iv LaserSense Nano Aspirating Smoke Detector Installers Handbook
EN 54-20 compliance
The installation must be designed using PipeCAD software, which is provided
free on the CD shipped with each detector. After designing the installation
including pipes, endcaps and sampling holes, enter the detector type. To select
the detector type, select Options, select Calculation options, and then select the
detector from the Type drop-down list.
Select Options > Calculate or click on the calculator icon. The software will
prompt you to choose from Use set hole sizes, Best flow balance, or Max.
permissible transit time. Select the appropriate option, and then click OK. The
results for each pipe (View > Results) show calculations for each sampling hole
on the pipe with the nearest to the detector at the top of the screen, and the
endcap hole at the bottom.
The classification of each sampling device configuration and associated
sensitivity settings are determined by the column headed Hole sensitivity %
obs/m, which shows the predicted sensitivity for each hole. For the installation to
comply with EN 54-20 depending on the class of installation, each sampling hole
must be no less sensitive than the following:
Class A: 0.80% obs/m
Class B: 1.66% obs/m
Class C: 7.54% obs/m
The calculation can be further refined by leaving a working detector in the
protected area for at least 24 hours at the intended alarm factor for the
installation (this could be done before or after installation). The detector
sensitivity can be read from the Sensitivity figure on the histogram screen of the
Remote software supplied with each detector. Click Options > Calculation options
to open the Hole calculation options dialog box. Enter the sensitivity value
obtained from the practical test, and then click OK. The new calculated value will
use the real sensitivity from the practical test.
The PipeCAD software will determine the classification of any used configuration.
Commissioning and periodic system tests must involve smoke tests to verify that
the system performs as expected and enters Fire 1 alarm within the time
determined by PipeCAD from the farthest hole. The detector sensitivity must also
be inspected to ensure it has not radically fallen from the installed figure. If it has
changed for any reason, the new figure must be re-entered into PipeCAD and the
recalculated hole sensitivities must be confirmed to be within the class limits
shown above.
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