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MV & LV SERIES ENGINEERED DRY CHEMICAL FIRE EXTINGUISHING SYSTEM
OPERATION, DESIGN, & SERVICE MANUAL
REV C
Document # DOC324
Issued: April 26, 2018
Revised: March 22, 2022
UL FILE # EX27541
4.1.5 Installing Discharge Pressure Switch
In a single cylinder system, pressure to operate the discharge pressure switch is supplied from the discharge
piping. It must be installed using a tee on the supply piping no less than 12 inches (305 mm) above the pipe
run to minimize the amount of dry chemical that enters the pressure switch. It shall not be installed on any
dead-ended pipe runs or branches where dry chemical is likely to accumulate.
In a multiple cylinder system, the discharge pressure switch shall be connected to the remote pneumatic
actuation/rack kit outlet port opposite the outlet port connected to the rest of the pilot actuation line so that it
is supplied nitrogen pressure from the remote nitrogen actuation cylinder.
Section 4 System Installation
e discharge pressure switch has a SPDT contact for
connection to the control panel. e switch will send a signal
to the control panel confirming system actuation. If a control
panel is not included, the discharge pressure switch can provide
necessary control functions for closing any doors or dampers in
the room or enclosure or to initiate the shut down of equipment
that may deplete agent concentration.
1. Mount the switch box securely onto a wall or structural
member using the mounting holes provided. e switch
should be located so that it can be manually reset following
actuation. Preferred mounting is upright with pipe
connections to the bottom.
2. Connect 3/4 inch conduit and appropriate wiring to the
electrical connection on the switch box.
3. To switch loads heavier than the switch rating, or requiring
more than two contacts, the switch should be used to
operate a relay or contactor to control the load.
4. Connect the 1/4 inch NPT connection at the bottom of
the front plate to the agent piping using 1/4 inch steel
pipe, 1/4 inch or 3/16 inch O.D. copper tube, or 3/16 inch
flex hose. Install a union fitting at base of cover to allow
removal of front plate for testing.
Figure 4.1.5 Discharge Pressure Switch Installation
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