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Fisher™ VBL Volume Booster
Fisher VBL volume booster
The Fisher VBL volume booster is used in conjunction with a positioner on a throttling control valve to increase stroking speed.
The booster incorporates fixed deadband, soft seat construction, and an integral bypass restriction to eliminate positioner saturation problems. The volume booster delivers high volume output for fast stroking when large, rapid input signal changes occur.
Fisher™ VBL Volume Booster


Area Classification
Modulating Control
Input Signal
Max Outlet Pressure
150 psig
Mounting Type
Actuator Mount
Operating Temperature
Standard Temperature
Position Control
Modulating Control
Safety Certification
SIL 3 capable
Supply Media
Air, Natural Gas
Other Configurations
Contact your local Emerson business partner or sales office to learn about additional specifications or options for this product.


  • Delivers the volume needed for rapid actuator stroking when large input changes suddenly occur.
  • Integral bypass restriction tunes the booster response so that smooth actuator motion follows the slow signal changes.
  • Soft seats provide tight shutoff to reduce unnecessary air consumption and eliminate saturation of positioner relays.
  • Permits high actuator stroking speeds upon demand without degrading the positioner steady-state accuracy.


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