Quarter turn electric actuator with battery backup as standard
On/off electric actuator for quarter-turn ball valves 3/8″ to 1-1/4″. SZ-25-AC covers AC 110V, 220V and 380V; SZ-25-DC covers DC 24V and 48V. The lithium battery that closes the valve on power loss is built into every unit — it is not an add-on kit.
Battery return to closed is built in. So is 110–380V on one model.
On many actuators in this size class, return-to-closed on power loss is a separate kit or a separate model number. On the SZ-25 it is built in. Every unit ships with the lithium battery inside, and a full charge holds approximately 5,000 operations, so the valve keeps closing through repeated outages rather than saving one emergency stroke. The battery recharges whenever mains power is present.
The SZ-25 is a quarter turn electric actuator, on/off, for ball valves in 3/8″ to 1-1/4″. It comes in two models: SZ-25-AC for alternating current and SZ-25-DC for direct current.
The AC model is the one that saves you stock. It accepts AC 110V, 220V and 380V single phase on the same unit, so a distributor holds one part number instead of three, and a plant with mixed supply voltages does not have to work out which version each line needs. The DC model does the same across DC 24V and 48V. What it does not do is cross between the two — an AC site takes the AC model, a DC site takes the DC model. Either way you stock two part numbers, not six.
Control is on/off with dry-contact feedback for fully open and fully closed, and positioning is electronic. Full travel takes three seconds. Wiring runs through an aviation plug connector, so a technician connects or disconnects without opening the cover, and an LCD on the housing shows the battery level.
Different buyers ask for the same thing under different names. A ball valve actuator, a motorized valve actuator, an electric rotary actuator — for a quarter turn valve in this size range they all describe this unit. What matters is the stem interface and the torque, not the label.
The housing measures 152 × 133 × 131 mm. Ambient range is 0°C to 45°C and the actuator is built for indoor installation — the lithium battery sets that limit, so keep it out of rooftop and outdoor enclosures.
Does an electric valve actuator need a handwheel for manual override?
Not the SZ-25. Manual override is a push button on the housing — there is no valve handwheel, no declutchable gear override and no manual override gearbox to buy or fit. When mains power is lost, the built-in lithium battery drives the valve closed on its own — and the same battery powers the push button, so you can still open or close the valve by hand during the outage.
This covers quarter-turn valves from 3/8″ to 1-1/4″ (3–20 N·m), installed indoors at 0–45 °C. Larger valves that need a gear operator for torque are outside its range.
- Model
- SZ-25-AC · SZ-25-DC
- Power supply
- SZ-25-AC: AC 110–380V · SZ-25-DC: DC 24 / 48V
- Torque
- 3 N·m rated (9–11 mm shaft) · 10 N·m rated, 20 N·m max (14 mm shaft)
- Backup power
- Lithium battery
- On power loss
- Valve closes
- Signal output
- Dry contact — fully open / fully closed
- Size range
- For 3/8″–1-1/4″ quarter-turn ball valves
- Temperature
- 0°C to 45°C — indoor
- Operation
- On / off · 3 s full travel
Where it gets used
Every valve leak tested.
Each unit is checked for leakage before shipment.
Which voltages does it take?
There are two models. SZ-25-AC takes AC 110V, 220V or 380V single phase — all three on the same unit, so you stock one part number instead of three. SZ-25-DC takes DC 24V or 48V, again on one unit. The two do not cross over: pick the model that matches your supply.
What happens when the power fails?
The built-in lithium battery drives the valve to the closed position. No compressed air, no spring pack and no plant UPS are needed. The battery recharges, so it keeps working through repeated outages.
Is the battery backup an option or standard?
Standard. Every SZ-25 ships with the lithium battery inside. There is no separate kit to order, no second model number and no extra charge for it — it is part of the unit.
Does it need a handwheel or gear override for manual operation?
No. Manual override is a push button on the housing, and it runs on the built-in battery, so it still works during a power failure. On power loss the battery also closes the valve by itself, so there is no valve handwheel, declutchable gear override or manual override gearbox to add.
What if the battery is completely flat?
Reconnect mains power. The built-in lithium battery recharges automatically once the actuator is powered, so no battery replacement or manual charging step is needed.
Is an electric valve actuator the same thing?
Yes. Electric valve actuator is the broader term and this unit is one. What narrows it down is the valve it drives: this one is built for quarter-turn ball valves in 3/8″ to 1-1/4″. If your valve is a butterfly, a multi-turn gate valve or anything larger, send the type and the torque figure before you order and we will tell you whether it pairs.
Which valves does it fit?
Quarter-turn ball valves from 3/8″ to 1-1/4″. Rated torque is 3 N·m on the 9–11 mm output shaft and 10 N·m on the 14 mm shaft, with 20 N·m maximum. Tell us the valve size and we will confirm the pairing.
Can it be installed outdoors or on a roof?
No. The ambient range is 0°C to 45°C and it is built for indoor installation. The lithium battery sets that limit, so rooftop cabinets and outdoor enclosures are out of scope.
What signals does it give back?
Dry contacts for fully open and fully closed. That is the standard interface most control systems accept without a converter. Positioning is electronic and an LCD on the housing shows the battery level.
How is it wired?
Through an aviation plug connector on the housing, so a technician can connect or disconnect it without opening the cover. Full travel, open to close, takes three seconds.