"property of the material tested. They are however useful to compare different substances and is therefore widely used in road transportation and environmental safety regulations. Closed cup testers give lower values for the flashpoint than open-cup testers (typically 5–10 K) and are a better approximation to the temperature at which the vapour pressure reaches the ""lower flammable limit"" (LFL). Pensky–Martens closed-cup test The Pensky–Martens closed-cup flash-point test is a test for the determination of the flash point of flammable liquids. It is standardized as ASTM D93, EN ISO 2719 and IP 34 The United States Environmental Protection Agency (EPA) has"
"Lower flammable limit Lower flammability limit (LFL), usually expressed in volume per cent, is the lower end of the concentration range over which a flammable mixture of gas or vapour in air can be ignited at a given temperature and pressure. The flammability range is delineated by the upper and lower flammability limits. Outside this range of air/vapor mixtures, the mixture can not be ignited (unless the temperature and pressure are increased). The LFL decreases with increasing temperature; thus, a mixture that is below its LFL at a given temperature may be ignitable if heated sufficiently. For liquids, the LFL"
"component of the mixture. Lower flammable limit Lower flammability limit (LFL), usually expressed in volume per cent, is the lower end of the concentration range over which a flammable mixture of gas or vapour in air can be ignited at a given temperature and pressure. The flammability range is delineated by the upper and lower flammability limits. Outside this range of air/vapor mixtures, the mixture can not be ignited (unless the temperature and pressure are increased). The LFL decreases with increasing temperature; thus, a mixture that is below its LFL at a given temperature may be ignitable if heated sufficiently."
"Pyrophoricity A pyrophoric substance (from Greek πυροφόρος, ""pyrophoros"", ""fire-bearing"") ignites spontaneously in air at or below 55 °C (130 °F). Examples are iron sulfide and many reactive metals including plutonium and uranium, when powdered or thinly sliced. Pyrophoric materials are often water-reactive as well and will ignite when they contact water or humid air. They can be handled safely in atmospheres of argon or (with a few exceptions) nitrogen. Most pyrophoric fires should be extinguished with a Class D fire extinguisher for burning metals. The creation of sparks from metals is based on the pyrophoricity of small metal particles, and"
"source, such as a spark or hot material. Harry Julius Emeléus was the first to record their emission spectra, and in 1929 he coined the term ""cold flame"". Cool flame can occur in hydrocarbons, alcohols, aldehydes, oils, acids, waxes, and even methane. The lowest temperature of a cool flame is poorly defined and is conventionally set as temperature at which the flame can be detected by eye in a dark room (cool flames are hardly visible in daylight). This temperature slightly depends on the fuel to oxygen ratio and strongly depends on gas pressure – there is a threshold below"
"Cool flame Cool flame is a flame having maximal temperature below about . It is usually produced in a chemical reaction of a certain fuel-air mixture. Contrary to conventional flame, the reaction is not vigorous and releases very little heat, light, and carbon dioxide. Cold fires are difficult to observe and are uncommon in everyday life, but they are responsible for engine knock – the undesirable, erratic, and noisy combustion of low-octane fuels in internal combustion engines. Cool flames were accidentally discovered in the 1810s by Sir Humphry Davy, who was inserting a hot platinum wire into a mixture of"
"liquid is the highest temperature (and pressure) it will actually boil at. See also Vapour pressure of water. The element with the lowest boiling point is helium. Both the boiling points of rhenium and tungsten exceed 5000 K at standard pressure; because it is difficult to measure extreme temperatures precisely without bias, both have been cited in the literature as having the higher boiling point. As can be seen from the above plot of the logarithm of the vapor pressure vs. the temperature for any given pure chemical compound, its normal boiling point can serve as an indication of that"
"Low emissivity Low emissivity (low ""e"" or low thermal emissivity) refers to a surface condition that emits low levels of radiant thermal (heat) energy. All materials absorb, reflect and emit radiant energy according to Planck's law but here, the primary concern is a special wavelength interval of radiant energy, namely thermal radiation of materials. In common use, especially building application, the temperature range of approximately -40 to +80 degrees Celsius is the focus, but in aerospace and industrial process engineering, much broader ranges are of practical concern. Emissivity is the value given to materials based on the ratio of heat"
