Model 4500A Volume Boosters from Rotork Fairchild

Rotork Fairchild Model 4500A Volume BoosterModel 4500 Pneumatic Volume Boosters are popular due to their rugged design and high flow capacity in an economical package. In its pilot-operated regulator design, the M4500 handles up to 250 psig, [17.0 BAR], (1700 kPa) supply pressure and has five available signal-to-output ratios to meet most control element requirements.

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 4500A Volume Booster Features

  • Flow capacity of 150 SCFM (255 m3/HR) - extremely fast and responsive operation
  • Five signal to output ratios - versatility to meet most control element requirements
  • Control sensitivity of 1" water column allows use in precision applications
  • Soft supply and exhaust valve seats minimize air consumption
  • A separate control chamber isolates the diaphragm from the main flow to eliminate hunting and buzzing
  • An optional remote feedback port minimizes pressure drop at the final control element under flow conditions
  • Optional adjustable by-pass needle valve (includes bubble-tight exhaust valve) - allows tuning for optimum dynamic response (1:1 ratio only) and cycle-free operation with valve positioners
  • Certification for use in all Canadian territories and provinces

Specifications

Model 4500A Volume Booster Specifications

Rotork Fairchild 4500A Volume Booster Specifications

Dimensions

Model 4500A Volume Booster Dimensions

Rotork Fairchild Model 4500A Volume Booster Outline Dimensions

Q & A

Q&A Section with Expand/Collapse Icons

Model 4500A Volume Booster Q & A

+What are the flow capacity and pressure ratings for the Model 4500A?
The Model 4500A offers a high flow capacity of up to 150 SCFM (≈255 m3/h) in its forward or exhaust mode, which corresponds to a Cv factor of approximately 3.0. It handles a maximum supply pressure of 250 psig (≈17 bar/1,700 kPa). These high ratings make it well-suited for applications that require rapid pneumatic response — such as large valves, cylinders, or actuation systems in industrial automation.
 
+How do I select the correct signal-to-output ratio and connection type for my application?
The Model 4500A comes with multiple signal-to-output ratio options (five ratios available) so you can match the booster to your control system’s needs. For example, you might have 1:1, 1:2, 1:3, etc. configurations depending on how much you need to amplify the signal. Additionally, connection size and thread type matter: confirm port size, thread standards (NPT vs BSP), and compatibility with your regional piping norms (especially between North America vs Europe). Ensuring the correct ratio and connections helps optimise performance and reduce installation issues.
+What are the key installation, maintenance, and service considerations for the booster?
Installation should use clean, dry, oil-free compressed air, with proper filtration upstream to avoid contamination of the diaphragm and valve assembly. The Model 4500A’s separate control chamber isolates the diaphragm from the main flow to reduce hunting and buzzing. Maintenance includes cleaning the inner valve assembly, ensuring the exhaust vents are clear, and verifying that diaphragms and soft seats are intact.
 
+ What are the common applications for the Model 4500A, and what performance benefits does it offer?
This booster is ideal for high-flow pneumatic systems used in process control, manufacturing automation, and heavy-duty actuation (valves or cylinders) where response speed and control stability are critical. Its large flow capacity (150 SCFM) and strong design yield fast, responsive operation. Benefits include reduced lag, better control of large pneumatic loads, and improved stability under flow conditions. The “no-bleed” or soft supply/exhaust valve seats in the design also minimise air consumption and help system efficiency.  
 
 
+ How do supply pressure variations and downstream conditions affect the performance of this booster?
Although the Model 4500A is designed to handle robust conditions, system performance still depends on how stable the supply pressure is and how the downstream piping, valves, or actuators are sized. The datasheet notes a maximum supply pressure of 250 psig, and the booster has been engineered to perform under flow-demand conditions. However, if your piping has excessive restrictions, leaks, or if the actuator demand is higher than what the booster’s flow capacity allows, you may experience slower response or undesired pressure drop. For best performance, ensure your compressed-air supply is clean and adequate, and that downstream components are properly sized and maintained.
 


 

Downloads

Download Rotork Fairchild Model 4500A Pneumatic Volume Booster Datasheet

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