The ultrasonic level transducer and transmitter technology uses an acoustic pulse that is emitted from a transducer towards the liquid surface to be measured. This acoustic pulse is reflected back towards the transducer and the time taken for the pulse to return is measured by microprocessor-based electronic circuitry. Varying liquid levels produce different return (reflection) times for which the acoustic pulse travels; consequently a continuous electrical signal of varying magnitudes is produced by the transducer and fed to a transmitter.

The transmitter’s microprocessor mathematically evaluates the signal and transposes it into an analog signal that is readable and quantified over a range which is predetermined and proportional to the minimum and maximum surface levels of the liquid being measured.

This analog signal is commonly produced in the form of an electrical current in the range of four to 20 mA where the current of four mA represents the minimum liquid level and 20 mA represents that of the maximum liquid level.

The ultrasonic level transmitter shall produce a four to 20 mA analog signal for the purpose of pump control and alarm functions.

Instrumentation components for the sensing and monitoring of the flow and wetwell levels shall be: