Order of work realization

Beforehand wash with petrol and place the preheated crucible 1 in a sand bath 2 so that the level of sand is the same height as the level of fuel in the crucible. Then reinforce the tripod foot 4 with thermometer 3 at such a height that the mercury bulb of the thermometer is placed in the middle between the bottom of the crucible and the liquid level. When testing a flash of liquid fuel up to 210 °C, the liquid level must be at a distance of 12 mm from the edge of the crucible.

Turn on the electric heating sand bath. Initially, the speed product temperature of 10 °C/min, and then 40 °C to the expected temperature of the flash 4 °C/min. Over 10 °C before the outbreak of expected temperatures begin every 2 second to test the flash, spending on the edge parallel to the surface of the crucible fuel the flames of incendiary device. This makes two turnovers: one clockwise, the other – against. The duration of the test shall be no more than 2 – 3. The moment of the appearance of the flash of blue flame liquid fuel, usually accompanied by a slight explosion, in which noted the appearance and run fast disappearing blue flame. For flash point thermometer indication should be taken at the time of the outbreak. Allowable discrepancy between two parallel definitions for liquid fuel with a flash point above 150 °C is in the range of 6 °C.

The temperature of the liquid fuel ignition is determined after the establishment of the flash point. For this purpose, the liquid fuel heating continued at 4 °C/min. Every 2 °C temperature rise fire incendiary devices carried horizontally above the surface of the crucible. The temperature at which the liquid fuel is ignited and remains lit for at least 5 seconds, is the ignition temperature. After the fuel ignition weakens the foot tripod and the crucible is removed from the thermometer. The crucible is covered with a lid to stop the access of air.

Permissible divergence between the two definitions, the ignition temperature is 6 °C. After determining the ignition temperature of the sand bath was stopped heating. By reducing the temperature of the liquid fuel in the 40 °C heat renew the sand bath and the test is conducted for the second time.

Processing of results

Flash point and ignition of the liquid fuel is determined with an accuracy of 1 °C using a thermometer. Air pressure in the experimental conditions measures according to the barometer.

Calculate flash point under normal pressure t₇₆₀ by the empirical formula (9.1). Data should be recorded in the table (Table. 9.1).

Determine the difference between the obtained characteristics of the liquid fuel.

Table 9.1

The experimental values ​​of the flash point and ignition

Methods of assessment of fire and explosive objects

There are two methods of evaluation of fire and explosive objects – deterministic and probabilistic. The deterministic natures are the following regulations: «All-Russian technological design standards» (ONTP) and «Rules of electrical devices» (PUE). The probabilistic method is based on the concept of acceptable risk and provides for the prevention of human exposure to PCE exceeding regulatory certainty. Normative document based on a probabilistic approach is GOST 12.1.004-91 «Occupational safety standards system. Fire safety. General requirements».

ONTP establish a methodology and procedure for determining the categories of premises and buildings of industrial and warehouse premises on the explosion and fire hazard. Depending on the category of appointed regulatory requirements for planning and building, number of floors, the choice of building designs and construction equipment. Categories of facilities (Table 9.2) are set depending on the state of aggregation of flammable substances and the flash point in the event of a possible cross-strait flammable liquids and combustible liquids. A quantitative measure of categorization is the maximum possible excess pressure ΔР, developed by the combustion of an explosive atmosphere of the room.

Table 9.2