Flowserve Limitorque L120 Multi-Turn Electric Actuator

Overview

The Flowserve Limitorque L120 is a multi-turn electric valve actuator built for petrochemical, power generation, and water and wastewater applications where actuator failure is costly and, in critical services, potentially catastrophic. Offered across eight unit sizes from L120-10 through L120-2000, the L120 delivers output torque up to 20,000 ft-lb (27,200 Nm) and thrust up to 500,000 lb (225,000 kg), covering rising-stem, non-rising-stem, and — when combined with a Limitorque WG or HBC quarter-turn gearbox — ball, butterfly, and plug valve duty as well. The Flowserve Limitorque L120 has more than 30 years of proven performance across a wide range of process control environments.

With engineering support in Muscat, Seven Star LLC supplies the Limitorque L120 multi-turn electric actuator range (with WG or HBC gearboxes for quarter-turn valves) to refineries, power plants, and water utilities across Oman, Muscat, and the wider GCC. Seven Star LLC supplies the Flowserve Limitorque L120 with manufacturer documentation and technical support with selection suited to the high ambient temperatures and coastal conditions found throughout the Sultanate of Oman.

Operating Principle

The Flowserve Limitorque L120 uses a double-reduction gear train — a worm gear paired with a spur gear, or on the larger L120-190 through L120-2000 frames, an additional helical gear stage — driven by a three-phase induction motor rated for short-time duty (typically 15 minutes) to deliver high output torque from a compact motor package. A four-position, 16-contact geared limit switch tracks valve travel and signals end-of-stroke position to the control system, while a dedicated torque switch, rated to 300V and dedicated to actuator torque protection in each direction, protects the valve and actuator from mechanical overload by interrupting motor power the instant preset torque is reached in either direction. A manual declutch lever allows the handwheel to be engaged for local manual operation, automatically disengaging and returning to motor drive as soon as the motor is energized again.

For torque-only duty the L120 uses a removable steel bushing on its output drive; for combined thrust-and-torque applications on rising-stem valves, a splined bronze stem nut housed in a ductile iron thrust base and supported on thrust bearings converts rotary output into linear travel. The practical result is an actuator that self-protects against jammed or over-torqued valves, reports accurate position and torque status to the plant control system, and can be operated locally by hand during maintenance or power loss without any risk of damaging the gear train.

Engineering Design of the Flowserve Limitorque L120

The L120-10 through L120-40 frames use die-cast aluminum housings and compartment covers, while the L120-85 and larger frames are built in cast iron as standard. All gearing is fully enclosed and lubricated, running on anti-friction bearings throughout, and exterior surfaces carry a TGIC polyester powder coating (L120-10 through L120-40) or a Valspar epoxy/polyurethane coating (L120-85 through L120-2000), both suitable for 500-hour salt spray — a significant advantage in the humid, saline coastal environments typical of Omani ports and desalination sites. Electrical compartment covers are O-ring sealed cast aluminum, and weatherproof enclosures are rated FM types 3, 4, and 4X and CSA types 3 and 4; explosion-proof (XP) versions carry FM and CSA Class I/II, Division 1/2 certification, and submersible variants meet NEMA 6 and IP68 for below-grade or flooded-vault installations.

Control packages range from a simple No Controls Unit (NCU) for open/close duty through Basic Integral Controls (BIC) with integrally mounted reversing contactors and control transformers, up to the UEX electronic control package, which is built on Flowserve’s MX technology platform and adds an absolute encoder for continuous position feedback, an on-board LCD status display in eleven languages, and network connectivity via Modbus, Foundation Fieldbus, Profibus DP, Profibus PA, or DeviceNet. The L120 can also be direct-mounted for torque-only duty or coupled through Limitorque V series bevel or SR series spur gearboxes for rising-stem thrust applications, or through WG or HBC worm gearboxes for quarter-turn butterfly, ball, and damper duty.

