Victaulic FireLock NXT 764 Series User Manual

SECTIONVIEWDRAWINGANDDESCRIPTION–
SERIES746-LPADRYACCELERATOR
(OPTIONAL)
The Series 746-LPA Dry Accelerator is a quick-opening device, which
When a rapid loss of system air pressure occurs, such as an open
exhausts air from the Series 776 Low-Pressure Actuator to speed valve
sprinkler, air escapes from the closing chamber faster than it escapes
operation.
from the opening chamber. As the sprinkler system’s pressure continues
to decay, a differential pressure develops across the diaphragm. When
A diaphragm separates the Series 746-LPA Dry Accelerator into two
this differential pressure reaches 3 – 5 psi/21 – 34 kPa/0.2 – 0.3 Bar,
chambers. The closing chamber contains a compression spring, which
the opening chamber’s pressure overcomes the compression spring’s
maintains the chamber in the closed position. The closed position is
closing force, causing the closing chamber to open to the atmosphere.
maintained as long as the pressure differential between the opening and
The closing chamber opens immediately and releases pressure from the
closing chambers is less than 3 psi/21 kPa/0.2 Bar.
actuator, resulting in valve operation.
When the system introduces air pressure into the dry accelerator, air
NOTE: The Series 746-LPA Dry Accelerator must be used only on
enters the closing chamber and passes through a check valve to the
systems operating below 30 psi/206 kPa/2.1 Bar of air. If air pressure
opening chamber. The check valve, which allows flow into the opening
higher than 30 psi/206 kPa/2.1 Bar is required, the Series 746 Dry
chamber, prevents pressure from escaping the opening chamber.
Accelerator should be used.
Therefore, air can escape only through the restrictor.
Exaggerated for Clarity
To Pressure
Gauge
Air Inlet
CROSS-SECTION WITH UPPER CHAMBER ROTATED
45° AND BOLT REMOVED FOR CLARITY
15
1
14
13
11
12
8
6
7
10
2
3
5
4
9
4
Bill of Materials
1 Opening/Air Chamber 9 O-Ring
2 Restrictor 10 Seal Support
3 Piston 11 Closing Chamber Seal
4 O-Ring 12 Button-Head Cap Screw
5 Diaphragm 13 Washer
6 Actuator Shaft 14 Adjustable Seat
7 Closing Chamber 15 Check Valve
8 Compression Spring
I-768_8
FireLockNXT™DryValve
SERIES768
I-768
INSTALLATION,MAINTENANCE,ANDTESTINGMANUAL
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VICTAULIC IS A REGISTERED TRADEMARK OF VICTAULIC COMPANY. © 2007 VICTAULIC COMPANY. ALL RIGHTS RESERVED. PRINTED IN THE USA.
REV_D

Victaulic FireLock NXT 764 Series Specifications

General

Brand	Victaulic
Model	FireLock NXT 764 Series
Category	Control Unit
Language	English