lab.asp Address: Gladsaxe Møllevej 15, DK-2860 Søborg. Tel. (+45) 39 55 59 99 |
| 73 | The reference laboratory is currently working on several new method sheets, including a method sheet for PCB |