6
AIR MAINTENANCE TRIM
Proper Air Supplies for
Series 758 Preaction
Valves:
1. When a riser or base-
mounted air compressor
supplies air to a system
utilizing a Series 753-A Dry
Actuator, it is not necessary to
use the air maintenance trim
assembly with the air
regulator. In this
circumstance, the airline of
the compressor connects to
the valve’s trim at the fitting
where the air maintenance
trim is normally installed.
When the valve is used with
this setup, it is the engineer’s/
system designer’s
responsibility to size the
compressor so that it brings
the entire system to the
required pressure within 30
minutes. The engineer/system
designer must not oversize the
compressor to provide more
airflow because it will slow
down, or possibly prevent, the
operation of the valve.
Furthermore, a base-mounted
compressor does not provide
any backup air to the system.
Therefore, the system requires
continuous service (24 hours
per day, 7 days per week) in
order to prevent the valve from
false tripping due to a loss of
air pressure.
Due to the large on/off
differential available on
pressure switches that control
base-mounted compressors,
you must adjust the
compressor pressure switch so
that the “ON” contact of the
pressure switch is at the
recommended air supply for
the valve.
2. When shop air or a tank-
mounted air compressor is
used, you must use Victaulic
Company’s Air Maintenance
Trim Assembly (AMTA). The
AMTA provides the proper air
regulation to the sprinkler
system, which will ensure the
proper operation of the fire
safety valve.
3. When a Series 746 Dry
Accelerator is used in
conjunction with the Series
753-A Dry Actuator, you must
use the AMTA with the air
regulator.
In the event that a compressor
becomes inoperative, the
tank-mounted air compressor
provides the greatest
protection. With a properly
sized tank, air can be supplied
continuously to the sprinkler
system for an extended time,
even without an operating
compressor.
COMPRESSOR REQUIREMENTS
0.0
2.0
4.0
6.0
8.0
10.0
12.0
SYSTEM CAPACITY (GAL.)
REQUIRED FLOW RATE (CFM)
20 PSI System Air
40 PSI System Air
50 75 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000
AIR PRESSURE – PSI
MAXIMUM WATER SUPPLY PRESSURE - PSI (Peak)
RECOMMENDED AIR PRESSURE FOR DRY AND PNEUMATIC ACTUATED SYSTEMS
60
50
40
30
20
10
0
5 10 15 20 25 50 75 100 125 150 175 200 225 250 275 300
NOTES:
1) You must use an air
regulator with Series 758
Preaction Valves that utilize an
accelerator.
2) The recommended air
pressures shown on the chart
apply to valves utilizing a
Series 753-A Dry Actuator.
These pressures involve an 8
to 1 water-to-air ratio, plus a
ten-pound safety factor.
3) If you install systems with
multiple, pneumatic-actuated
valves, isolate the systems by
using a spring-loaded, soft
seat check valve to ensure air
integrity to each system.
To Next Page
Loading...
Need help?
General
