Abstract: The present invention relates to a process and system for continuously monitoring and calculating the flow rate of a fluid medium in a flow line. The system includes a camera for viewing and capturing an image of a chart having different colored trace lines representing manometric pressure upstream of an orifice in a plate in the flow line and differential pressure across the orifice plate, a color filter for creating a modified image of the chart, an electronic digitizer for digitizing the images, and a microprocessor for determining the fluid flow rate from the captured and/or modified images. The system also includes monitors for displaying any of the iamges and manually operated devices for editing the images and for providing the microprocessor with instructions.