Electric control valve

Product Overview

The Electronic Single‑seat Control Valve is a straight‑through control valve driven by an electronic (smart) electric actuator. It is widely used in automatic control systems across industries such as petrochemical, chemical, power generation, metallurgy, water treatment, and HVAC. The valve receives a standard analog control signal (4–20 mA or 0–10 V DC). The built‑in microprocessor of the electronic actuator drives the motor to precisely position the plug, changing the flow area between the plug and seat to regulate flow rate, pressure, temperature, or liquid level.

Compared with conventional electric control valves, the electronic version offers higher control accuracy (±0.5%), faster response, optional digital communication interfaces (HART, RS485, Modbus, Profibus), and self‑diagnostics with fault alarm. The single‑seat design ensures low leakage (ANSI Class IV–VI) and high allowable differential pressure. The valve features flanged connections, with nominal diameters from DN15 to DN300, pressure ratings from PN16 to PN160 (Class 150–900), and body materials including cast iron, carbon steel, and stainless steel.

Product Structure

The Electronic Single‑seat Control Valve mainly consists of the electronic (smart) electric actuator and the valve body assembly.

Electronic Electric Actuator:

1. Motor: Reversible servo motor or stepper motor, low inertia, high response.

2. Gearbox: Precision gear or worm‑gear reducer, high transmission efficiency, low backlash.

3. Position Sensor: Non‑contact Hall sensor or high‑precision potentiometer, high resolution, long life.

4. Microprocessor Control Board: Receives the external control signal, compares it with position feedback, and uses PID or intelligent algorithms to drive the motor for precise positioning.

5. Digital Communication Interface (optional): HART, RS485 (Modbus RTU), Profibus DP, etc., supporting remote parameter setting, valve position reading, and fault diagnostics.

6. LCD Display (optional): Real‑time display of valve position, setpoint, fault codes, etc.

7. Handwheel Mechanism: Manual override for on‑site commissioning and emergency operation.

8. Limit Switches: Electronic and mechanical dual protection.

9. Terminal Box: For connecting power, control signal, communication bus, etc.

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Valve Body Assembly:

1. Body: Cast or forged body in carbon steel (WCB), stainless steel (CF8/CF8M), etc. Flanged ends conforming to GB/T 9113, ANSI B16.5, EN 1092‑1, etc. Straight‑through flow path.

2. Plug (Disc): Single‑seat plunger‑type plug. The sealing face can be hardfaced with Stellite or covered with PTFE/PEEK. The plug profile determines the flow characteristic (linear, equal percentage, quick opening).

3. Seat: Removable seat forming the sealing pair with the plug, made of matching material.

4. Valve Stem: Stainless steel stem, connected to the actuator output shaft at the top and the plug at the bottom.

5. Packing Box: Contains PTFE or flexible graphite packing, compressed by a packing gland to prevent external leakage.

6. Bonnet: Connected to the body, housing the packing and stem. Available in standard, extension (for high/low temperature), or bellows seal types.

7. Cage (Guide Bushing): Optional cage for guiding the plug and reducing noise.

Compact construction; the electronic actuator can communicate digitally with a host system or DCS/PLC.

Function

1. High‑Accuracy Flow Regulation: The microprocessor precisely positions the plug, achieving control accuracy of ±0.5% and hysteresis ≤ 0.5%.

2. Pressure / Temperature / Liquid Level Control: Combined with sensors and controllers, the valve forms a closed‑loop control system for automatic regulation of process parameters.

3. High Shut‑Off Performance: The single‑seat design provides very low leakage. Soft sealing achieves ANSI Class VI (bubble‑tight), and metal sealing achieves Class IV.

4. High Allowable Differential Pressure: The single‑seat design withstands higher pressure drops than double‑seat valves, making it suitable for high‑pressure‑drop applications.

5. Multiple Flow Characteristics: Plugs can be profiled for linear, equal percentage, or quick opening characteristics to meet different control requirements.

6. Smart Communication & Remote Monitoring: Via HART, RS485, or other protocols, users can remotely read valve position, set parameters, and receive self‑diagnostic alarms, facilitating integration with DCS/PLC.

7. Self‑Diagnostic Function: Real‑time monitoring of actuator status (e.g., motor temperature, stroke deviation, stall) with fault alarm output.

8. No Compressed Air Required: Only electrical power and a control signal are needed – ideal for locations without an air supply.

9. Remote / Local Control: Supports remote automatic control, on‑site manual operation (via handwheel), and centralized monitoring via communication bus.

10. Power/Signal‑Loss Protection (optional): Optional supercapacitor or backup battery module drives the valve to a preset safe position on power failure.

Working Conditions

1. Applicable Media: Water, oil, gas, steam, chemical media, corrosive liquids, etc.

2. Temperature Range: –29°C to +200°C (standard PTFE packing); –29°C to +400°C (graphite packing); –196°C to +450°C (bellows seal + extension bonnet).

3. Pressure Rating: PN16, PN25, PN40, PN63, PN100, PN160 (Class 150, 300, 600, 900).

4. Nominal Diameter: DN15 – DN300 (1/2″ – 12″).

5. Power Supply: AC 220V or AC 380V (standard); DC 24V optional.

6. Control Signal: 4–20 mA, 0–10 V DC, or digital communication (HART, RS485, Profibus, etc.).

7. Feedback Signal: 4–20 mA valve position feedback (standard), plus digital communication data.

8. Typical Applications:

   1. High‑accuracy batching systems in chemical plants

   2. Remote automated control in factories without compressed air

   3. Precise metering in water treatment chemical dosing systems

   4. Variable flow regulation of chilled/hot water in HVAC

   5. Automatic boiler feedwater control

   6. Heat exchanger outlet temperature control

   7. Smart control stations with direct digital communication to DCS/PLC

Summary

The Electronic Single‑seat Control Valve, with its advantages of high‑accuracy smart control, digital communication and self‑diagnostics, single‑seat low‑leakage design, and no need for compressed air, is an upgraded solution for modern industrial automation systems compared with conventional electric control valves. Compared with ordinary electric control valves, the electronic version offers higher control accuracy (±0.5%), faster response, and direct digital communication with DCS/PLC via HART or RS485, enabling remote parameter setting, valve position monitoring, and fault diagnostics.

The single‑seat design ensures tight shut‑off and high allowable differential pressure. The valve features flanged connections and is suitable for steam, water, oil, chemical media, and many other services. For pipeline systems that demand high control accuracy, intelligent management, and remote centralized monitoring, the Electronic Single‑seat Control Valve is an ideal choice.