"or may cause or contribute to fire through friction. Readily combustible solids are powdered, granular, or pasty substances that easily ignite by brief contact with an ignition source, such as a burning match, and spread flame rapidly. The technical definitions vary between countries so the United Nations created the Globally Harmonized System of Classification and Labeling of Chemicals, which defines the flash point temperature of flammable liquids as between 0 and and combustible liquids between and . Flammability is the ability of a substance to burn or ignite, causing fire or combustion. The degree of difficulty required to cause the"
"defined by their flash-point. The flash-point is the temperature at which the material will generate sufficient quantity of vapor to form an ignitable mixture. The flash point determines if an area needs to be classified. A material may have a relatively low autoignition temperature yet if its flash-point is above the ambient temperature, then the area may not need to be classified. Conversely if the same material is heated and handled above its flash-point, the area must be classified for proper electrical system design, as it will then form an ignitable mixture. Each chemical gas or vapour used in industry"
"An explosion is the bursting or rupture of an enclosure or container due to the development of internal pressure from a deflagration or detonation as defined in NFPA 69. Lower flammability limit (LFL): The lowest concentration (percentage) of a gas or a vapor in air capable of producing a flash of fire in presence of an ignition source (arc, flame, heat). The term is considered by many safety professionals to be the same as the lower explosive level (LEL). At a concentration in air lower than the LFL, gas mixtures are ""too lean"" to burn. Methane gas has an LFL"
"A relatively small energy, often as little as 0.2–2 millijoules, is needed to ignite a flammable mixture of a fuel and air. For the common industrial hydrocarbon gases and solvents, the minimum ignition energy required for ignition of vapor–air mixture is lowest for the vapor concentration roughly in the middle between the lower explosive limit and the upper explosive limit, and rapidly increases as the concentration deviates from this optimum to either side. Aerosols of flammable liquids may be ignited well below their flash point. Generally, liquid aerosols with particle sizes below 10 micrometers behave like vapors, particle sizes above"
"Smouldering Smouldering (British English) or smoldering (American English; see spelling differences) is the slow, low-temperature, flameless form of combustion, sustained by the heat evolved when oxygen directly attacks the surface of a condensed-phase fuel. Many solid materials can sustain a smouldering reaction, including coal, cellulose, wood, cotton, tobacco, cannabis, peat, plant litter, humus, synthetic foams, charring polymers including polyurethane foam and some types of dust. Common examples of smouldering phenomena are the initiation of residential fires on upholstered furniture by weak heat sources (e.g., a cigarette, a short-circuited wire), and the persistent combustion of biomass behind the flaming front of"
"device may be called an atomic hydrogen torch, nascent hydrogen torch or Langmuir torch. The process was also known as arc-atom welding. The heat produced by this torch is sufficient to weld tungsten (3422 °C), the most refractory metal. The presence of hydrogen also acts as a shielding gas, preventing oxidation and contamination by carbon, nitrogen or oxygen, which can severely damage the properties of many metals. It eliminates the need of flux for this purpose. The arc is maintained independently of the workpiece or parts being welded. The hydrogen gas is normally diatomic (H), but where the temperatures are"
"a liquid will normally catch fire only above a certain temperature: its flash point. The flash point of a liquid fuel is the lowest temperature at which it can form an ignitable mix with air. It is the minimum temperature at which there is enough evaporated fuel in the air to start combustion. Combustion of gaseous fuels may occur through one of four distinctive types of burning: diffusion flame, premixed flame, autoignitive reaction front, or as a detonation. The type of burning that actually occurs depends on the degree to which the fuel and oxidizer are mixed prior to heating:"
"Enthalpy of vaporization The enthalpy of vaporization, (symbol ∆H) also known as the (latent) heat of vaporization or heat of evaporation, is the amount of energy (enthalpy) that must be added to a liquid substance, to transform a quantity of that substance into a gas. The enthalpy of vaporization is a function of the pressure at which that transformation takes place. The enthalpy of vaporization is often quoted for the normal boiling temperature of the substance; although tabulated values are usually corrected to 298 K, that correction is often smaller than the uncertainty in the measured value. The heat of"
"Autoignition temperature The autoignition temperature or kindling point of a substance is the lowest temperature at which it spontaneously ignites in normal atmosphere without an external source of ignition, such as a flame or spark. This temperature is required to supply the activation energy needed for combustion. The temperature at which a chemical ignites decreases as the pressure or oxygen concentration increases. It is usually applied to a combustible fuel mixture. Autoignition temperatures of liquid chemicals are typically measured using a flask placed in a temperature-controlled oven in accordance with the procedure described in ASTM E659. When measured for plastics,"
"be high enough to ignite the waste gas. Most organic compounds ignite at the temperature between and . To ensure near destruction of hazardous gases, most basic oxidizers are operated at much higher temperature levels. When catalyst is used, the operating temperature range may be lower. Residence time is to ensure that there is enough time for the combustion reaction to occur. The turbulence factor is the mixture of combustion air with the hazardous gases. The simplest technology of thermal oxidation is direct-fired thermal oxidizer. A process stream with hazardous gases is introduced into a firing box through or near"
"as a stand-alone product in many applications but can also be used in combination systems with mass insulation where higher R-values are required. Low emissivity Low emissivity (low ""e"" or low thermal emissivity) refers to a surface condition that emits low levels of radiant thermal (heat) energy. All materials absorb, reflect and emit radiant energy according to Planck's law but here, the primary concern is a special wavelength interval of radiant energy, namely thermal radiation of materials. In common use, especially building application, the temperature range of approximately -40 to +80 degrees Celsius is the focus, but in aerospace and"
"atmosphere. A lower flash point indicates higher flammability. Materials with flash points below are regulated in the United States by OSHA as potential workplace hazards. Combustibility and flammability Flammable materials are those that ignite more easily than other materials, whereas those that are harder to ignite or burn less vigorously are combustible. The degree of flammability or combustibility in air depends largely upon the chemical composition of the subject material, as well as the ratio of mass versus surface area. Take wood as an example. Finely divided wood dust can undergo explosive combustion and produce a blast wave. A piece"
"Deflagration Deflagration (Lat: ""de + flagrare"", ""to burn down"") is subsonic combustion propagating through heat transfer; hot burning material heats the next layer of cold material and ignites it. Most ""fires"" found in daily life, from flames to explosions such as that of Black powder, are deflagrations. This differs from detonation, which propagates supersonically through shock waves, decomposing a substance extremely quickly. In engineering applications, deflagrations are easier to control than detonations. Consequently, they are better suited when the goal is to move an object (a bullet in a gun, or a piston in an internal combustion engine) with the"
"lowest temperature at which a small test flame passing over the surface of the liquid causes the vapor to ignite is considered the chemical's flash point. This apparatus may also be used to determine the chemical's fire point which is considered to have been reached when the application of the test flame produces at least five continuous seconds of ignition.Temperature range of this apparatus is 120 to 250 degree c The other principal methods of establishing chemical flash points are the Pensky–Martens closed-cup test and the Tagliabue cup method (often called simply the ""Tag method""). Cleveland open-cup method The Cleveland"
"to be vaporized is typically heated until its vapor pressure is high enough to produce a flux of several Angstroms per second by using an electrically resistive heater or bombardment by a high voltage beam. Vacuum evaporation Vacuum evaporation is the process of causing the pressure in a liquid-filled container to be reduced below the vapor pressure of the liquid, causing the liquid to evaporate at a lower temperature than normal. Although the process can be applied to any type of liquid at any vapor pressure, it is generally used to describe the boiling of water by lowering the container's"
"that the temperature is lower. This is because there is a lack of oxygen in the room and therefore there is incomplete combustion and the flame temperature is low, often just . This means that a lot of carbon monoxide is formed (which is a flammable gas) which is when there is greatest risk of backdraft. When this occurs, combustible gases at or above the flash point of spontaneous combustion are exposed to oxygen, carbon monoxide and superheated hydrocarbons combust, and temporary temperatures of up to occur. This is a rough guide to flame temperatures for various common substances (in"
"tested that it does not exceed 80% of the auto-ignition temperature of the specific gas or vapor in the area where the equipment is intended to be used. The temperature classification on the electrical equipment label will be one of the following (in degree Celsius): The above table tells us that the surface temperature of a piece of electrical equipment with a temperature classification of T3 will not rise above 200 °C. The auto-ignition temperature of a liquid, gas or vapor is the lowest temperature at atmospheric pressure at which the substance will ignite without any external heat source, such"
