Fluid formulations across a spectrum of industries, from delicate biological cultures to complex paint emulsions, share a common vulnerability: sensitivity to mechanical stress, known as shear. When these sensitive liquids are subjected to excessive agitation or turbulence during pumping, their intricate structures can degrade, leading to compromised product quality, reduced efficacy, and significant financial loss. This fundamental challenge in fluid transfer necessitates a pumping solution engineered for gentle handling, preserving the integrity and value of these often high-value materials.

Ovell Pump recognises this critical need, offering diaphragm pump technology specifically designed to address the complexities of pumping shear-sensitive fluids. Our expertise as diaphragm pump manufacturers focuses on delivering solutions that maintain product quality, ensuring that delicate formulations reach their destination without degradation.

Understanding Shear Sensitivity: What it is and Why it Matters

Shear sensitivity refers to a fluid's susceptibility to damage when exposed to mechanical forces that cause layers of the fluid to slide past each other at different velocities. This phenomenon is often generated by high-speed rotating parts, sharp turns in flow paths, or turbulent mixing within a pump. The impact on the fluid varies greatly depending on its nature:

• ‍Polymers and Resins: High shear can break long molecular chains, reducing viscosity, altering rheological properties, and compromising the final product's strength or performance.
• Emulsions and Suspensions: Shear can destabilise these mixtures, causing droplets to coalesce or particles to settle out, leading to separation, reduced shelf life, and inconsistent product appearance. Examples include lotions, creams, sauces, and certain paints.
• Biological Fluids (e.g., Cell Cultures, Proteins, Enzymes): Delicate cell membranes can rupture, and complex protein structures can denature or aggregate under high shear, rendering biological products inactive or useless.
• Food Products with Particulates: Fruit pulps, yoghurts with fruit pieces, or delicate vegetable purees can be bruised, crushed, or homogenised undesirably, affecting texture, appearance, and taste.‍
• Paints and Coatings: Shear can break down pigment dispersion, affecting colour consistency, gloss, and application properties. It can also damage the rheological additives that give paint its desired flow characteristics.

The consequences of shear damage are far-reaching. They can lead to off-specification products, increased waste, costly re-processing, and, ultimately, damage to a brand's reputation. Preserving product integrity is not just about efficiency; it's about value and consistency.

How Conventional Pumps Can Compromise Sensitive Formulations

Many common industrial pump types, while excellent for robust fluids, are inherently unsuitable for shear-sensitive applications:

• ‍Centrifugal Pumps: These rely on high-speed impellers to impart kinetic energy to the fluid. This high rotational velocity creates intense shear forces, making them particularly damaging to delicate fluids. Their turbulent flow patterns further contribute to product degradation.
• Gear Pumps: While positive displacement, the meshing gears can pinch and shear fluids, especially those with particulates or high viscosity, leading to particle degradation or emulsion breakdown.
• Rotary Lobe Pumps: Though generally gentler than gear pumps, they still involve rotating elements that can cause some shear, particularly with very fragile materials.

These pump types, by their very design, prioritise high flow rates and pressure generation through mechanisms that are inherently aggressive towards fluid structure.

Gentle Positive Displacement

Ovell air operated double diaphragm pump technology stands out as the ideal solution for protecting shear-sensitive formulations. The fundamental operating principle of these diaphragm pumps inherently minimises shear, making them a preferred choice for industries where product integrity is paramount.

An air operated diaphragm pump operates by air pressure alternating between two opposing chambers, moving two flexible diaphragms back and forth. This creates a positive displacement action, drawing fluid into one chamber while expelling it from the other. Crucially, the fluid is displaced by the movement of the diaphragm, not by high-speed impellers or tight-tolerance rotating parts that generate shear.

Key Design Features that Minimise Shear

• ‍No Rotating Parts in the Fluid Path: Unlike centrifugal or rotary pumps, Ovell AODD pumps do not have impellers, rotors, or gears in contact with the fluid. The only moving parts are the diaphragms and valve balls, which move linearly. This eliminates the primary source of high-shear forces.
• Smooth, Laminar Flow: The gentle, reciprocating action creates a relatively smooth, linear flow through the pump. While there is an inherent pulsation, this can be further mitigated with the addition of an Ovell pulsation dampener on the discharge side, producing a nearly continuous, laminar flow that is exceptionally gentle on the fluid. This contrasts sharply with the turbulent flow often found in centrifugal pumps.
• Variable Flow Control: The flow rate of an air diaphragm pump is easily controlled by simply adjusting the air supply pressure and volume. This allows operators to run the pump at slower speeds when handling extremely fragile fluids, further reducing any potential shear. This fine-tuning capability helps optimise the pumping process for maximum product preservation.
• Sealless Design: The diaphragms act as a complete barrier, isolating the fluid from the air motor. This sealless design eliminates the need for dynamic seals that can leak, trap solids, or create localised shear points. It also prevents contamination of the product.
• Ability to Handle Solids Gently: Even when working with shear-sensitive fluids that contain delicate particulates (e.g., fruit pieces in yoghurt), the large, unobstructed flow path and gentle valving action of a double diaphragm pump ensure that solids are transferred without crushing or degrading their structure.

