Sulfur dioxide (SO2) is irritating to eyes, skin and respiratory system. Volcanic Smog (vog) is produced from SO2 gas and is a hazard in Hawaii. Scientists monitor SO2 emission rates at KÄ«lauea volcano. Gas Plume during the 1984 eruption of Mauna Loa, Hawaii blocks out the sun.
Control Unit (CU) A control unit (CU) handles all processor control signals. It directs all input and output flow, fetches code for instructions from microprograms and directs other units and models by providing control and timing signals.
Control Valves. A combination of a valve and an actuator is usually referred to as a control valve. The system which provides automatic control of flow consists of a valve, a valve actuator, and a sensing device. Two types of controllers and actuators commonly used in irrigation are electric and hydraulic. Globe and angle valves are commonly adapted for automatic control due to the tight shutoff of these valves.