Hochiki DRD-E User Manual download pdf (Page 7)

DRD-E Flame Detector Installation Manual Page 7 of 12

2-3-0-1376/ISS1/NOV10

3 Quantities and Positioning

The number of detectors required and their position depends on:

 the anticipated size of the flame

 the distance of the flame from the detector

 the angle of view of the flame detector

The DRD-E flame detector is designed to have a class 1 performance as defined in BS EN54-10 on the high

sensitivity setting. That is the ability to detect an n-heptane (yellow) fire of 0.1m² or methylated spirit (clear)

fire of 0.25m² at a distance of up to 25m within 30 seconds.

In fact, the DRD-E flame detector will detect fires at distances of up to 40 metres, but the flame size at such

distances needs to be proportionally greater in order to be sure of reliable detection. Thus the yellow

flickering flame that can be detected at 25m, provided that its size is not less than 0.1m², will have to be

0.4m² in order to be detected at 40metres.

In a rectangular room the distance from the flame detector to the fire is calculated by the formula:

Fig 3 : Calculation of distance from detector to flame

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Hochiki DRD-E User Manual Page 7