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Flender/Flender Gear Units/Helical gear unit H4

hejbal et al., 1; Shejbal, 1; Tranchino, 1; Tranchino et al., . Initial guidelines for the use of 2on stored cereals were developed in Australia in the early 1s (Banks and Annis, . The nitrogen is removed from air with large com-mercial membrane technology units or applied from compressed gas tanks. Nitrogen ispuried by cryogenic separation of liquied air or from compressed air by pressure-swing absorption (carbon acting as molecular sieve) (Bell and Armitage, . The maindrawback to 2fumigation is that structures must be completely airtight. Any gas leakage allows 2to enter the structure, causing the fumigation to fail. The production of combustion gases from portable internal combustion engines burning clean propane or methane can be an effective fumigation technique. The intro-duced gas contains less than 1% 2, close to 2% CO 2, and the balance 2(Storey, 1; McGaughey and Akins, . These gases can be produced as needed to ush the bulk Controlled Atmosphere Storage of Grain 2 grain and maintain low 2levels, even in leaky bolted grain bins if plastic sheet is placed over the surface of the grain bulk (McGaughey and Akins, . The gas generatormay operate on the principle of catalytic conversion (Navarro et al., or open-amecombustion (Storey, . Carbon dioxide fumigation is generally favored because moderate levels of CO will kill insects even at relatively high 2levels because of () complex physiological processes in the insects (Nicolas and Sillans, , and () dessication because spiraclesremain open and water loss cannot be regulated (Mellanby, 1; Jay et al., 1; Navarroand Calderon, 1; Jay and Cuff, . Unlike standard phosphine fumigation, which is rapid neurotoxin, for which about 2 ppm are initially generated from solid tablets, gradually decreasing over sev- eral days through bin leakage (levels must remain above 1 ppm, 0.0% for 3 days), CO 2must be maintained at high levels. About 6% CO 2seems near-optimal but lower levels ( /H1%) are eff