Description
ATEX Ex ia Intrinsically Safe Solenoid Valve – PU221 / PU321
The Nass Magnet PU221 and PU321 are compact ATEX and IECEx Ex ia intrinsically safe solenoid valves designed for hazardous area pneumatic control, process automation and instrumentation systems.
Available as either a 2/2 way normally closed PU221 or 3/2 way normally closed PU321, both valves use a direct acting design requiring no minimum differential pressure for operation.
The 24V DC intrinsically safe solenoid system combines a low 1.6 Watt power requirement with brass valve construction, stainless steel internals and IP65 protection. When installed with a suitably approved intrinsically safe barrier, the valve provides reliable hazardous-area switching for compressed air, inert and compatible gases, water, compatible liquids and vacuum applications.
Two temperature classifications are available, with T6 versions suitable for ambient temperatures down to -40°C and up to +50°C, and T4 versions extending the maximum ambient temperature to +85°C.
Valve Specification
Function:
PU221 – 2/2 way normally closed
PU321 – 3/2 way normally closed
Operation: Direct acting
Port sizes:
1/8" BSP
1/4" BSP
Optional thread: NPT
Exhaust port: M5 on 3/2 way PU321
Operating differential pressure: 0 to 8 Bar
Maximum working pressure: 12 Bar
Orifice: 0.8mm
Kv flow factor: 0.3 L/min
Recommended mounting: Coil upright
Construction & Materials
Body: Brass
Internal components: Stainless steel
Armature tube: Stainless steel
Seals: NBR
Coil encapsulation: Thermoset resin
Suitable Media
Compressed air
Inert gases
Compatible gases
Water
Compatible liquids
Vacuum to 10⁻³
Media must be chemically compatible with the valve materials of construction.
Coil & Electrical Specification
Voltage: 24V DC
Power consumption: 1.6 Watts
Duty cycle: 100% ED continuous duty
Insulation class: Class F, 155°C
Protection: IP65 with ATEX connector
Electrical connection: DIN 43650A Form A
Voltage tolerance: ±10%
Minimum switching current: 37mA
Nominal coil resistance: 275Ω
ATEX / IECEx Certification
T6 Version
ATEX marking: II 2G Ex ia IIB/IIC T6 Ga
IECEx marking: Ex ia IIB/IIC T6 Ga
Ambient temperature: -40°C to +50°C
Coil: 125930.1-00/5146
T4 Version
ATEX marking: II 2G Ex ia IIB/IIC T4 Ga
IECEx marking: Ex ia IIB/IIC T4 Ga
Ambient temperature: -40°C to +85°C
Coil: 125950.1-00/5146
Intrinsically Safe Operation
Unlike a conventional explosion-protected solenoid, an Ex ia intrinsically safe valve is designed to operate from an intrinsically safe electrical circuit where the electrical energy available within the hazardous area is restricted.
The PU221 and PU321 therefore require connection through a suitably approved intrinsically safe barrier or associated apparatus matched to the electrical and certification requirements of the solenoid.
This low-energy design makes the valves particularly suitable for instrumentation, process control and hazardous-area automation where intrinsically safe control circuits are specified.
2/2 Way PU221 Operation
The PU221 is a 2/2 way normally closed direct acting solenoid valve.
With the coil de-energised, the valve remains closed.
Energising the intrinsically safe solenoid lifts the armature and opens the flow path.
Because the valve is direct acting, operation is possible from zero differential pressure.
3/2 Way PU321 Operation
The PU321 provides 3/2 way normally closed directional control with an M5 exhaust connection.
This configuration is suitable for pneumatic pilot signals, small pneumatic actuators, instrumentation and other hazardous-area applications requiring pressure supply and exhaust functions from a compact intrinsically safe valve.
Vacuum Operation
The direct acting construction also allows the PU221 and PU321 to be used in compatible vacuum applications, with the stated specification extending to 10⁻³.
This makes the range useful where an intrinsically safe electrical control signal is required within pneumatic, gas or vacuum equipment.
Components Supplied
Intrinsically safe valve assembly
Nass Magnet Ex ia solenoid coil
ATEX electrical connector
Stainless steel armature assembly
Typical Applications
Hazardous-area pneumatic control
Process automation
Chemical processing
Oil and gas installations
Paint spraying systems
Instrument air systems
Pneumatic pilot circuits
Safety and interlock systems
Process instrumentation
Vacuum equipment
OEM hazardous-area machinery
Industrial gas control
Quality & Reliability
The PU221 and PU321 combine a compact direct acting valve with a genuine Nass Magnet intrinsically safe solenoid system for reliable hazardous-area control.
The low 1.6 Watt electrical requirement, stainless steel internal components, 100% continuous-duty rating and choice of T6 or T4 temperature classifications make the range particularly suitable for industrial process and instrumentation applications where Ex ia protection is required.
Technical Information
Valve types: 2/2 or 3/2 normally closed
Operation: Direct acting
Port sizes: 1/8" or 1/4" BSP
Exhaust: M5 on PU321
Orifice: 0.8mm
Kv: 0.3 L/min
Differential pressure: 0 to 8 Bar
Maximum working pressure: 12 Bar
Body: Brass
Internals: Stainless steel
Seals: NBR
Voltage: 24V DC
Coil power: 1.6 Watts
Protection: IP65
Insulation: Class F
Duty: 100% ED
ATEX / IECEx protection: Ex ia
Temperature classes: T6 or T4
Ambient range: -40°C to +85°C depending on version
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