Model 4900A Volume Booster from Rotork Fairchild

Rotork Fairchild Model 4900A Volume BoosterModel M4900A is a High Flow Pneumatic Volume Booster designed for high precision applications. With its Cv of 9 in both forward and exhaust modes, this pilot-operated booster provides fast response, very low deadband, and high precision control.

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.

Features

Model 4900A Volume Booster Features

  • In its pilot-operated regulator design, the M4900A handles up to 250 psig, [17.0 BAR], (1700 kPa) supply pressure and delivers an output pressure up to 150 psig [10.0 BAR] (1000kPa)
  • Cv = 9; Flow capacity of 500 SCFM (850 m3/HR) - fast response for quick valve opening and closing times
  • Ratio accuracy of 0.5% - highly accurate valve control for your system
  • Very low deadband between the operation of the supply valve and exhaust valve - provides excellent pressure control
  • High-capacity exhaust valve provides efficient dynamic reverse flow characteristics
  • Large area diaphragms provide high accuracy, sensitivity, and excellent low-pressure performance
  • Soft seat supply and exhaust valves provide efficient leak leak-free operation
  • Pressure-balanced supply valve prevents changes in control characteristics when supply pressure changes
  • Damped diaphragm control chamber provides very stable operation
  • Two accessory ports connected to the outlet chamber provide convenient access to the outlet for additional control accessories and pressure monitoring
  • Tapped exhaust port allows for easy collection of exhaust air or the use of a silencer

Specifications

Model 4900A Volume Booster Specifications

Rotork Fairchild Model 4900A Volume Booster Specifications

Dimensions

Model 4900A Volume Booster Dimensions
 

Rotork Fairchild Model 4900A Volume Booster Outline Dimensions

Q & A

Q&A Section with Expand/Collapse Icons

Model 4900A Volume Booster Q & A

+What are the key specifications and performance capabilities of the M4900A?
The Fairchild M4900A is a high-flow, pilot-operated pneumatic volume booster designed for fast response and accurate pressure control. It can handle supply pressures up to 250 psig and deliver output pressures up to 150 psig with a flow capacity of around 500 SCFM. With a Cv of 9 in both forward and exhaust modes and a ratio accuracy of about 0.5%, it is built for demanding applications requiring stability, precision, and high-volume airflow. Its construction—typically aluminum with steel trim and optional nitrile or fluorocarbon elastomers—supports a wide range of industrial environments.
 
+How do I know if the M4900A is the right fit for my system?
The M4900A is ideal for applications requiring rapid actuator movement, large airflow demand, and highly accurate pressure control. It works well in systems that operate with higher supply pressures and need a responsive volume booster to manage dynamic conditions or reverse flow. Choosing the right unit involves checking pressure requirements, flow needs, actuator size, elastomer compatibility, and environmental conditions such as temperature or humidity. If your system requires fast valve actuation and high-volume airflow, the M4900A is typically an excellent match.
+What should I know about installation and maintenance?
Installation should begin with clean, debris-free piping, correct use of thread sealants, and ensuring that the exhaust port is not overly restricted, as restrictions can damage internal components. The booster can be mounted in any orientation and requires standard periodic maintenance such as diaphragm inspection, cleaning internal valve assemblies, and replacing elastomer kits when worn. For long-term reliability, operators should follow the manufacturer’s recommended service intervals and use proper exhaust silencers or venting configurations.
 
+Can the M4900A replace my existing volume booster or integrate with my current actuator setup?
Yes, the M4900A is commonly used as a retrofit option thanks to its high flow capacity and compatibility with many pneumatic control systems. Before replacing a booster, check port sizes, thread types, available pilot signal ports, and whether your system can benefit from the increased airflow. It integrates effectively with most actuator and positioner configurations, especially when faster stroking speeds or improved dynamic response are needed. Selection of the right variant ensures a smooth drop-in replacement without performance issues.  
 
 
+What regional considerations should I keep in mind when purchasing?
Global buyers should verify certifications such as CRN for Canada or ATEX/IECEx for certain regions, depending on installation requirements. Availability of spare parts and service kits may vary by region, so sourcing through local Rotork distributors can shorten lead times and reduce downtime. Environmental conditions—such as extremely cold climates in Canada or humid offshore environments in Asia—may affect material selection. Ensuring that the chosen variant meets local industry standards and environmental requirements helps protect long-term system performance.
 


 

Downloads

Download Rotork Fairchild Model 4900A Pneumatic Volume Booster Datasheet

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