Fiber optic-based hazardous environmental flowmeter

A flowmeter system that is part of a purge and pressurization system associated with a painting robot that purges hazardous gases from the robot before robot operation and maintains positive pressure within the robot during operation of the robot, said flowmeter system comprising:

• a flowmeter including a body having a flow input end and a flow output end and defining a flow channel therebetween and a recess in fluid communication with the channel, a paddle wheel positioned in the recess and extending into the channel and being rotatable on a shaft in response to gas flow through the flow channel, a check valve positioned in the flow channel proximate the output end of the body, said check valve allowing gas flow through the flow channel from the input end to the output end and preventing gas flow through the flow channel from the output end to the input end, and a gas flow conditioner mounted to the input end of the body, said gas flow conditioner including a plurality of holes through which the gas flows and into the flow channel so as to reduce turbulence in the gas flow, said flowmeter being located in the robot;
• an optical input cable coupled to the body proximate the recess;
• an optical output cable coupled to the body proximate the recess;
• and
• processing electronics including an optical source providing a light beam on the optical input cable that crosses the recess and is received by the optical output cable, said processing electronics further including a light detector that receives the light beam from the optical output cable, wherein the light beam is intermittently interrupted by the paddle wheel as the paddle wheel rotates so that the light beam on the optical output cable is a pulsed light beam, and wherein the processing electronics converts the pulsed light beam to a rotational speed of the paddle wheel that is converted to a gas flow rate through the flow channel, said processing electronics being located outside of the robot in a non-hazardous environment.