产品名称：73N-FR内置式阀门定位器 Valve Positioners

Features & Benefits：
Single-axis, force-balance principle of operation, ensures accurate and stable positioning

Feedback circuits direct the actuator’s position, ensuring adherence to the control instrument signal

Range spring capability accommodates a wide variety of valve strokes and instrument spans

Description
     The Series 73 Built-in Valve Positioners use the full force of their air supply to drive and maintain the piston or diaphragm in a pneumatic actuator to position a valve to what is required by a control instrument, regardless of the presence of forces that change valve position.

      This line of compact instruments incorporates a single-axis,force-balance principle of operation to ensure accurate and stable control valve positioning. In all cases, including bottom-loading applications, a Model 73 Built-In Valve Positioner is mounted directly on the topwork of the valve, with no external levers or other exposed mechanisms.
      Each positioner receives a signal from a control instrument,and using an air supply as high as 100 psig, the positioner
strokes the valve actuator to the required position.
      Like all valve positioners, the Model 73 Built-In Valve Positioners have feedback circuits designed to measure the
position of the actuator's piston or diaphragm. The positioner then supplies or exhausts air to bring the actuator within the required range for its corresponding control instrument.
      The position of the piston or diaphragm in the valve actuator is sensed by the amount of compressive force exerted by a range spring on the valve positioner's diaphragm assembly.By selecting the appropriate range spring from the wide
selection available almost any combination of valve stroke (from 1/4" to 4") and instrument span (from 2 to 24 psi) can
be obtained.

Specifications
Functional Specifications
Input Range：3-15, 3-9, 9-15, 6-30, 3-27 psig
Valve Travel：Minimum: 1/4"
                   Maximum: 4"
Supply Pressure：Minimum: 3 psi above required actuator pressure
                     Maximum: 100 psig
Air Consumption：(In balance condition with 20 psig supply and 9 psig  dead-ended output)
                    • 73N_F: 0.25 scfm
                    • 73N_B: 0.6 scfm
Overrange Limit：150 psig to any connection
Response Level：(output sensitivity to input pressure changes)
  • 73N_F: 0.1% of input span
  • 73N_B: 0.25% of input span
Functional Mechanical：
Materials of Construction：Aluminum, brass, stainless steel, Neoprene®, and/or Buna-N
73N12F：   Top-loading, direct-acting, input spans of 2 to 12 psi
73N24F：   Top-loading, direct-acting, input spans over 12 to 24 psi
73N-FR：    Top-loading, reverse-acting
73N-B：      Bottom-loading, direct-acting, with top air-cushion loading
73N-B1：    Bottom-loading actuators w/actuator range spring