Grains upper limit

The upper limit depends quantitatively on the viscosity that can be processed through the casting fixtures in reasonable time. Too high a viscosity may also lead to problems under certain flow conditions as, for example, when propellant folds over on itself to form a void space which may remain as a defect in the cured grain. If the propellant grain is to be formed and cured by screw extrusion, however, somewhat higher viscosities can be handled. A viscosity of 1600 poise has been reported (9) for a PVC plastisol propellant processed this way. 

Stable fluidization requires a distribution of particle sizes, preferably in the range of a few hundred microns. Normally a size of 4 mm or so is considered an upper limit, but the coal dryers of Tables 9.15(a) and (b) accommodate sizes up to 0.5 in. Large and uniformly sized particles, such as grains, are dried successfully in spouted beds [Fig. 9.13(f)] Here a high velocity gas stream entrains the solid upward at the axis and releases it at the top for flow back through the annulus. Some operations do without the mechanical draft tube shown but employ a naturally formed central channel. 

It will be seen from the last equation that once a stationary state has been reached only 12 Faraday s charges out of 18 are used in the formation of chlorate, while the remaining six are wasted in deposition of 3 grain-atoms of oxygen, which freely escapes from the electrolyzer. From the moment when the concentration of hypochlorite attains a constant value, the yields of hypochlorite drop to zero and the yields of chlorate attain the upper limit of 66.67 per cent, supposing that no oxygen will be lost in any process apart from reaction... 

It should be emphasized that this siderophile cutoff should never be constmed as an upper limit, sine qua non, and nor should data below the cutoff be taken as complete proof of pristine composition. In evaluating suspected pristine samples all relevant traits, such as texture and mineralogy (silicates in gross disequilibrium, or more obviously FeNi metal with typical meteoritic kamacite composition, can be indicators of impact mixing), other aspects of bulk composition (absence of KREEP contamination can be a mildly favorable indicator of pristinity) and isotopic data (an extremely old age can be mildly favorable) should be assessed, if possible (cf. Ryder et al., 1980 Warren, 1993). Of course, a fine-grained texture, disequilibrium (zoned) silicates, and KREEP contamination, all are inevitable (but fortunately, high siderophile concentrations are not), if the pristine rock happens to be KREEP basalt. 

Strictly speaking, only very low upper limits on the abundance of Ne and Ne in the R and G components are known (Table 3). But it is generally accepted that Ne-R [=Ne-E(L)] is pure Ne, the decay product of Na (Ty = 2.6 a), which in turn was trapped when the grains condensed. This apparently radiogenic origin led Amari et al. 

The upper limit (UL) for human daily iodine intake recommended by the German, Austrian and Swiss Societies of Nutrition (D-A-CH, 2000) is 500 pg/day. Consumption of only 250 ml of the milk produced during period 4 of the study would result in ingestion of more than 500 pg iodine. As a result of this experiment, the European Food Safety Authority reduced the maximum allowed iodine intake of cows and hens in the EU from lOmg/kg feed to 5mg/kg grain dry matter equivalent (EU, 2003, 2005 EFSA, 2005). 

---