From NFPA 17A:
2-4.3 Shutoff Devices.
2-4.3.1 Exception No. 2
Exaust fans and dampers are not required to be shut down upon system activation as the systems have been tested under both zero- and high-velocity flow conditions.
Although this does not say the exhaust must be on, it has been interperted as the exhaust must be 'on' during a supression activation.
based on this, I have to correct my initial reply above to restate from that the exhaust fan MUST be "ON", and restate that it CAN be "ON"
That all said, it has been common accepted practice that the exhaust is "ON" during activation of supression. Some opinions are to remove smoke/fumes, and expel same to the exterior.
Last edited by HotLine1; 11/09/10 11:07 PM. Reason: corrected error in sentence
