Description
1/2"–2" Stainless Motorised Ball Valve Spring Return – MK3-2
The Queen MK3-2 is a heavy-duty 2/2 way stainless steel motorised ball valve with spring return fail-safe operation, designed for automatic isolation of water, air, oil, vacuum, gases and compatible industrial liquids.
Available as either failsafe normally closed or failsafe normally open, the MK3-2 automatically returns to its designated safe position if electrical power is removed. The fast spring-return actuator provides a 2.5 second failsafe closing time and has a rated service life exceeding 60,000 operating cycles.
Featuring a full-port stainless steel ball valve, PTFE seals and robust aluminium alloy actuator housing, the MK3-2 is available from 1/2" to 2" BSP with operating pressures from 0 to 10 Bar. Its simple two-wire electrical connection and IP65 enclosure make it particularly suitable for industrial automation, water control and safety shut-off applications.
Valve Function & Operation
Function: 2/2 way
Operation: Electric motor driven with spring return
Available functions:
Failsafe normally closed
Failsafe normally open
The MK3-2 uses an electric motor actuator to drive the stainless steel ball valve during normal powered operation.
The integrated spring-return mechanism automatically returns the valve to its predetermined failsafe position when electrical power is removed.
For a failsafe closed configuration:
Power applied → Valve OPEN
Power removed → Valve CLOSES
For a failsafe open configuration:
Power applied → Valve CLOSED
Power removed → Valve OPENS
This provides a mechanical failsafe response without relying upon electrical power to move the valve to its required emergency position.
Port Sizes & Connections
Available BSP port sizes:
1/2"
3/4"
1"
1¼"
1½"
2"
The valve uses a 2-way full-port ball valve design, helping minimise restriction through the valve when fully open.
Orifice sizes:
1/2" → 15mm
3/4" → 20mm
1" → 25.4mm
1¼" → 32mm
1½" → 38mm
2" → 50mm
Pressure & Performance
Operating pressure: 0 to 10 Bar
Minimum pressure: 0 Bar
Maximum pressure: 10 Bar
Failsafe operating time: 2.5 seconds
Actuator life: 60,000+ cycles
Duty rating: 100% continuous duty
Unlike pressure-assisted solenoid valves, the motor-operated ball valve does not require a minimum pressure differential to operate.
This allows the MK3-2 to control systems from zero pressure through to its maximum 10 Bar working pressure.
Construction & Materials
Ball valve body: Stainless steel
Ball valve: CF8M stainless steel
Internal components: Stainless steel
Seals and gaskets: PTFE
Actuator housing: Aluminium alloy
The stainless steel full-port ball valve and PTFE sealing provide a durable construction suitable for a wide range of compatible industrial fluids.
The manufacturer specifies a CF8M stainless steel ball valve together with stainless steel internal parts and PTFE seals and gaskets.
Media Compatibility
Suitable media include:
✓ Water
✓ Compressed Air
✓ Oil
✓ Vacuum
✓ Compatible Gases
✓ Compatible Liquids
Media must be chemically compatible with the stainless steel valve construction and PTFE sealing materials.
Temperature Range
Media temperature: -5°C to +120°C
Actuator ambient temperature: 0°C to +50°C
This provides a wide process temperature range for industrial water, air, oil and compatible fluid-control applications.
Spring Return Failsafe Operation
The principal advantage of the MK3-2 is its mechanical spring-return actuator.
In normal operation, the electric motor drives the valve against the actuator spring.
If electrical power is interrupted, the stored spring force automatically drives the valve to its predetermined failsafe position.
This provides predictable valve positioning following:
✓ Electrical Power Failure
✓ Emergency Shutdown
✓ Control Circuit Failure
✓ Equipment Isolation
✓ Process Shutdown
The valve can be configured as either failsafe closed or failsafe open, allowing the safe position to be selected according to the application.
Fast 2.5 Second Failsafe
The MK3 actuator provides a 2.5 second failsafe operating time.
This rapid spring-return action makes the MK3-2 particularly useful where a conventional slow motorised ball valve would take too long to reach its safe position following power loss.
