Measurement of ignition characteristics of distillate fuels

Apparatus for measuring the ignition delay of distillate fuel comprising:

• a block having an ignition cavity;
• means for heating said block to an elevated temperature above the ignition temperature of said fuel so that the temperature in said cavity is substantially uniformly the same temperature as said block;
• means for injecting samples of said fuel into said ignition cavity as said block cools from said elevated temperature;
• means for measuring the pressure in said cavity;
• means for measuring the temperature in said cavity;
• a digital computer having:
• means for controlling the time of injection of said samples;
• said pressure and temperature measuring means being connected to said digital computer:
• means in said digital computer for measuring ignition delay as the time between the injection of a sample and ignition as indicated by a peak in measured cavity pressure or temperature;
• means for recording said ignition delay as a function of the cavity temperature when ignition occurred;
• and
• solenoid valves actuated by said digital computer for flushing and exhausting said cavity, said valves being closed during injection and ignition of a sample and thereafter being opened to flush said cavity before injection of another sample.