Using a Torque Sensor in a Chemical Mixing Application

This document is part of a comprehensive tutorial on industrial Digital I/O and Counter/Timer hardware. Learn about National Instruments product offerings for digital and timing I/O, the Industrial Feature Set including watchdog timers and isolation, complementary devices like relays, solenoids and encoders, concepts like sinking and sourcing, and see how these devices can be used in your industrial application.

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Using a Torque Sensor in a Chemical Mixing Application

Mixing is an essential operation for engineers and scientists in most chemical process industries. In order to convert the raw materials into a finished product, various ingredients must be properly combined at some point in a manufacturing process. A large mixing tank is used to combine the substances. In order to assure proper mixing without over-mixing, the density and viscosity of the mixture must be measured and analyzed throughout the process.




The density of the final mixture can be calculated ahead of time and is related directly to the mixture’s viscosity. By measuring the torque of the mixer shaft, the viscosity of the mixture can be determined. As the mixture combines over time, the torque of the mixer shaft gradually changes. Using this simple measurement of the torque, an engineer or scientist can determine when a mixture is ready for the next stage of the manufacturing process.


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A chemical mixing system can implement a basic torque transducer, such as the S.I. Instruments Stamosens 0125 DF Torque Sensor, to properly analyze the mixture of the chemicals. The rotor of the torque sensor can be directly connected to the mixer shaft to provide a frequency output of the torque. The output frequency will be on the order of a 100 kHz square wave and can potentially have a 30 VDC, peak-to-peak value.

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