SECTION VIEW DRAWING AND DESCRIPTION –
SERIES 767 ELECTRIC/PNEUMATIC ACTUATOR
The Series 767 Electric/Pneumatic Actuator is a single-unit device
used in the actuation of Series 769 FireLock NXT Preaction Valves with
double-interlocked, electric/pneumatic release trim.
Diaphragms separate the Series 767 into four chambers. The upper
and upper-middle chambers control the actuation, while the lower and
lower-middle chambers act as the water control valve.
During system charging, air pressure enters the upper-middle chamber
of the Series 767 (entry point not shown). Pulling up on the Auto Vent,
which is located on the Series 767 trim, sets the air pressure in this
(upper-middle) chamber. Water supply pressure from the diaphragm
charge line enters the upper chamber, and the normally closed sole-
noid, which is built into the Series 767, sets the water pressure. THERE
IS NO NEED TO ACTIVATE THE SOLENOID TO SET THE SYSTEM.
System air pressure in the upper-middle chamber exerts a closing
force on the diaphragm in the middle chamber of the Series 767.
Additionally, the water supply pressure exerts a closing force on the
middle diaphragm through a piston that connects the upper and middle
diaphragms. These pressures close the water path of the lower-middle
chamber.
When the diaphragm charge line is open, water enters the lower cham-
ber of the Series 767; this water flows to the lower-middle chamber
through the inlet. The middle diaphragm traps water in the lower-middle
chamber. Supply water pressure in the upper chamber and system air
pressure in the upper-middle chamber hold the lower-middle diaphragm
assembly closed.
Since the area of the lower diaphragm (exposed to water pressure in
the middle chamber) is greater than the area of the lower chamber, the
lower chamber seals off. No water flows to the outlet of the Series 767,
and the supply water pressure creates the water seal.
When the system air pressure decays to 7 psi/48 kPa/0.5 Bar, the Auto
Vent’s compression spring exerts a force greater than the air pressure
in the upper-middle chamber. The Auto Vent opens, and all air pres-
sure in the upper-middle chamber evacuates. During this condition, the
Series 767 will not actuate, since water pressure in the upper chamber
maintains a closing force on the water seal of the lower-middle chamber.
Likewise, if there is an electrical detection event, the solenoid on the
upper chamber will activate and cause the upper chamber’s water pres-
sure to release. The Series 767 will not actuate, since the upper-middle
chamber’s air pressure exerts a closing force on the lower-middle
chamber’s water seal.
The Series 767 will actuate only when an electrical detection and loss
of system air pressure occur. During this condition, the closing force on
the lower-middle diaphragm’s water seal is removed, and the lower-mid-
dle chamber’s water pressure releases. This allows the lower diaphragm
to lift and water to flow from the Series 767’s inlet to the outlet. This
water flow releases water pressure from the preaction valve’s diaphragm
and allows the diaphragm to retract. The preaction valve’s clapper
opens, and water flows into the sprinkler system
.
10
11
89
7
15
26
18
19
16
17
To Drain
To Drain
Water In
21
22
20
Exaggerated for Clarity
Water In
5
23
6
4
3
1
25
24
2
Plunger shown for
reference only
Bill of Materials
1 Upper Chamber 14 Auto Vent Screw
2Upper Diaphragm 15 Outlet Orifice
3Upper-Middle Chamber 16 Gasket
4Middle Diaphragm 17 Upper Piston
5Lower-Middle Chamber 18 Isolating Diaphragm
6Lower Diaphragm 19 Lower Piston
7Strainer Assembly 20 Middle Spring
8Strainer O-Ring 21 Lower Spring
9Strainer Screen 22 Outlet Eyelet
10 Lower Chamber 23 Inlet Eyelet
11 Solenoid Valve 24 Isolating Diaphragm Retainer
12 Auto Vent 25 Upper Diaphragm Retainer
13 Auto Vent Sleeve 26 Outlet Orifice O-Ring
14 13
12
The auto vent, shown above, is
located in the trim of the upper-
middle chamber. NOTE: The auto
vent is shown in the set position
with the sleeve resting on the body
and the screw elevated.
I-769P-EPA_6
FireLock NXT™ Preaction Valve
with Series 767 Electric/Pneumatic Actuator
SERIES 769
(DOUBLE-INTERLOCKED, ELECTRIC/PNEUMATIC RELEASE)
I-769P-EPA
INSTALLATION, MAINTENANCE, AND TESTING MANUAL
www.victaulic.com
VICTAULIC IS A REGISTERED TRADEMARK OF VICTAULIC COMPANY. © 2007 VICTAULIC COMPANY. ALL RIGHTS RESERVED. PRINTED IN THE USA.
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