TFP1450
Page 8 of 28
Electric/
Pneumatic
Actuation
System Design Considerations
Because a double interlock preac-
tion system requires time for a drop in
system air pressure to occur (concur-
rently with the response time for the
separate fire detection system) before
it will allow water to enter the system
piping, this system has characteristics
similar to a dry pipe sprinkler system.
Therefore, the system design con-
siderations for a dry pipe system are
normally applied to a double interlock
preaction system — including a 30%
increase in design area; a maximum 1
minute water delivery time for system
capacities of 500 gallons (1890 liters)
or more; and, prohibition of gridded
system piping.
In order to readily perform the System
Inspection Procedure described in
the Care and Maintenance section,
it is recommended that a System
Shut-Off Valve be installed above the
DV-5a Valve, as shown in Figure 5. The
System Shut-Off Valve should be a
listed or approved (as appropriate) indi-
cating valve with a supervisory switch
to monitor the normally open position.
Detection System
The Double Interlock Preaction System
With Electric/Pneumatic Actuation
Trim provides for electric operation of
the DV-5a Valve by a detection system
consisting of electrical devices such
as heat sensitive thermostats, smoke
detectors, and/or electric manual pull
stations. Information on the various
types of separately ordered Solenoid
Valves that may be used with this trim
package is given in Technical Data
Sheet TFP2180. Nominal installation
dimensions for the Double Interlock
Preaction System With Electric/Pneu-
matic Actuation Trim are shown in
Figure 11.
The Deluge Valve Releasing Panel
(automatic control unit) with battery
back-up, fire detection devices, manual
pull stations, and signaling devices
that are utilized with the Double Inter-
lock Preaction System with Electric/
Pneumatic Actuation must be UL
Listed, ULC Listed, C-UL Listed, or FM
Approved, as applicable.
NOTICE
The normally closed, de-energized
solenoid Valve is separately ordered
and selected based on the required
laboratory approval acceptable to the
authority having jurisdiction. Refer to
technical data Sheet TFP2180 for spe-
cific laboratory approvals.
Consult with the authority having juris-
diction regarding installation criteria
pertaining to electric actuation circuitry.
Due to the functionality of the Model
MRA-1 Manual Reset Actuator, the
release circuit of the releasing panel
need only provide the minimum typical
ten minutes of alarm condition intended
to energize the Solenoid Valve to
open. After the ten minute duration, at
which point should the Solenoid Valve
become de-energized and close (espe-
cially while operating under battery
back-up), the MRA-1 will have already
automatically opened, thereby prevent-
ing the DV-5a Diaphragm Chamber
from becoming re-pressurized, and
preventing an inadvertent closing of
the DV-5a during a fire event.
SYSTEM PIPING WITH AUTOMATIC SPRINKLERS - NORMALLY DRY
ELECTRIC DETECTION SYSTEM
(TYPICALLY 24 VOLTS DC)
HEAT DETECTORS, SMOKE DETECTORS,
MANUAL PULL STATIONS, ETC.
SYSTEM DRAIN VALVE
(NORMALLY CLOSED)
MAIN
DRAIN VALVE
(NORMALLY
CLOSED)
LOCAL
MANUAL
CONTROL
STATION
MAIN
CONTROL VALVE
(NORMALLY
OPEN)
SYSTEM
SHUT-OFF VALVE
(NORMALLY OPEN)
WATER
DIAPHRAGM CHAMBER
PRESSURE GAUGE
WATER SUPPLY
PRESSURE
GAUGE
MANUAL RESET
ACTUATOR
WATERFLOW
PRESSURE
ALARM
SWITCH
SOLENOID
VALVE
(TYPICALLY
24 VOLTS DC)
DELUGE VALVE
RELEASING PANEL
(AUTOMATIC
CONTROL UNIT
WITH BATTERY
BACK-UP)
MANUAL ELECTRIC
PULL STATION
(AS REQUIRED)
POWER
SUPPLY
(TYPICALLY
120 VOLTS AC)
AUTOMATIC
AIR/NITROGEN
SUPPLY
(GRAPH A)
DRY PILOT
ACTUATOR
SUPERVISORY
LOW PRESSURE
ALARM SWITCH
DV-5A
VALVE
RESTRICTION
DRAIN
DRAIN
DRAIN
DRAIN
DRAIN
SYSTEM AIR
PRESSURE
WATER SUPPLY SHUT-OFF
DIAPHRAGM
CHAMBER SUPPLY
CONTROL VALVE
(NORMALLY OPEN)
DIAPHRAGM CHAMBER
FIGURE 5
DV-5a VALVE - DOUBLE INTERLOCK PREACTION ELECTRIC/PNEUMATIC ACTUATION
SCHEMATIC DIAGRAM
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