Four nines

Thomas F. McGowan, P.E., Senior Consultant, RMT/Four Nines Member, American Institute of Chemical Engineers, American Society of Mechanical Engineers, Air and Waste Management Association (Section 25, Waste Management)... 

Molecular models indicate that cavitand (259) has a tall, vase-shaped architecture in which the four benzene rings and four nine-membered rings combine to form a concave cavity to which is attached the four diazanaphthalenes (Moran, Karbach Cram, 1982). The latter groups resemble flaps which may occupy either equatorial or axial positions. In the former arrangement, the inner surface area of the cavity is quite reduced and hence a considerable decrease in the inclusion ability of this form is expected. 

Values that have at least two nines (0.99) are satisfactory for some devices, but values with up to three nines, and sometimes four nines, are attainable in some cases. 

By federal law (as described in Chapter 22), hazardous waste incinerators must meet a minimum destruction and removal requirement, i.e., that the principal organic hazardous constituents (POHCs) of the waste feed be incinerated with a minimum destruction and removal efficiency (DRE) of 99.99% ( four nines ). The destruction and removal efficiency is the fraction of the inlet mass flowrate of a particular chemical that is destroyed and removed in the incinerator or, equivalently. 

As described113 we take J =6 and consider excitation of the rotator from the j = 0 state to levels up to/ = 2,4,6 giving sets of four, nine and sixteen coupled differential equations, respectively. Following Berstein115 and Allison113 the reduction of the interval [0, oo] to [0, xq] is obtained. The wavefunctions then vanish in this region and consequently the boundary condition (243) may be written as... 

Each zone shall be so defined as to provide information representative of the neutron flux levels sdong the total socleil direction of the reactor within the flattened portion of the reactor.. Figure 2, Division of Reactor Into Zones, shows an example of a two, four, nine and sixteen zone reactor. A single high level system may be used If It divides the reactor Into nine or more zones and has a response time of seconds or less with fixed or percentage level trips. 

The leachaint is then filtered to remove the cement. The efficiency of this process is good enough to produce a pure electrolyte that ensures a four-nines lead final product. Of course, the concentration of impurities in the electrolyte does not translate directly to the concentration of impurities in the lead because of competitive electrodeposition. The metallic lead content of the cement is above 90%. The cement is re-melted and absorbed into secondary alloyed or other commercial grades of lead in the factory. 

Incinerators burning solid PCB wastes must have a 99.9999% destmction efficiency (six-nines). For each 1 milUon g of PCBs fed, only 1 g is allowed to leave the stack. TSCA standards are much more restrictive than RCRA, which allows 1 g to be released for each 10,000 g of waste fed (99.99%, or four-nines destruction efficiency). 

Most primary lead is sold as soft lead or pig lead , with a purity of at least 99.90 per cent. High quality lead is specified as four nines or 99.99 per cent plus. Specifications for impurity contents are given in various Standards as shown in Table 14.1. Otherwise a wide range of alloys is produced to customer specifications, particularly antimonial and calcium-tin alloys and have not been standardised. Each battery manufacturer tends to have its own particular requirements to suit its own manufacturing needs and battery specifications. 

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