Detector window contamination – Hochiki IFD-E User Manual

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Hochiki Europe (UK) Ltd



Fig 3

Detector Field of View Plot

The flame detector should be positioned at the perimeter of the room, pointing directly at the anticipated
flame or at the centre of the area to be protected. If the detector cannot ‘see’ the whole of the area to be
protected, one or more additional detectors may be required.

The flame detector is not affected by normal light sources but should be positioned so that sunlight does
not fall directly onto the viewing window.

Detector Window Contamination

It is important to keep the detector window clean and checks should be carried out at regular intervals –
determine locally according to the type and degree of contamination encountered – to ensure optimal
performance of the flame detector. Although the IR detectors can detect flames when the window is
contaminated, there may be a reduction of sensitivity as shown in Table 1.


Typical percentage of normal response

Water spray


Steam 75%

Smoke 75%

Oil film


Salt water film


Dry salt deposits


Table 1 IR Detector window contamination

UV/IR detectors are more susceptible to window contamination and must be kept clean