Flowserve Positioner LOGIX 3200 Series - 3200MD-28-N6-E-04-40-OG-OF

The Logix 3200 Series operates using a two-stage, stem-positioning algorithm that combines an inner loop for fast spool valve control and an outer loop for stem position control. The process involves comparing a control command to the measured stem position, and if a deviation exists, the inner loop uses a piezo valve to adjust the spool position, which in turn moves the stem to correct the deviation. This digital positioner uses a 4-20 mA signal, HART protocol, and software for configuration and auto-tuning to achieve accurate and responsive valve control.

Detailed working principle

• Two-stage control: The positioner uses a two-stage control loop to manage the valve's movement.

• Inner-loop (Spool Control): This loop quickly adjusts the position of an internal spool valve. It receives a signal from the outer loop and uses a piezo valve to modulate the air pressure under a diaphragm.
• Outer-loop (Stem Position Control): This loop compares the desired position (from the input signal) with the actual stem position, which is measured by a stem position sensor. It sends a signal to the inner loop to make corrections as needed.

• Actuation: The inner loop's adjustment of the spool valve changes the air pressure to the actuator. This pressure change moves the valve stem until the stem's position matches the desired control command, at which point the deviation becomes zero and the process stops.

Configuration and tuning:

• Digital Characterization: Instead of mechanical cams, the positioner uses software to map the input signal to the desired output, allowing for linear, equal percent, or custom 21-point curves to be configured digitally via software or a handheld communicator.
• Auto-tune: An automatic tuning feature helps select the correct gain settings for optimal performance by cycling the actuator and analyzing its response.
• HART communication: The positioner uses the HART protocol for two-way communication, enabling remote configuration and diagnostic data retrieval through devices like handheld communicators or software like ValveSight.
• Power and signal: The positioner is a two-wire device that is completely powered by the 4-20 mA input signal.

Key components and their function

• Microprocessor: The "brain" of the positioner, the 32-bit microprocessor continuously reads the input signal and the position sensor's feedback. It runs the control algorithm to determine any necessary adjustments.
• Input Signal: The positioner is a 2-wire, loop-powered device that receives a 4–20 mA current signal from a control system (like a DCS or PLC). This signal represents the desired valve position (e.g., 4 mA = 0% open, 20 mA = 100% open).
• Piezoelectric Valve Pressure Modulator: This is the core of the control mechanism. The microprocessor sends a voltage to a piezo beam bender, which deflects to precisely modulate the air pressure being sent to the valve actuator.
• Stem Position Sensor: This sensor provides continuous feedback on the actual position of the valve stem. This information is crucial for the closed-loop control system to detect and correct any deviation from the desired position.
• Two-Stage Positioning Algorithm: The microprocessor runs a specialized algorithm to maintain position:

• Outer Loop (Stem Position Control): Compares the incoming control command with the valve stem's actual position. If a difference (deviation) exists, the algorithm sends a signal to the inner loop.
• Inner Loop (Spool Control): Receives the signal from the outer loop and quickly adjusts the position of the spool valve using the piezo pressure modulator. This changes the air pressure to the actuator, causing the valve stem to move.

• HART Communication: The positioner supports the HART (Highway Addressable Remote Transducer) communication protocol, which allows for remote configuration, calibration, and diagnostics using a HART handheld device or software.

The operational cycle

1. The Logix 3200 receives a 4–20 mA command signal from the central control system.
2. The stem position sensor provides a real-time feedback signal of the valve's actual position to the microprocessor.
3. The microprocessor's control algorithm compares the command signal to the feedback signal to determine if there is a deviation.
4. If a deviation is detected, the microprocessor adjusts the voltage to the piezo pressure modulator in the inner control loop.
5. The piezo modulator then controls the air pressure delivered to the valve actuator, causing the valve stem to move toward the desired position.
6. The position sensor instantly registers the movement and provides new feedback, allowing the algorithm to continuously correct the position until the deviation is zero.

 Full Datasheet

Positioner Transmitter Feature  

• Manufacturer: LOGIX 3200
• Product No. :  3200MD-28-N6-E-04-40-OG-OF
• 3200 MD - Protocol hart, Diagnostics Standard, Material Aluminum, White Paint (Valtek), Design Version MD
• Certifications: 28 - ATEX: Mylar, Multiple Concept Label: Explosion Proof: II2G Ex d IIB+H T5; II2D Ex tD A21 Intrinsically Safe: ll1G Ex ia llC, T4 ll1D Ex iaD 20 T95 °C Non-incendive: ll3G Ex nL nA llC, T4 ll3D Ex tD A22 T95 °C
• Shaft: N6 - NAMUR 316 Stainless Steel (VDI/VDE 3845)
• Threaded Connections: 1 - Mounting: 5/16" 18 UNC, Pneumatics: 1/4" NPTF, Conduit: 1/2" NPTF, Vents 1/4" NPTF
• Conduit Connections: E - 1/2 in. NPT
• Action: 04 - Four-way (Double-Acting)
• Temperature: 40 - Low Temperature (refer to certification table)
• Gauges: OG -  SS with brass internals, psi (bar/kPa) (Valtek Standard)
• Special Options: OF - 4-20 mA Position Feedback

There are several Model of positioner, for more details read the PDF below 

Basic Ordering Information