Description
1/2"–2" 3-Way Stainless Motorised Ball Valve Spring Return – MK3-3
The Queen MK3-3 is a heavy-duty 3/2 way stainless steel motorised ball valve with spring return fail-safe operation, designed for automatic flow switching, diverting and changeover applications involving water, air, oil, vacuum, gases and compatible industrial liquids.
Available with L-port or T-port 3-way ball valve configurations, the MK3-3 provides multiple flow arrangements together with automatic spring-return operation. The actuator drives the valve electrically during normal operation and automatically returns it to its predetermined failsafe position if electrical power is removed.
Featuring a full-port CF8M stainless steel ball valve, PTFE seals and robust aluminium alloy actuator housing, the MK3-3 operates from 0 to 10 Bar and provides a fast 2.5 second failsafe operating time, with an actuator life exceeding 60,000 cycles.
Valve Function & Operation
Function: 3/2 way
Operation: Electric motor driven with spring return
Ball valve configurations:
L-Port
T-Port
The MK3-3 combines a three-way stainless steel ball valve with an electric spring-return actuator, allowing flow to be automatically switched between different ports.
The electric motor drives the ball valve to its powered operating position. If electrical power is removed, the internal spring mechanism automatically drives the valve back to its predetermined failsafe position.
This provides a mechanical failsafe response without requiring electrical power to return the valve to its designated safe flow path.
L-Port Flow Control
The L-port version is primarily designed for diverting or selecting flow between two alternative paths.
Depending upon the selected configuration, the valve can direct the common inlet towards one of two outlet ports.
The MK3-3 L-port configuration can be supplied with the required normally closed or normally open flow arrangement according to the installation.
T-Port Flow Control
The T-port version provides additional flow-path flexibility and is available in four different operating configurations.
Depending upon the selected T-port arrangement, the valve can be configured for diverting, mixing, selecting or connecting different combinations of the three valve ports.
The required T-port function should therefore be selected when ordering to ensure the spring-return and powered positions provide the correct flow paths for the application.
Ports & Connections
Available BSP port sizes:
1/2"
3/4"
1"
1¼"
1½"
2"
Full-port orifice sizes:
1/2" → 15mm
3/4" → 20mm
1" → 25.4mm
1¼" → 32mm
1½" → 38mm
2" → 50mm
The manufacturer specifies the standard MK3-3 L and T configurations at 0–10 Bar, with larger sizes and alternative configurations available upon request.
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
The motor-operated ball valve does not depend upon process pressure to operate, allowing reliable switching from zero pressure through to the maximum 10 Bar working pressure.
Construction & Materials
Ball valve: CF8M stainless steel
Internal components: Stainless steel
Seals and gaskets: PTFE
Actuator housing: Aluminium alloy
Mounting bracket: Metal construction
Drive socket: Carbon steel
The full-port stainless steel valve and PTFE sealing provide a robust construction suitable for a wide range of compatible industrial fluids.
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 seals.
Temperature Range
Media temperature:
-5°C to +120°C
Actuator ambient temperature:
0°C to +50°C
The wide process temperature range makes the MK3-3 suitable for industrial water, air, oil, gas and compatible process applications.
Spring Return Failsafe Operation
The principal advantage of the MK3-3 is its mechanical spring-return actuator.
During powered operation, the electric motor drives the three-way valve against the actuator spring.
If electrical power is interrupted, stored spring energy automatically returns the valve to its predetermined failsafe flow position.
This can provide automatic response following:
✓ Electrical Power Failure
✓ Emergency Shutdown
✓ Control Circuit Failure
✓ Process Shutdown
✓ Equipment Isolation
The required L-port or T-port failsafe flow arrangement should be selected according to the safety and operational requirements of the system.
Fast 2.5 Second Operation
The MK3 actuator provides a fast 2.5 second operating time.
This makes the MK3-3 particularly useful for three-way process applications where rapid flow changeover is required following an electrical failure.
