User's Manual

Design
September 2013 3-72 P/N 81-CO2MAN-001
The response time of a pneumatic detection system is dependent upon a number of factors,
such as:
1. Fire intensity
2. HAD spacing and location
3. Control head setting and vent size
4. Volume of tubing
The system will actuate when the entire sensing volume (i.e., HAD's, copper tubing, and
pneumatic control head sensing chamber) is pressurized to a level greater than the control
head setting (e.g., 4-inches of water). To ensure adequate response to a fire, the tubing
system must be limited to a total length of 200 ft. (61 m) or less.
3-13.4.3.1 Tandem Control Heads
For actuation of two or more adjacent pilot cylinders, pneumatic operated control heads may
be connected in tandem to a single set of HAD's and actuation cable. The tandem control head
shall have the same actuation pressure as the primary control head (See Paragraph 2-3.5). A
cable housing (See Paragraph 2-3.6.1) shall be installed between each control head to protect
the cable, if used.
3-13.4.3.2 Main and Reserve System Actuation
For systems with a connected reserve agent supply, a single set of HAD's is connected to the
Pneumatic Main-to-Reserve Valve, Part No. 81-871364-000. The two valve outlets are
connected to the pneumatic control heads on either the main or reserve supply, providing a
means of manually selecting either supply.
NOTE: There is no means of providing main/reserve selection for a connected cable operation.
3-13.4.4 ELECTRICALLY OPERATED ACTUATION
Electrical actuation uses an electrically operated control head and a suppression-releasing
panel, which is alarmed by automatic detectors and manual pull stations. See Paragraph 3-14
for additional information.
3-13.4.5 NITROGEN PRESSURE OPERATED ACTUATION
Nitrogen pressure actuated systems provide a means of actuating multiple components from
a single control. Pressure from a nitrogen cylinder actuates one or more pressure operated
control heads attached to carbon dioxide cylinders or stop valves. In addition to these
components, N
2
actuation is required to drive the discharge delay when FM Approval is
required. The nitrogen cylinder is actuated by a lever, cable, electrical, or pneumatic heat
detector operated system, as discussed in previous sections.
3-13.4.5.1 Direct N2 Operation of CO2 Cylinders and Stop Valves
To achieve minimum actuation pressure in the pilot line, length limitations must be observed.
See Table 3-13 for limits.