Spirax Sarco EL3500 series electric linear actuators are designed for on/off or modulating control of a wide range of industrial valves, including SPIRA-TROL KE/LE series, self-acting valves (BX, BM, SB, KA, KB, KC, NS), and TW three-port valves. These actuators convert synchronous motor drive into linear motion through a spur gear transmission, with an integrated spring package limiting the stem force to a constant 600 N thrust.

Operation and Variants

The range includes standard versions and spring reserve models (SE for Spring Extend, SR for Spring Retract) providing fail-safe operation on power failure. Integrated torque switches automatically shut off the motor when the specified stem force is reached.

• EL3501/EL3502: VMD control (230 Vac or 24 Vac).
• EL3501SE/EL3502SE: VMD control with spring extend.
• EL3512 Series: 24 Vac with 0-10 Vdc or 4-20 mA modulating control (requires 500 Ω resistor for current signals).

Technical Specifications

Model	EL3501	EL3502	EL3501SE	EL3502SE	EL3512	EL3512SE	EL3512SR
Supply Voltage	230 Vac	24 Vac	230 Vac	24 Vac	24 Vac	24 Vac	24 Vac
Power Consumption	6.5 VA	4 VA	12 VA	11 VA	5 VA	12 VA	12 VA
Actuator Speed	0.32 mm/s	0.32 mm/s	0.19 mm/s	0.19 mm/s	0.32 mm/s	0.19 mm/s	0.19 mm/s
Control Signal	VMD	VMD	VMD	VMD	0/2-10V	0/2-10V	0/2-10V
Spring Reserve	NO	NO	YES	YES	NO	YES	YES
Manual Handle	YES	YES	NO*	NO*	YES	NO*	NO*

Note: Spring reserve models have a manual override handle under the cover for commissioning.

Materials of Construction

Part	Material
Yoke	Aluminium die casting
Base	Glass fibre reinforced plastic
Cover/Handle	ABS-FR (Flame resistant to UL 94-V0)

Maximum Differential Pressures (bar) for SPIRA-TROL Valves

Applicable to KE, LE, KEA, and LEA valves with PTFE or graphite stem seals (20 mm travel).

Valve Size	DN15	DN20	DN25	DN32	DN40	DN50
Class IV Shut-off (PTFE)	9.8	6.3	2.2	2.1	-	-
Class VI Shut-off (PTFE)	24.4	19.3	12.8	9.9	4.2	3.0
Class VI Shut-off (Graphite)	9.5	7.5	5.0	3.8	1.6	1.1

Installation and Accessories

Actuators are rated IP54 and should be mounted in orientations that respect pipeline temperature limits. Standard media limits are +150°C, extendable to +250°C using the EL3905 high temperature kit.

• EL3904/EL3906: Linkage kits for KE/LE valves.
• EL3808/EL3809: Linkage kits for self-acting and TW valves.
• EL3903: Auxiliary switches for remote position indication.
• EL3901/EL3902: Auxiliary potentiometers for position feedback.

Safety Caution

The spring reserve is a safety feature intended for emergencies only. Repeated use of the spring reserve to actuate the valve quickly may cause premature failure of the unit.