Fisher Vbl Volume Boosters Pneumatic Volume Booster Vbl-1 Vbl-3 Vbl-4 Vbl-2

1. Description

    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 that can occur with volume boosters that do not have these features. Adjustment of the integral bypass restriction is necessary for system stability. This adjustment does not affect the deadband of the volume booster, but does permit the control valve to respond to small input signal changes without sacrificing steady-state accuracy. It also allows the booster to deliver high-volume output for fast stroking when large, rapid input signal changes occur. The volume booster is used to improve stroking speed. If precision valve control is required, the use of a positioner is recommended. If the volume booster is to be used only with an actuator, for on-off control, the integral bypass restriction on the booster must be closed (turned fully clockwise).
   Connectors and piping can be installed with the VBL volume booster for diagnostic testing.

2. Features

 1) Fast Response—Booster delivers the volume needed for rapid actuator stroking when large input changes suddenly occur. X0648 

 2) Adjustable Response—Integral bypass restriction tunes the booster response so that smooth actuator motion follows the slow signal changes. 

 3) Efficient Operation—Soft seats provide a tight shutoff to reduce unnecessary air consumption and eliminate saturation of positioner relays. 

 4) Maintains Accuracy—Booster permits high actuator stroking speeds upon demand without degrading the positioner's steady-state accuracy.

3. Specifications