The actuator information also confirms approximately 2.5-second movement between operating positions.
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 straightforward two-wire electrical arrangement helps simplify installation compared with reversible motor actuators requiring separate open and close control circuits.
Voltage Options
Available AC voltage ranges:
✓ 100–115VAC 50/60Hz
✓ 200–240VAC 50/60Hz
Voltage tolerance:
-10% / +15%
The broad voltage ranges cover common industrial 110VAC and 230VAC control supplies.
Mounting Position
Recommended mounting:
Upright
Vertical ±15°
The actuator can also be installed upside down where required by the installation.
Adequate clearance should be provided around the actuator for electrical connection, servicing and valve removal.
Full-Port 3-Way Ball Valve
The MK3-3 uses a full-port three-way stainless steel ball valve, providing large internal flow passages compared with reduced-bore valve designs.
Available bore sizes extend from 15mm on the 1/2" valve through to 50mm on the 2" version.
This makes the range particularly useful for applications where unnecessary flow restriction or pressure loss through the valve needs to be minimised.
Typical Applications
✓ Automatic Flow Diversion
✓ Process Flow Changeover
✓ Water Distribution Systems
✓ Heating & Cooling Systems
✓ Compressed Air Systems
✓ Oil & Fluid Control
✓ Vacuum Systems
✓ Process Control Systems
✓ Emergency Flow Diversion
✓ Industrial Machinery
✓ OEM Equipment
✓ Process Automation
✓ Mixing Applications
✓ Diverting Applications
L-Port or T-Port – Which to Choose?
Choose the L-port version where the primary requirement is to divert flow from one common connection between two alternative flow paths.
Choose the T-port version where a more flexible three-way arrangement is required, including applications where multiple ports may need to be connected in one of the operating positions.
The MK3-3 provides four T-port arrangements, allowing the powered and spring-return positions to be selected to suit the required process flow path.
Long-Life Industrial Actuator
The MK3 spring-return actuator is designed for a service life exceeding 60,000 operating cycles.
Its robust aluminium alloy housing protects the internal motor, spring, gearing and switching mechanism while providing IP65 environmental protection.
Combined with the CF8M stainless steel ball valve and PTFE sealing, the assembly is suitable for demanding industrial automation applications.
Fully Assembled & Tested
Each MK3-3 is supplied as a complete assembled three-way motorised valve package.
The actuator, mounting assembly and stainless steel ball valve are supplied fully assembled and function tested, reducing installation work and ensuring the complete assembly operates correctly before dispatch.
Additional Options
Available configurations include:
L-port ball valve
T-port ball valve
Alternative failsafe positions
Larger valve sizes
Higher pressure versions
Flanged connections
Alternative actuator combinations
The standard MK3-3 range can therefore be adapted for applications beyond the standard threaded 0–10 Bar configuration.
Why Choose the Queen MK3-3?
The Queen MK3-3 combines the versatility of a 3-way full-port stainless steel ball valve with the safety advantages of a fast mechanical spring-return actuator.
Its L-port and T-port options provide considerable flexibility for diverting, selecting and changing process flow paths, while the spring-return mechanism automatically moves the valve to its designated failsafe position following loss of electrical power.
With 0–10 Bar operation, stainless steel construction, PTFE seals, media temperatures up to +120°C, IP65 protection and a 2.5 second spring return, the MK3-3 provides a practical solution for industrial three-way flow control where reliable power-loss positioning is required.
Ordering Information
Select the required:
Port – 1/2", 3/4", 1", 1¼", 1½" or 2" BSP
Ball configuration – L-Port or T-Port
Failsafe flow arrangement
Voltage – 100–115VAC or 200–240VAC
For T-port valves, select the required flow configuration to ensure the powered and failsafe positions match the process requirements.
Please contact us for quantity discounts, larger sizes, higher pressures or alternative actuator configurations.
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