The mechanical spring return operates independently of electrical power once released.
Actuator & Electrical
Actuator: Queen MK3 Series
Operation: Motor driven with spring return
Power consumption: 80VA
Duty rating: 100%
Protection: IP65
Electrical connection: 2 lead wires
Frequency: 50/60Hz
The simple electrical arrangement helps reduce installation complexity compared with motorised valves requiring multiple control wires or external reversing circuits.
Available AC voltage ranges:
✓ 100–115VAC 50/60Hz
✓ 200–240VAC 50/60Hz
Voltage tolerance: -10% / +15%
The broad AC voltage ranges make the MK3-2 suitable for industrial installations using common 110VAC or 230VAC control supplies.
Mounting Position
The MK3-2 can be installed:
Upright
Vertical ±15°
Upside down where required
Correct actuator orientation and sufficient clearance should be considered during installation to allow access for electrical wiring, maintenance and valve removal.
Full-Port Ball Valve Design
The MK3-2 uses a full-port stainless steel ball valve, providing a large unrestricted flow path when the valve is fully open.
Available valve bore sizes increase with the pipe connection:
1/2" → 15mm
3/4" → 20mm
1" → 25.4mm
1¼" → 32mm
1½" → 38mm
2" → 50mm
This makes the MK3-2 particularly useful for applications where minimising unnecessary flow restriction and pressure loss is important.
Typical Applications
✓ Automatic Water Isolation
✓ Industrial Water Systems
✓ Compressed Air Systems
✓ Oil & Fluid Control
✓ Vacuum Systems
✓ Process Control Systems
✓ Emergency Shut-Off Systems
✓ Cooling Water Systems
✓ Building Services
✓ Industrial Machinery
✓ OEM Equipment
✓ Process Automation
✓ Power-Loss Isolation
✓ Failsafe Fluid Control
Failsafe Closed Applications
The failsafe closed version automatically shuts the pipeline if electrical power is lost.
Typical uses include water isolation, process shut-off, equipment protection and applications where continued flow following power failure would be undesirable.
This configuration provides an electrically opened valve with mechanical spring-return closure.
Failsafe Open Applications
The failsafe open version automatically opens the pipeline if electrical power is lost.
This can be useful for cooling circuits, circulation systems and other applications where maintaining a flow path following electrical failure is required.
The correct failsafe position should always be selected according to the safety requirements of the complete system.
Long-Life Industrial Actuator
The MK3 spring-return actuator is rated for more than 60,000 operating cycles.
Combined with the robust aluminium alloy actuator housing, stainless steel ball valve and PTFE sealing, this makes the MK3-2 suitable for industrial automation applications requiring frequent dependable operation.
Fully Assembled & Tested
Each MK3-2 motorised ball valve is supplied as a complete assembled actuator and valve package.
The actuator, mounting arrangement and stainless steel ball valve are assembled and function tested before dispatch, reducing installation work and ensuring the complete valve assembly operates correctly.
Additional Options
Alternative configurations are available upon request, including:
Larger valve sizes
Higher pressure versions
Flanged ball valves
Alternative actuator combinations
Failsafe open operation
Failsafe closed operation
The MK3-2 range can therefore be adapted for applications beyond the standard threaded 0–10 Bar configuration.
Why Choose the Queen MK3-2?
The Queen MK3-2 combines the low flow restriction of a full-port stainless steel ball valve with the safety advantages of a fast mechanical spring-return actuator.
Unlike a conventional motorised ball valve that may remain in its last position following loss of electrical power, the MK3-2 automatically returns to its specified failsafe position.
With 0–10 Bar operation, sizes from 1/2" to 2", media temperatures up to +120°C, IP65 protection and a 2.5 second spring return, it provides a practical solution for industrial applications where reliable power-loss positioning is required.
Ordering Information
Select the required:
Port – 1/2", 3/4", 1", 1¼", 1½" or 2" BSP
Function – Failsafe closed or open
Voltage – 100–115VAC or 200–240VAC
Please contact us for quantity discounts, larger sizes, higher pressure versions or alternative actuator configurations.
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