SCS Series Manual —
P/N 15712:L 7/18/16
105
Section 4: Restrictions
4.1 Equipment
Pressurization is the most desired means of controlling smoke. If at all possible utilize pressurization over airflow. Airflow is not the most
practical method of limiting the movement of smoke because of the large quantities of air required.
The process of purging is not an acceptable method of smoke control, however, it can be used as a supplement to airflow or pressurization.
The FSCS must provide full monitoring and manual override control capability for all smoke control systems and equipment.
Smoke dampers are classified as 0, I, II, III, or IV based on the amount of leakage they allow. See Table 2.2 for the maximum leakage rates
allowed for each classification.
Duct detectors should not be used for activation of the smoke control systems. Manual pull stations should not be used for the activation of
zoned smoke control systems, but can be used to activate stairtower pressurization systems.
One of the main concerns with single-injection systems is that the pressurization of the stairtower could fail when a few doors near the sup-
ply fan are open. The supply air being injected into the stairtower for the purpose of pressurization could be lost through these openings, thus
preventing the pressure differences necessary to limit the movement of smoke. For this reason it is recomended that single injection systems
be used in buildings that are eight stories or less. Buildings of more than eight stories should utilize a multiple injection system.
For systems implementing elevator smoke control, the open vent at the top of the hoistway should be eliminated.
A graphic representation for the location and function of each switch is to be mounted adjacent to the FSCS. This graphic representation
must clearly identify each switch.
4.2 Installation
The dipswitch setting of all dipswitches OFF is a factory setting and must not be used.
There are only 32 valid addresses in the FACP for each EIA-485 circuit, numbered 1-32, and each address provides 64 points of monitor and
control capability. Each SCS must be set to one of the available addresses.
The EIA-485 circuit cannot be T-Tapped; it must be wired in a continuous fashion from the control panel to the SCS-8.
The maximum wiring distance between the panel and the last SCS-8 or annunciator is 6,000 feet @ 16 AWG. However, all SCS-8⁄SCE-8
modules must be contained in the same room with the FACP or Network Control Annunciator in FSCS mode.
The built-in 120 ohm resistor must be installed on the SCS-8 module if it is located at the physical end of the EIA-485 Loop, by turning ON
dipswitch 8 on the SCS-8. Turn OFF dipswitch 8 on all other SCS-8 modules.
For Canadian applications, the Smoke Control System must be installed in an enclosure separate from the main fire alarm control panel, and
all wiring between the two cabinets must be in conduit.
4.3 Operation
According to the requirements of NFPA 92A, after the first alarm, automatic operation will be inhibited for the entire FSCS (i.e. lockout).
Manual intervention is then required to make any changes to the state of smoke control points.
After the first fire alarm, subsequent fire alarms will not initiate any further Control-By-Event functions for smoke control elements within
the system. Additional control after the first fire alarm requires manual intervention at the SCS⁄SCE.
All smoke control elements (fans, dampers, etc.) must be configured to provide feedback from all control and monitor points present in the
toggle switch group type. Dedicated Systems employ feedback constantly to monitor system operation when the SCS⁄SCE is in manual mode
only. If the correct feedback is not received within the specified trouble delay time, a trouble condition will be indicated within the toggle
switch group and at the FACP.
Reset of the FACP will be inhibited until all SCS⁄SCE switches are returned to the AUTO position.
For FSCS Mode B operation, see Appendix C.2, “Mode B Operation”.
The HVAC mode is not a listed smoke control function and should never be used as such. HVAC mode without manual control is the only
mode supported by the INA, as well as the NFS-640 without an NCA and the NFS-320/NFS2-640 without an NCA-2.
4.4 Programming
If a toggle switch group number is not to be used:
•
program all four associated annunciator points as software type ACON (AM2020/AFP1010)
•
program all four associated annunciator points to any unused control point (NFS2-3030, NFS-640).
•
program all four associated annunciator points, using ACS programming, to the source N000L01M001 when smoke control modules
are on an NCA or NCA-2 in FSCS mode.
If an SCE is not used: