When designing distribution loops for Purified Water (PW), Water for Injection (WFI), or Pure Steam (PS), the choice of valve is critical. It often determines whether the system fully complies with FDA requirements or faces validation challenges.
− Valve Types and Hygienic Design
Not all valves are suitable for PW/WFI/PS loops. International guidelines such as ASME BPE and EHEDG define what makes a valve “hygienic”:
• Diaphragm Valves (Two-Way):
Considered the gold standard for PW and WFI systems. They allow full drainability and eliminate dead legs.
• Ball Valves & Butterfly Valves (Conventional):
Contain cavities and dead zones, making them unsuitable for hygienic loops unless designed specifically for pharmaceutical applications.
• Check Valves (Spring-less Design):
Must be spring-free to avoid microbial growth.
− Types of Block T-Valves
• Standard Use Point: single outlet for distribution.
• With Sampling Port: additional outlet for QC sampling.
• With Drain/Return Port: for loop return or point drainage.
− Outlet Design
Key design aspects:
• Required flow rate at the point of use.
• Velocity ≥ 1.0 m/s to prevent biofilm formation.
• Outlet angle < 90° (preferably 45°–60°) to ensure proper drainage.
• Branch length ≤ 1.5D (per ASME BPE).
− Point of Use Cooling
In large pharma facilities, WFI is distributed hot (80–85°C) to maintain microbial control. However, certain applications require cooled WFI (20–25°C):
• Filling machines
• QC laboratories
− Possible solutions:
• Install a POU cooler directly after the Block T-Valve.
• Use an integrated Block T-Valve with cooler.
− Advantages:
• Instant cooling without stagnant zones.
• Space-saving, easy to clean and sterilize (CIP/SIP).
• Better integration into pharmaceutical processes.