Algas SDI VAPORAIRE M-Series, Operation & Maintenance Manual

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Operation
4-22
Algas-SDI Operations & Maintenance Manual – P/N - 54264
SINGLE VENTURI SYSTEMS
MIXER OPERATION
The vaporized LPG rises into the vapor header and exits through the vapor
outlet. The vapor pressure will close the Low Vapor Pressure Switch and
activate the Mixed Gas Pressure Control Switch. The Mixed Gas Pressure
Control Switch will cycle the venturi on and off based on load requirements.
The venturi solenoid opens, feeding LPG vapor through a pressure regulator and
then through the venturi nozzle. The LPG creates a pressure lower than
atmospheric pressure in the venturi housing as it exits the venturi nozzle.
The natural atmospheric pressure will force the air into the housing. Both air and
LPG streams are mixed and compressed in the diffuser section. The discharged
gas is then stored in the surge/accumulator tank. When the pressure in the
surge/accumulator reaches a preset level the venturi solenoid valve will close.
As the mixed gas is drawn off, the mixed gas pressure will decrease allowing the
venturi solenoid valve to reopen. This process continues until the unit is
switched off or shut down by a safety condition.
MIXED GAS OPERATING PRESSURE ADJUSTMENTS
The Mixed Gas Pressure Control Switch is also referred to as Venturi Control or
System Delivery Pressure Switch. The Mixed Gas Pressure Control Switch is
wired normally closed and is set to open at the mixed gas pressure setpoint. The
pressure control for mixed gas pressure is a pressure switch with an adjustable
mixed gas pressure setting. When the switch is closed, the venturi solenoid
valve is open, and the venturi is mixing gas and air.
SPECIFICATIONS:
Pressure Adjustment Range: 3 – 30 PSIG
Fixed Deadband: 0.4 PSIG @ 3 PSIG to 1.5 PSIG @ 30 PSIG
Contact Rating: 15amp, 277 VAC Res. Max.
Adjusting Mixed Gas pressure setpoint ( Refer to data sheet for setpoint ).
Control box must be open to adjust.
1. Put the system on a load so that the single venturi is cycling on/off.
2.
Adjusting Mixed Gas pressure setpoint.
Note adjust the surge/accumulator tank pressure as the venturi is cycling.
If the surge /accumulator tank pressure is above or below the desired mixed
gas pressure, turn the adjusting screw on the Mixed Gas Pressure Control
Switch. Turn the screw counterclockwise (out) to lower the set point or
clockwise (in) to raise the set point. Note that the surge/accumulator tank
pressure will “follow” or increase/decrease respectively as the set point is
increased or decreased. The Mixed Gas Pressure Control Switch has a fixed
deadband differential that will change with the setpoint.