Electric control valve

Product Overview

The Electric Three‑Way Control Valve is an electric control valve with three ports (one inlet/two outlets or two inlets/one outlet), designed for mixing (combining two inlet flows into one outlet) or diverting (splitting one inlet flow into two outlets) applications. It is driven by a linear‑stroke electric actuator and receives a standard analog control signal (4–20 mA or 0–10 V DC). The motor moves the plug linearly to proportionally distribute flow among the ports.

Compared with pneumatic three‑way control valves, the electric version requires no compressed air, offers simpler installation, high control accuracy, and remote manual/automatic switching capability. A single three‑way valve can replace two single‑seat control valves plus a tee fitting, providing compact construction and lower investment cost. This valve is widely used in petrochemical, chemical, power generation, metallurgy, HVAC, heat exchanger temperature control, and ratio control applications. Available in nominal diameters from DN15 to DN300, pressure ratings from PN16 to PN63 (Class 150–300), with body materials such as carbon steel and stainless steel. Connection type is flanged.

Product Structure

The Electric Three‑Way Control Valve mainly consists of the linear‑stroke electric actuator and the three‑way valve body assembly.

Linear‑Stroke Electric Actuator:

1. Motor: Reversible servo motor or stepper motor providing driving force.

2. Gearbox: Gear or worm‑gear reducer converting high‑speed motor rotation to low‑speed, high‑torque output.

3. Position Feedback Device: Potentiometer or Hall sensor providing real‑time valve position feedback.

4. Control Unit: Receives the external control signal, compares it with the position feedback, and drives the motor for precise positioning.

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

6. Limit Switches: Mechanical or electronic limits to protect the valve from over‑travel at fully open/fully closed positions.

7. Terminal Box: For connecting power, control signal, feedback signal, etc.

8. Output Shaft: Linear reciprocating output shaft directly connected to the valve stem.

   ---

Three‑Way Valve Body Assembly:

1. Body: Cast or forged three‑way body in carbon steel (WCB), stainless steel (CF8/CF8M), etc. The flow path is T‑pattern or L‑pattern, with three ports – inlet, outlet A, outlet B (diverting type) or inlet A, inlet B, outlet (mixing type). Flanged ends conforming to GB/T 9113, ANSI B16.5, EN 1092‑1, etc.

2. Plug: Special three‑way plug (linear‑moving type), typically double‑seated or single‑seated balanced. The sealing face can be hardfaced with Stellite or covered with PTFE/PEEK. The plug position determines the flow area ratio among the ports.

3. Seats: Two or three seats forming sealing pairs with the plug.

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 to prevent external leakage.

6. Bonnet: Connected to the body, housing the packing and stem; available in standard or extension (for high temperature) types.

Compact construction; the linear‑stroke actuator pushes the plug in a straight line, and a single valve completes mixing or diverting control.

Function

1. Mixing Function: Two inlets, one outlet. As the plug moves linearly, the flow ratio from the two inlets changes; the total flow is the sum of both inlets. Suitable for proportional mixing of two fluids.

2. Diverting Function: One inlet, two outlets. As the plug moves linearly, the inlet flow is proportionally distributed to the two outlets. Suitable for splitting one fluid stream to two users.

3. Temperature Control: In heat exchangers or HVAC systems, mixing or diverting adjusts the ratio of hot and cold media, achieving precise outlet temperature control.

4. Proportional Regulation: Continuously and linearly adjusts the flow ratio among ports with no on‑off shock, providing smooth control.

5. Good Shut‑Off Performance: Double‑seated three‑way valves have slightly higher leakage (ANSI Class III–IV); single‑seated balanced types can achieve Class IV–V.

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

7. Remote / Local Control: Supports remote automatic control and on‑site manual operation (via handwheel).

8. Valve Position Feedback: Can output a 4–20 mA or 0–10 V position signal for monitoring by a host system.

9. Fail‑Safe Option (optional): Optional power‑loss/signal‑loss protection module drives the valve to a preset safe position on failure.

Working Conditions

1. Applicable Media: Water, hot water, thermal oil, steam, refrigerant, chemical liquids, gas, etc.

2. Temperature Range: –29°C to +200°C (standard PTFE packing); –29°C to +400°C (graphite packing).

3. Pressure Rating: PN16, PN25, PN40, PN63 (Class 150, 300).

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, etc.

7. Feedback Signal: 4–20 mA (standard or optional).

8. Typical Applications:

   1. Heat exchanger bypass temperature control (mixing or diverting)

   2. Chilled/hot water system conversion from two‑way to three‑way regulation in HVAC

   3. Hot/cold media ratio control for chemical reactors

   4. Boiler feedwater recirculation systems

   5. Lubricating oil cooler temperature control

   6. Proportional mixing of two liquids

   7. Fluid distribution control in plants without compressed air

Summary

The Electric Three‑Way Control Valve (linear‑stroke actuator), with its advantages of integrated three‑way body, mixing/diverting dual functionality, precise linear‑stroke electric positioning, and no need for compressed air, is an ideal choice for fluid distribution and temperature control systems. Compared with pneumatic three‑way control valves, the electric version requires no air compressor, air piping, or I/P converter, simplifying installation and maintenance – especially suitable for locations without an air supply or where direct integration with a host computer is required.

The linear‑stroke electric actuator provides straight‑line motion directly to the plug, offering simple and reliable construction. The valve features flanged connections and is suitable for steam, water, oil, chemical media, and many other services. One valve replaces two single‑seat valves plus a tee fitting, greatly simplifying piping design and reducing investment cost. For pipeline systems that require proportional mixing or diverting of fluids and pursue remote automatic control, the Electric Three‑Way Control Valve is an efficient and reliable solution.