WHY IS SCALE UP FROM LAB TO PILOT SO DIFFICULT?
Lab mixing and small batch mixing can produce good results, simply because the vessel size is small. The BACH impeller uses the fluid to mix the fluid. It uses a pre whirl event, to start the vessel contents moving and once the fluid flow is setup, the internal velocity differentials and pressure differentials become constant. Sudden acceleration and deceleration zones are eliminated. Tip speed becomes an irrelevant variable, since you are only concerned with the speed at which the cell is moving around in relation to the fluid that is carrying it. Since the fluid itself is doing the mixing, these speeds become the same. The BACH impeller uses an internal, compound log spiral hub to compensate for material entering the impeller and preventing it from decelerating too fast. Scaling up the BACH impeller does NOT scale up shear. Period.
WHY ARE NANO PARTICLES SO HARD TO MIX?
They have almost no mass. No weight. They just don’t go where they are supposed to go under gravity, even when you shake them or stir them. Turbulence is very ineffective on materials of no mass. Keep them in a non chaotic fluid flow pattern and evenly distribute them with the BACH impeller.
WHAT IS SHEAR SENSITIVE?
When a force hits a liquid and the viscosity changes suddenly. Corn starch is a good example. Soap is another. Shear damage is a result of a shear stress that does not reverse. Shear can break polymer chains, damage organics and heat the fluid. Velocity changes represent a major cause of damage to cells. Uniform velocities, laminar flow, and simplified flow dynamics are the solution. Simply put, if your live cell is moving through your bioreactor and it is moving the same speed as the fluid it is suspended in, the shear caused by velocity differentials is dramatically reduced.
WHY NO BAFFLES?
The BACH impeller is a mixed flow (axial and radial) device that prevents swirling conditions and eliminates the need for mixing baffles in a tank. Bioreactors that have walls with ridges to prevent vortexing, are damaging cells as they suddenly decelerate and collide with them.
WHY LESS ENERGY?
Simple. The BACH impeller technology ,enables and creates a fluid flow structure that then mixes the fluid. The fluid mixes the fluid. This feature uses much less power; about half the power that would be consumed by a propeller.
WHY LESS CELL DAMAGE?
Any power that you put into a bioreactor is translated into mixing. The less power you put in, the less damage you cause. The more efficient you are at utilizing that energy to move material around, the less damage you cause.
HOW IS GAS TRANSFER IMPROVED IN GAS REACTORS?
The BACH impeller has a very low pressure differential mechanism that allows it to recirculate gas saturated liquid without stalling or flooding. The gas particles are treated as actual particles and kept in solution longer. Since the BACH impeller only has one mixing zone, there is a shorter time period for a gradient. The BACH impeller is 60 percent more efficient than a propeller, and since gas transfer is axiomatic with mixer efficiency, gas transfer is more efficient.
HOW CAN IT BE SO FAST?
The BACH impeller moves about 3.5 times more fluid in one rpm as a same diameter propeller. It uses a complex, helical inflow aided by a compound log spiral interface at the hub to allow a free flowing path for cells with little velocity disruption to create a vortex that pulls materials 30 times its diameter from the bottom of the tank, which brings more fluid to the mix zone. In water like materials we see 5x faster using half the shaft horsepower. Mixing is faster, but basically shear free.