System Sensor FAAST Comprehensive - Manual (Page 35)

TABle 2. hole SiZeS For lArGe DuCTS
DuCT WiDTh no. oF
holeS hole SiZe nominAl pipe
FloW rATe (CFm)
3 ft . 4 in . (1 m) 6 9/64 in .
(3 .5 mm)
1 .77 cfm
(50 .2 L/min)
5 ft . (1 .5 m) 8 1/8 in .
(3 mm)
1 .80 cfm
(50 .9 L/min)
6 ft . 6in . (2 m) 10 1/8 in .
(3 mm)
2 .10 cfm
(59 .6 L/min)
The information shown in Table 1 and Table 2 applies to a 15 ft. (4.6 m) inlet
pipe and a 10 ft. (3 m) exhaust pipe. Always check with local codes and stan-
dards for hole size and spacing.
hole orientation
Sampling response time can also be improved by avoiding low and high veloc-
ity air flows. Holes on the inlet pipes should be facing into the airflow. Holes
on the exhaust pipe should be facing away from the airflow.
moniTorinG voiDS
In these high air exchange environments, detection systems should be in-
stalled in any void, unless the void is completely empty and presents no
fire risk. If the void contains cabling and/or equipment that can initiate or
contribute to a fire, monitoring for combustion is highly recommended. The
sampling-hole spacing for these areas is the same as the requirements for the
rest of the area, in accordance with the relevant local codes and standards.
When sampling pipes are installed in shallow voids having poor ventilation,
special care should be taken to position the piping as close to the top of the
void as possible. This gives the best early warning due to the likelihood of the
initial smoke layer taking up only the top 10% of the void height.
Local codes and standards normally recommend the area of coverage per sam-
pling hole. Most standards define different pipe and hole spacing, depending
on certain criteria, such as air exchange rates, etc. Careful adherence should
be made to relevant local codes and standards.
For more information see the cold storage white paper at systemsensor.com/faast.
FiGure 4. lArGe DuCT SAmplinG pipe plACemenT
ASP-37
Large Diameter Duct
Air Flow Inlet Pipe
Outlet Pipe
3H/4
H/4
H/2
SS-400-007 36 E56-3621-003
Application and Design
© System Sensor 2013
TrADemArKS
System Sensor, the System Sensor Logo, FAAST Fire Alarm Aspiration Sensing Technology and PipeIQ, are registered trademarks and/or trademarks of Honeywell International, Inc.
in the United States and/or other countries.
Autodesk, and AutoCAD are registered trademarks or trademarks of Autodesk, Inc., and/or its subsidiaries and/or affiliates in the USA and/or other countries. All other brand names,
product names, or trademarks belong to their respective holders. Autodesk reserves the right to alter product and services offerings, and specifications and pricing at any time without
notice, and is not responsible for typographical or graphical errors that may appear in this document. © 2010 Autodesk, Inc. All rights reserved.
Microsoft, Internet Explorer, and Windows are either registered trademarks or trademarks of Microsoft Corporation in the United States and/or other countries.