Description
ATEX Ex ia 5/2 Bi-Stable Solenoid Valve – Rotex 57440A
The Rotex 57440A is a high-performance ATEX and IECEx Ex ia intrinsically safe 5/2 way bi-stable solenoid valve designed for hazardous-area directional control applications requiring the valve to remain in its last switched position until the opposing electrical signal is applied.
Featuring double-solenoid bi-stable operation with internal pilot control, the 57440A is particularly suited to double-acting pneumatic actuators and cylinders where positional memory is required. Working pressure is 2 to 10 Bar, with a minimum pressure differential of 0.5 or 1 Bar depending on configuration.
Available with aluminium, brass or 316 stainless steel CF8 bodies, the valve combines bubble-tight shut-off, 9G vibration resistance, switching rates up to 900 cycles per minute and a life expectancy exceeding 20 million cycles.
Valve Function & Operation
Function: 5/2 way bi-stable
Actuation: Double solenoid
Operation: Internally piloted
Unlike a monostable valve, the 57440A does not rely on a spring return to determine its normal position. Energising one solenoid switches the valve in one direction, while energising the opposite solenoid switches it back.
The valve therefore maintains its last selected position after the electrical signal is removed, making it useful for applications where actuator position must be retained without continuously energising a solenoid.
The internal pilot system requires sufficient pressure differential for reliable switching.
Operating pressure: 2 to 10 Bar
Minimum differential: 0.5 or 1 Bar, depending on configuration.
Ports, Orifice & Flow
Standard connection: 1/4" BSP
Optional connection: 1/4" NPT
Orifice: 6mm
Water flow: 14 L/min at 1 Bar pressure drop
The 5/2 configuration is particularly suited to directional control of double-acting pneumatic actuators and cylinders.
Construction & Materials
Body options:
Aluminium
Brass
316 stainless steel CF8
Internals: Stainless steel
Shading ring: Copper
Optional shading ring:
Silver
Without shading ring
Available seal materials:
NBR
FKM (Viton®)
EPDM
Fluorosilicone
Media compatibility should be confirmed against the selected body, internal and sealing materials for the specific application.
Media Compatibility
Suitable media include:
Air
Water
Gases
Compatible process fluids
For conventional 5/2 directional control applications, clean compressed air would normally be the primary medium.
Performance & Reliability
The Rotex 57440A provides excellent mechanical performance for demanding hazardous-area automation:
Bubble-tight shut-off
Vibration resistance: Up to 9G
Maximum cycling: 900 cycles/minute
Life expectancy: >20 million cycles
The bi-stable design can also reduce continuous electrical consumption because the valve does not require a continuously energised coil merely to maintain its last selected position.
ATEX & IECEx Intrinsic Safety
The Rotex 57440A uses intrinsically safe solenoid operators certified for hazardous gas and dust atmospheres.
IECEx certificate: IECEx BAS 12.0128X – Issue 1
ATEX certificate: Baseefa12ATEX0243X – Issue 1
Gas marking:
Ex ia IIC T5 Ga
-60°C ≤ Ta ≤ +75°C
Ex ia IIC T6 Ga
-60°C ≤ Ta ≤ +60°C
Dust marking:
Ex ia IIIC T200 125°C IP67 Da
-60°C ≤ Ta ≤ +75°C
The Ga and Da equipment protection levels provide a very high level of protection for hazardous gas and dust applications when correctly incorporated into an intrinsically safe installation.
Intrinsically Safe Coil
Coil: III 14mm with booster circuit
Nominal voltage: 24V DC
Maximum power: 2.3 Watts
Protection: IP67
Insulation: Class H
The low-power booster circuit provides the actuation energy required by the internally piloted valve while remaining suitable for an intrinsically safe control circuit.
Intrinsically Safe Parameters
Entity parameters:
Ui: 32V DC
Ii: 230mA
Pi: 2.3W
Li: 0
Ci: 0
Minimum operating parameters:
Voltage: 10V
Current: 20mA
Power: 0.20W
The associated intrinsically safe barrier or galvanic isolator must comply with these certified entity parameters and the requirements of the complete hazardous-area circuit.
Typical Applications
Typical applications include double-acting pneumatic actuators, process valve automation, oil and gas installations, petrochemical plants, chemical processing, offshore equipment, process skids, industrial automation and hazardous-area machinery requiring bi-stable directional control.
Why Choose the Rotex 57440A?
The key advantage of the Rotex 57440A is its combination of Ex ia intrinsic safety and bi-stable 5/2 directional control.
The valve can retain its last selected position without continuously energising a solenoid, while providing 2–10 Bar operation, 14 L/min water flow, switching rates up to 900 cycles per minute and a life expectancy exceeding 20 million cycles.
For applications where a double-acting actuator must remain in its last commanded position following removal of the electrical signal, the 57440A offers a particularly useful alternative to the spring-return 51440A monostable version.
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