The OFS-2000W model is equipped with Automatic Gain Control (AGC) to compensate for variations in opacity caused by particulate matter or moisture carried in the flow.

OSi's patented Optical Flow Sensor (OFS) makes drift-free measurements across the entire stack, duct or pipe diameter and calculates a true average flow reading. The OFS 2000-W model is equipped with Automatic Gain Control (AGC) to compensate for variations in opacity caused by particulate matter or moisture carried in the stack flow. The OFS uses our EPA Method 14 approved optical scintillation technology. The optical scintillation technique relies on advanced Digital Signal Processing (DSP) electronics to "see" and measure the movement of turbulence found in a gaseous flow stream to provide highly accurate, path-averaged air velocity measurements. The accuracy of the OFS has been proven both in the NIST wind tunnel, and time after time in real-world applications.

The OFS consists of DSP/multiprocessor - based control unit teamed with a set of optical transmit and receive heads which are easily installed on opposite sides of a stack, duct, vent or pipe. The OFS heads mount fully outside of the media volume behind optical windows for easy access, more accurate measurements, and greater durability. The transmit head sends a visible diverging light beam (easy to align and vibration resistant) directly across and perpendicular to the flow (although existing angled-path port can be used). The control unit processes the fluctuations seen by the receive head and displays the flow data locally and transmits it to a PC, PLC, DAS or other data collection device that accepts a serial data link and/or a 4-20 mA current loop. The control unit can be configured from either the local keypad and display, or from a laptop or portable terminal.