China 
Africa 
Explore chapters and articles related to this topic
Ignitable and Explosive Atmospheric Hazards
Published in Neil McManus, Safety and Health in Confined Spaces, 2018
Flammable gases and vapor from flammable and combustible liquids and solids can be ignited by an energetic source of ignition within specific limits of concentration (Figure 4.1). Under equilibrium conditions, these concentrations correspond to a range of temperature in air or oxygen. The lower limit of concentration at which ignition by an energetic source can occur is the lower flammable limit (LFL). Under equilibrium conditions for volatile liquids and solids, this occurs at the flash point. A flame does not propagate away from the source of ignition at concentrations below the lower flammable limit. The upper limit of concentration is the upper flammable limit (UFL). The difference between these concentrations is the flammable range. Values of the LFL and UFL for many chemical substances are available from standard sources (NFPA 1991a).
Safety and Health Considerations
Published in Frank R. Spellman, Hydraulic Fracturing Wastewater, 2017
For fire to start, three components must be present: temperature (heat), fuel, and oxygen. Because oxygen is naturally present in most environments on Earth, fire hazards usually involve the mishandling of fuel or heat. The fire triangle helps us understand fire prevention, because the objective of fire prevention and firefighting is to separate any one of the fire ingredients from the other two. To prevent fires, it is necessary to keep fuel (combustible materials) away from heat (as in airtight containers), thus isolating the fuel from oxygen in the air. To gain a better perspective of the chemical reaction known as fire, remember that the combustion reaction normally occurs in the gas phase; generally, the oxidizer is air. If a flammable gas is mixed with air, there is a minimum gas concentration below which ignition will not occur. That concentration is known as the lower flammable limit (LFL). When trying to visualize the LFL and its counterpart, the upper flammable limit (UFL), it helps to use an example that most people are familiar with—the combustion process that occurs in the automobile engine. When an automobile engine has a gas/air mixture that is below the LFL, the engine will not start because the mixture is too lean. When the same engine has a gas/air mixture that is above the UFL, it will not start because the mixture is too rich (the engine is flooded). When the gas/air mixture is between the LFL and UFL levels, however, the engine should start (Spellman, 1996b).
Background on Facilities Modification for Natural Gas Fueled Bus Use
Published in Paul R. DeCicco, Special Problems in Fire Protection Engineering, 2019
Thomas J. Forsythe, Ralph Kerwin
Natural gas is flammable at concentrations of 5 percent to 15 percent in air. The lower flammable limit (LFL) of 5 percent is the fuel-lean limit and the upper flammable limit (UFL) represents the fuel-rich limit Burning of the gas will occur only if an ignition source is in contact with a volume of gas which is between the LFL and UFL.
Odorants for use with flammable refrigerants (1794-TRP)
Published in Science and Technology for the Built Environment, 2020
With the assumption that the refrigerant and the odorant would not separate after leaking from a refrigerant loop (no condensation of either odorant or refrigerant), the mass of odorant required, Modor, could be estimated as follows: where Mref is the mass of refrigerant, FSafety is the factor of safety applied to the odorant detection threshold, Throdor is the detection threshold of the odorant (by vol), ρodor is the vapor density of the odorant, FLFL is the safety factor applied the lower flammability limit of the refrigerant, LFLRef is the lower flammable limit of the refrigerant and ρRef is the vapor density of the refrigerant. For example, carbonyl sulfide, which has a detection threshold of 0.055 ppm (vol.) and a vapor density of 2.46 kg/m3 (0.153 lb/ft3), would require 0.0036 g per kg of R-32, or 3.6 ppm(mass) of the odorant in the refrigerant, to be detectable with a safety factor of 2 at 25% of the LFL of 14% by volume for R-32.