User's Manual

Component Descriptions
September 2013 2-30 P/N 81-CO2MAN-001
Figure 2-34. Explosion Proof Electric and Cable Operated Control Head
2-3.5 Pneumatic Control Heads
The pneumatic control head (Figure 2-35) is a non-electric mechanical device that allows for
automatic actuation of carbon dioxide cylinders, stop valves, and directional valves by means
of pressure pulses transmitted from heat-actuated detectors (HADs) via copper tubing. These
control heads can also be remotely activated using a cable attached from the control head to
a cable operated manual pull station. The control heads are also equipped with a manual lever
for emergency local operation.
Pneumatic control heads operate on the rate-of-temperature-rise principle. This means that a
sudden increase in the temperature must occur to cause the control head to operate.
The control head must be used in conjunction with a pneumatic heat detection system (rate-
of rise) and operates as follows: A pneumatic HAD is connected to the control head by copper
tubing. As the temperature changes, the pressure within the detector varies. If the pressure
increases rapidly, as in the event of fire, a diaphragm in the pneumatic control head will trip a
lever mechanism, causing the control head to operate. The pneumatic control head is fitted
with a vent so that slight changes in pressure due to normal changes in ambient temperature
can be vented to atmosphere. The sensitivity of the pneumatic control head is determined by
the internal pressure required to trip the control head lever. This pressure is called the setting
and is measured in inches of water. Vent sizes are rated in terms of the time (in seconds)
required to relieve two inches of water column pressure in the diaphragm chamber. The higher
Table 2-10. Explosion Proof Control Head
Control Head
Part Number
Type Voltage Amps. Power Rating
WK-897494-000 Explosion Proof 24 Vdc 1.65 continuous 33.0 Watts
SET
RELEASED
TO RESET
USE SCREWDRIVER
FOR
MAINTENANCE
SEE
INSTRUCTIONS
CABLE
PULL
ELECTRIC
CONTROL HEAD
PART NO.
MADE IN U.S.A.
KIDDE-FENWAL, INC.
400 MAIN STREET
ASHLAND, MA 01721
VOLTS
HZ AMPS
CONNECTION FOR CABLE
HOUSING TO SECOND CONTROL
HEAD IF USED
3/8 in. NPS FEMALE
USE PNEUMATIC CONTROL
HEAD CABLE HOUSINGS
INDICATOR AND
RESET STEM
CONNECTION WIRES
36 in. (914 mm) LONG
7-3/8 in.
(187 mm)
SWIVEL NUT
1-1/2 in. (38 mm) HEX
1-1/4 in. -18 NF-3 THREAD
LOCAL MANUAL
RELEASE LEVER
CONNECTION FOR
REMOTE PULL BOX
PIPE OR CONDUIT
3/8 in. NPS MALE
SEAL WIRE
LOCKING PIN
CONNECTION FOR FLEXIBLE
ELECTRIC CONDUIT 1/2 in. NPT
FEMALE
4-15/16 in.
(125 mm)
OPERATING SOLENOID UL LISTED
FOR USE IN THE FOLLOWING
HAZARD LOCATIONS:
I C -13 TO +150 F
(-25 TO +65 C)
I D -40 TO +150 F
(-40 TO +65 C)
II E, F, G
CLASS GROUP OP TEMP
oo
oo
oo
oo
oo
oo
-40 TO +150 F
(-40 TO +65 C)