Filled level of vessels monitored by radiation pulses - through period defined by fall and rise of received signal caused by presence of vessel

摘要

Liq. level in vessels as they pass between a radioactive source emitting a low-dose beam and a receiver is monitored by summating the pulses received within a specific period and comparing the integrated total with a predetermined threshold value. The measurement period is defined from the graph of the pulse rate plotted against time as the vessel passes. Pref. the measurement period is defined as the time interval between two instants at which the pulse rate corresponds to a predetermined fraction of the pulse rate when no vessel is present. More specifically, a reduced time interval may be used, which elapses between those instants which lie between the first two time instants and are at a specific instant from them. The threshold levels may be of equal size and the time differences used for defining the reduced interval may also be of equal value. No separate of photoelectric cell or other device of notifying the presence of the vessel is required; the triggering of the measurement is a function of the direct presence of the vessel a as read by the pulses.