Dispersion calculations for odorous substances according to the models VDI 3782 part 4 and Factor-10-Method
2. Odor models
3.1 Global parameters
4.1 Batch processing
5.1 Within the forms
With P&K_ODOR we offer a PC program to carry out dispersion calculations for odorous substances according to the models VDI 3782, part 4 and the Factor-10-Method.
Both models use the Gaussian Plume Model according to TA Luft as a basis model for calculation of half-hour average values of the odor concentration. They differ in modelling of the fluctuation.
The calculation with the Factor-10-Method determines how often the average value (which was increased by a factor (usually 10)) exceeds the odor threshold.
A gamma distribution is used in the model VDI 3782, part 4 to describe the fluctuation. The model parameters are accessible in the forms.
The dispersion conditions are described in the statistical data of dispersion categories according to TA Luft. The result of an odor ambient air concentration prognosis is the time-assessed frequency of odor; also known as frequency of perception.
A large number of point sources, line sources, and area sources can be considered in the calculation as well as receptor points and evaluation areas with pre-pollution.
Pre-condition to access the calculation function of the program is to apply the selection (generation) with help of the file administrator ("Files").
The option "Inputs" equips the program with forms and tables to define the input data. To control the inputs, the area map and the wind distribution can be viewed graphically or distributed to a printer.
The results of the calculation are available in the main menu in "Prognosis". A result log shows the input data and the calculation results as text in a ASCII-file and a Report shows this in HTML-Format.
The prognosticated characteristics can be illustrated in colored squares
(surfaces), placed numbers, or Isolines. They also can printed as well as
transferred to other programs.
Just start the installation program and follow instructions
The program can be started by executing pk_odor.exe. For simplification a link to a user defined program group has been produced during the installation.
The parameter settings of an project are stored in a set of files with the same name but with different extensions. The selection of a set of data ("Files") or the input of appropriate data is required to access further program functions.
Functions for all necessary file handlings are available in the file
The following files are placed and initialized in the data path:
For each project a set of files with different extensions and the same
name will be put into the current data path by the file manager and
administered from there:
The calculation of statistical characteristics requires existing
statistical data of dispersion categories (AKS). The AKS can be put under any
name into an individual path. The program comes with a fictitious AKS with the
In P&K_ODOR, a context-sensitive help is integrated. It can be
pulled up at any location in the form by pressing the function key "F1". In the
help screen, if necessary, highlighted cross references (links) are
interspersed, which, by clicking on them, provide more detailed information.
The calculation with the Factor-10-Method determines how often the average value (which was increased by a factor (usually ten)) exceeds the odor threshold. A time assessment is included; so the results can be compared with the perception frequency of the VDI model. They appear in the appropriate column of the result log. The re-standardization and the objective frequency of odor are meaningless in this model. The related columns in the log have the value zero.
see Odor model data
The model VDI 3782, part 4 uses a gamma distribution, which is dependent on the dispersion parameters (sigmas) and the wind velocity, to describe the fluctuation.
A great deal of care was taken over the draft of the guideline VDI 3782, part 4 in our program. The results have been checked with two other, absolutely independent software implementations. The basis model (TA Luft 86) shows in the result list of our program the annual average value for the odor concentration, which was added together from the half hour average values. The annual average value is identical with the pollutant concentration, which standard business TA Luft programs supply under the same conditions.
The parameters disputed in the guideline can be set individually:
or meet reasonable assumptions in the program:
Dispersion parameters (Sigma)
In an accompanying text of the guideline draft (VDI volume 16, page 34) it is indicated that better results are to be expected, if the "dispersion parameters are seen as dependent from the source distance and not only from the Lee distance".
This is taken into consideration (not part of the guideline draft) by calculating sigmay=F*sqrt(x2+y2)f and sigmaz=G*sqrt(x2+y2)g outside the basis model (TA Luft).
Waste gas plume rise
The guideline draft plans a rise model for the waste gas plume deviating from TA Luft (VDI 3782, part 4, appendix 1).
This model shows a mixture from rise models according to VDI 3782, part 3 and TA Luft 86
This action is certainly worthy to explore. That's why there are alternative rise models available in our program.
Time assessment and cumulating low odor
The guideline draft (VDI 3782, part 4, chapter 5) plans, besides the odor frequency, a second characteristic in the form of a cumulated odor frequency (or frequency of perception).
The odor frequency for a dispersion period will be increased to 100%, if it is greater than the time assessment threshold. According to the guideline draft, the lower frequencies should disappear. This can, with mainly low values (odors), cause the perception frequency to disappear; an effect which is hard to understand. The program offers alternatives to keep the low odors while calculating the cumulated odor frequency.
In the guideline draft lambda=0.22 is set and in the accompanying text of the guideline draft lambda=0.2 is set (VDI volume 16, page 21).
For the vertical wind profile an exponential statement is selected in
the calculation of the mean of sum of curves (TA Luft 86) as well as in the
re-standardization of this average value (VDI 3782, volume 4, section 2.1).
This exponential statement leads to infinite ambient air concentrations for
heights which are converging towards zero. For the first case it is the source
height, in the second case it is the receptor point height. In the absence of a
better statement, a constant wind profile below 3 m is assumed in P&K_ODOR
as well as in the TA Luft Model (UBA-materials 2/87 section 3.1.3)
The statement (diverted from the multiplication theory of the perception frequency), suggested in the text of the guideline draft (chapter 3.1) is mathematically plausible in the case of independent sources (with statistically interfered fluctuations). This can certainly be assumed, when the temporal width of the concentration fluctuations (in the dimension of a second), which are generated by air schlieren, clearly stay below the duration differences of the sources to the receptor point. This can be assumed for source distances of several meters.
This statement is also used for handling the line and area sources
(which are transformed into point sources according to the guideline VDI 3782,
Data is to be entered into forms and tables and will be stored in a set of files for later access. These files obtain a common project name with a different extension.
Two forms are for entering all non-tabular project names which are stored with the extension ODP.
The model dependent data is to be entered in the form "Odor model data" and is described in chapter 3 of the manual.
The inputs, not binding on the model, are to be entered in the form
"Global parameters of characteristic calculation" and will be described in the
Two lines of text will be stored along in the result log to describe the calculation.
The name of the statistical dispersion category can be selected from a list, if this list exists with the extension AKS in the directory for statistics.
The basis model (TA Luft) requires that during the characteristics calculation, the 10°-wind direction sectors of the AKS are divided into 2°-sectors. With a checkbox, this step can be turned off to increase the computing speed. In particular, when calculating many sources or several dispersion category statistics, the error which occurs is negligible (low percentage). In individual cases, the deviation should be checked by test calculations.
The structure of the statistical dispersion categories is explained in chapter 4.2 of this manual.
The characteristic calculation can be limited to dispersion categories, wind direction and wind velocity categories. This limited calculation will supply results, as if these conditions were continuing for the entire time.
The characteristic calculation can be limited regarding dispersion, wind direction and/or wind velocity categories. The category zero (selection "all") causes the consideration of all categories. The limited calculation supplies results, which could be expected if these conditions would be continuous for the entire time. The definition of the categories is explained in chapter 4.2 of this manual.
The odor threshold value is defined as the concentration of odorous substances from the moment that odor occurrences are perceived. They are counted as soon as they are perceived.
If the pre-pollution values for the evaluation areas are unknown in the fullest details (all pre-pollution inputs in the collective list are equal to zero), it can be calculated with the same pre-pollution for the entire area.
When calculating the expected odor frequency, the syncronicity of the emission is of decisive influence. Odor frequencies of source emitting in the same time are added according to the multiplication theorem of the likelihood calculation (see chapter 2.3 of the manual).
With the plan of the time periods a simple way to describe the simultaneity is offered. The total time, depending on the demands of the project, is distributed among 5 periods. A relative time share is allocated to each period. In which period a source did emit or not is to be stated. E.g. these are the following source types in a company with 3 shifts (8 hours each):
From this the following periods result:
For the sources set the following buttons:
The 5th period is not necessary.
Characteristics can be calculated for individual receptor points or together for a collective of receptor points. The functions for generating receptor point rasters can be found in one form and for editing and modifying the receptor point data can be found in another form.
The definition of the receptor point array is located in a table, which holds the coordinates of these points. The collectives and pre-pollutions are in another table.
For each receptor point collective, a pre-pollution for the odor frequency is the first value in each line. If in the collective table all of the pre-pollution values is not equal to zero, the pre-settings of the pre-pollution from "global parameters" are used in the characteristic calculation.
For more comfortable handling, this program is equipped with a function for the generation of a circular point network with square meshes and uniform point heights.
This generator is configured in a form in which center point coordinates, radius of the area, mesh-size of the network, height of the receptor points and number of the receptor points per mesh are entered. Only meshes which fit completely in the circular area, are created.
A square area can contain 4 receptor points, one on each corner, or an additional 5 points (for a total of 9) in the middle of the edge length between the corners and in the center.
