Description
Shako PU225 Normally Open Solenoid Valve Seal & Diaphragm Repair Kit
The Shako ZGPU225AN Series is a replacement seal, diaphragm and plunger repair kit for PU225 Series 2/2 way normally open pilot-operated solenoid valves.
Designed for genuine Shako brass and stainless steel normally open 225 Series valves, the repair kit contains the principal internal moving and sealing components required when servicing an existing valve, including the normally open plunger, plunger spring, armature tube O-ring and diaphragm.
Available for valve sizes from 3/8" to 2", with a choice of NBR, FKM/Viton, EPDM or HNBR seal materials.
A dedicated WRAS EPDM option is also available for water applications, incorporating a controlled 0.5–3 second slow-closing design to help prevent water hammer.
Compatible Solenoid Valves
Manufacturer: Shako
Repair Kit Series: ZGPU225AN
Compatible Valve Series: PU225 Normally Open
Valve Type: Pilot-operated diaphragm solenoid valve
Function: 2/2 way normally open
Failsafe Position: Open
Compatible Valve Bodies: Brass & stainless steel
Available Port Sizes: 3/8" to 2"
These kits are specifically for normally open Shako 225 Series valves. They should not be confused with the ZGPU225 repair kits used for normally closed PU225 valves.
ZGPU225AN Repair Kit Contents
Each repair kit consists of:
✓ Normally open plunger
✓ Plunger spring
✓ Armature tube O-ring
✓ Replacement diaphragm
The normally open plunger configuration is important because its operating arrangement differs from the corresponding normally closed PU225 valve.
Normally Open Operation
A 2/2 way normally open solenoid valve is open in its normal de-energised state.
When the solenoid is energised, the pilot mechanism operates the diaphragm to close the valve.
When electrical power is removed, the valve returns to its normally open / failsafe open position.
This makes normally open valves particularly useful where fluid flow is required to continue or automatically resume following loss of electrical power.
Seal Material Options
Four standard seal materials are available.
NBR – Nitrile / Buna
Temperature Range: -15°C to +80°C
General-purpose elastomer commonly used with air, water, oils and compatible industrial fluids.
FKM / Viton
Temperature Range: -10°C to +180°C
High-temperature elastomer offering good resistance to many oils, fuels and compatible industrial fluids.
EPDM
Temperature Range: -5°C to +130°C
Commonly selected for water, hot water and compatible aqueous applications.
HNBR
Temperature Range: -40°C to +150°C
Provides excellent low-temperature performance combined with an elevated maximum temperature capability.
Actual permissible operating temperature is also dependent upon the complete valve specification, coil, pressure, media and operating conditions.
Available Repair Kit Sizes
22503 – 3/8" & 1/2" Valves
Diaphragm Diameter: 40mm
Valve Port Sizes: 3/8" and 1/2"
22506 – 3/4" & 1" Valves
Diaphragm Diameter: 66mm
Valve Port Sizes: 3/4" and 1"
22512 – 1¼" & 1½" Valves
Diaphragm Diameter: 90.5mm
Valve Port Sizes: 1¼" and 1½"
22520 – 2" Valves
Diaphragm Diameter: 107.5mm
Valve Port Size: 2"
WRAS EPDM Slow-Close Seal Kit
A dedicated WRAS EPDM seal kit is available for water applications requiring the appropriate WRAS sealing configuration.
Seal Material: WRAS EPDM
Temperature Range: -5°C to +130°C
The WRAS version incorporates a slow-closing diaphragm design, with a closing time of approximately 0.5 to 3 seconds.
This controlled closure helps prevent the sudden interruption of water flow that can cause hydraulic shock and water hammer within the pipeline.
Anti-Water-Hammer Operation
Water hammer can occur when flowing water is stopped too rapidly, producing a sudden pressure surge through the pipework.
The WRAS EPDM diaphragm uses a controlled slow-close action to extend valve closure to approximately 0.5–3 seconds.
By reducing the rate at which the water flow stops, the valve helps minimise pressure shock within the installation.
