Page 82 of 97
Title FireVu Detector Standalone Installation Manual
NetVu Ltd.
No 1 Thellow Heath Park, Northwich Road, Northwich, Cheshire. CW9 6JB
Once the Black Body pixels representing the glowing soot particles in flame source have been
identified, then further tests are made to determine if there are sufficient of them, and that they
vary sufficiently.
The rate at which ‘awareness’ increases is set by the Awareness Ratio
for each region, and then
there is a threshold at which there has been sufficient changing activity of Black Body pixels to be
determined as a Flame source.
If these thresholds are set too low, then a brief Black Body pixel match would result in a trigger.
This may be a high intensity light, or even High-Visibility jackets reflecting sunlight. However, as a
result of this processing, a continuing changing flame pattern has to be detected for a minimum
number of pixels, represented by the Minimum (Min) Active Area.
The default Min Active area is 16 pixels, and is suitable for many circumstances, including the
presence of high intensity yellow / orange beacons. This level would typically detect a standard
(EN54-TF5) test pan fire (330mm x 330mm x 50mm
(13” x 13” x 2”) pan with 500ml (1.06 US Pints)
of fuel) at twice the target distance.
The threshold can be reduced to as little as 8 pixels, giving greater sensitivity, resulting in detection
of a standard test pan fire at three or more times the target range. However, in the event of fork
lifts or similar with rotating beacons in the foreground there may be a small risk of false positives.
The preferred solution is to increase the lower row or two to 24 and 32 respectively which will still
provide excellent protection to any flame sources in the foreground, while maintaining immunity
from such sources, even if close to, and in the direct line of view.
Click the “Save” button when you have finished.
Network Web-pages
Listed below are descriptions of the Web-
pages to be found by navigating to the “Network“ Web
-
page.
