Combustible substances

Other early match-like devices were based on the property of various combustible substances mixed with potassium chlorate to ignite when moistened with strong acid. More important was the property of chlorates to form mixtures with combustibles of low ignition point which were ignited by friction (John Walker, 1827). However, such matches containing essentially potassium chlorate, antimony sulfide, and later sulfur (lucifers), mbbed within a fold of glass powder-coated paper, were hard to initiate and unreHable. 

The term oil includes a variety of liquid or easily liquefiable, unctuous, combustible substances that are soluble in ether but not in water and that leave a greasy stain on paper and cloth. These substances can include animal, vegetable, and synthetic oils, but usually the word oil refers to a mineral oil produced from petroleum (qv). An oil that has been used or contaminated, or both, but not consumed, can often be recycled to regain a useful material, regardless of its origin. For the purposes of this article, only the recycling of used petroleum oils is considered. 

Explosion protection encompasses the measures implemented against explosion hazards in the handhng of combustible substances and the assessment of the effectiveness of protective measures for the avoidance or dependable reduc tion of these hazards. The explosion protection concept is vahd for all mixtures of combustible substances and distinguishes between ... 

Elash point The lowest temperature at which vapors above a volatile combustible substance ignite in air when exposed to a source of ignition. 

HS(Gjl31 Energetic and spontaneously combustible substances identification and safe handling... 

Combustible substances (e.g.. Easily oxidized vegetable oils, which generate heat sufficient to cause ignition) diat may undergo sufficient oxidation at ordinaiy temperatures to reach tlieir AIT... 

Organic combustible substances subject to microbial tliermogenesis (e.g.. Agricultural products such as liay and grain)... 

Rocket propellant is a mixture of combustible substances that is burned inside the combustion chamber of a rocket engine. Burning is the chemical process of decomposition and oxidation of the propellant. The resulting highly heated and compressed gas (propulsive mass) is ejected from a combustion chamber and facilitates propulsion—movement of the aggregate attached to the rocket engine. In physi-... 

For a fuel mixture composed of combustible substances i = 1, 2.the heating... 

Substances, which after short exposure can cause serious effects that are likely to be irreversible, even if prompt medical treatment is undertaken. People who have been exposed need to be kept away from these. Also included in this category are materials which give highly toxic combustion substances and corrosive substances. 

Substances which can cause temporary disabilities or possible permanent injuries following intense or continuous exposure if no prompt medical treatment is undertaken. Included are all substances that require a breathing insulating mask, substances that give off toxic combustion gas. In addition to these are highly irritant combustion substances and those that can release toxic substances, which cannot be identified. 

Spontaneously Combustible and Pyrophoric Substances Spontaneously combustible substances will readily react with the oxygen in the atmosphere, igniting and burning even without an ignition source. Ignition may be immediate, or may result from a self-heating process that may take minutes or hours (hence, some spontaneously combustible substances are known as self-heating materials). 

Pyrophoric and other spontaneously combustible substances will generally be identified as such on their product literature, material safety data sheets (MSDSs), or International Chemical Safety Cards (ICSCs). If transported, these substances should be identified as DOT/UN Hazard Class 4.2 materials for shipping purposes and labeled as spontaneously combustible. For pyrophoric substances, the NFPA 704 diamond for container or vessel labeling has a red (top) quadrant with a rating of 4, indicating the highest severity of flammability hazard (NFPA 704, 2001). Note that pyrophoric materials often exhibit one or more other reactivity hazards as well, such as water reactivity. 

Lists of pyrophoric materials that include less common chemicals, including metals, can be found in volume 2 of Brethericks Handbook of Reactive Chemical Hazards (Urben, 1999). Other spontaneously combustible substances are tabulated by their proper shipping names and UN/NA numbers in the U.S. Dept, of Transportation regulation 49 CFR 172.101. 

Question 7 Pyrophorics and Other Spontaneously Combustible Substances... 

Inadequate cleanout of equipment containing spontaneously combustible substances, prior to opening to the air for maintenance... 

Capable of igniting and burning in air without the presence of an ignition source. Pyrophoric materials are spontaneously combustible, although some pyrophorics require the presence of a minimum amount of moisture (humidity) to spontaneously ignite. Other spontaneously combustible substances and mixtures may require more time or an insulating environment to self-heat to the point of ignition. 

Spontaneously combustible substances, screening methods, 43 5 Springfield, Massachusetts incident, 7 Startup/full-scale operation, chemical reactivity hazard management, 23-24 Storage... 

In 1667 Becher published another book, Physica Subterranea, in which he expounded a theory that was to profoundly affect chemistry for more than a century. In the book Becher accepted only two of the traditional four elements, earth and water. He then divided earth into three types, so that in effect there were still four elements. He named the three kinds of earth terra lapida, terra pinguis, and terra mercurialis. The second of these, which he described as an oily earth, was supposed to be present in all combustible substances and was released when those substances burned. 

When a combustible substance is mixed with air, the mixture will explode only when it is neither too rich nor too lean. The lower explosion limit (LEL) is the minimum volume percent of the substance in air with flammability, which is separated from the upper explosion limit (UEL) by the explosive concentration range. The tabulations in handbooks are based on experimental data, and sometimes derived from estimation methods based on the elemental composition of the fuel as CmEtxOy. Figure 6.11 shows the LEL for the series of normal paraffins and of 1-alcohols versus the number of carbon atoms. There are two ways to plot the results, which show that, for paraffins, the volume percent shows a steeply declining trend, but the weight percent shows a mildly increasing trend. One may conclude that a smaller volume percent of higher paraffin... 

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