Category: Mixer/Agitator

There are a number of factors that decide the type and size of the tank mixer to be used for a specific application. They range from the shape of the vessel to the volume to the viscosity of the media to be mixed. Ultimately though when all  factors are considered we will come to pick a mixer/ agitator that considers the shear sensitivity of the contents to be mixed and the pumping capacity.

Novaseptic Mixer / agitator - Magnetic drive

What is the benefit of a bottom mounted magnetic mixer?

The  bottom-mounted design means no mechanical lifting device is required. The risk of leakage is eliminated due to NovAseptic’s magnetic drive. Tank integrity is maintained as no shaft is led through the tank wall. Easy to clean and sterilize in place (CIP/SIP).

What is shear?

Shear seems like a simple enough concept to most people until they’re asked to define it. Related to liquids, shear is defined as relative motion between adjacent layers of a moving liquid. Some of the simplest examples include spreading butter on bread or applying sunscreen. In each case one level of the liquid (butter on the knife) is moving relative to the adjacent layer (butter on the bread). By also considering the velocity of this relative motion, we can calculate the shear rate. Shear rate is defined as the measure of the extent or rate of relative motion between adjacent layers of a moving liquid. Therefore: Shear Rate = Velocity / Distance.

Tank mixer / agitator

Shear sensitive liquids can behave very differently when sheared. Some require shear to get them to the ideal viscosity for transfer or application. Others can be temporarily or irrevocably damaged by shear. It’s important to discuss the liquid’s nature with the manufacturer or to have a rheology test performed to determine how the liquid behaves when sheared over time. As soon as the liquid enters the vessel and enters the suction piping, it begins to shear as the liquid travelling through the middle of the pipe moves in relation to the pipe walls. The pump imparts shear as well between the rotating pumping elements and the stationary casing. Calculating these shear rates is possible using the equation above and considering the flow rate, pipe diameters, pump rotational speed, and internal pump dimensions. Combined with the liquid’s rheology data, this can help to make an educated decision regarding mixer selection and sizing.

What is Pumping Capacity?

Pump capacity is a term used to describe the maximum flow rate through a pump/mixer at its designed conditions. It is a measurement usually given in gallons per minute (gpm) or cubic meters per hour (m3/h).

What does GMP mean?

GMP stands for Good Manufacturing Practice

What is the difference between Newtonian and Non-Newtonian Liquids?

Newtonian liquids are those that hold their viscosity regardless of shear rate. Consider stirring a glass of water; no matter how fast you stir, the water retains its viscosity. Conversely, non-Newtonian liquids change in viscosity depending on the shear rate. Paint for example is shear thinning, decreasing in viscosity as it is stirred. A corn starch and water mixture (sometimes referred to as oobleck) is shear thickening, literally allowing someone to run across the liquid’s surface, but sink in slowly if they remain stationary.

Call us in Ireland at +353 21 4510900 or UK at+44 1633 877505 or message us via our online form or web chat.

Let's Connect!

Get in touch with our dedicated team. We are here to help!