The OCB350 Series is a fluid sensor with self-calibration circuitry that requires only an optical device and power supply for operation. Like the original OPB350 Series sensors, these devices use an LED/phototransistor to sense the change in refractive properties between full and empty tubing as it passes through the sensor housing, creating multiple output states such as "fluid present," "no fluid present," and "no tube present."
The presence of clear liquid causes the phototransistor to sink the maximum current, while the presence of dark liquid causes it to sink the minimum current. As bubbles pass through the tube, the signal will vary between the "liquid present" and "no liquid" states. If no tube is present, the phototransistor sinks current between the dark fluid and clear fluid states.
When the system calibrates the sensor, it raises the current through the LED from 0mA to 14mA, until the phototransistor reaches the preset point. Once calibrated, the setting will remain constant, allowing for faster start up.