While electric diaphragm pump options also exist and offer precision for dosing, the inherent non-electrical nature and robust design of the air operated double diaphragm pump make it exceptionally versatile and safe for a wide array of demanding, shear-sensitive applications, especially in hazardous environments. A diaphragm vacuum pump, while not directly for transfer, also relies on diaphragm technology for precise, gentle vacuum creation, underscoring the versatility of diaphragm mechanics.

Critical Applications Benefiting from Ovell's Low-Shear Pumping

The ability of Ovell's diaphragm pumps to minimise product shear makes them indispensable across various industries:

Food and Beverage Industry

Dairy Products: Yoghurt, sour cream, soft cheeses, and custards. Shear can break down their texture and consistency.

Fruit and Vegetable Processing: Purees, concentrates, and products with whole fruit pieces are preserved in their natural state.

Sauces and Dressings: Emulsions like mayonnaise and salad dressings maintain their stability and texture.

Breweries: Handling yeast slurries or craft beer without introducing unwanted shear that affects fermentation or flavour profiles.

Confectionery: Transferring delicate syrups or chocolate coatings without altering their rheology.

Pharmaceutical and Biotechnology

Cell Cultures: Protecting delicate mammalian or microbial cells during transfer, crucial for vaccine production or biopharmaceutical manufacturing.

Enzymes and Proteins: Preventing denaturation or aggregation of sensitive biological molecules.

Blood and Plasma Products: Gentle handling to preserve the integrity of blood components.

Active Pharmaceutical Ingredients (APIs): Transferring slurries or solutions containing valuable APIs without compromising their molecular structure.

‍Paints, Coatings, and Inks

Water-Based Paints: Preventing pigment flocculation and maintaining emulsion stability.

Specialised Coatings: Ensuring uniform particle dispersion and consistent application properties for high-performance coatings.

Inks: Preserving the integrity of pigment suspensions to maintain colour saturation and print quality.

Cosmetics and Personal Care

Lotions, Creams, and Gels: Maintaining the emulsion stability and desired texture of cosmetic products.

Shampoos and Conditioners: Preserving the integrity of surfactants and conditioning agents.

Chemical Industry

Polymers and Resins: Transferring polymers in solution or as emulsions where shear can cause molecular degradation or irreversible changes in viscosity.

Catalysts: Handling delicate catalyst slurries without damaging their surface area or structure.

Adhesives: Maintaining the precise rheological properties of adhesive formulations. For highly corrosive chemical media, a specialised chemical diaphragm pump would be selected from Ovell’s range to ensure material compatibility while providing gentle transfer.

Material Selection: Tailoring the Pump to the Fluid

Beyond the inherent low-shear design, the choice of wetted materials is paramount for diaphragm pump longevity and product purity, especially with sensitive or high-value formulations. As dedicated diaphragm pump manufacturers, Ovell offers a broad spectrum of material options for casings, diaphragms, valve balls, and seats:

• ‍FDA-Compliant Materials: For food, beverage, and pharmaceutical applications, materials like polished stainless steel, PTFE, and certain elastomers are chosen for their non-leaching properties and ease of cleaning, meeting strict sanitary standards.‍
• Chemical Compatibility: For chemical diaphragm pump applications, materials such as polypropylene, PVDF, and PTFE diaphragms are selected to resist aggressive acids, bases, or solvents, preventing pump degradation and product contamination.‍
• Abrasion Resistance: Even in shear-sensitive applications, some fluids might contain mild abrasives. Santoprene or specific polyurethane materials for diaphragms, and hardened valve balls, offer a balance of gentleness and wear resistance.

This meticulous approach ensures that the chosen Ovell diaphragm pump not only handles the fluid gently but also remains durable and uncontaminated by chemical attack or wear.

Optimising the System for Delicate Fluids

While the Ovell double diaphragm pump is a cornerstone for shear-sensitive applications, optimising the broader pumping system can further enhance product integrity:

• ‍Pulsation Dampeners: Integrating an Ovell pulsation dampener on the discharge line significantly reduces pressure fluctuations, creating an even smoother, almost laminar flow. This is critical for preventing agitation and maintaining product uniformity, especially in continuous processes or those requiring precise dosing.‍
• Correct Pipe Sizing and Routing: Minimising sharp bends, sudden diameter changes, and excessive pipe lengths helps reduce overall system friction and turbulence, further protecting the fluid from shear.‍
• Flow Rate Control: Utilising the variable flow capabilities of air operated diaphragm pump by adjusting air pressure allows for precise control of the shear rate experienced by the fluid. Slower pumping speeds inherently mean lower shear.

Conclusion

Protecting the integrity of shear-sensitive fluids is a non-negotiable requirement in many industrial processes. The inherent design limitations of conventional pumps often lead to product degradation, impacting quality, increasing waste, and eroding profitability. Ovell's air operated double diaphragm pump technology provides a robust and elegant solution to this challenge.

By offering a uniquely gentle, low-shear, positive displacement action, combined with versatile material options and precise control, Ovell diaphragm pumps are ideally suited for transferring delicate polymers, fragile biological fluids, sensitive emulsions, and particulate-laden food products without compromising their structural or functional properties. As dedicated diaphragm pump manufacturers, Ovell empowers industries to preserve product quality, optimise processes, and ultimately enhance the value of their sensitive formulations. Choosing the right diaphragm pump from Ovell is an investment in product integrity and operational excellence.

‍