Need for Optical Isolation in a Chemical Pigment 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.

For more information return to the Complete Industrial Digital I/O and Timing Tutorial

Need for Optical Isolation in a Chemical Pigment Mixing Application

Chemical pigment mixing is a process that mixes inorganic chemicals for pigments and dyes. A chemical flow pump and a hydraulic control valve regulate the rate of flow for the two chemicals that are used. The pump and valve each have their own ground reference, and the pump is connected to an emergency stop switch that has the same ground reference. Furthermore, the two ground references differ by 5V.

In the absence of isolation, all three devices must be directly connected to one another at the ground reference, causing a ground loop due to the voltage differences.




Isolation physically and electrically separates two parts of a circuit. This breaks ground loops, improves common-mode voltage and noise rejection, and permits the two parts of the circuit to be at different voltage levels. Many industrial applications such as these require isolation to protect the electronics from transient voltage spikes and provide greater common mode noise rejection in electrically noisy environments containing machinery and inductive loads.

Recommended Products that Feature Optical Isolation

NI 6514
NI 6515
NI 6528
NI 6624

Learn More About Optical Isolation

The Industrial Feature Set: Optical Isolation

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