| 摘要 |
<p>There is a method and disclosed apparatus for detecting for the presence within a gaseous atmosphere of a gas of a concentration above a preset level. The detecting apparatus comprises a sensor including a heater/anode element and a collector/cathode element disposed to define a space therebetween through which the gaseous atmosphere flows. An actuable power supply is coupled to the heater/anode element and to the collector/cathode element for applying power thereto, whereby ionization of the gas causes a current flow through the collector/cathode element of a magnitude proportional to the concentration level of the gas in the gaseous atmosphere. An actuable alarm means provides an indication of the presence of the gas above the preset level. Detecting apparatus control operates the detecting apparatus in a monitoring mode, wherein the power supply is actuated and the alarm deactuated to detect and compare the current flow with the preset level. Upon first detecting current which is equal to or exceeds the preset level, the control operates the detecting apparatus in a leak wait mode, wherein the power supply is actuated and the alarm deactuated to initiate the timing of a period while comparing throughout the period detected current flow with the preset level. If the detected current flow remains equal to or greater than the preset level until the period times out, the control operates the detecting apparatus in an alarm mode, wherein the power supply is deactuated and the alarm is actuated. <IMAGE></p> |
