Flash Point
This is the lowest temperature of a volatile material that the material can vaporize to form an ignitable mixture with air. Here, the word volatile means the tendency of the material to vaporize.
If we put the volatile material into a closed container and keep the temperature of the mateial at it’s flash point, and then we put an ignition source into the container, the vapor mixture burns with a pop sound. Below the flash point, this incident doesn’t occur. At the flash point, the burning of the air and fuel mixture stops quickly because the vapor is not produce at the rate that it is burned.
Fire point
Fire point is a temperature that is higher than the flash point of a same substance. At the fire point, the air and fuel mixture continues to burn even after the ignition source is removed from the mixture. This is caused because, the rate of production of fuel vapor from the liquid fuel is somewhere near the rate of burning of the vapor. Usually, the fire point is defined as the temperature of a liquid and vapor system of a certain substance, when ignited, burn for at least 5 seconds. Considering a typical lubrication oil, usually, the fire point is higher than about 10 ᐤc from the value of the flash point.
Importance of these temperatures
1. Some liquids cause explosions. Because, they should be stored and transported very carefully. Liquids with lower flash points (also low fire points) tends to burn at lower temperatures. So, we should impose more care when handling those liquids with lower flash points. So, flash point is important to know which amount of care should be taken handling liquids.
2. Liquids are categorized as flammable and combustible. Fluids with relatively higher flash points are categorized as flammable. Liquids with relatively low flash points are categorized as combustible. The exact temperature of the temperature used to categorize, depends on the standardization used.
3.Flash point is important when selecting a proper lubricant.In some machinery, very high temperatures are imposed on the lubricants. It is important in most cases, the lubrcation material is a fire proof one. Looking at the flash point of a certain material, we can say that this particular lubricant is appropriate for the lubricant in the particular machinery.
Importance of flash point for engine lubrication oil
In an engine, high temperatures and pressures are applie
d upon lubrication oils. So, if the lubrication oil has a law flash point, it might get ignited. So, high flash point is always desirable for engine lubricants.
Flash point of a engine lubricant is an important measure to check the performance of the machine valves and seals. If the fuel of the engine or some other fluid used in the engine leaks through the seals, valves or other fastenings to the lubricant, the flash point of the lubricant changes. (usually, addition of substances to a particular oil increases it's flash point). So,measuring the flash point of an engine lubricant, gives us the information of how good is the performance of the seals,fittings,valves...etc. of the engine.
Not only the temperatures by the combustion proces
s is a positive effect for the lubricant to ignite. But also, some failures of the engine causes the lubricant to ignite. As examples, bearing failures, some other mechanical failures. So, keeping the flash point of the engine lubricant high avoids unnecessary effects caused by failures of the engine.
PROCEDURE
Connect the gas lines to the gas supply
Clean the brass vessel.
Pour the oil to be tested into the brass vessel till it is filled up to the indicated mark on the wall of the vessel.
Place the cover on the vessel.
Place the vessel in the appropriate place design to place it in the tester.
Place the thermometer in the pocket of the flash point tester.
Ignite the Bunsen burner and place it under the Pensky Martin flash point tester.
Adjust the burner to give a small and blue flame.
Use the wire mess the spread the flame by the Bunsen burner around the tester base uniformly.
Steer the oil in the vessel continuously with the rod attached to the flexible spring fastened to the top of the vessel's cover.
When the temperature of the ol reaches a considerable figure, reduce the gas supply to give very small flame.
Test for the flash point by inserting the ignition source(knurled knob) into the vessel containing oil. The time of the application of the ignition source should approximately 3 seconds.
Test for flash point per increase of each 5 degrees of Fahrenheit.(Flash point can be easily recognized by the pop noise and the quick lighting of a flame)
After the flash point was reached, continue for about 50 degrees above.
Let the oil to cool by closing the gas supply.
Test for flash point when the mixture is getting cool.
Table the recorded data.
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