Four different area types can be generated:
The possibility of an edge length of 250 meters and nine points per mesh
and meshes symmetrical around the center complies with the demands of the odor
ambient air concentration guideline of the regions (GIRL)
see Form Definition of a receptor point net
Under the menu Edit / Sources, one can create and define sources.
A source with the expansion zero in X and Y direction is a point source; a source with the expansion zero in just one direction is a line source.
Line and area sources will be replaced by a set of point sources as mentioned in the appendix 2 of the guideline VDI 3782 part 1.
When heat emission is present (exhaust gas temperature over 10° C), only the thermal lift is calculated. Only with cold sources is the mechanical lift (taking into consideration the stack opening diameter) the cause for the waste gas plume rise.
In case of line and area sources, the specification of the heat emission refers to the entire source.
The diameter of a stack opening determines the mechanical lift of a cold waste gas plume with given exhaust volume rate according to VDI 3782 part 3. In case of heat emission or for calculations according to TA Luft this specification is meaningless.
Temperature and exhaust volume rate determine the heat emission and with
that the thermal lift of the exhaust. The surrounding temperature of 10 °C
must not be exceeded. The exhaust volume rate is to be entered in standard
In the context of the characteristic calculation for the project (specified under the menu "Statistic"), a complete calculation is carried out and results are posted into a log. This log is the data input for illustration of the results and the Export-program.
Before the start of a time-consuming complete calculation (particularly when intending to use batch processing), the inputs can be verified with the function check for plausibility. A further tool for verification can be the area map.
The project (including results) must be saved after a prognosis has been committed!
The result of the calculation is also stored in an ASCII file with the file extension ODO and this can be viewed with an editor.
The calculation of the characteristics requires (in case of a Pentium II Processor with hard disk-cache) the total statistical data of dispersion categories and 2°-wind sectors in the Factor-10-Model 0,12 seconds and in the model VDI 3782 part 4 ca. 0,3 seconds for a pair of receptor sources.
Line and area sources are divided into several sources for close
receptor points, whereby the computing time increases substantially. Likewise,
the number of the dispersion situations is a factor of the computing time. A
calculation with 10°-wind sectors reduces the computing time by a factor of
The result covers the following result tables and relevant input data of the calculations:
If the calculation was limited to certain wind direction, wind velocity and/or dispersion categories, the characteristics show the values when the reduced statistic would have carried on for the entire year.
The odor ambient air concentration guideline of the regions (GIRL) defines the total pollution as the arithmetical sum from additional and pre-pollution. These characteristics are shown in additional columns in the result log.
The results can be viewed under the menu Prognosis / Report or
Prognosis / Log.
The characteristics of the result table are illustrated graphically on the display.
There is one value for each receptor point collective in the calculation result:
for the additional pollutions
for the pre-pollution of the subjective frequency of perception
The columns of the result table in the log are optionally illustrated on the display.
There are forms for the setting at the view port. In addition, the graphic title can be set in the form Parameter of the characteristic output. With File/Print the graphic can be printed.
Parameter of the result graphic
For the illustration of color areas and contour lines, inputs are expected for the threshold values. From the threshold range and the number of thresholds, appropriate equidistant threshold values will be calculated in the form Configuration of the color scale. This can be overwritten.
In the form "Parameter of the characteristic output" the graphic type and a column can be selected from the result table for illustration.
For the graphic output of the results, symbols, numbers and colors of the geometric elements can be activated here.
Map of the area
Derived from the information in the result table, the map of the area illustrates the placement of the sources, receptor points etc. on the screen. The objects will be drawn in colors which can be chosen. In addition, the output of the symbols and numbers of the geometric elements can be activated.
see form Parameter of area map output
A column of the result table will be shown on the screen in the form of placed numerical information. For a large number of receptor points, this is legible in a reduced viewport of the area only. Legible numbers can be generated by the display factor and by the number of decimal digits. The factor will be added to the title.
see form Configuration of the color scale
Color area representation
Around each evaluation area a quadratic colored area will be drawn, which represents the result value. The value, which is related to each color in the legend, describes the lower limit for the corresponding value interval. The value corresponding to the following color describes the upper limit of the interval.
see form Configuration of the color scale
Representation of the contour lines
One column of the result table is shown in the form of contour lines on the screen. The number value corresponding to the line color is listed in the legend.
The contour line generation selects between two methods automatically, depending on the receptor point area:
see form Configuration of the color
In the menu item "Batch processing" functions are available to carry out calculations for concentration arrays and characteristics.
