Flowserve Limitorque LQI Compact Quarter-Turn Electric Actuator

LQI compact quarter-turn electric actuator: range overview and model naming

The LQI is a compact intrusive quarter-turn electric actuator in the Flowserve Limitorque line. It turns ball, butterfly and plug valves through 90 degrees, and it is also used on dampers. The maker positions it as a simple, cost-effective actuator with torque and limit switches and discrete position feedback, with a wide choice of control options. Seven Star LLC supplies LQI actuators in Oman and the GCC as an independent supplier in Muscat. The LQI is a model range, so the exact size and options have to be fixed from valve torque and plant supply data.

The model suffix identifies the output size. Numbered sizes LQI 1 to LQI 13 climb from 35 N·m to 4,500 N·m, and the letter models LQI A, AM, F, G and H sit between them. Each size is offered in a weather-proof (WP) body and, for LQI 1 to LQI 8 and A/AM, in an explosion-proof (EX) body.

LQI technical specifications

How the LQI works

A compact AC or DC motor drives a self-locking epicyclic gear set, so the valve stays in position without a brake when power is removed. Travel is set by limit switches and by externally accessible adjustable mechanical stops, while a mechanical position indicator on top shows the valve position at a glance. A clutchless manual override lets an operator move the valve by hand without declutching. With the modulating option, an analog input board and a position potentiometer allow the actuator to follow a 4-20 mA signal. For on-off or floating service, a local control unit adds Local / Remote and Open / Stop / Close selector switches in an IP67, NEMA 4X enclosure.

LQI sizes, torque and flange selection

Torque, weather-proof weight, running time per 90 degrees and flange come from the maker’s technical table. Running time is based on 110 V AC at 60 Hz and 30% duty on on-off or floating control, and the EX body differs slightly in weight and time.

Explosion-proof LQI versions

The explosion-proof body is available for LQI 1, A, AM and 2 to 8. The maker lists ATEX II 2 GD marking Ex db IIB T4 Gb and Ex tb IIIC T130°C Db at -30 to +70 °C, with the same markings under IECEx and a CSA listing for Class I Zone 1 and Class II Zone 21 areas. Hazardous-area details are stated for the EX models only, so a weather-proof LQI must never be used in a classified area. A separate IOM covers the ATEX unit.

Where the LQI fits and related Limitorque actuators

The LQI covers the lighter quarter-turn duties in the Flowserve Limitorque electric range. For heavier or smarter quarter-turn service the QX smart actuator is the usual step up, with network communication and a local display. For rising-stem valves and larger multi-turn work see the SMB and the non-intrusive MXa. Choose the LQI when the need is a straightforward on-off or modulating actuator rather than a networked smart unit.

Selection and ordering checklist for the LQI

• Valve torque at maximum differential pressure, with a safety margin, to choose the size from LQI 1 to LQI 13.
• Valve ISO 5211 flange and drive square or bore, to match the F-number in the table.
• Weather-proof or explosion-proof body, and the zone or class if hazardous.
• Supply voltage and phase: 12 V or 24 V DC or AC, 110-120 V or 220-240 V single phase, or three phase on selected sizes.
• Control type: on-off, floating or modulating, and the input signal range.
• Duty cycle needed: 30%, 50% or 75%, especially for modulating service.
• Feedback needs: potentiometer, analog output, Modbus RTU, auxiliary switches.
• Conduit thread (NPT or M20), paint system and IP rating.

Installation, commissioning and maintenance of the LQI

Mount the actuator on the valve flange using the correct adapter, check that the valve and actuator are both in the same end position, and set the mechanical stops before powering up. Use the manual override to check free travel. Adjust the limit switches and confirm the indicator reads correctly. The maker’s design is permanently lubricated, so regular upkeep is mainly checking the cover seals, conduit entries and captive screws, and verifying that the anti-condensation heater is energized. Keep the cover closed and seals intact on outdoor installations. In Gulf conditions, pay attention to dust and humidity ingress during conduit connection.

Typical LQI applications in Oman and the GCC

The maker lists power, oil and gas, chemical, water and general industry. Locally this means butterfly valves on cooling water and seawater lines, ball valves on utility headers and chemical dosing, dampers on air handling and boiler systems, and small isolation valves in desalination and water treatment plants. The C5 paint option and IP68 enclosure are worth considering for coastal sites with salt-laden air.

Information to send with an RFQ for the LQI

• Valve make, type, size and the torque value including safety factor.
• Flange and drive details of the valve.
• Supply voltage, phase and frequency.
• Control signal and feedback required, and any fieldbus demands.
• Area classification and ambient temperature range.
• Quantity, paint and enclosure requirements.

Documents and quotation

The maker’s LQI brochure with the technical tables and order matrix is attached on this page. Use it to shortlist a size, then confirm the ordering string with us.

Send the LQI size, voltage and control type to Seven Star LLC and we will prepare a quotation for delivery in Oman and the GCC.