Key Parameters & Specifications Parameter / Feature Category Description Product Name Fisher™ 461 Series Pneumatic Force-Balance Indicator / Transmitter Type Pneumatic Force-Balance Transmitter & Local Indicator Primary Function To provide a local visual indication of a process variable (pressure, level) and/or transmit a proportional pneumatic signal to a control room. Input (Process) Pressure: Various ranges, commonly from 0-30" H₂O (0-7.5 kPa) up to 0-800 psig (0-55 bar). Level: For liquid level applications, using the hydrostatic head pressure. Output Signal Standard Pneumatic Signal: 3-15 psig (0.2-1.0 bar). Supply Pressure Standard: A clean, regulated air supply of 20 psig (1.4 bar) is typical. Must be higher than the output signal (e.g., >18 psig). Accuracy Typically ±0.5% of span for the indicating scale. Scale Large, easy-to-read dial. Can be calibrated in various engineering units (psi, kPa, inches of water, % level, etc.). Operation Two-Wire Pneumatic System: A single supply air line powers the device, and the output signal is superimposed on this supply, varying between 3 and 15 psig. Mounting Direct mounting to a process connection (e.g., a tank nozzle or pipe tap) or to a manifold. Enclosure Rugged, weather-resistant aluminum case with a glass or plastic window. Key Models & Versions • 461: General purpose indicator/transmitter. • 461L: Specifically designed for liquid level measurement. • 461R: Functions as a receiver to display a remote 3-15 psi signal locally.
