This consistency monitor is primarily designed to reliably measure
massecuite consistency in sugar vacuum pans. It provides a continuous indication
of this important variable in pan operation over all ranges encountered in high- or low-grade
sugar boiling.
In addition to pan consistency measurement, this instrument's narrow viscosity range makes it useful in measuring concentration in sugar melters, evaporator syrups and molasses dilution tanks. In industries other than sugar where consistency is an important variable, this instrument monitors the concentration of evaporated whey, distillery slops, fruit and vegetables or tomato products.
This consistency monitor is a convenient guide for experienced operators and an invaluable tool for training new sugar boilers. The zero and span adjustments expand readability in critical viscosity or consistency ranges. The monitor has a standard electrical output signal of 4-20mA (other outputs are available).
The most suitable consistency to carry varies with pan design. Many sugar boilers tend to maintain excessively "tight" massecuites to the detriment of pan circulation. This can be counteracted by experiment on a particular pan. Boilers can then be instructed to hold the consistency at the most suitable value. Likewise, an optimum dropping consistency that produces high crystal yield without unduly long discharging time can be pinpointed. In addition to pan consistency measurement, the instrument's narrow viscosity range makes it useful in measuring concentration in sugar melters, evaporator syrups, molasses dilution tanks and even slurries such as milk of lime where density is a troublesome measurement and can introduce serious time lags into control loops.
The measuring element consists of a stainless steel probe which is installed below the pan heating surface terminating in a small propeller-type rotor driven by a DC motor. Increasing viscosity of pan contents raises the torque on the rotating element and lowers its speed, causing an increase in motor armature current which is measured by the monitor.
The 0-100 scale can be set to cover one or several decades of viscosity by means of the span and zero adjustments. For sugar pans, the zero is normally set with the probe running in syrup of the lowest concentration of interest, say 60 Brix (6-8 centipoise), and the span set to read 100 with the motor stalled (infinite viscosity). When boiling relatively high purity strikes, the reading will be around 35% with the massecuite well "pulled together" to a 15 or 20% crystal yield and will rise to 85 or 90% during final concentration to dropping consistency. Mid-scale will be about 450 cp.
For more details, please download the appropriate installation manual: