Abstract: 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.

Abstract: There is disclosed a method and apparatus for repetitively taking samples of a predetermined quantity of a test gas in a liquid and introducing these samples to a test chamber. Each sample is agitated to release therefrom the test gas. The released gas is then conveyed to a sensor, which monitors the released gas for the presence of a concentration above the threshold level to produce an alarm indicative thereof. The samples of the test gas in a liquid may be repetitively taken from one zone of a plurality at a time until each zone is sampled. After one sample has been tested in the test chamber, it is discharged therefrom and the test chamber is flushed with a sample of the liquid and test gas taken from the next zone of the plurality before introducing the next sample from the same, next zone.