The flow monitors operate on the principle of the float type flow indicator. The float contains permanent magnets. The reed switch is contained in an adjustable switch housing external to the flow circuit. The flowing medium raises the float in the direction of flow. As soon as the float with its permanent magnets reaches the contact position, the reeds close together. As the flow increases, the float rises further i.e. the contact remains closed thus ensuring bistable switching. The top edge of the float serves to indicate the flowrate on the measuring glass scale.
The switch ranges given below refer to the limits within which the switch point may be infinitely adjusted. The actual flow throughput can, depending on the flow velocity, be much greater.
- wide switching ranges
- small switch hysteresis
- infinitely adjustable switch point
- high reliability
Hysteresis is the difference in flow between the switch closing and opening again. The difference is the result of the movement required by the float to reclose the open contact. The shorter the distance, the smaller the hysteresis and therefore the more accurate the instrument. By means of the careful choice of magnets and reed switches with especially close tolerances, hysteresis is kept to an absolute minimum. Low hysteresis is of great advantage where particular accuracy is demanded, especially in flow systems where only small increases in flow throughput above the necessary minimum can be achieved.
Monitoring of cooling circuits in welding machines, induction heating plants, transformers, compressors, heat exchangers and centrifuges. Monitoring of sealing media for seals and pump dry running, motor cooling systems etc.
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