INSTRUMENTS IN THE REFRIGERATION AND AIR-CONDITIONING INDUSTRY ARE WIDELY USED, AND TEMPERATURE, PRESSURE, LIQUID LEVEL, FLOW, ETC. NEED TO BE MEASURED AND CONTROLLED. FOR EXAMPLE, THE LIQUID LEVEL INSTRUMENT CAN BE USED TO DETECT THE POSITION OF THE COLD COAL IN THE EVAPORATOR OR CONDENSER OF THE CENTRAL AIR-CONDITIONING UNIT, AND IT CAN ALSO DETECT THE HEIGHT OF THE COLD COAL IN THE ACCUMULATOR OF THE BARREL PUMP UNIT.

THE QUALITY OF THE INDOOR ENVIRONMENT HAS IMPORTANT IMPLICATIONS FOR OUR HEALTH. GOOD AIR QUALITY AND A COMFORTABLE INDOOR TEMPERATURE ARE CRITICAL. NOT ONLY THE TEMPERATURE MEASUREMENT OF HEATING SYSTEMS, BUT ALSO THE APPLICATION OF HOT WATER, VENTILATION AND AIR VENTILATION.