MAN2285-9
Page 19
Above ceiling sampling with detector mounted in ceiling void
FastSense 25
False Ceiling
Sampling Pipe
Sampling Hole
Always locate the sampling points in a position to which smoke may reasonably be expected to travel. This
may sound obvious, but, for example, do not expect ceiling mounted sampling points to operate satisfactorily if
air flow prevents the cool smoke from an incipient fire from reaching ceiling level. In this instance it is usually
better to locate the sampling pipe directly in the airflow (for example across the return air register of an air
conditioning unit). There is no substitute for carrying out smoke tests prior to installation of pipe work to
indicate suitable sampling point location.
To assist in design and to verify system performance, it is advisable to use the PipeCalculator sampling pipe
modelling software.
IMPORTANT notes on sampling pipe design.
The FastSense 25 detector is primarily designed to be capable of localising incipient fire incidents. As such, it
has very limited sampling pipe capability in comparison to products such as the FastSense PLUS, which would
normally be used for large area protection. The manufacturer strongly recommends that the design
requirements provided here be strictly adhered to.
6.1
Pipework
Please consider these important notes below when designing a system employing the FastSense 25 detector.
Maximum sampling pipe capability is 25 metres with 10 sampling points. This will only be achievable in still air.
Air movement in the vicinity of the sampling pipes will reduce this sampling pipe capacity greatly.
If the FastSense 25 detector is employed to sample high velocity air (greater than 5 metres per second), as
found in the vicinity of Air Handling Unit air intakes, then maximum sampling pipe length will be reduced to 6
metres.
No more than ONE Air Handling Unit may be protected with one FastSense 25 detector.
