M4900A0 pages

Model 4900A Pneumatic Volume Booster
Features

C

Model
4900A

The Fairchild Model 4900A volume
booster is a precision pneumatic
valve designed for demanding
applications requiring the ultimate
in sensitivity, accuracy, and flow
capacity. The booster is designed
with very low deadband between
the operation of the supply
valve and exhaust valve and
achieves superb pressure control
characteristics between forward
flow and exhaust flow conditions.
The high capacity exhaust valve is
very usefull in dynamic dual flow
direction applications producing
high reverse flow conditions.

• Very low deadband between the
operation of the supply valve and
exhaust valve.
• High capacity exhaust valve provides
efficient dynamic reverse flow.
• Large area diaphragms provide high
accuracy, sensitivity and excellent low
pressure performance.
• Soft seat supply and exhaust valves
provide efficient leak free operation.
• Pressure balanced supply valve prvents
changes in control characteristics.
• Damped diaphragm control chamber
provides stable operation and protects
valves from damaging oscillation under
high flow conditions.
• Two accessory ports connected to the
outlet chamber
• Tapped exhaust port for exhaust or for
incorporation of a
silencer.
•
Canadian Registration Number (CRN)
Certification for all territories and provinces

Operating Principles
When signal pressure on the top of the Signal
Diaphragm creates a downward
force on the Diaphragm Assembly, the Supply
Valve opens. Output pressure flows through
the Outlet Port and the Aspirator Tube to the
Control Chamber to create an upward force
on the bottom of the Control Diaphragm.
When the setpoint is reached, the force of the
signal pressure that acts on
the top of the Signal Diaphragm balances
with the force of the output pressure that
acts on the bottom of the Control Diaphragm
to close the Supply Valve.
When the output pressure increases above
the signal pressure, the Diaphragm Assembly
moves upward to close the Supply Valve and
open the Exhaust Valve. Because the Poppet
Valve is closed,
pressure flows down the Connecting Tube to
the bottom of the Motor Diaphragm. This pressure keeps the Supply Valve tightly closed
while in the exhaust mode. The Poppet Valve
opens and excess output
pressure exhausts through the vent in the
side of the unit until it reaches the setpoint.

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800-334-8422
www.fairchildproducts.com