Agitators or stirrers come in a vast array of shapes and sizes, including marine propellers, foils, axial and radial flow turbines, gate and anchor stirrer/scrapers, etc. These different types of impeller blades characterise the flow produced and allow agitators to be used for the broadest range of viscosities and batch sizes. If the viscosity is relatively low (for instance, 1 cP or less) these devices can handle batches up to several hundred thousand gallons. As for the viscosity range that can be accommodated, turbine type agitators can operate with fluids of up to 75,000 cP. Slow-speed gate or anchor and gate configurations can handle up to 500,000 cP.
Despite the wide range of capacities and viscosities they can handle, the low shear nature of agitators limits their effectiveness to performing simple tasks such as blending liquids of like viscosities, maintaining in-tank uniformity, and producing flow in a vessel to promote heat transfer from jacketed vessel walls. Where the product has to be processed in some way – liquids of differing viscosities are being blended, powders dispersed and hydrated, an emulsion or suspension formed, solids dissolved or disintegrated and so on, an agitator can take a long time to achieve the required results or, more often than not, is simply not capable. Silverson High Shear Rotor/Stator mixers are ideal for these types of applications and can cut mixing times by up to 90%, offering improved yield and product quality and greater batch-to-batch consistency.
These advantages are further increased by the use of easily interchangeable workheads and screens which allow any one Silverson mixer to perform the duties that in the past may have required several different pieces of process equipment.