Multi-Turn Electric Actuators

On/Off Isolation Duty (S2 Rating)

Engineered for open/close isolation service on gate valves, sluice gates, and emergency boiler feed globe valves. Features S2-15 min / S2-30 min rated high-starting-torque motors with dual mechanical limit and torque switches to guarantee bubble-tight wedge seating without mechanical stem binding.

• Class A & B isolation duty (EN 15714-2)
• Double-torque trip protection in opening and closing strokes
• Standard 380V/415V/440V 3-phase AC or 220V 1-phase AC options

Continuous Modulating Duty (S4 Rating)

Built for precise process throttling, pressure balancing, and water flow regulation in high-differential pipelines. Driven by inverter-grade motors rated for S4 duty (up to 1,200 starts per hour at 50% ED) with integrated intelligent servo amplifiers responsive to 4–20 mA or digital fieldbus commands.

• Continuous multi-turn positioning accuracy within ±0.5%
• Real-time valve position feedback via non-contact absolute encoder
• Supports Modbus RTU, Profibus-DP, and Foundation Fieldbus protocols

Massive Linear Thrust & Output Torque

Direct output torque ranges from 50 Nm to 5,000 Nm, delivering over 300 kN of linear stem thrust. Seamlessly pairs with multi-turn spur or bevel gearboxes to achieve up to 50,000+ Nm for massive high-pressure penstocks and large gate valves.

Dual Mechanical Torque Protection

Equipped with independent Belleville spring-loaded torque limit switches for both opening and closing directions. Instantly trips the motor when foreign obstacles or thermal stem expansion cause over-torque, preventing valve stem buckling.

ISO 5210 Thrust Base Adaptability

Fully compliant with ISO 5210 (flange sizes F07 to F30). Features detachable drive bushings: Group A (thrust-bearing base absorbing heavy axial loads from rising stems) and Group B1/B2/C/D (torque transmission for non-rising stems and gearboxes).

Non-Intrusive Infrared & LCD Setup

Intelligent digital electronics allow complete field calibration—including torque cutoff limits, stroke travel limits, and bus communication addresses—using an infrared handheld setting tool without ever opening the terminal housing in rainy or explosive atmospheres.

True IP68 Submersible & ATEX Safety

Double-sealed enclosure rated to IP68 (continuous immersion up to 10 meters for 72 hours), ideal for deep underground valve vaults. Available with ATEX and IECEx flameproof certification (Ex d IIC T4 Gb) for volatile oil, gas, and petrochemical refining zones.

Motor-Priority Declutchable Handwheel

Features a pad-lockable manual override clutch lever. Upon electrical motor restart, the internal clutch mechanism automatically disengages the manual handwheel back to motor drive, eliminating handwheel spin hazards and guaranteeing operator safety.

1. Why is mechanical torque-dependent seating critical for wedge gate and globe valves?

Unlike quarter-turn ball valves that seat strictly by travel angle (position-dependent), wedge gate valves and globe valves require positive seating thrust (torque-dependent) to press the disc firmly into the metal valve seats for bubble-tight closure. DELCO multi-turn actuators utilize dual mechanical torque switches that shut off the motor precisely when the preset closing torque is reached, preventing valve stem buckling or seat galling caused by thermal expansion or over-travel.

2. What is the difference between ISO 5210 Group A and Group B drive bushings?

ISO 5210 specifies how multi-turn actuators couple with valves:

• Group A (Thrust Base): Contains heavy-duty internal thrust bearings and a threaded stem nut. It absorbs the entire axial thrust generated by rising valve stems, protecting the actuator's internal gearbox.

• Group B1/B2/C/D (Non-Thrust Base): Transmits pure torque via keyed bore, splines, or drive claws. Used when the valve bonnet itself has built-in thrust bearings, or when coupled to secondary bevel or spur gearboxes.

3. How does the actuator safeguard the motor during unexpected valve jamming?

If pipeline sediment, scale, or debris obstructs the valve gate midway, the output torque spikes immediately. The actuator's sensitive Belleville spring torque sensor trips the motor contactor within milliseconds and outputs an over-torque fault signal to the central DCS/PLC. Additionally, the motor stator windings are embedded with thermal switches (thermostats) that cut off control power if operating temperatures exceed safe limits.

4. Can multi-turn actuators be retrofitted with multi-turn gearboxes for higher torque?

Yes. For large-diameter pipeline valves (DN600 / 24" and above) or high-pressure steam isolation services requiring up to 50,000+ Nm of torque, DELCO multi-turn actuators couple seamlessly with high-efficiency multi-turn spur gearboxes (GS series) or right-angle bevel gearboxes (GB series). This mechanical multiplication allows smaller motors to effortlessly operate massive valves while maintaining safe operating speeds.