Liquid Level Indicator Model PLI-1

The Liquid Level Indicator PLI-1 ultrasonically detects the level of the Liquid to Vapor interface in pressurized cylinders, such as with CO2, Halon, etc.). The instrument operates on the principle that an ultrasound pulse responds differently to the presence or absence of liquid. The PLI-1 generates a sound pulse transmitted by the magnetic based sensor that travels through the steel cylinder wall and into the liquefied gas. It interprets the changes in the echoes that occur as the sound beam responds to the different characteristic impedance of the liquid and the gas or air above the liquid level. The change in response is indicated by the deflection of the meter pointer. The setup procedure for the instrument insures maximum deflection of the meter at the gas/liquid interface, thus making possible a reliable determination of the liquid level.