ISO 09096:2003 pdf download

ISO 09096:2003 pdf download.Stationary source emissions一Manual
determination of mass concentration of particulate matter.
a) an adequate quantity of dust is collected during the sampling, which is at least 5 times the corresponding overall blank value;
b) the gas stream in the duct at the sampling location has a sufficiently steady and identified velocity, temperature and pressure, and a sufficiently homogeneous composition;
c) the flow of gas is parallel to the axis of the nozzle;
d) sampling is carried out without disturbance of the gas stream, using a sharp-edged nozzle facing into the stream;
e) isokinetic sampling conditions are maintained throughout the test;
f) samples are taken at a preselected number of stated positions in the sampling plane to permit obtaining a representative sample for a non-uniform distribution of particulate matter in the duct or stack;
g) the sampling train is designed and operated to avoid condensation and to be leak-free;
h) calibration criteria are satisfied;
i) sampling blank and leak-check criteria are met;
j) dust deposits upstream of the filter are recovered and/or taken into account;
k) the sampling and weighing procedures are adapted to the expected dust quantities as specified in this International Standard.
4.2 Interferences
a) Positive interference
Gaseous species present in stack gases that are capable of reacting to form particulate matter within the sample train can result in positive interference. Examples include the potential reaction of sulfur dioxide (SO2) to an insoluble sulfate compound in the high-humidity portion of the system, such as with limestone in flue gas following a wet flue-gas desulfurization system (FGDS) to form calcium sulfate (CaSO4), or the reaction with ammonia gas (N H3) to form ammonium sulfate (NH4SO4) [see 7.1 a)].
b) Negative interference
1) Certain acid gaseous species can erode the filter material, resulting in negative interference. For example the reaction of hydrogen fluoride (HF) with glass components in the sample train (see 6.2.5).
2) Volatile matter existing in solid or liquid form in the stack gas may vaporize after collection on the sample train filtration material, due to continued exposure to the hot sample stream during the sampling period. Such occurrence would result in a negative interference (see 8.1).
5 Sampling plane and sampling points
5.1 General
Representative sampling is possible when a suitable location is available, having a sufficiently homogeneous gas velocity at the sampling plane.
Sampling shall be carried out at a sufficient number of sampling points, usually located on several sampling lines. Convenient access ports and a working platform shall be available for the testing.
5.2 Sampling plane
The sampling plane shall be situated in a length of straight duct (preferably vertical) with a constant shape and cross-sectional area. The sampling plane shall be as far downstream and upstream as possible from any obstruction that may cause a disturbance and produce a change in the direction of flow (disturbances caused by e.g. bends, fans or pollution abatement equipment).
5.3 Requirements for sampling points
Preliminary measurements at all the sampling points defined in 5.4 and Annex B shall prove that the gas stream in the sampling plane meets the following requirements:
a) the angle of gas flow is less than 15° with regard to the duct axis (a recommended method for estimation is indicated in Annex C of ISO 10780:1994);
b) no local negative flow is present;
c) the minimum velocity is higher than the detection limit of the method used for the flowrate measurement (for Pitot tubes, a differential pressure larger than 5 Pa);
d) the ratio of the highest to lowest local gas velocities is less than 3:1.
If the above requirements cannot be met, the uncertainty will be higher than that specified by this International Standard and the sampling location is not in compliance with this International Standard (see 7.4.6).
The above requirements are generally fulfilled in sections of duct with at least five hydraulic diameters of straight duct upstream of the sampling plane and two hydraulic diameters downstream (five hydraulic diameter from the top of a stack). Therefore, it is strongly recommended that sampling locations be selected accordingly.
5.4 Minimum number and location of sampling points
The dimensions of the sampling plane dictate the minimum number of sampling points. In general, this number increases as the duct dimensions increase.
Tables 1 and 2 give the minimum number of sampling points to be used for circular and rectangular ducts respectively. The sampling points shall be located at the centres of equal areas in the sampling plane (in accordance with Annex B).
Sampling points shall not be located within 3 % of the sampling line length (if d> 1,5 m) or 5 cm (if d < 1,5 m) from the inner duct wall. Choose the inner edge of the area when calculations result in sampling point positions within this area. This may arise when selecting more than the minimum numbers of sampling points presented in Tables 1 and 2, for example in cases of unusual duct shape. NOTE When the requirements for the sampling plane (see 5.2) cannot be met, it may be possible to improve representative sampling by increasing the number of sampling points above those specified in Tables I and 2. See also 7.3.2 for sampling-point premeasurement procedures.