Key Features

Specifying the Flowserve Limitorque L120 gives instrumentation and rotating equipment engineers a proven actuator platform sized for the most demanding valve automation duty:

• Eight unit sizes (L120-10 through L120-2000) deliver torque from 100 to 20,000 ft-lb and thrust up to 500,000 lb.
• Double-reduction worm and spur gearing, with helical gearing on larger frames, provides high torque density in a compact footprint.
• Dedicated torque switch and geared limit switch protect the valve and actuator from mechanical overload in both directions.
• Weatherproof, explosion-proof (FM/CSA Class I/II), and submersible (NEMA 6/IP68) enclosure options cover the full range of plant hazardous-area classifications.
• TGIC polyester (L120-10 to -40) or Valspar epoxy/polyurethane (L120-85 to -2000) coatings suitable for 500-hour salt spray suit coastal installations.
• Manual declutch handwheel provides local override during commissioning, maintenance, or power loss.
• UEX electronic controls add absolute-encoder position feedback and multi-protocol fieldbus connectivity for networked plants.
• Compatible with Limitorque V, SR, WG, and HBC gearboxes for both rising-stem thrust duty and quarter-turn butterfly, ball, and plug valve automation.

Industrial Applications

The Limitorque L120 the Flowserve Limitorque L120 is specified across petrochemical installations such as refineries, pipelines, terminals, tank farms, cokers, and offshore platforms, where its explosion-proof certification and resistance to lightning, EMI, and fire are essential safety requirements. Power generation plants rely on the L120’s rugged construction to withstand vibration, high-pressure steam, and extreme temperature swings on main steam, feedwater, and cooling water isolation valves, while water and wastewater treatment facilities use the L120’s low-maintenance, AWWA-compliant design for sluice gates, penstocks, and modulating flow-control valves across intake and treatment trains.

Backed by genuine manufacturer documentation, Seven Star LLC distributes the Flowserve Limitorque L120 across Oman and the GCC to EPC contractors and plant operators serving refining and petrochemical complexes, RO desalination plants, and district cooling networks from Muscat through the Sohar and Salalah economic zones. Seven Star LLC supplies common Flowserve Limitorque L120 frame sizes and control packages on request, with lead time confirmed at quotation, for both new-build EPC projects and plant turnaround work.

Technical Specifications

The Flowserve Limitorque L120 technical specifications below summarize the core data for the Flowserve Limitorque L120 multi-turn electric actuator; contact Seven Star LLC for full ordering codes and gearbox compatibility data.

L120 Unit Sizes and Performance Ratings

Flowserve lists eight L120 unit sizes. The L120-10 delivers a maximum torque of 100 ft-lb (136 Nm) and 10,000 lb of thrust, the L120-85 reaches 850 ft-lb (1,156 Nm) and 45,000 lb, the L120-800 reaches 8,000 ft-lb (10,880 Nm) and 250,000 lb, and the L120-2000 reaches 20,000 ft-lb (27,200 Nm) and 500,000 lb. Output speed ranges from 12-250 rpm on the smaller frames at 60 Hz to 12-60 rpm on the L120-2000.

The L120-10 through L120-40 use die-cast aluminum housings and compartment covers to keep weight down, while the L120-85 through L120-2000 use iron housings for strength. Approximate weights with a standard compartment range from 90 lb (41 kg) for the L120-10 to 2,550 lb (1,155 kg) for the L120-2000. Flowserve also notes that performance ratings and dimensions for an L120-6000 are available on request.

Mounting Bases and Drive Options

L120 actuators can be direct-mounted to valves for torque-only duty, using a Type B4 standard steel bushing or a Type BL splined bushing for rising or rotating stem valves. For thrust duty a Type A1 alloy bronze stem nut in a thrust base is used. Bases are supplied to the MSS standard with English taps, and ISO bases are optional.

Coupled to a V series bevel or SR series spur gearbox, an L120 can drive rising-stem valves with thrust up to 921,000 lb and torque up to 19,000 ft-lb. With a WG or HBC worm gearbox, it can operate quarter-turn valves or dampers, with torque outputs up to 449,000 lb-ft.

Request a Quote for Flowserve Limitorque L120 Multi-Turn Electric Actuator

For every Flowserve Limitorque L120 inquiry, Seven Star LLC supports formal RFQs, actuator sizing, and gearbox package selection for the Flowserve Limitorque L120, with availability and lead time confirmed at quotation. Technical datasheets and dimensional drawings are available on request through our valve actuation and instrumentation division. Working closely with plant engineers in the region, Seven Star LLC gives EPC contractors and plant operators a single point of contact for genuine product, warranty, and commissioning support — contact our team today to request a quotation.

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