The settings of the project must have been completed beforehand in the form with the functions of the menu item "Inputs".
The projects must recide in one folder, which has to be selected to enable the other functions. It is a good idea to copy projects into the batch folder, because they will be overwritten automatically.
The tasks entered into the table will be executed one after the other. Check System-Log for errors after the batch has been processed.
The statistics can be obtained from the meteorological services, (e.g. Deutscher Wetterdienst in Offenbach), or can be generated with our P&K MET from sampled data. The Klug-Manier statistics come in the form of ASCII files on diskette or magnetic tape.
From the DWD, two different formats are available:
Seven dispersion categories (I to V and unknown) with 32 wind velocity categories (1 to 32 knots and greater) and 38 wind direction classes (Calmen, sector 1 to 36 and circulating winds).
TA Luft Format:
Six dispersion categories (I to V) with nine wind velocity categories (class 1 to 9) with 36 wind direction classes (sector 1 to 36).
This number matrix can have header lines (preceding text lines). There is usually one in the DWD format one and five in the TA Luft format.
With the TA Luft format, calculations can only be carried out according to the TA Luft model, because the VDI 3782 mode supposes 15 wind velocity categories and the TA Luft format has only nine categories. The DWD format is useful for both models.
When using an AKS in the DWD format, the unknown dispersion category, Calmen, and circulating winds get distributed according to their quantity, which influences the calculation according to the specifications of the TA Luft 86.
Except for the header lines, line terminations are not relevant. Also the distance between the numbers is arbitrary.
The statistics are based on an anemometer height, which cannot be inferred from the file. Therefore, it is very important that the anemometer height used for the calculation of the concentration array is identical to that used for the dispersion category statistics.
The dispersion categories are derived in both models (TA Luft and VDI 3782) from the same pattern developed by Klug/Manier. The dispersion category statistics obtainable from the DWD are classified according to this regulation.
The wind velocity categories are dependent on the model derived as
The wind direction is divided into thirty-six 10°-sectors, beginning
with the sector 6° to 15° in the windrose (north wind slightly east)
progressing in the clockwise direction. Inside the program, depending on the
position of the checkbox "Sub plumes", the calculation is made with
10°-sectors or with 2° sub sectors with the same frequency.
For selected measuring stations of the DWD, so-called four-dimensional statistics are available. These consist of two complete three-dimensional statistics: one for the dry times and one for the times with precipitation (with an intensity over 0.1 mm/h).
Also available are yearly or diurnal variations of the dispersion
situations. In a file are a multiplicity of identically structured statistics:
for the diurnal variation there is one for each hour of the day and for the
yearly variation there is one for each month of the year. In order to access a
certain statistic, the preceding lines must be skipped (number of header
Statistical data of dispersion categories, which can be present as a file with the extension AKS, can be selected under "File/Open" (in Tools/Windrose).
Data of a dispersion category can be viewed graphically or in the form of a table in the menu item "Tools/Windrose".
For the graphic output, a summary illustration or a single illustration can be chosen (the frequency of all categories will be added together). The output can be limited to one dispersion category and/or one wind velocity category.
With "File/Print" the graphic or table can be printed.
see P&K Windrose
With this program, result tables of the P&K 3782 program can be exported to be used by other programs. As examples programs like "Surfer", "AutoCad", spreadsheet programs and text processing programs are mentioned.
For various settings, the form P&K Export settings is available, which can be found in "Options/Settings". Under "Options", configuration files can be opened and saved.
see P&K Export
In den Bildschirmformularen erfolgen die Eingaben in Formularfeldern. Mit den Tasten Cursor rauf, Cursor runter, Tab und Shift Tab oder mit der Maus kann der Cursor über die Felder bewegt werden. Cursor links und Cursor rechts bewegen den Cursor zeichenweise innerhalb eines Feldes.
Reelle Zahlen können mit Punkt oder Komma oder auch als 1e-6 für 10-6 eingegeben werden. Der Fehlerton kann bei der Eingabe ignoriert werden, er wird nur als Warnung ausgelöst, weil 1e oder 1e- keine gültige Zahl ist.
Gegebenenfalls (wenn im Formular gekennzeichnet) kann eine Auswahlliste von diskreten Eingabewerten geöffnet werden.
Mit F1 wird zu einem Formularfeld oder zum ganzen Formular eine kontextbezogene Hilfe angeboten und das integrierte Handbuch zugreifbar.