"exploits the increased reactivity of metal atoms or small particles relative to the bulk elements. Enthalpies of vaporization of common substances, measured at their respective standard boiling points: Enthalpy of vaporization The enthalpy of vaporization, (symbol ∆H) also known as the (latent) heat of vaporization or heat of evaporation, is the amount of energy (enthalpy) that must be added to a liquid substance, to transform a quantity of that substance into a gas. The enthalpy of vaporization is a function of the pressure at which that transformation takes place. The enthalpy of vaporization is often quoted for the normal boiling"
"about 500–700 volts cannot produce easily visible sparks or glows in air at atmospheric pressure, so by this rule these voltages are ""low"". However, under conditions of low atmospheric pressure (such as in high-altitude aircraft), or in an environment of noble gas such as argon or neon, sparks appear at much lower voltages. 500 to 700 volts is not a fixed minimum for producing spark breakdown, but it is a rule-of-thumb. For air at STP, the minimum sparkover voltage is around 327 volts, as noted by Friedrich Paschen. While lower voltages do not, in general, jump a gap that is"
"Vapor In physics a vapor (American) or vapour (Rest of the World) is a substance in the gas phase at a temperature lower than its critical temperature, which means that the vapor can be condensed to a liquid by increasing the pressure on it without reducing the temperature. A vapor is different from an aerosol. An aerosol is a suspension of tiny particles of liquid, solid, or both within a gas. For example, water has a critical temperature of , which is the highest temperature at which liquid water can exist. In the atmosphere at ordinary temperatures, therefore, gaseous water"
"order of severity and depth. For more info, see Burn#Signs and symptoms. According to Jackson's thermal wound theory, there are three zones of major burn injury. The minimum temperature that can cause a burn in a finite amount of time is 44 °C (111 °F). From 44° to 51 °C (111° to 124 °F), the rate of burn increases by a factor of approximately four with each Celsius degree risen or twice per Fahrenheit degree risen, from six hours down to six seconds. The burn would develop in less than a second if the exposure temperature is at least 70"
"which boils at about -196 °C (77K), is the most common and least expensive coolant in use. Liquid air is used to a lesser extent, due to its liquid oxygen content which makes it prone to cause fire or explosions when in contact with combustible materials (see oxyliquits). Lower temperatures can be reached using liquified neon which boils at about -246 °C. The lowest temperatures, used for the most powerful superconducting magnets, are reached using liquid helium. Liquid hydrogen at -250 to -265 °C can also be used as a coolant. Liquid hydrogen is also used both as a fuel"
"worked to obtain even lower temperatures. Absolute zero Absolute zero is the lowest limit of the thermodynamic temperature scale, a state at which the enthalpy and entropy of a cooled ideal gas reach their minimum value, taken as 0. The fundamental particles of nature have minimal vibrational motion, retaining only quantum mechanical, zero-point energy-induced particle motion. The theoretical temperature is determined by extrapolating the ideal gas law; by international agreement, absolute zero is taken as −273.15° on the Celsius scale (International System of Units), which equals −459.67° on the Fahrenheit scale (United States customary units or Imperial units). The corresponding"
"useful in comparing fuels where condensation of the combustion products is impractical, or heat at a temperature below cannot be put to use. The above is but one definition of lower heating value adopted by the American Petroleum Institute (API) and uses a reference temperature of . Another definition, used by Gas Processors Suppliers Association (GPSA) and originally used by API (data collected for API research project 44), is the enthalpy of all combustion products minus the enthalpy of the fuel at the reference temperature (API research project 44 used 25 °C. GPSA currently uses 60 °F), minus the enthalpy"
"Incandescence Incandescence is the emission of electromagnetic radiation (including visible light) from a hot body as a result of its temperature. The term derives from the Latin verb ""incandescere,"" to glow white. Incandescence is a special case of thermal radiation. Incandescence usually refers specifically to visible light, while thermal radiation refers also to infrared or any other electromagnetic radiation. For information on the intensity and spectrum (color) of incandescence, see thermal radiation. In practice, virtually all solid or liquid substances start to glow around (977 ˚F), with a mildly dull red color, whether or not a chemical reaction takes place"