8
RECOMMENDED AIR PRESSURES FOR SERIES
758 PREACTION VALVES WITH SERIES 79N
ELECTRIC/PNEUMATIC ACTUATORS
NOTES:
1)
The recommended air pressures, shown in the chart above, apply
to preaction valves that use a Series 79N Electric/Pneumatic Actua-
tor at 13-psi (90-kPa) minimum and 18-psi (124-kPa) maximum.
NOTE:
If the air pressure is higher than 18 psi (124 kPa), a Series
746 Dry Accelerator should be installed.
2)
For base or riser-mounted compressors, the recommended air
pressures are the "on" or "low" pressure settings for the compressor.
3)
For tank-mounted compressors, the recommended air pressures
are the set point for the air regulator. The "on" pressure of the com-
pressor should be at least 5 psi (34 kPa) above the set point of the
regulator.
4)
The Victaulic air regulator is a relief-type design. Any pressure in
the system that is above the set point of the regulator will be
released. Therefore, charging the regulator above the set point
could cause premature operation of a valve that contains a Series
746 Dry Accelerator.
Air Maintenance Trim Assembly
(AMTA)
COMPRESSOR AND AIR
MAINTENANCE TRIM
REQUIREMENTS
COMPRESSOR REQUIREMENTS
Air Supply Design
1.
The engineer/system designer is responsible for sizing
the compressor so that it brings the entire system to the
required pressure within 30 minutes.
DO NOT
oversize
the compressor to provide more airflow, since it will slow
down or possibly prevent valve operation.
2.
Continuous service (24 hours per day, 7 days per week)
is required to prevent the valve from false tripping due to
a loss of air pressure.
3.
Regulate the air pressure to the proper system air pres-
sure. Air pressure differing from the required system air
pressure could adversely affect system operation.
4.
Restrict the air supply to ensure that air being
exhausted from an open sprinkler or manual release valve
is not replaced by the air supply system as fast as it is
being exhausted.
BILL OF MATERIALS
Item
Description
1
¹⁄₈
-inch (3,2-mm) Restrictor
2
Slow-Fill Ball Valve (Normally Open)
3
Air Regulator
4
Strainer (100 Mesh)
5
Spring-Loaded, Soft-Seated Ball Check Valve
6
Fast-Fill Ball Valve (Normally Closed)
AIR
P
RESSURE
–
P
S
I
MAXIMUM WATER SUPPLY PRESSURE - PSI (Peak)
30
25
20
15
10
5
0
5 10 15 20 25 50 75 100 125 150 175 200 225 250 275 300
1
6
5
4
2
3
NOTICE
• In the event that a compressor becomes inoperative, a properly sized tank-
mounted air compressor provides the greatest protection for systems that use a
Series 746 Dry Accelerator. In this situation, air can be supplied continuously to
the sprinkler system for an extended time period.
• If multiple preaction valves are installed with a common air supply, isolate the
systems by using a spring-loaded, soft seat-check valve to ensure air integrity for
each system.
• Good practice is to include a control valve for isolation and service of each
individual system.
• Air supply systems must be properly sized.
Failure to follow this instruction could cause
improper valve operation, resulting in serious
personal injury and/or property damage.
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
50
System Capacity (in gallons)
Required Flo
w Rate (CFM)
COMPRESSOR REQUIREMENTS
150
250
350
450
550
650
750
850
950
1050 1150 1250 1350 1450 1550 1650 1750
55 psi
(379 kPa)
40 psi
(276 kPa)
20 psi
(138 kPa)
13 psi
(90 kPa)
DISCONTINUED
PRODUCT
