Standard Fittings for Compressed Gas

STANDARD FITTINGS FOR COMPRESSED GAS CYLINDERS Thomas J. Bruno and Paris D.N. Svoronos... 

Container valve connections that do not fit must not be forced. Threads on regulator connections or other auxiliary requirements must match those on the container valve outlet. The valve outlet connection should conform to recognized standards such as ANSI/CGA V-1, American National, Compressed Gas Association Standard for Compressed Gas Cylinder Valve Outlet and Inlet Connections [14]. However, it must be acknowledged that connections other than those found in ANSI/CGA V-1 may exist. If a user chooses such a connection, extreme care must be taken to ensure that such connections do not cross-connect with existing connections in ANSI/CGA V-1, and that they have been properly engineered for the intended gas service and pressure. The threads on a cylinder valve outlet, as well as on regulators and other ancillary equipment, should be examined at frequent intervals to ensure they are clean and undamaged. 

Every utility that is provided should be properly identified with a clear, unambiguous label. Color-coded discs with engraved name labels which screw into each service fixture are available from at least one company for most common service utilities. All fittings and connectors should be provided according to appropriate standards. For example, aU gas fittings should comply with the provisions of the Compressed Gas Association Standard V-l(1994). Every utility, if used improperly, can cause safety problems, the only difference being that some require more of an effort on the part of a user todo so than do others. 

CGA E-1, Standard Connections for Regulator Outlets, Torches and Fitted Hose for Welding and Cutting Equipment, 3 ed.. Compressed Gas Association, Inc., 1725 Jefferson Davis Highway, Arlington, VA 22202. 

Centrifugal compressors Centrifugal compressors deliver actual volumetric flows (cubic decimeters per second and performance should not be expressed as mass, mols or standard volumetric flow). Assume compression ratios equal in all stages. Maximum number of stages that can be on one shaft or fit in the frame = 8 minus 1 stage for each side nozzle. Compression ratio 2.5-4. The pressure coefficient = 0.5-0.65 assume 0.55. The pressure differential increases with increase in suction gas density (increased molar mass, suction pressure or decrease inlet temperature, decrease in k). Power up to 7.5 kW/m /s. Efficiency of large centrifugal compressors 76-78%. 

For this purpose, we reanalyze all the available static EOS data for Th, as shown in table 1, with a set of three different EOS forms, and compare the effect of the different EOS forms with the effects resulting from different data sets. As EOS forms we use the Birch equation (Birch 1978) in second order, BE2, and two recently proposed forms (Holzapfel 1990,1991) in second-order form, H02 and HI2, which are related to the Thomas-Fermi theory and are distinguished by the fact that H12 is bound to approach the Fermi-gas limit at infinite compression. A close inspection of table 1 shows very clearly that most of the data are fitted almost equally well by any of these forms, without any significant difference in the fitted parameters Kq and K g or in the minimized standard deviation of the pressure, Tp. In contrast to many other publications, table 1 presents the unrestricted standard deviations of Kq and K, which correspond to the extreme values of the error ellipsoids presented in fig. 11, and not just to the width of the error ellipsoids along and K at the center points, which are usually given as (restricted) statistical errors. Thus, it becomes obvious that... 

---