Preventing biofilm development
MEASUREMENT & MONITORING
WFI LOOPS
BURKERT
Preventing biofilm development
Within Water for Injection( WFI) loops, the potential for biofilm development is a critical threat that is primarily caused by laminar flow and the presence of dead zones in the pipework. Flow metering and control are crucial to prevent biofilm accumulation, and to achieve this, Surface Acoustic Wave( SAW) technology has significant advantages over traditional methods. Contactless, precision measurement and a straight measuring tube optimise hygiene while maintaining the critical flow rate. Bürkert’ s Business Development Manager for Pharma & Biotech, Damien Moran, explains.
Ensuring Flow Precision in WFI Loops: The Role of SAW Technology
Water for Injection( WFI) is a critical component in the production of parenteral drugs, requiring it to be completely free from impurities. To meet these strict standards, WFI is circulated through a closed loop system designed to maintain consistent purity. However, the loop itself cannot fully guarantee water quality— one of the biggest risks lies in the formation of biofilms from trace bacterial contamination.
Even microscopic levels of bacteria, which may enter through system cracks or during maintenance, can form biofilms under favorable conditions like minimal nutrient presence, temperature shifts, or insufficient cleaning. To prevent this, maintaining consistent and turbulent flow is essential, as stagnation or low-flow areas— known as dead zones— enable bacteria to settle and multiply. Flow velocity must be high
enough to ensure turbulence and dislodge potential contaminants.
Traditional Coriolis meters, while effective at measuring mass flow, have limitations in WFI loops. Their curved tube design enhances mass measurement precision but introduces low-flow areas that can harbor bacteria and cause pressure drops. This compromises water velocity and encourages biofilm formation. While increasing pump speed could offset this, it leads to greater energy consumption, faster pump wear, and additional maintenance. The complexity and cleaning difficulty of curved tubes further adds to operational challenges.
A more effective solution lies in Surface Acoustic Wave( SAW) technology, exemplified by Bürkert’ s FLOWave Type 8098 flow meter. SAW meters use ultrasonic waves to measure real-time volumetric flow, flow velocity, temperature, and volume, all without inserting sensors into the fluid path. The design features a straight stainless steel tube with an ultra-smooth internal finish( Ra < 0.4 µ m), eliminating dead zones and making cleaning more efficient.
FLOWave’ s high measurement accuracy(± 0.4 %, repeatability ± 0.2 %) ensures turbulent flow is consistently maintained, promoting both hygiene and energy efficiency. Unlike electromagnetic meters, which are ineffective with ultra-pure water due to lack of conductivity, SAW meters perform reliably regardless of fluid properties or bubble presence.
Additionally, SAW meters require minimal recalibration, experience no mechanical wear, and are lightweight for easy installation. Compatible with modern communication protocols, they integrate seamlessly into existing systems.
Ultimately, SAW flow meters provide the optimal solution for WFI loops by focusing on critical hygiene factors and enabling precise flow control, making them the most suitable choice for pharmaceutical-grade water systems.
For further information, please visit www. burkert. co. uk
76 PECM Issue 75