This unit uses a high stability Electro-chemical sensor with built in temperature compensation and a programmable display for controlling the concentration of oxygen in an enclosed compartment. Day to day calibration is carried out from the display panel. All the calibration and alarm parameters are retained in non volatile memory. Principle of Operation Oxygen concentration is sensed and displayed on the controller, a programmable set point is used to select the required Oxygen level. If the Oxygen concentration sensed by the fuel cell is below the control set point value, the controller will operate the solenoid valve for a user defined time period in the range 0 to 255 seconds. After the injection period the solenoid valve will close for a further user defined time period in the range 0 to 255 seconds, to allow for mixing. If the Oxygen level is still below the control set point the cycle repeats until the required Oxygen is reached. Specifications Operating Principles : Electro-chemical Range : 0 to 100% Oxygen Accuracy : 1% of Full Scale Response Time : 90% in 12 Seconds Relay Output : 8 Amp change-over relay Warranty : 12 months ( sensor 9 months ) Power Requirements : 110, 220 VAC or 24 VDC 6 W Optional Extras : O2 Clean, Solenoid valve Dimensions Height = 128 mm Width = 106 mm Depth = 218 mm