Fluorescence oil in water measurement technology uses ultraviolet and near ultraviolet light to cause the chemicals in various oils, fuels and heat transfer fluids to fluoresce. Fluorescence is the emission of light energy from molecules that are excited by the UV light. Fluorescence is a well known and understood measurement technology that is specific to oils and fuels or specific dyes and immune to interference from non-fluorescfluorescing material such as suspended solids. This allows very low detection limits in the very low parts per billion (ppb) range which means the earliest detection of hydrocarbon leaks into cooling water and steam systems. Early detection means less process or environmental damage. Fluorescence detects crude oil, fuel oil, lubricating oil, diesel, gasoline, heat transfer fluids, phenol, styrene, and BTEX and more.