Ultraviolet Transmission (UVT) is a relative measurement comparing how much light passes through a water sample vs a pure water sample at 254nm expressed at a 1cm path length. This measurement is used for UV control to allow energy savings by adjusting the output to match water quality and flow in real-time. This avoids over dosage and reduces overall operating cost without compromising disinfection performance.
For long-term, in-situ continuous monitoring of ultraviolet transmission, a self-cleaning UVT sensor is usually necessary to avoid fouling of the sensor and maintain accuracy. Xylem | WTW products use ultrasonic cleaning to extend deployments and include many advanced features such as real-time turbidity compensation to provide the best quality real-time measurement in difficult applications.