Fail-Safe Spring Return Electric Actuator for Valves
Automatically returns to open or closed on power loss, with ISO 5211 mounting, IP67 protection, and torque options from 40 to 420 Nm.
Fail-Safe Spring Return Electric Actuator for Valves
- Torque Rotational Moment : 40 Nm ~ 420 Nm
- Motor Power : 380 V AC 3Ph , 220 VAC 2Ph, 50/60 Hz ± 10%
- Temperature : -20°C ~ 60°C
- Flanged Connection : ISO 5211 or DIN 3337 Standard
- Control : On-off or Proportional Control
- Accessories : Proportional Card, limit switch can be added, 4-20mA Output Smart Type Electric Actuators.
- Protection Class : Weather proof- IP67
- Application : Ball Valves, Butterfly Valves, Dampers
Custom Actuator Housing Color
We customize actuator housing colors (RAL/Pantone) with durable epoxy powder coating to match your corporate brand identity, system color-coding, or specific project aesthetic requirements.
Custom OEM Label
We offer private label solutions for distributors and OEM valve makers. Choose corrosion-resistant metal plates (stainless/aluminum) with laser-etched logos, or high-tack weatherproof industrial stickers.
18-Month Factory Warranty
Every actuator includes an 18-month warranty from the shipment date, providing a 6-month buffer beyond industry standards for ocean transit, customs clearance, and warehouse stocking.
Description of Spring Return Electric Actuator
When main power cuts out unexpectedly, a stuck valve can lead to costly downtime or catastrophic pipe damage.
Hearken Flow HUS Series spring return electric actuator gives you total peace of mind. During normal operation, the electric motor drives your valve while simultaneously compressing a heavy-duty internal spring. If power drops, the spring instantly releases its stored mechanical energy—automatically returning your valve or damper to a preset safe position (fully open or fully closed) without relying on auxiliary batteries or backup generators.
Key Benefits of HUS Series Spring Return Electric Actuator
Pure Mechanical Fail-Safe (No Battery Hassles)You don’t have to worry about replacing dead batteries or servicing backup UPS systems. Hearken Flow HUS Series spring-return electric actuator relies on an internal spring pack that mechanically resets your valve the exact moment the main power cuts out. Designed for SIL 2/3 safety loops, our spring-return electric actuator is available in both standard weatherproof and explosion-proof enclosures to match your specific working environment—with zero electrical maintenance. Built-In Protection Against Water HammerWhen a valve closes too fast, it can damage your pipes. Unlike basic spring return actuators that slam shut, Hearken Flow HUS Series Electric Actuator controls its spring release speed to give you a smooth, predictable shutdown. This absorbs kinetic energy, preventing destructive pressure surges (water hammer) and protecting your high-value equipment. Fits Tight Layouts with Direct ISO 5211 MountingYou get high-torque fail-safe power without taking up extra space. The HUS Series spring return electric actuator combines the electric motor, spring storage, and locking mechanism into a compact, gear-driven housing. It mounts directly onto your quarter-turn valves using standard ISO 5211 / DIN 3337 interfaces, making installation and replacement quick and straightforward. Clear Site Visibility & Interference-Free Manual OverrideYou can easily check the valve position on-site, even from a distance. HUS Series spring return electric actuator features a high-visibility 3D position indicator and built-in limit switches for rapid signal feedback. When you need to make manual adjustments during maintenance, the optional push-button manual override lets you lock the valve in place without messing up automated electric operation. |  |
Materials and Components
| NO. | Part Name | Material | NO. | Part Name | Material |
| 1 | Upper Cap | ADC12 | 11 | Space Heater | Ceramic |
| 2 | Body | AL104 | 12 | Electrical Motor | Integrated Set |
| 3 | Side Cap | ADC12 | 13 | Adjustment Cam | ADC12 |
| 4 | Connection Lock | Nylon | 14 | Microswitch | Integrated Assembly |
| 5 | Safety Spring | Spring Steel | 15 | Mounting Retaining Plate | Q235 |
| 6 | Piston | ADC12 | 16 | Output Shaft | 45# Steel |
| 7 | Spacing Block | 45# steel | 17 | Locating Bearing | Bearing Steel |
| 8 | Driving Gear | 40CR | 18 | Position Indicator | Nylon |
| 9 | Display Window | Tempered Glass | 19 | Capacitor | Composite Material |
| 10 | Wiring Terminal | Flame-retarded Nylon | 20 | Brake | Integrated Set |
Built-In Quality Control & Export Protection
Protecting your shipment, your project schedules, and your business reputation.
Zero out-of-the-box failures on your client sites.
Every Hearken Flow HUS Series Spring Return Electric Actuator completes full-stroke torque testing and power-on calibration in our workshop before shipping. You receive 100% functional, ready-to-mount actuators that install smoothly without time-consuming on-site troubleshooting.
Protect your cargo through long-distance ocean transit.
We pack Hearken Flow HUS Series Spring Return Electric Actuators in heavy-duty, fumigation-free wooden crates with custom-molded foam inserts. Your inventory arrives clean, scratch-free, and ready for deployment—saving you from freight claim headaches and project shipping delays.
Clear client site audits with complete documentation on request.
Individual Factory Acceptance Test (FAT) reports, material certificates, and dimensional drawings are readily available upon request. You get full digital document support whenever needed to clear customs, satisfy client QA requirements, and pass site inspections without hassle.
Technical Specifications
| Model | Spring End Torque | Power | Running Time (Sec) | Return Time (Sec) | Running Current | Weight Kg | |||
| N.m | In.ibs | 24VDC | 110VAC-120VAC | 220VAC-240VAC | |||||
| HUS2 | 40 | 353 | 23W | 15 | 7 | 4A | 1A | 0.5A | 8 |
| HUS3 | 90 | 885 | 36W | 15 | 7 | 2.8A | 0.7A | 0.34A | 18 |
| HUS4 | 140 | 1239 | 90W | 15 | 7 | 7A | 1.7A | 0.85A | 31 |
| HUS4 | 300 | 2655 | 131W | 15 | 7 | 9.6A | 2.3A | 1.2A | 31 |
| HUS5 | 420 | 3717 | 150W | 15 | 7 | 11A | 2.7A | 1.4A | 44.5 |
*The AC frequency that this product can withstand is 50-60Hz. This table shows the performance at 50Hz.
| Power Supply | 24VDC、110VAC-120VAC 50/60Hz、220VAC-240VAC 50/60Hz |
| Motor | DC motor |
| Limit Switches | Mechanical Limiter + Electrical Limiter |
| Stall Protection | Built-in overheat protector |
| Travel Angle | 90° |
| Pointer Dial | For valve position indication, it will rotate with the valve |
| Space Heater | 2~4w Anti-Condensation |
| Cable Conduit | NPT1/2 |
| Lubrication | grease |
| Shell | Aluminum alloy, anodized and coated with polyester powder |
| Ambient Temp. | -20℃~+60℃(-4°F~140.00°F) |
How Hearken Flow HUS Series Spring Return Electric Actuator Simplifies Your Field Operations & Protects Your Reputation
Micro-adjust valve seating angles on site without opening the cover.
External mechanical limit bolts allow your field crew to fine-tune full-open and full-close seating angles directly on the valve. You cut assembly time during OEM factory integration while keeping the weatherproof enclosure seal completely intact.
Instantly verify valve status and send clean feedback to your PLC.
The high-visibility 3D position indicator gives your site operators immediate visual status from a distance. Built-in limit switches provide volt-free open/close feedback signals, making PLC system integration fast and straightforward.
Simplify field wiring and eliminate installation mistakes.
Designed with clear terminal block layouts and intuitive control schemes, Hearken HUS allows your electricians to complete site wiring in minutes, ensuring smooth project handover without setup headaches.
Protect your valve stems from jam damage and cut warranty claims.
High spring torque margins and internal mechanical protections keep your valve assemblies running smoothly through sticky media, preventing motor burnout and saving your business from expensive aftermarket service calls.
Optional Smart Control Board with OLED Screen (For Modulating Models)
For projects requiring 4–20mA continuous modulating control, specify our smart control board option. It adds a real-time OLED display for position, current, and fault diagnostics, plus on-board button calibration without carrying extra signal tools.
Certification & Compliance
Fully certified to help you win project tenders, pass client FAT audits, and clear customs with ease.
| Certification / Standard | Compliance Level | Target Region & Project Application |
| ISO 9001:2015 | Factory Certified System | Global / OEM Factory Audits & Quality Control |
| CE Marking | Compliant (LVD & EMC Directives) | European Union & International Trade |
| ATEX (2014/34/EU) | Optional (For Ex Models) | Hazardous Zones & Offshore Platforms |
| SIL 2 / SIL 3 (IEC 61508) | Functional Safety Assessed | Emergency Shutdown (ESD) & Safety Loops |
| IP67 Enclosure Rating | Verified Test Report | Outdoor Weatherproof & Heavy Washdown Duty |
| EAC Declaration of Conformity | TR CU Compliant | Russia & Eurasian Economic Union (EAEU/CIS) |
| RoHS Directive | Compliant (2011/65/EU) | Environmental Compliance for Green Tenders |
Dimension of HUS Series Spring Return Electric Actuator
HUS2 Spring Return Electric Actuator
HUS3 Spring Return Electric Actuator
HUS4 Spring Return Electric Actuator
HUS5 Spring Return Electric Actuator
Built For Your Valve Lines
Zero-latency mechanical fail-safe protection for your 90° quarter-turn valve packages.
| Valve & Equipment Type | What You & Your Buyers Get |
Ball Valves (Floating & Trunnion-Mounted) | Automate your ball valves with Hearken Flow HUS Series Actuator for hassle-free ESD packages. Hearken HUS mounts directly to your floating and trunnion ball valves via ISO 5211. You give your buyers instant, battery-free emergency shutoff, while protecting your business from costly aftermarket warranty calls. |
Butterfly Valves (High-Performance & Triple-Offset) | Pass strict FAT tests without water hammer complaints. Built-in spring damping in the Hearken HUS controls closure speed on large-bore butterfly valves. Your complete valve assemblies close smoothly during power loss, helping you meet strict municipal specs and pass Factory Acceptance Testing (FAT) on the first try. |
| Plug Valves | Keep your plug valve packages running without motor jams. Hearken’s high spring torque margin easily overcomes stiff plug valve seating friction. You get a reliable fail-safe package that pushes through sticky media, saving you and your clients from unexpected field downtime. |
| Dampers & Air Louvers | Win more HVAC and smoke tenders with fewer stocked models. Hearken Flow HUS Series Spring Return Electric Actuator offers flexible fail-open and fail-close spring setups for dampers. You can bid on diverse ventilation projects using a single actuator series, cutting your stocking costs while expanding your market reach. |
Industry Applications For Hearken HUS Series Spring Return Electric Actuator
| Industry Sector | How Hearken Helps You Win & Protect Your Margins |
| Oil, Gas & Petrochemical | Win high-value ESD tenders with total compliance. Combine Hearken HUS with your valves to bid on strict hazardous-zone projects. SIL 2/3 compliance and optional explosion-proof housings let you meet tough oil and gas specs with confidence, helping you win profitable project contracts. |
| Water & Wastewater Treatment | Protect your margins on municipal water projects. Built-in spring damping in the Hearken Flow HUS Series Electric Actuator absorbs kinetic energy during power cuts, preventing pipeline water hammer. You give your buyers a safe valve package for pump discharge lines, avoiding costly post-handover complaints. |
| Chemical Processing Plants | Offer your clients 100% reliable blackout shutoff. Pure mechanical spring action in Hearken Flow HUS Series Spring Return Electric Actuator guarantees instant fluid isolation when factory power drops. You give plant engineers a dependable emergency shutoff solution while protecting your company’s brand reputation. |
| Power Plants & Utilities | Submit competitive utility bids with zero battery headaches. Hearken Flow HUS Series Spring Return Electric Actuator cuts out the high cost and ongoing maintenance of backup battery systems. You can quote a more attractive price on steam venting and cooling water tenders while keeping strong profit margins for your business. |
How to Order Your Hearken Flow HUS Spring Return Electric Actuator
4-Step Model Selection
Step 1: Base Model & Torque Output (T)
HUS: Spring Return Electric Actuator Series
[Torque]: Specify required operating torque (e.g.,
050,100,200Nm based on your valve dynamic torque requirements).
Step 2: Control Method (K)
MO: Modulating Control (V1.5 signal control)
Step 3: Power Supply (V)
Select your main operating voltage:
D: 220VAC – 240VAC (50/60 Hz)E: 110VAC – 120VAC (50/60 Hz)F: 24VDC
Step 4: Options & Fail-Safe Action (B)
Select your required fail-safe direction and environmental protection options:
CW: Fail-Closed (Rotates clockwise to fully close valve/damper upon power loss)CCW: Fail-Open (Rotates counterclockwise to fully open valve/damper upon power loss)X: Anti-Condensation Heater (Recommended for low-temperature or high-humidity environments)
Ordering Example:
HUS - 90 - MO - D - CW - X(HUS Series, 90 Nm Torque, Modulating Control V1.5, 220–240VAC Power, Fail-Closed on power loss, equipped with internal anti-condensation heater)
Selection Criteria And Configuration Reference
| HUS | T | K | V | B | |
| Model No | Torque | Control method | Power Supply | Options | |
| Control Method (K): | Power Supply ( V) : | ||||
| MO:Modulating control V1.5 | D:220VAC-240VAC(50/60hz) E:110VAC-120VAC(50/60hz) F:24VDC | ||||
| Opitions(B): | |||||
| X:Heater(Recommended for high humidity and low temperature working environment) CW:When power lost,The spring reset function of the product will cause the product to completely close (clockwise rotation) CCW:When power lost,The spring reset function of the product will cause the product to completely open(counterclockwise rotation) | |||||
Wiring Diagram (24VDC)
Wiring Diagram (110VAC~240VAC)
| Power Supply | |
| Port 2 & Port 3: | Port 2 connect with AC power L,port 3 connect with AC power N to power supply; |
| Modulating Control(4-20mA) | |
| (Need to switch control mode in setting menu first) | |
| Port 4 & Port 5: | This port(4 and 5)is used to input 4-20mA analog quantity control signal; |
| Port 6 & Port 7: | This port(6 and 7)is used to output 4-20mA analog control signal; |
| ON/OFF Control | |
| (Need to switch control mode in setting menu first) | |
| Port 12 & Port 13: | Connect this port(12 and 13)to open the valve; |
| Port 14 & Port 15: | Connect this port(14 and 15)to close the valve; |
| AUX.Contact | |
| Port 8 & Port 9: | This port(8 and 9)will connect when the valve position reaches full Open. |
| Port 8 & Port 10: | This port(8 and 10)will connect when the valve position reaches full Close. |
| Port 8 & Port 11: | This port(8 and 11)will connect when the product fails to work. |
FAQ About Spring Return Electric Actuator
Q1: What is the difference between a spring return electric actuator and a standard electric actuator?
A: A standard electric actuator holds its last position on power loss (fail-in-place). A spring return electric actuator uses a pre-compressed internal spring to mechanically drive the valve to a preset safe position — fully open or fully closed — without any external power or control signal. It is the standard choice for ESD, fire & gas, and SIL-rated shutoff applications.
Q2: When is a spring return electric actuator required instead of a standard electric actuator?
A: Use a spring return electric actuator when the application requires a defined fail-safe position on power loss: emergency shutoff valves, SIS loops rated SIL2 or SIL3, fire & gas systems, or any service where leaving the valve in an undefined position creates a safety or process risk.
Q3: How do I size an electric actuator spring return for my valve?
A: Match the electric actuator spring return torque output — not the motor torque — against the valve’s maximum required torque (BTO/ETO/BTC/ETC with safety factor applied). Spring torque is always lower than motor torque and is the limiting value for fail-safe operation. Provide your valve model, bore size, and differential pressure and we can issue a sizing confirmation.
Q4: Can a spring return electric actuator be used for modulating (proportional) control?
A: Yes. The Hearken Flow HUS Series spring return electric actuator supports modulating control (e.g., 4–20 mA or 0–10 V input signals). It allows precise proportional positioning during regular operation while maintaining instant mechanical spring-return fail-safe protection during main power loss.
Q5: How is the fail-safe direction (fail-close vs. fail-open) determined? Can it be changed in the field?
A: The fail-safe direction of an electric actuator spring return is set at the mechanical level during manufacturing — FC (fail-close) or FO (fail-open). It cannot be reversed in the field. Specify FC or FO at the time of order to avoid post-delivery rework.
Q6: How fast does the spring return? Can the return speed be adjusted?
A: Our HUS Series spring return electric actuators typically reset within 15 seconds, depending on torque rating and spring preload. To protect your valves and piping from water hammer, HUS actuators are engineered with built-in speed damping for a smooth, controlled shutdown sequence.
Q7: Does the electric actuator spring return interface comply with ISO 5211? Will it mount directly to my valve?
A: Yes. The HUS series flange and drive sleeve conform to ISO 5211. If your valve top works also follows ISO 5211, direct mounting requires no additional bracket. For non-standard valve interfaces, provide the valve top drawing and we will confirm or supply a custom adapter.
Q8: What control input does a spring return electric actuator accept? Does it require a separate controller?
A: The standard spring return electric actuator accepts a two-wire on/off signal — power on drives the valve to the working position; power off triggers spring return. No separate PLC or controller is required. Limit switches provide volt-free open/close position feedback as standard. 4–20 mA position feedback or fieldbus options (Modbus, HART) are available on request.
Need Technical Specifications or CAD Drawings?
Get complete engineering support and detailed documentation for your valve assembly projects.
📄 [ Download HUS Series Installation, Operation & Maintenance Manual (PDF) ]
(Includes step-by-step guidance on electrical wiring, stroke calibration, and site menu configurations.)
📩 Talk to a Hearken Flow Application Engineer
Have a specific valve torque calculation or tender specification?
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