This is particularly useful in water systems where a conventional fast-closing solenoid valve could generate unwanted hydraulic shock, pipe movement or noise.
Choosing the Correct Repair Kit
Select the kit according to the valve port size:
3/8" or 1/2" → 22503 → 40mm diaphragm
3/4" or 1" → 22506 → 66mm diaphragm
1¼" or 1½" → 22512 → 90.5mm diaphragm
2" → 22520 → 107.5mm diaphragm
Then select the required seal material:
✓ NBR
✓ EPDM
✓ FKM / Viton
✓ HNBR
✓ WRAS EPDM slow-close
Most importantly, confirm that the existing valve is normally open before ordering this repair kit.
Normally Open vs Normally Closed Repair Kits
Shako PU225 valves are available in both normally closed and normally open configurations.
This ZGPU225AN repair kit is for normally open valves and incorporates the appropriate normally open plunger arrangement.
For a normally closed PU225 valve, select the corresponding normally closed ZGPU225 repair kit instead.
Maintenance & Repair
The diaphragm, plunger and associated seals are operating components that can eventually deteriorate through repeated cycling, contamination, temperature and exposure to the controlled media.
Replacing the appropriate ZGPU225AN repair kit can help when servicing problems associated with:
✓ Worn or damaged diaphragm
✓ Internal valve leakage
✓ Sticking plunger
✓ Damaged plunger spring
✓ Worn armature tube O-ring
✓ Slow or unreliable operation
✓ Preventative maintenance
✓ Existing valve refurbishment
Before servicing, isolate both the electrical and fluid supplies and ensure all pressure has been safely released from the valve.
Typical Applications
✓ Shako PU225 normally open valve servicing
✓ Solenoid valve diaphragm replacement
✓ Normally open valve repair
✓ Solenoid plunger replacement
✓ Water valve maintenance
✓ WRAS water systems
✓ Industrial fluid systems
✓ Preventative maintenance
✓ OEM machinery servicing
✓ Existing solenoid valve refurbishment
Why Repair a PU225 Normally Open Valve?
Where the existing brass or stainless steel valve body, solenoid tube and electrical components remain serviceable, replacing the internal diaphragm, plunger and seals can provide a cost-effective alternative to replacing the complete valve.
The ZGPU225AN kit renews the principal moving and sealing components while retaining the existing valve body and pipe connections.
With sizes covering 3/8" through 2" and several elastomer choices, the repair kit can be selected to suit the existing valve size and operating conditions.
Technical Specification
Manufacturer: Shako
Repair Kit Series: ZGPU225AN
Compatible Series: PU225 Normally Open
Product Type: Solenoid valve seal & diaphragm repair kit
Valve Function: 2/2 normally open
Failsafe Position: Open
Valve Operation: Pilot / diaphragm operated
Compatible Valve Bodies: Brass & stainless steel
Port Sizes: 3/8" to 2"
Kit Contents: Diaphragm, normally open plunger, plunger spring & armature tube O-ring
Seal Materials: NBR, FKM/Viton, EPDM or HNBR
NBR Temperature: -15°C to +80°C
FKM/Viton Temperature: -10°C to +180°C
EPDM Temperature: -5°C to +130°C
HNBR Temperature: -40°C to +150°C
WRAS Option: EPDM
WRAS EPDM Temperature: -5°C to +130°C
WRAS Closing Time: Approximately 0.5–3 seconds
22503 Diaphragm: 40mm
22506 Diaphragm: 66mm
22512 Diaphragm: 90.5mm
22520 Diaphragm: 107.5mm
Application: Maintenance & repair
Ordering Information
Select Valve Port Size:
22503 → 3/8" & 1/2"
22506 → 3/4" & 1"
22512 → 1¼" & 1½"
22520 → 2"
Then select the required seal material:
NBR
EPDM
FKM / Viton
HNBR
WRAS EPDM Slow-Close
Important: This page is for normally open PU225 valves. For normally closed PU225 valves, use the corresponding normally closed repair kit.
Related Products & Categories.
