Classification of Gases

Nonliquefied Gases—do not liquefy at ambient temperatures at pressures up to about 2500 psig. Examples are helium, hydrogen, nitrogen, and oxygen. 

Liquefied Gases—liquids at ambient temperature under pressures of about 25 to 2500 psig. Examples are ammonia, carbon dioxide, chlorine, nitrous oxide, propane, and sulfur dioxide. 

Dissolved Gases—gases carried as a solution in another material. The common example is acetylene, which is dissolved in acetone. The acetone in turn is adsorbed on a porous mass that fills the interior of a cylinder. 

Fuel Gases—gases intended for burning in air or oxygen. Examples are acetylene, butane, hydrogen, liquefied petroleum gas (LPG), methyl acetylene-allene mixture (MAPP gas), propane, and other hydrocarbons. 

Fumigant/Sterilant Gases—gases used to kill vermin or to sterilize medical supplies and equipment. Examples are carbon dioxide, ethylene oxide, methyl bromide, and propylene oxide. 

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Classification of gases, chemical vapour and volatile liquids... 

The classification of gases, vapour and volatile liquids according to their ignition temperatures has been given in Table 7.4. The basic requirements of these enclosures,... 

Classification of Gases, Vapors and Dusts for Electrical Equipment in Hazardous (Classified) Locations... 

NMAB. 1982. Classification of Gases, Liquids and Volatile Solids Relative to Explosion-Proof Electrical Equipment. Report NMAB 353-5. National Academy Press, Washington, DC (August 1982). 

FPN No. 1) For additional information on the properties and group classification of Class I materials, see Manual for Classification of Gases, Vapors, and Dusts for Electrical Equipment in Hazardous (Classified) Locations, NFPA 497M-1991, and Guide to Eire Hazard Properties ofElammable Liquids, Gases, and Volatile Solids, NFPA 325—1994. 

NFPA. 1986. Manual for classification of gases, vapors, and dusts for electrical equipment in hazardous (classified) locations. Quincy, MA National Fire Protection Association, NFPA publication no. 497M. 

Classification of gases by families can sometimes be misleading because individual gases may often be used in a number of very different ways. Nitrous oxide, for example, belongs to several families—it is a prominent member of the medical gases family, is used as a propellant gas, and also is used as a refrigerant gas. 

Physiological Classifications of Contaminants. The physiological classification of air contaminants is difficult, because the type of action of many gases and vapors depends on concentrations (55). For example, a vapor at one concentration may exert its principal effect as an anesthetic but, at a lower concentration, the same vapor may iujure the nervous system, the hematopoietic (blood-forming) system, or some visceral organ (see Toxicology). 

For fully developed incompressible cocurrent upflow of gases and liquids in vertical pipes, a variety of flow pattern terminologies and descriptions have appeared in the hterature some of these have been summarized and compared by Govier, Radford, and Dunn Can. J. Chem. Eng., 35, 58-70 [1957]). One reasonable classification of patterns is illustrated in Fig. 6-28. 

At least two ac tions can take place in the freeboard classification of solids and reaction of solids and gases. 

Cbarcoal usually is ground in hammer mills with screen or air classification. For absorption of gases it is usuahy crushed and graded to about No. 16 sieve size. Care should be taken to prevent it from igniting during grinding. 

NFPA 497 Classification of Flammable Liquids, Gases, or Vapors and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas, 1997 edition. National Fire Protection Association, Quincy, MA. 

The tubes that are around the flame get most of their heat energs t rom radiation. The tubes in the top of the chamber get their heat from com ec-tion as the hot exhaust gases rise up through the heater and heat ihc process fluid in the tubes. The principal classification of fired heaters relates to the orientation of the heating coil in the radiant section. The tube coils of vertical fired heaters are placed vertically along the walls of the combustion chamber. Firing also occurs vertically from the Hoor of the heater. All the tubes are subjected to radiant energy. 

Basic Classification of Flammable and Combustible Liquids Fire Hazard Properties of Flammable Liquids, Gases, and Volatile Solids... 

Magison, E. C. 1987. Hazardous Material Classification m the United States History, Problems, and Needs. Proe. Inti. Symposium on the Explosion Hazard Classification of. Vapors, Gases and Dusts. National Materials Advisory Board, Washington, DC. 

Underwriters Laboratories Classification of Comparative Hazard to Life of Gases and Vapors... 

FPN No. 2) The explosion characteristics of air mixtures of gases or vapors vary with the specific material involved. For Class I locations. Groups A, B, C, and D, the classification involves determinations of maximum explosion pressure and maximum safe clearance between parts of a clamped joint in an enclosure. It is necessary, therefore, that equipment be approved not only for class but also for the specific group of the gas or vapor that will be present. 

FPN No. 3) The classification of mixtures of gases or vapors according to their maximum experimental safe gaps and minimum igniting currents is described in lEC publication 79-12 (1978). 

FPN No. 1) As a guide in determining when flammable gases are present continuously, for long periods, or under normal conditions, refer to. Recommended Practice for Classification of Locations for Electrical Installations of Petroleum Facilities, API RP 500-1991, Electrical Apparatus for Explosive Gas Atmospheres, Classifications of Hazardous Areas, lEC 79-10 and. Institute of Petroleum Area Classification Code for Petroleum Installations, IP 15. 

NFPA-325 Guide to Fire Hazard Properties of Flammable Liquids, Gases and Volatile Solids, (1994 ed.), NFPA-321 Basic Classification of Flammable and Combustible Liquids (1991 ed.), NFPA-497A, Classification of Class 1 Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas (1992 ed.), and NFPA-497B, Classification of Class II Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas (1991 ed.), National Fire Protection Association, Quincy, MA. 

In this article it will be argued that the classification of the elements is an objective feature of the world and not open to conventional choice and relativism. It will also be argued that the element helium belongs objectively and most naturally either to the alkaline earths or the noble gases regardless of whether such a question may be settled at present.8... 

The old classification of bodies into solids, liquids, and gases, based on differences in viscosity and elasticity, is not altogether satisfactory. We shall therefore adopt a method in which bodies are divided into two classes according to the nature of their... 

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