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Integrated Fire Protection System
D
Air Supply - Preaction System
FM-076A-0-86C
4.2 Accelerator
The Viking Model E-1 accelerator is a quick-opening
device featuring automatic reset. The Viking Model E-1
accelerator is used without the anti-flood device to speed
the action of a pneumatic release system on preaction
system.
Operation
The Viking Model E-1 accelerator operates on the principle
of unbalanced pressures. As the accelerator is
pressurized, air enters the inlet chamber, goes through the
screen filter into the middle chamber and through an orifice
into the lower chamber. From the middle chamber, air
slowly enters the upper chamber through a filtered orifice
restriction in the cover diaphragm.
In the SET position, the system air pressure is the same in
all chambers. When a sprinkler or release device
operates, the pressure in the middle and lower chambers
is reduced at the same rate as the system pressure. The
orifice restriction in the cover diaphragm restricts the air
flow from the upper chamber, temporarily causing higher
pressure in the upper chamber.
The pressure differential forces the cover diaphragm down,
pushing the actuator rod down. This action vents the
pressure from the lower chamber to the outlet vent,
allowing residual pressure in the inlet chamber to force the
clapper diaphragm open. After the clapper diaphragm
opens, any pressure remaining in the inlet chamber and
associated piping is vented to atmosphere.
On a pneumatic release system, when the accelerator
operates, the outlet pressure is vented to atmosphere,
speeding the release system operation.
To enable the accelerator device
1.
OPEN
the isolation valve of the accelerator.
CAUTION !
The system air pressure should be higher or
equal to the upper chamber of the accelerator prior to
opening the main water supply valve
(D1)
.
Note :
Ensure that the isolation valve of the accelerator is
open in normal supervisory mode.
To isolate the accelerator device
This operation can be necessary in order to verify the
pressure adjustments or to allow the pressure switches
adjustments.
1.
CLOSE
the isolation valve of the accelerator.
Refer to instructions described on Viking datasheet #122
(form No. 071692).
To reset the accelerator device
Make sure the system is properly drained and reset.
Observe the upper chamber pressure of the accelerator.
The gauge must read zero before the accelerator will
automatically reset. It may be necessary to loosen,
remove and re-install the accelerator air gauge (using the
appropriate wrench) to vent trapped air pressure from the
upper chamber, even when the gauge indicates zero if the
air supply is on while performing the reset.
Make sure system is pressurized according to
recommended settings.
WARNING
Do not exceed 60 PSI (414 kPa).
After every operation, and each time water is allowed to
enter the system
1. Inspect the interior of the accelerator for the presence of
water. Dampness or condensation may indicate that
the air supply is not being dried adequately. If water is
allowed to enter the middle or upper chamber of the
accelerator, it may contaminate the accelerator orifices
and prevent it from operating properly.
2. Remove the 1/2"-NPT (15 mm) plug from the base of
the accelerator. If water or dampness is present, the
accelerator must be disassembled, cleaned and dried.
For more information about this procedure, refer to
Viking datasheet #122 (form No. 071692).
3. Weekly inspection is recommended unless system is
provided with low air alarm, then monthly inspection
may be adequate.
4. Check the upper chamber pressure of the accelerator.
The air pressure should be equal to the air pressure
maintained in the system on which it is installed.
A difference in pressure other then slight variation due
to gauge calibration may indicate gauge malfunction,
plugged accelerator orifices and/or filters, or other
maintenance is required.
Note :
Standard tolerance allowance in pressure gauge
calibration may result in a slight variation when pressure
readings of any two gauges are compared.
5. Verify that all other trim valves are in their normal
operating position.
6. Check for signs of mechanical damage and/or corrosive
activity. If detected, perform maintenance as required
or, if necessary, replace device.
7. Verify that the main water supply valve
(D1)
is
OPEN
and
secure and that the by-pass valve
(1)
is
OPEN
.
