The accurate measurement and control of viscosity is absolutely critical in many processes as it determines the product’s characteristics and quality, and can optimise input material costs. Two common ways to measure viscosity are lab measurement and in situ or inline measurement. With the lab method, the process has to be interrupted while the sample is being taken and since viscosity can be influenced by factors like temperature and time, there is always some difficulty relating lab results to the actual process conditions. The lab never shows the same values as a direct-in-process or in situ measurement. In situ measurements, although more accurate historically, require rotational instruments to be placed in the process and are thus difficult to install, maintain and clean.
For Bendotti, the first step in the production is coating potato wedges with batter – the quality of which is assessed by its viscosity. If the water/flour mixture is too thin, the batter does not adhere; if it is too thick, the potato wedges are unsuitable for consumption. Bendotti typically measured the batter viscosity in the lab and would discard an entire batch if they were unable to achieve the required batter quality.
The company recently approached Endress+Hauser who supplied an inline viscosity-measuring solution based on its Promass 83I Coriolis mass flowmeter. At the Bendotti plant, the flour mix and water are blended in a large storage vessel with an agitator at the top and a take-off line at the bottom connected to a mixing pump. Endress+Hauser fitted the Promass 83I into the return line and also installed a valve to ensure constant back pressure in the pipe. After passing the flowmeter, the batter is fed back into the top of the mixing vessel. The Promass 83I continuously measures the viscosity and is used to control the addition of extra flour or water to achieve the desired viscosity, thereby eliminating the cost of discarding bad batches of batter.
Bendotti are also able to control the mass flow and the temperature with this device because the Promass 83I is a multivariable meter that independently measures massflow, temperature, density and viscosity. Because of the Promass 83I’s real-time measurement, Bendotti has also been able to speed up their production process since there are no longer delays in processing the lab results.
As the Promass 83I is a straight single-tube Coriolis system, Bendotti simply had to install a longer piece of pipe into their existing equipment, leaving the rest of the assembly and even the cleaning process, unchanged. The patented torsion mode balancing (TMB) design makes the system immune to typical external plant influences such as pipework vibrations.
Endress+Hauser’s Promass 83I is suited to a range of applications requiring minimal shear stress to the fluid and low pressure loss. With its 3A and EHEDG certification, the flowmeter is ideally suited for the food processing industry as well as in plants processing cosmetics, pharmaceuticals, paints, solvents and liquefied gases.