Gases liquefied

The COSTALD (Corresponding states liquid density) method was originally developed for calculating the densities of liquefied gases its use has become generally widespread. 

Students should distinguish carefully between the animal charcoal used for decolorisation, and the wood charcoal which is used for absorbing easily liquefiable gases, and which is therefore used in gas respirators and also, when chilled in liquid air, for obtaining high vacua. 

Low-temperatiire liquefied gases are shipped in special ships with insulation between the niiU ana an inner tank. Poisonous materials are shipped in separate tanks built into the ship. This prevents tank leakage from contaminating harbors. Separate tanks are also used to transport pressurized gases. 

The approach developed will be used for working up of a new generation of the corresponding standai ds. The same approach may be also adapted for analysis of some other products of gas industry, such as liquefied gases, natural gas, etc. 

Unstable gas condensate (UGC) is a large-tonnage raw material for producing of liquefied gases, motor fuels and other products. It is characterized with very complicated composition being under pressure up to 10 MPa. That is why analysis of UGC samples is rather complicated task. 

NFPA 55 Standard for the Storage, Use and Handling of Compressed and Liquefied Gases in Portable Cylinders, 1998 edition. National Fire Protection Association, Quincy, MA. 

A liquefied gas or any mixture of liquefied gases, which is flammable in air and has a boiling point <0°C (measured at 1 bar absolute), when held under refrigeration or cooling at a pressure <1.4 bar absolute. 

CLASS c FIRE A firc involving gases or liquefied gases in the form of a liquid spillage, or a liquid or gas leak. 

Liquefied gases may be stored fully refrigerated, with the liquid at its bubble point at near atmospherie pressure fully pressurized, i.e. at ambient temperature or semi-refrigerated with the temperature below ambient but the vapour pressure above atmospherie pressure. Of the gases listed in Table 4.6, all those with eritieal temperatures below ambient must be maintained under refrigeration to keep them in the liquid phase. 

Dry powders are effeetive on flammable liquid or eleetrieal fires. Speeial powders are available for use on metals. Dry powder extinguishers may be used on Class C fires, ineluding gases and liquefied gases in the form of a liquid spillage or a liquid or gas leak. This must be aeeompanied by other aetions, e.g. stopping the leak this is neeessary to avoid aeeumulation of an unburned flammable gas-air mixture whieh eould subsequently result in an explosion. Aetivation may be automatie by a deteetion system, or manual. 

A further hazard exists when eompressed air jets are used to elean maehine eomponents in workplaees flying partieles have eaused injury and blindness. Cylinders may fail if over-pressurized or weakened by the applieation of heat. Liquefied gases, e.g. butane or propane, respond more rapidly to heat than the permanent gases sueh as nitrogen or oxygen. Cylinders are normally proteeted by pressure relief valves, fusible plugs or bursting dises. 

Harris (1987) provides an excellent set of guidelines for the design of storage facilities for liquefied gases to minimize the potential for vapor clouds ... 

Attention focused on events that cold release a quantity of flammable, explosive or to,xic vapors, hence, operations involving toxic liquefied gases such as ammonia and hydrogen fluoride, and flammables such as LNG and LPG. 

Tanks containing liquefied gases that are kept liquid by refrigeration sometimes have electric heaters beneath their bases to prevent freezing of the ground. When such a heater on a liquefied propylene tank failed, the tank became distorted and leaked—but fortunately, the leak did not ignite. Failure of the heater should activate an alarm. As stated in Section 5.2, frequent complete emptying of a tank can weaken the base/wall weld. 

Tank trucks or cars that carry liquefied gases under pressure at ambient temperature present additional hazards. 

Many suppliers of liquefied gases state that they use different hose connections for liquid oxygen and liquid nitrogen so mistakes cannot arise. However, mistakes have occurred, possibly because of the well-known tendency of operators to acquire adaptors. 

Relief Yalve normally selected for liquid relief service such as hydraulic systems, fire and liquid pumps, marine services, liquefied gases, and other total liquid applications. The valve characteristically opens on overpressure to relieve its rated capacity, and then reseats. 

Loss Prevention and Safety Promotion in the Process Ind.iLStries, 4th International S)Tnposium, Vol. 1 Safety in Operations and Processes Vol. 2 Hazardous Chemicals and. Liquefied Gases-Safe Transport, Vol. 3 Chemical Process Hazards, The Institution of Chemical Engineers, Symposium Series No. 82, 1983. 

Part 2 Specification for automotive LPG BS 5500 Unfired fusion welded pressure vessels BS 7122 Welded steel tanks for the road transport of liquefiable gases... 

Apart from the toxic nature of many gases, the additional hazards are those of excessive release of gas due to pressure changes, spontaneous ignition of flammable gases and sudden vaporisation of liquefied gases. 

At the other temperature extreme we have the measurements of specific heats executed at the temperatures of liquefied gases. A known mass of the substance is dropped into liquid carbon dioxide (— 78°), oxygen (— 183°), or hydrogen (— 250°), and the volume of gas liberated is measured. 

Berthelot showed that the mean compressibility between 1 and 2 atm. does not differ appreciably from that between 0 and 1 atm. in the case of permanent gases, and either may be used within the limits of experimental error. But in the case of easily liquefiable gases the two coefficients are different. According to Berthelot and Guye the value of aJ can be determined from that of aj by means of a small additive correction derived from the critical data, and the linear extrapolation then applied Gray and Burt consider, however, that this method may lead to inaccuracies, and consider that the true form of the isothermal can only be satisfactorily ascertained by the experimental determination of a large number of points, followed by graphical extrapolation. 

Similar gases have similar heats of adsorption (CO2, NH3 SO2, CHC13) difficultly liquefiable gases have much smaller values. 

Table 2.1. Angular momentum correlation times tj of various molecules in liquefied gases [93J.

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