2020-07-01
89
Increasing the pressure increases the flashpoint. The interrelation between a flash point at normal pressure and t760 and tp at different flashpoint barometric pressure ρ (mm of mercury) is expressed by the empirical formula
t 760 = tр+ 0,00012(760 –ρ)(273 + tр). (9.1)
A flash point determined according to standard procedures in both open and closed crucibles. The difference between the flash point, determined in open and closed, is 20... 60 °C. In closed crucibles vapors generated by heating the liquid fuel, are not removed to the surrounding space. The concentration of fuel vapor mixed with air at which the flare is achieved by heating a lower temperature than in open crucibles. At low temperature liquid fuels flash determine it’s normally closed, and at high - in open crucibles. The flash point of fuel oil of different brands should not be below 80 – 140 °C.
Description of laboratory installation
And flash ignition temperature is determined in the outdoor unit. An open-type device consists of the metal crucible diameter of 64 ± 1 mm, a height of 47 ± 1 mm and placed in a sand bath electric heating 2 (Fig. 9.1).
Fig. 9.1. Apparatus for determining the flash point and ignition of liquid fuel:
1 –metal crucible; 2 – steel sand bath with electric heating;
3 – thermometer; 4 – movable foot
3 is a thermometer for measuring the temperature of the liquid fuel, the upper end of which is fixed to the tripod by means of movable legs 4. The lower end of the thermometer is immersed in liquid fuel. Heating of a sand bath 2 is made with an electric heater, which turning on by two buttons on the instrument panel. Power of electric heating is selected by including the appropriate button 150 or 250 watts.
