Description
Shako 225 Normally Closed Solenoid Valve Armature Assembly – System 13
The Shako 225 Series 2/2 way normally closed armature assembly is a replacement System 13 solenoid operator for Shako PU225 brass and SPU225 stainless steel solenoid valves.
Manufactured with a 430F stainless steel armature, 304 stainless steel tube and 302 stainless steel return spring, the assembly is available with a copper shading ring, silver shading ring or without a shading ring, allowing the operator to be configured for standard fluids, corrosive media and AC or DC electrical supplies.
This second-generation design features a one-piece extruded armature tube formed from the base without welding, together with an increased 0.3mm internal clearance designed to reduce debris build-up and improve service life.
Suitable for pressures up to 25 Bar, with NBR, EPDM, FKM/Viton, HNBR and PTFE sealing options.
Function & Operation
Function: 2/2 way normally closed
Failsafe Position: Closed
Operation: Solenoid operated armature
Armature System: Nass Magnet System 13
Maximum Pressure: 25 Bar
Mounting Thread: M20 × 1mm
The armature is the moving magnetic component within the solenoid operator. When the coil is energised, its magnetic field lifts the armature against the return spring to operate the valve.
When electrical power is removed, the 302 stainless steel spring returns the armature to its normally closed position.
Shading Ring Options
Three configurations are available depending upon the electrical supply and controlled media.
Copper Shading Ring – Standard
Suitable for:
✓ AC operation
✓ DC operation
✓ Air
✓ Water
✓ Oils
✓ Gases
✓ Compatible industrial fluids
The standard copper version should be used where the controlled media does not adversely react with copper.
Silver Shading Ring – Corrosive Media
Suitable for AC 50/60Hz operation where the controlled media is unsuitable for copper.
Typical applications include:
✓ Pure water
✓ RO water
✓ Demineralised water
✓ Compatible corrosive media
The silver shading ring retains the AC stabilising function while removing the standard copper ring from the wetted armature arrangement.
No Shading Ring – DC Only
Designed for DC operation only where the controlled media is incompatible with copper.
Typical applications include:
✓ Pure water
✓ Reverse osmosis water
✓ Demineralised water
✓ Compatible corrosive fluids
Because a DC magnetic field does not pass through the repeated zero crossings associated with AC power, a shading ring is not required for DC-only operation.
What Does the Shading Ring Do?
With an AC solenoid, the magnetic field varies continuously with the alternating electrical supply.
The shading ring helps maintain magnetic attraction through the alternating-current cycle, preventing the armature from repeatedly releasing and attracting as the AC waveform passes through zero.
This reduces solenoid buzzing or chatter and provides stable AC operation.
The standard version uses copper, while the silver option provides the same basic function where copper is unsuitable for the controlled media.
Improved Second-Generation Design
This second-generation armature assembly incorporates a one-piece extruded stainless steel tube formed directly from the base rather than using a welded tube construction.
The internal clearance has also been increased by approximately 0.3mm.
This increased clearance is designed to reduce the likelihood of dirt and debris accumulating between the moving armature and tube, helping improve reliability and service life in contaminated industrial fluid systems.
Construction & Materials
Armature: 430F stainless steel
Armature Tube: 304 stainless steel
Spring: 302 stainless steel
Mounting Thread: M20 × 1mm
Standard Shading Ring: Copper
Corrosive Media AC Shading Ring: Silver
Corrosive Media DC Version: No shading ring
The stainless steel construction provides good mechanical strength and corrosion resistance across a wide range of compatible industrial fluids.
Seal Options
The armature assembly is available with:
✓ NBR
✓ EPDM
✓ FKM / Viton
✓ HNBR
✓ PTFE
This provides a particularly broad range of temperature and chemical compatibility options.