Mit OK oder ABBRECHEN wird das aktuelle Formular verlassen.
Siehe auch: Calculator
The order and the width of all columns can be changed by clicking into a column header or between column headers and dragging as desired. This is practical if values are in a particular order, because Tab has to be pressed just once in order to reach the next column.
If the data in the columns are too wide to be displayed, then the symbols (in brackets) will be hidden in the column titles (e.g. Temperature (T0) ). Widening of the column will show that particular symbol.
The buttons "+" and "-" are used to insert or delete data sets. With the button "Dup" the current data set can be duplicated. The new row will become the last row in the table. This is useful if a data set is to be generated with minor difference to the current one. To insert a row, select the lower gray row before pressing the "+" button.
Individual fields, in which a selection is possible, are marked yellow. To activate the selection click once in a cell in order to select this; click a second time in order to activate the selection (no doubleclick).
With the cursor or Tab key, the focus can be moved between individual fields.
The illustrated section can be scrolled one row up or down by moving the cursor across the upper or lower edge of the table form.
Some tables can be sorted. With a right mouse button click into the considerable column, a Pull-Down Menu will be opened, and Sort Ascending or Sort Descending can be selected.
In some tables, a Row-Editor can be invoked. The Row-Editor shows one dataset only and can have more or less features then the grid dialog.
Sometimes single Columns can be imported via the Popup Menu. From the selected file, the values are taken and written to the position, from which the dialog was invoked. One value will be read per line from an ASCII file (includes CSV format) .
Sometimes single Columns can be imported via the Popup Menu. From the selected file, the values are taken and written to the position, from which the dialog was invoked. One value will be read per line from an ASCII file (includes CSV format) .
Some tables feature a search function. See Find in table
This feature allows to filter out a column with its value. Only rows with this value in the filtered column and not this column will be shown. The filter can be set to most of the columns (except when they are declared unique). All available column names are shown in the selector next to "Filter:". Once a column is selected, a corresponding value out of this column can be selected in the selector to the right of the equal sign. Filtering is accomplished on a text basis rather than on a value basis (e.g. 1.0 doesn't equal 1).
Using the filter feature will reorder the rows. Only columns, which are not defined as unique, can be selected. Some table can be sorted (Right Mouse Button Click into the column of regard.)
A filter might be active during import / export to exclude or include rows of data.
Table Import and Export
In most tables, data can be imported or exported with the buttons in the tool bar. The sequence of the columns and which columns are used, depends on the current column order and the current filter setting. With a button in the tool bar, a form can be opened which gives information about the current settings.
Single Columns can be imported via the Popup Menu. From the selected file, the values are taken and written to the position, from which the dialog was invoked. One value will be read per line from an ASCII file (includes CSV format) .
Available formats for import and export
The formats can be selected in the appropriate dialogs under the type of file. The filter function is switched off for other formats than CSV, TXT and *!
The tables can be viewed appealingly as an HTML-file by using the preview function. see Report function.
Most of the graphics can be zoomed; therefore a rectangle has to be opened with the mouse from the upper left corner to the lower right corner. To reset the zoom, a rectangle from the lower right corner to the upper left corner has to be opened with the mouse. Also the graphic can be moved; therefore the graphic is to be dragged with the right mouse button pressed.
Some dialogs can also be opened by clicking onto the axis, the legend, the title or double clicking the drawing area.
The button has to be down for all functions, which are activated by clicking into the drawing area.
Graphical illustrations on the screen can be printed with File/Print or the button .
The Export of Images can be done with . Images can also be copied to the clipboard with .
Setup (Layout, Export and Format)
A form in which more graphic parameters can be set. Functions for export and graphics formats are also in this form.
Alterations made in will not be saved automatically. In some illustrations it might be possible to save and load configuration changes under the file menu, but it might cause strange effects, because the configuration might not fit to the current illustration. Series, which are not needed in the current illustration and which are not automatically destroyed can be made inactive. Data are managed in so called Series. The configuration can be saved with or without data. The data are normally replaced with the current ones, despite this, sometimes it might still be important to save the data along with the configuration.
Modifications and settings in other forms or of the calculated data can overwrite made changes in Setup!
It is recommended to set the graphic type to the configuration to be loaded.
With the button MAX the scale settings are maximized.
The graphic can be illustrated isometrically by using the button ISO. This has to be repeated after changing the size of the graphic.
The dispersion category can be changed with the cursor key <up> and <down>, the wind velocity category with <left> or <right>. To change the graphic type press <Page up> or <Page down>.
Compatibility with previous versions