Victaulic 746 Series Instructions Manual

INSTALLATION AND REPAIR KIT INSTRUCTIONS
Series 746 and 746-LPA Dry Accelerators
INSTRUCTIONS FOR INSTALLING AND REPAIRING DRY ACCELERATORS
IMPORTANT INFORMATION
WARNING
• Read and understand all
• Wear safety glasses, hardhat, and
Failure to follow these inst ructions
could result in serious personal
injury, property damage, and/or
product failure.
The following information is a guide for proper installation of Victaulic Series 746 and Series 746-LPA Dry Accelerators. Always refer to the
installation, maintenance, and testing manual for the applicable valve for detailed system setup, operation, and maintenance instructions.
NOTE: THE SERIES 746 DRY ACCELERATOR SHOULD NOT BE USED ON VALVES EQUIPPED WITH SERIES 776 LOW-PRESSURE
ACTUATORS, SERIES 767 ELECTRIC/PNEUMATIC ACTUATORS, OR SERIES 798 DOUBLE-PNEUMATIC ACTUATORS. FOR THESE
INSTALLATIONS, A SERIES 746-LPA DRY ACCELERATOR MUST BE USED.
Dry Accelerators are quick-opening devices, which exhaust air from the actuator to speed valve operation.
A diaphragm separates the Dry Accelerator into two chambers. The closing chamber contains a compression spring, which maintains the chamber
in the closed position. The closed position is maintained as long as the pressure differential between the opening and closing chambers is less than
3 psi/0.2 Bar.
When the system introduces air pressure into the dry accelerator, air enters the closing chamber and passes through a check valve to the opening
chamber. The check valve, which allows flow into the opening chamber, prevents pressure from escaping the opening chamber. Therefore, air can
escape only through the flow restrictor.
When a rapid loss of system air pressure occurs, such as an open sprinkler, air escapes from the closing chamber faster than it escapes from the
opening chamber. As the sprinkler system's pressure continues to decay, a differential pressure develops across the diaphragm. When this differential
pressure reaches 3 – 5 psi/0.2 – 0.3 Bar, the opening chamber's pressure overcomes the compression spring's closing force, causing the closing
chamber to open to the atmosphere. The closing chamber opens immediately and releases pressure from the actuator, resulting in valve operation.
NOTE: The Series 746-LPA Dry Accelerator must be used only on systems operating below 20 psi/1.4 Bar of air. If air pressure higher than
20 psi/1.4 Bar is required, the Series 746 Dry Accelerator should be used.
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REV_D
instructions before attempting
to perform maintenance on any
Victaulic piping products.
foot protection.
I-746/746-LPA
WARNING
• Depressurize and drain the
piping system before attempting
to remove, adjust, or perform
maintenance on any Victaulic
piping products.
Failure to follow this instruction
could result in serious personal injury
and/or property damage.
I-746.LPA_1