Octane Test Engine combustion air is drawn through the intake air system from the room where the engine is installed. The intake air system incorporates intake air humidity refrigeration unit. It includes an electric heater, and piping to direct the conditioned air into the throat of the engine carburetor. Intake air temperature is measured by a thermometer installed in the inlet air pipe. The octane test engine uses a temperature sensor installed in the inlet piping to provide the input signal for a temperature controller.
The intake air humidity refrigeration system unit delivers air saturated at approximately 0℃, resulting in a moisture content of 0.00356 – 0.00712 kg of water per kg (25-50 grains of moisture) prescribed of dry air.
An intake air humidity refrigeration unit provides filtered combustion air that is dehumidified by passage of the air across a tube and fin cooling exchanger that has refrigerant circulating through the tubing.
Fill the coolant reservoir with 5000~5500ml of ethylene glycol. There will be an audible alarm when the coolant is not enough.
The chilling intake air temperature should be in the range of 0℃±3℃(0±37.4°F).
The cooling system hoses are connected with the fourth bowl of the octane test engines carburetor by the quick connections.
Standard Test Method for Research Octane Number of Spark-Ignition Engine Fuel (ASTM D2699) and Standard Test Method for Motor Octane Number of Spark-Ignition Engine Fuel (ASTM D2700), require specific intake air temperatures (I.A.T.), as follows:
Research Method：52℃±1℃(125°F+/- 2°F)at standard barometric pressure (760 mm Hg). At other barometric pressures, the specified I.A.T. is listed in ASTM D2699. And it is less than 52℃(125°F) for barometric pressures lower than the standard value and higher than 52℃(125°F) for barometric pressures higher than the standard value.
Motor Method：38℃±2.8℃ (100°F +/- 5°F)