Seal Temperature Ranges
NBR
-15°C to +80°C
EPDM
-5°C to +130°C
FKM / Viton
-10°C to +180°C
HNBR
-40°C to +150°C
PTFE
-196°C to +200°C
These figures relate to the stated seal material temperature ranges. The allowable operating temperature of the complete valve assembly may be lower depending upon the valve body, coil, media, pressure and other components.
Pressure Rating
Maximum Pressure: 25 Bar
The armature assembly is suitable for compatible valve applications with pressures up to 25 Bar maximum, subject to the pressure rating of the complete valve configuration.
Shako 225 Series Compatibility
The armature assembly fits Shako normally closed 225 Series brass and stainless steel solenoid valves.
This includes compatible:
PU225 Series → Brass solenoid valves
SPU225 Series → Stainless steel solenoid valves
It can therefore provide a common replacement operator across multiple 225 Series valve sizes and body materials.
Nass Magnet System 13 Compatibility
Armature System: Nass Magnet System 13
Function: 2/2 way normally closed
Mounting Thread: M20 × 1mm
This also makes the assembly relevant when identifying replacement operators by System 13 compatibility and M20 × 1mm mounting, rather than solely by the Shako valve model.
Helpful Hint – Corrosive Media
For applications involving pure water, RO water, demineralised water or other media that may attack copper, select either:
AC supply → Silver shading ring
DC supply → No shading ring
For standard compatible fluids:
AC or DC → Copper shading ring
DC Coil Options
When using the no-shading-ring version, a DC solenoid coil must be used.
Available DC coil voltages include:
✓ 12V DC
✓ 24V DC
✓ 48V DC
✓ 110V DC
✓ 220V DC
Where only an AC supply is available, a fully rectified DIN 43650 connector can be used with an appropriate DC coil to convert the incoming AC supply to DC.
This can provide a useful solution where the process media requires the copper-free armature configuration.
Maintenance & Replacement
Replacement of the complete armature assembly may be appropriate where an existing valve has:
✓ Worn armature components
✓ Damaged armature seal
✓ Corroded internal components
✓ Damaged return spring
✓ Sticking or sluggish operation
✓ Excessive AC buzzing
✓ Debris contamination
✓ Internal pilot leakage
✓ Preventative maintenance requirements
Always isolate the electrical supply, fluid supply and system pressure before dismantling the solenoid valve.
Typical Applications
✓ Shako PU225 valve servicing
✓ Shako SPU225 valve servicing
✓ Solenoid armature replacement
✓ Water control systems
✓ RO water systems
✓ Demineralised water systems
✓ Compressed air systems
✓ Industrial process fluids
✓ Corrosive media applications
✓ OEM machinery maintenance
Technical Specification
Manufacturer: Shako
Product Type: Solenoid valve armature assembly
Armature System: Nass Magnet System 13
Function: 2/2 normally closed
Failsafe Position: Closed
Armature Material: 430F stainless steel
Tube Material: 304 stainless steel
Spring Material: 302 stainless steel
Mounting Thread: M20 × 1mm
Maximum Pressure: 25 Bar
Standard Shading Ring: Copper
Corrosive Media AC Option: Silver shading ring
Corrosive Media DC Option: No shading ring
Seal Options: NBR, EPDM, FKM/Viton, HNBR or PTFE
NBR Temperature: -15°C to +80°C
EPDM Temperature: -5°C to +130°C
FKM/Viton Temperature: -10°C to +180°C
HNBR Temperature: -40°C to +150°C
PTFE Temperature: -196°C to +200°C
Compatible Valve Series: Shako 225 normally closed
Valve Body Compatibility: Brass & stainless steel
Tube Design: One-piece extruded, non-welded
Additional Internal Clearance: 0.3mm
Ordering Options
Copper Shading Ring
Standard option for compatible media
AC or DC operation
Silver Shading Ring
For pure water, RO water, demineralised water and compatible corrosive media
AC 50/60Hz operation
No Shading Ring
For pure water, RO water, demineralised water and compatible corrosive media
DC operation only
Then select the appropriate seal material for the media and temperature.
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