Inventors:
Robert E. Johnson - Pembroke MA
Assignee:
Pyrotector, Inc. - Hingham MA
International Classification:
G08B 1710
Abstract:
An ionization detector of the type having a housing with electrodes and a radiation source for causing ion current flow between the electrodes, collector means for detecting, by a change in voltage, a drop in ion current flow, and means responsive to a predetermined change in collector voltage to provide an output signal, in which a test electrode is provided in the housing and means is provided for applying to the test electrode a predetermined voltage of a value that causes said predetermined change in voltage at the collector, whereby said output signal is provided when said predetermined voltage is applied to the test electrode if said detector is operating satisfactorily.