Continuous Liquid Level Indicator is achieved by using hermetically sealed magnetic reeds and fixed precision resistors arranged in a linear network. A continually variable resistance in incremental steps, is generated by using a magnetic float as a "wiper". The sensor operates much like a typical potentiometer. An excitation voltage is applied to the sensor and the variable signal, which represents liquid level, is used to drive a meter or transmitter.
Repetitive Accuracy to within ¼ of liquid level is constant throughout the length of the unit which is directly proportional to the depth of the tank. At any position the float may occupy, a sequential reed closing/opening pattern varies the resistance in the circuit. Because of the positioning of the reeds, a positive signal change occurs with every ¼ of liquid level movement.
Direct Contact Measurement eliminates the need for time consuming calibrations or adjustments which plague more complicated measurement devices. The simple operation of the potentiometer-type circuit operated by a positive acting float provides trouble free operation apart from completing calculations or interpretation circuitry. The float is in CONTACT with the liquid and level change is DIRECTLY read as a changing voltage.
|STANDARD MODELS (Up to 10' in Length)
|Stainless & Buna-N (shown above)|
|Stainless & Polyproylene (shown above)||
||National has constructed special sensors up to 18' in length with 8" diameter floats for various applications. Inquire for details|