Understanding LPG

Understanding LPG

Following are cases either true or not, along with little commends, enlightening, to our opinion, many questions of people using with LPG.

No need to convert liquid phase in gaseous to be burned, true or false?

False: Liquid fuels (as well as solids) must be in gaseous state (steam) in order to preserve a sort of burning. What is burned is the mixture of the oxygen of the air with the gaseous fuel or the vapour above the burning liquid. The high temperature of the atmosphere or the heat from a fire will produce additional gas or vapour from the liquid fuel. Regarding LPG, atmosphere itself has enough heat to vaporize adequate amount at ordinary temperatures and feed a flame.

If there is no air, there is no fire, true or false?

True: Fire is the burning of fuel with the presence of oxygen in the atmospheric air.

When there is LPG in gaseous phase, and sufficient heat, can it burned, true or false?

False: We must repeat that without oxygen LPG will not burn.

The vapours of gasoline and LPG are lighter than atmospheric air, true or false?

False: They’re heavier (unlike NG) and this should be taken into consideration at all times, in every stage of using LPG or gasoline.

LPG tanks located in an area where a fire bursts, usually explode when heated enough, true or false?

False: All tanks installed in accordance with regulations and by responsible companies are equipped with pressure relief valves proportional to their surface ,to prevent explosion, whatsoever. As a prerequisite of course, the tanks and their relief valves (safety mechanisms) will be retested periodically.

Flame can be sucked into the interior of the tank or LPG cylinder followed by explosion, true or false?

False: For the flame to be preserved there must always be oxygen, which is not true neither inside the tank nor the cylinder, nor inside the LPG diversion conduit towards the atmosphere.

The burning will continue if the fuel temperature drops below the flash point, true or false?

False: burning will stop when the temperature of the liquid falls below the flashpoint which is -105°C and -60°C for propane and butane respectively.

Nitrogen of the atmosphere burns and/or helps in burning, true or false?

False: Nitrogen is an inert gas and is used, similarly to the CO2, for cleaning containers, pipes, etc. (procedure called “gas free”).

The flame spread speed is the same for all fuel vapours, true or false?

False: The speed varies from fuel to fuel. The speed, however, of the flame of liquefied gases is very close to that of natural gas, when, of course, at a stoichiometric ratio with the combustion air.

Ignition point, is the temperature at which the fuel is ignited by itself, without the presence of a flame or spark, true or false?

True: The ignition point temperature of propane and n-butane, when they are mixed with the theoretically required combustion air (at atmospheric pressure), is 470°C and 365°C respectively.

Dry powder or CO2 of extinguishers are useful in the diffusion of vapour produced during the combustion of a liquid fuel, true or false?

True: This occurs when large quantities of extinguishing substance is dropped onto fires of a less volatile liquid fuel. In the case of LPG, extinguishers are mainly used to protect the surrounding area. First we need to stop the flow of LPG to the point of burning leakage and after that begin fire fighting efforts.

Stopping the supply of fuel to the fire is the most effective way to extinguish a fire of fuels, particularly liquefied ones, true or false?

True: Preferably, the fire must not be completely extinguished, if the leaking of LPG has not been completely stopped.

Gaseous phase of LPG (vapor) is lighter than air, true or false?

False: The weight of LPG at atmospheric pressure is about twice the air.

Adequate ventilation disperses vapors of any kind, true or false?

True: Strong natural ventilation and mechanical by means of a fan can disperse vapours of LPG also. Of course, electrical installations (in case of electric ventilation) must be explosion-proof and, creating sparks, in general, must be avoided.

The vapours of LPG are trapped in the lower region of a place, true or false?

True: Indeed, this fact must be taken into account when designing the ventilation. However, gradually, after a while, LPG like all vapours or gaseous fuels, tends to spread completely.

Gaseous fuels detection systems are valuable in determining certain leaks, true or false?

True: Not only they detect the leak, but also indicate whether the air-gas mixture is within the range of flammability. However, we must bear in mind that in some places on the edges of a quantity which may have leaked, we might encounter a flammable mixture, even if in its centre the mixture is above the upper-limit of flammability (lower limit LEL = 1,5%, upper limit HEL = 10% by volume).

For LPG to be in liquid form should be stored under pressure. This makes LPG more dangerous than gasoline, true or false?

False: Because as long as LPG is in the tanks or pipes there is no risk. If leaked, may create a situation which, sometimes, might be more dangerous and sometimes less dangerous than the case of gasoline that leaks. When a liquid phase gas leak is encountered, vaporization immediately occurs, and vapours may be dispersed adequately prior to causing a fire. On the contrary, gasoline or diesel will remain for quite some time in the same area and eventually they might also flow at some distance. When imparting of heat from a fire is encountered on LPG tanks, similarly to those of gasoline, increase in pressure will occur due to the warming of the content. For this reason, tanks are designed in accordance with the regulation and carry the necessary relief valves.

Propane is similar to the combination (80% butane - 20% propane) with regard to its behavior in case of fire, true or false?

True: The differences in some values (as shown in the Physical Characteristics Table) must not imply any change in the way fire situations should be treated.

Liquefied petroleum gases in Greece are of three qualities: propane, butane and mixture, true or false?

True: Commercial propane is also available as “BULK” in cylinders. Butane-propane mixture is also available as “BULK” in cylinders. Commercial butane as available in cartridges by PetroGaz. In some applications, odourless LPG mixture is also available. It should be noted that this characteristic odour is derived from a specific substance that is added to LPG, so that any leakage can be detected, and long before it reaches a concentration below the lower flammability limit.

Sudden release of gaseous phase sometimes looks like a white cloud, true or false?

True: The sudden heat absorption from the atmosphere creates condensation of air moisture so that produces a view of a white cloud.