Electronic circuit to limit overfilling of storage tank - provides intrinsically safe operation of electrically operated valve on tank inlet

摘要

An intrinsically safe electronic circuit is used to overcome difficulties of mechanical or hydraulic systems which limit the refilling of liquid storage tanks to prevent overflowing. A storage tank (0) is filled through an electrovalve (8) to the level of a probe (1) which is connected to a signalling lamp (3) and electronic control circuit (5). A second probe (2) with signalling lamp (4) is also connected to the electronic circuit and enables the pipework to be emptied into the tank. The electronic circuit is driven from 24 volts (13) obtained (10-12) from the mains supply (9) and contains a failsafe circuit to close the valve when power fails or when a fault occurs at the probe.