Experiments for the determination of flash and fire points of flammable liquids

Objectives of the experiment 1. To master the definition of flash point and ignition point of flammable liquids and the reasons for the flash-over phenomenon of liquids; 2. To master the method of measuring the flash point and ignition point of flammable liquids with open cup and closed cup flash point tester. Experimental principle When the liquid temperature is relatively low, due to the low evaporation temperature and slow evaporation rate, the concentration of vapor molecules formed above the liquid surface is relatively small, which may be less than the lower explosion limit. At this time, the mixed gas formed by the vapor molecules and air cannot meet the fire source. ignited. With the continuous increase of temperature, the concentration of vapor molecules increases. When the concentration of vapor molecules increases to the lower limit of explosion, the mixed gas formed by saturated vapor of combustible liquid and air will be extinguished in a flash when it encounters a fire source. This kind of instantaneous combustion phenomenon that flashes and disappears is called flashover. Under the specified experimental conditions, the lowest temperature corresponding to the flashover of the liquid surface is called the flash point of the liquid. At the flash point temperature, the liquid can only flash but not sustain combustion. This is because at the flash point temperature, the evaporation rate of the flammable liquid is less than its combustion rate, and the vapor above the liquid surface burns out and the vapor cannot be replenished in time, causing the flame to extinguish itself. Continue to increase the temperature, and the vapor concentration above the liquid surface increases. When the mixture formed by vapor molecules and air encounters a fire source and can burn for no less than 5 seconds, the liquid is ignited at this time, and its corresponding temperature is called the temperature. The ignition point of the liquid. From the fire protection point of view, flashover is a warning of fire danger and a prelude to fire. By mastering the burning phenomenon of flash combustion, it is possible to prevent fires or reduce the harm caused by fires. Basic parts of experimental instruments: container for oil sample, heating and heating device, temperature control circuit, temperature measurement device, ignition source 1. Manual open cup flash point and ignition point tester: inner crucible, outer crucible, gas conduit, thermometer, electric furnace, The electrical device, windshield, etc., the structure diagram is shown in Figure 1. (1) The material of the inner crucible is 0.3 high-quality carbon structural steel, and the inner diameter of the upper mouth is 64±1mm, bottom inner diameter is 38±1mm, total height is 47±1mm, there is a scribe line at 12mm from the edge of the upper mouth and 18mm on the inner wall, and the surface is black-plated. (2) The material of the outer crucible is the same as that of the inner crucible, and the inner diameter of the upper mouth is 100±5mm, bottom inner diameter is 56±2mm, total height is 50±5mm, the surface is black plated. (3) The diameter of the gas duct nozzle is 0.8-1.0mm, and the surface of the inner hole is smooth, which can adjust the flame into a spherical flame with a diameter of 3-4mm, and the total height is 50±5mm. (4) The bracket is composed of a base, a vertical rod, an electric furnace holder, and a thermometer clip. The electric furnace holder, the thermometer clip and the fastening screws are fixed on the pillar, and the height can be adjusted up and down. The thermometer clip should ensure that the thermometer is located in the center of the inner hole of the electric furnace. . (5) The electric furnace part is composed of silicon carbide electric furnace plate, silicon carbide gasket, and 220V/800W heating wire. According to the requirements of use, the heating power is controlled by electrical devices. (6) The electrical device consists of a set of electronic voltage regulation circuits, indicator lights, toggle switches, transformers, precision multi-turn wire-wound resistors and AC ammeters. 2. Manual closed cup flash point and ignition point tester: oil cup, stirrer and oil cup cover, electric stove, slide plate, igniter, electrical device, thermometer, windshield, etc. The structure is shown in Figure 2. (1) The inner diameter of the standard oil cup is 50.8mm, the depth is 56mm, the oil test capacity is about 70mm, and the depth of the test oil capacity marking line is 34.2mm. (2) The aperture of the igniter is 0.8mm. (3) The electric heating device is composed of a voltage regulating thyristor and a 600W electric heating wire, and the heating rate of the test oil is in the range of 1 to 12 °C/min. (4) The electric stirring device is composed of a constant speed motor and a stirring blade, and the size of the stirring blade is 8×40mm, the transmission mode is flexible shaft transmission, and the stirring speed is 105r/min. 3. Semi-automatic open cup flash point and fire point tester: Cleveland oil cup, igniter, electric stove, thermometer, temperature sensor, microcomputer control panel, control keyboard, display, windshield, etc. Experimental drug 1. Kerosene 2. Diesel Experiment content and method Basic steps: sample loading→placed on the stove→Install a thermometer→Heating and heating (as specified)→ignition test→Recording data 1. Manual open cup flash point tester (1) Put the inner crucible into the outer crucible containing the spun yarn, make the surface of the spun yarn about 12mm from the edge of the mouth of the inner crucible, and make the bottom of the inner crucible and the bottom of the outer crucible close to each other. A sand layer with a thickness of 5-8mm is maintained between. (2) Pour the sample into the inner crucible. For samples with flash points below 210 °C and below 210 °C, the liquid level is 12 mm from the edge of the crucible mouth (that is, at the upper scale line in the inner crucible). For samples above 210°C, the liquid level is 18mm from the edge of the crucible mouth (that is, at the lower tick mark in the inner crucible). Note: First put the crucible on the test bench, then pour the medicine into the small beaker, and then add the small beaker to the crucible. When the addition is almost flush with the scale line, use a dropper instead. The sample should not be splashed when injecting, and the crucible wall above the liquid level should not be stained with the sample. (3) Place the crucible with the sample on it smoothly on the electric furnace on the stand, then fix the thermometer vertically on the thermometer clamp, and make the mercury ball of the thermometer in the center of the inner crucible, which is in contact with the bottom of the crucible and the liquid surface of the sample. The distances are roughly equal.​​

Collectively, the effect of textile testing equipment on industrial society has been to eliminate tensile tester manufacturers and drastically reduce the time long associated with tensile tester manufacturers.

GESTER International Co.,Limited’s mission is to be the leading global innovator, developer and provider of textile testing equipment tensile tester manufacturers products, systems, and services.

Rewards and discount programs give customers more reason to come back for textile testing equipment again, especially in the competitive retail and services markets.

Time is one of the biggest challenges cited by manufacturing textile testing equipment.

GESTER International Co.,Limited will need to find one that fits our needs and budgets, and still turns out a quality product.