EFX-Q is FFC's intelligent part-turn electric actuator platform. It handles quarter-turn valves — ball, butterfly, plug, damper — where the actuator rotates the stem through 90 degrees (or a configurable fractional angle for damper service) between fully open and fully closed. This article describes the design decisions that distinguish EFX-Q from the multi-turn EFX-D platform, and where each fits in a project.
The drive uses a brushless DC or PMSM motor coupled to a planetary gearbox optimised for quarter-turn output torque. Quarter-turn duty has a shorter stroke than multi-turn but typically higher torque at break-seat and seat-load; the gearbox is sized to deliver peak torque without exceeding motor thermal limits. Standard output drives follow ISO 5211 flange dimensions (F05 / F07 / F10 / F12 / F14) so the actuator mounts directly on most industrial part-turn valves without an adapter.
Control electronics are common across EFX-D and EFX-Q: position feedback, torque sensing, configurable ESD behaviour, partial-stroke testing, MODBUS RTU / PROFIBUS DP / 4-20 mA / discrete control, and a local control panel. Position feedback resolution is typically configurable from 1 percent down to 0.1 percent of stroke depending on the application — modulating duty benefits from higher resolution, on/off isolation does not.
Sealing is built around the same wiring cavity / motor housing separation as EFX-D, with IP66 / IP67 standard and IP68 optional. The lower stem opening uses an IP-rated boot suitable for outdoor and washdown environments. Cable glands are project-specific. Material options on housing, fasteners, and external linkage cover standard industrial, marine, and chemical-resistant variants depending on the order.
The EFX-Q model range covers two size families — EFX-Q05-50 (5-50 N·m output torque) and EFX-Q60-120 (60-120 N·m output torque) — sized against the valve torque envelope at break, run, and seat. Larger torque requirements move to EFX-D with a quarter-turn linkage. Detailed torque, motor power, weight, and electrical data are documented in the FFC EFX-D / EFX-Q Actuator V8.7 catalogue available in the downloads section.
Use EFX-Q when the valve is rotating; use EFX-D when the valve is travelling linearly through multiple turns. When in doubt, share the valve type, torque table, and duty profile and FFC will confirm the right platform — selecting the wrong family is the most common source of post-procurement rework.
