An flow meter includes a coupler, a support member, an image sensor, and one or more processors. The coupler is adapted to couple to a drip chamber. The support member is operatively coupled to the coupler. The image sensor has a field of view and is operatively coupled to the support member. The image sensor is positioned to view the drip chamber within its field of view. The one or more processors are operatively coupled to the image sensor to receive data therefrom. The one or more processors (1) receive image data from the image sensor, and (2) determine an existence of a free flow condition by identifying an optical distortion of an area behind the free flow condition within the drip chamber using the received image data.