ONICON Incorporated Unsurpassed Performance . . . Sensibly Priced! Established in 1988, ONICON is a leading manufacturer of high quality water flow meters, steam flow meters and BTU meters. Every ONICON product is wet calibrated against internationally recognized standards and custom-configured for its specific application. This attention to detail and commitment to service ensures that every flow and BTU meter will provide maximum accuracy and performance, even in difficult flow conditions.