Changing the Visible Risk Grade

As the term suggests, the Visible risk grade is what appears in the 3D window of Detect3D, i.e. if a risk grade with a 10 meter gas cloud is set as the visible risk grade then all the gas detectors in the 3D window will appear with a 10 meter gas cloud. This does not mean the coverage results will change when a new risk grade is made Visible. Coverage results are calculated based on the risk grade assigned to the associated zone or sub-zone. This means that coverage results for a sub-zone can be calculated based on a 5 meter gas cloud when the 3D window is showing a 10 meter gas cloud.


The contours for gas mapping will always display the gas cloud size in the Visible risk grade.


It is important to keep note of which risk grade is assigned to which zone as well as the Visible risk grade. To avoid confusion. some projects might be performed best with only one risk grade.



To change the Visible risk grade:

  1. Turn on the FOI visibility of the point and open-path gas detectors, if they are not already. Note that the gas cloud size from the Tutorial 2.d3d file is currently 10 meters, seen below.



    Tutorial 6 - Figure 03 - Gas detectors with the 10m gas cloud size for the Default Grade


  2. Make note that the Main Gas Zone has the Default Grade assigned. Thus the coverage results will remain based on the size of the gas cloud defined in the Default Grade regardless of what appears in the 3D window. At the moment the 1ooN coverage for the project is 87.1% 1ooN and 34.3% 2ooN.



    Tutorial 6 - Figure 04 - Showing the current coverage calculation for the Main Gas Zone with the Default Grade assigned



  3. Make the 5m Gas Cloud risk grade the Visible risk grade by right-clicking its name in the Project Items Tree and selecting Make Visible as shown below.


    Tutorial 6 - Figure 05 - Changing the Visible Risk Grade



  4. Once 'Make Visible' is selected, the 3D window will be updated to display the properties of the selected risk grade. The window should now appear similar to Figure 6 which also shows that the coverage results for the Main Gas Zone has not changed.



    Tutorial 6 - Figure 06 - Updated 3D window with 5m Gas Cloud Risk Grade Visible



This section has focused on the changing Visible Risk Grade which affects the 3D window and contours. Doing this has not affected the coverage results. The next section will go over the opposite situation - changing the risk grade assigned to the zone, which will affect the coverage calculation but not the 3D window.