The W71 is designed to safely separate two different process fluids—typically product and CIP—allowing simultaneous flow paths without the risk of cross-contamination. Its double-seat design and leakage chamber deliver proven hygienic protection.
waukesha W71 Series Valves
W71 Series: Mixproof Valves
Mix Proof valves provide safe separation of dissimilar products within the same valve body. For general purpose Mix Proof applications, WCB offers two basic valve types: The W71 Series for shutoff service, and the W73 Series for divert applications.
Double Seat Mixproof Shut-Off Valves
Key Features: Safe, Continuous Production & Cleaning:
- Proven mix proof valve design allows plants to maximize production and minimize downtime for cleaning.
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Full mix proof model portfolio for completely automated systems:
- W71 model for general purpose shut-off with safe separation in the failed-closed position
- W71 tank outlet version for safe separation between tank and servicing pipeline
- W73 models for non-slamming diverting of flow
Specifications:
- For general purpose mixproof applications, we offer the W71 Series for standard shutoff service.
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Materials:
- Product Wetted: Stainless Steel, ASTM 316L (UNS-S31603); (DIN-1.4404)
- Non-Product: Stainless Steel, ASTM 304 (UNS-S30400); (DIN-1.4301)
- Seat: Tri-Ring Compression Seal on Upper and Lower Stems
- Elastomers: EPDM or FKM (Fluoroelastomer)
- Finish: ≤ 32 Ra (≤0.8 m) Other finishes available upon request.
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Pressure Ratings (Operating Pressure)
- 1½" - 3" (38mm - 76mm) Sizes - 150 psig (10 bar)
- 4" (102mm) Size - 100 psig (7 bar)
- 4" (102mm) Sch. 5 Size - 150 psig (10 bar)
- 6" (152mm) Size - Consult Factory
- 6" (152mm) Sch. 5 Size - 150 psig (10.3 bar)
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Theory of Operation: Mixproof Valves
Mix proof valves are used to safely and efficiently process two different fluids (typically product and CIP) through the valve simultaneously. The mix proof design has two seats which isolate the upper and lower pipe lines when the valve is in the fail-safe closed position. The atmospheric vent cavity in between the seats creates a path for any leakage should the seats fail as well as a drain for CIP solution during seat cleaning. An optional external flush is available to clean the area between the seats and the vent drain while the valve is closed during production.
W71 Mixproof Valve Overview
This video explains how the double-seat technology ensures safe product separation, reliable CIP performance, and efficient operation in sanitary processing systems.
Frequently Asked Questions
The W71 represents an earlier generation of SPX mixproof technology. Systems needing advanced cleanability, improved modularity, and easier maintenance often transition to the newer D4 Series, which builds on W71 functionality with enhanced CIP performance and simplified topworks.
The W71 is widely used in food, beverage, dairy, and brewing applications where hygienic product separation and reliable cleaning are essential. It has long been a workhorse solution for facilities needing automation-ready valve manifolds.
