Flowserve Logix 520MD Smart Digital Positioner with ASCO Solenoid Valve HART Pneumatic Control
The Flowserve Logix™ 520MD+ is a two-wire, 4-20 mA digital valve positioner that uses the HART protocol for bidirectional communication. It is a fully electronic and pneumatic closed-loop instrument designed for precise stem-position control of single- or double-acting linear and rotary actuators. The positioner is powered solely by the 4-20 mA loop (minimum start-up current 3.8 mA) and incorporates an inner-loop (pilot-relay) and outer-loop (stem-position) control algorithm. Local configuration is possible via DIP switches, buttons and optional LCD; advanced diagnostics and configuration are performed with ValveSight DTM software or a HART handheld communicator.
- Dual-loop control with automatic inner-loop offset optimization during stroke calibration
- HART 5/6/7 protocol support with burst-mode capability
- Configurable characterization (Linear, Equal Percent, Custom 21-point) plus Soft Limits and Tight Shut-off
- Optional Multi-Function Card (AO 4-20 mA, Discrete Output, Discrete Input)
- Optional limit switches (mechanical, reed or inductive NAMUR) and remote-mount feedback
- ValveSight diagnostic levels (Standard / Advanced / Pro)
- Local user interface with status LEDs and optional LCD
- Intrinsically safe, Type n and Type t certifications (ATEX, IECEx, cFMus)
| Parameter | Value |
|---|---|
| Power / Signal | Two-wire 4-20 mA; Compliance 10.0 VDC @ 20 mA (520MD+) |
| Minimum operating current | 3.8 mA |
| Air supply | 1.5–6.2 bar (single-acting) / 1.5–10.3 bar (double-acting) |
| Output capacity (single-acting) | 9.06 Nm³/h @ 1.5 bar; 20.8 Nm³/h @ 4.1 bar |
| Output capacity (double-acting) | 14.3 Nm³/h @ 1.5 bar; 30.6 Nm³/h @ 4.1 bar |
| Performance (25 in² Mark I) | Resolution ≤ 0.25 %, Linearity ±1.25 %, Hysteresis ≤ 1.0 % |
| Operating temperature | –52 °C to +85 °C |
| Housing | Cast aluminum, IP65 / NEMA 4X |
| Weight (base unit) | 1.76 kg (single-acting) / 1.88 kg (double-acting) |
Precise positioning of control valves in oil & gas, refining, chemical, power generation and general process industries where HART diagnostics, hazardous-area certification and high-resolution control are required.
- Does the 520MD+ require external power? No – it is loop-powered.
- Can it be used on natural gas? Yes, with sweet natural gas and proper venting of exhaust ports.
- How is stroke calibration performed? Press and hold the QUICK-CAL button for 3–4 seconds after setting DIP switches.
- What is the difference between 520MD+ and 510+? The 520MD+ includes HART communication; the 510+ does not.
- Phone/WeChat/WhatsApp: +8613916209596
- Email: svetama@gbsxj.com
- Logix 510+ (non-HART)
- ValveSight DTM software
- Multi-Function Card
- limit-switch boards
- remote-mount kits
- mounting kits for Mark One / FlowTop / Valtek / MaxFlo / NAMUR actuators
- spare-part kits and gage blocks.
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