Smoke Alarm User Manual

Installation, Operation and Maintenance Manual
Issue 1 Page 5-11
February 2001
(4) Locate sampling pipe in the main supply duct return side, down stream of the filters a
minimum of six duct widths from any source of turbulence (bends, inlets or deflection
plates) to reduce the effects of stratification. In installations where the filter is capable of
removing smoke, install the sampling tube upstream of the filter.
NOTE
Where it is physically impossible to locate the sampling pipe accordingly, the sampling
pipe can be positioned closer than six duct widths, but as far as possible from inlets,
bends or deflection plates.
(5) Locate the sampling pipe so dampers do not restrict airflow at the sampling pipe.
(6) The sampling pipe should be located prior to exhausting air from the building or diluting
return air with outside air.
(7) Locate sampling pipe if close identification of the source of alarm is required.
(8) Locate sampling pipe on the downstream side of the filter to sense fire in the filters.
NOTE
If filters are blocked, sufficient airflow may no longer be present for proper operation.
(9) Do not locate sampling pipe immediately following outside air inlets except to monitor
smoke entry to the handling system for adjacent areas.
(10) When ever possible, locate sampling pipe upstream of air humidifiers and downstream of
dehumidifiers.
5.22 Sampling Pipe Requirements
(1) The intake sampling tube must face into the airflow.
(2) The intake sampling tube must go all the way through the duct and be closed-ended
(capped).
(3) Holes in the sampling tube must be spaced approximately every 100 mm (4 inches).
(4) The exhaust tube must extend a minimum of 60 mm (2 inches) into the duct.
(5) The total pipe network, including the return, must not exceed 188 meters (388 equivalent
feet).