WCB Globe Control Valve — Modulating Linear Electric Actuator with 4–20 mA Signal and ANSI 150 Flange

The WCB globe type control valve with linear electric actuator is the solution for flow, temperature, and pressure control loops in installations where compressed air is not available — or where direct digital integration with SCADA, DCS, or BMS systems is required without additional signal converters. The linear electric actuator receives the 4–20 mA signal from the PID controller and positions the globe plug at any point in the stroke with high repeatability, without the need for a separate electro-pneumatic positioner or compressed air supply.

The assembly includes a WCB globe body with ANSI 150 flanges, a linear electric actuator with a 4–20 mA input signal, 4–20 mA position feedback, IP67 protection, and limit switch signals — all assembled, calibrated, and tested at the Cematic workshop before shipping.

The advantage of linear electric actuators over pneumatic diaphragm actuators

The globe valve has historically been a pneumatic control component — the diaphragm actuator is economical and precise when compressed air is available. The linear electric actuator is the correct alternative when the process has any of these conditions:

• No compressed air network: The most frequent reason. Buildings, municipal water treatment plants, remote installations, HVAC systems, and many modern process plants do not have instrumented compressed air networks — or the control point is too far from the existing network. The electric actuator only requires a power cable and a signal cable.
• Direct digital integration: Modern electric actuators with Modbus RTU or HART protocol allow direct integration with the control system without intermediate signal converters — the actual valve position, fault alarms, and actuator diagnostics are available in the SCADA system without additional hardware.
• Higher positioning accuracy: The stepper motor or servo motor of the electric actuator can position the plug with 0.1% stroke resolution — superior to most pneumatic diaphragm actuators with conventional analog positioners.
• No continuous air consumption: The pneumatic actuator continuously consumes compressed air to maintain position against process variations. The electric actuator consumes energy only during movement — reducing operating costs in systems with many control valves.
• Less maintenance: No electro-pneumatic positioner, no air filter regulator, no signal tubing — the electric actuator has fewer components susceptible to failure than the equivalent pneumatic assembly.

Construction materials

• Body: WCB carbon steel (ASTM A216 Gr. WCB) — mechanical resistance for steam, hot water, gas, and general process fluids at high pressure and temperature
• Trim (plug and seat): SS316 stainless steel — corrosion resistance on control surfaces in contact with the fluid
• Stem packing: Standard expanded graphite for high temperatures; PTFE available for aqueous fluids at moderate temperatures
• Connection: ANSI 150 raised face (RF) flanges, ASME B16.5 drilling
• Linear electric actuator:
  • Input signal: 4–20 mA modulating
  • Position feedback: 4–20 mA
  • Protection: IP67 — submersible up to 1 meter, suitable for frequent washing
  • Power supply: 220 VAC or 24 VDC depending on model
  • Limit switches: integrated for open/closed position signal to the PLC

Technical specifications

• Type: Straight-through globe, linear motion
• Connection: ANSI 150 RF flanges — face-to-face according to ASME B16.10 Series 1
• Body material: WCB (ASTM A216)
• Trim: SS316
• Stem packing: Standard graphite; PTFE available
• Nominal diameters: ½" (DN15) to 4" (DN100)
• Nominal pressure: ANSI 150 — up to 19.6 bar at ambient temperature
• Operating temperature: Up to +425 °C with graphite packing
• Flow characteristic: Standard equal percentage
• Input signal: 4–20 mA modulating
• Position feedback: 4–20 mA
• Actuator protection: IP67
• Design standard: IEC 60534 / ASME B16.34

Flow coefficient Cv by diameter

The normal operating Cv should be between 20% and 80% of the maximum Cv to ensure control stability throughout the operating range.

Not sure about the correct diameter? Use the Cv Calculator → or consult our technical team at no cost.

Fail-safe — behavior upon loss of electrical power

Unlike pneumatic actuators whose fail-safe mode is defined by the mechanical spring, linear electric actuators have fail-safe options that depend on the actuator design:

• Fail-Last: The integrated actuator brake maintains the plug's position at the last value before power loss. This is the standard configuration — correct when the last control position is the safe condition for the process.
• Fail-Close with spring or capacitor: Available in models with a mechanical return spring or a backup capacitor — the actuator moves the plug to the closed position upon power loss. For services where fluid cutoff is the mandatory safety state. Consult for availability.

For services where mechanical spring fail-safe NC is a critical safety requirement without electronic dependence, the control valve with pneumatic diaphragm actuator → is the most reliable option.

Fluid compatibility

• ✅ Saturated and superheated steam up to 425 °C with graphite packing
• ✅ Hot water and boiler water
• ✅ Natural gas, LPG, and dry industrial gases
• ✅ Crude oil, oils, and hydrocarbon condensates
• ✅ Industrial process water with moderate dissolved salts
• ✅ Process fluids in industrial chemistry and petrochemicals
• ⚠️ Fluids with high chlorides at high temperatures: check with technical team
• ❌ Concentrated acids, HF: use SS316 body or special materials

Electric vs. pneumatic actuator — selection guide for globe control valves

Main industries and applications

• Municipal water treatment plants and WTTPs: The most frequent application of electric actuators in Mexico for globe control valves. Water operating agencies (SACMEX, CONAGUA, SIAPA, regional OOAs) use plants without instrumented compressed air networks — the electric actuator with Modbus integrates directly with the municipal SCADA. Control of treatment reagent flow and pressure regulation in distribution networks.
• Industrial HVAC and buildings: Control of steam and hot water in heating systems for hospitals, hotels, shopping centers, and office buildings where pneumatic infrastructure does not exist and BMS (Building Management System) with BACnet or Modbus is the integration standard.
• Pharmaceutical industry — plant services: Control of heating steam in autoclaves, sterilizers, and hot water systems where the IP67 rating of the actuator allows frequent washing in production areas. Modbus integration with the pharmaceutical process control system (DCS or SCADA) without additional converters simplifies system validation.
• Remote installations without pneumatic infrastructure: Water wells, remote pumping stations, decentralized treatment plants, and any installation where laying a compressed air network has a disproportionate cost compared to laying an electrical cable.
• Solar and renewable energy generation: Control of process fluids in solar thermal, geothermal, and biomass energy plants where compressed air infrastructure is not part of the original plant design.
• Food industry — washdown areas: The IP67 protection of the actuator allows installation in areas with frequent high-pressure washdown — food and beverage processing rooms where conventional pneumatic actuators require additional protective covers.

For the complete category of control valves, see Cematic Control Valves →

• Technical Data Sheet