Aluminum Fisher Gas Valve 2625 2625NS Volume Boosters Positioner Output

Fisher 2625 2625NS Volume Boosters

Fisher 2625 series volume boosters are used in conjunction with a positioner on a throttling control valve to increase stroking speed. The 2625NS is a nuclear service version and uses elastomeric components that better withstand high temperature and radiation environments. The 2625 and 2625SST are certified for use in Safety Instrumented System (SIS) applications. Certification is by exida Consulting LLC, a global provider of functional safety and control system security.

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 either 2625 or 2625NS volume booster for diagnostic testing.

The 2625 is certified for use in Safety Instrumented System (SIS) applications. Certification is by exida Consulting LLC, a global provider of functional safety and control system security. SIS certification is identified on the product by a label affixed to the ower housing.

Specifications

Supply Pressure Ranges

When used in conjunction with a positioner or other pneumatic accessory, always pipe the positioner and volume booster with one common supply through a Fisher 67D, 67DR, or 95H regulator . A high capacity filter, such as the Fisher 262K, should be installed in the supply line to the regulator. Supply pressure also must not exceed the maximum pressure rating of the actuator. Constructions are available in two maximum supply ranges.When Normally Used With Diaphragm Actuators: Up to 2.8 bar (40 psig) When Normally Used With Piston Actuators: Up to 10.3 bar (150 psig)

Input Signal Pressure

Positioner output

Maximum Input Signal Pressure

10.3 bar (150 psig)

Fixed Input‐to‐Output Pressure Ratio

1 to 1

Nominal Deadband

Percent of Positioner Output Span(1):

2.4 mm (0.094 inch) exhaust port: 2%

9.5 mm (0.375 inch) exhaust port: 3.5%

12.7 mm (0.5 inch) exhaust port: 5%

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Aluminum Fisher Gas Valve 2625 2625NS Volume Boosters Positioner Output Images