High pressure closures

The hysteresis loops to be found in the literature are of various shapes. The classification originally put forward by de Boer S in 1958 has proved useful, but subsequent experience has shown that his Types C and D hardly ever occur in practice. Moreover in Type B the closure of the loop is never characterized by the vertical branch at saturation pressure, shown in the de Boer diagrams. In the revised classification presented in Fig. 3.5, therefore. Types C and D have been omitted and Type B redrawn at the high-pressure end. The designation E is so well established in the literature that it is retained here, despite the interruption in the sequence of lettering. 

Figure 10-4C. High-pressure fixed-end closure and return-end closure. (Used by permission ALCO Products Co., Div. of NITRAM Energy, Inc.)...

Since excess pressure indicates malfunction of part of the system - usually a condenser fault or incorrect closure of a valve - the high-pressure switch should be reset manually, not automatically. 

For high-pressure operation, safety considerations are extremely important and care must be taken to ensure proper mechanical design. Closures must be designed to withstand the same maximum pressure as the rest of the autoclave. Various authors have treated the problems involved in designing medium- and high-pressure batch reactors (2-4). 

Clomiphene citrate is used as a mixture of E (58) and Z (60) isomers to treat infertility. Photolysis of a chloroform solution with a high-pressure mercury lamp gave the expected phenanthrenes (59) and (61), which were separated and identified by GC-MS. Study of the separate isomers (58) and (60) indicated that rapid cis-trans photoisomerization preceded ring closure so that each gave a mixture of phenanthrenes (60) and (61) (Scheme 2.2) [52],... 

Reviews " of pentacyanoferrate substitution kinetics have included a detailed consideration of high-pressure studies of thermal and photochemical substitution and electron transfer reactions of pentacyanoferrates-(II) and -(III). Photochemical activation can result in the loss of L or of CN . The best way to study the latter is through photochemical chelate ring closure in a pentacyanoferrate complex of a potentially bidentate ligand LL [Fe(CN)5(TL)]" rFe(CI 4(LL)] " +... 

The heart of the system is the oxidation vessel depicted in Figure 1. This vessel is a high pressure, 1000 cc, Hastelloy C-276, bolted closure reactor manufactured by Autoclave Engineers Inc. Hastelloy C-276 was chosen as the material of construction due to its excellent corrosion resistance to a wide variety of chemical process environments, which include processes utilizing strong oxidizers (5,6,7). The unit is fitted with 1/8" and 1/4" Hastelloy C-276 feed delivery and product outlet lines... 

Removable closures -for pressure vessels [HIGH PRESSURE TECHNOLOGY] (Vol 13)... 

Caps, Corks, and Wire Hoods. Crown caps are used for closures on bottles before secondary fermentation. The caps are 26 mm in diameter (one company uses 29 mm) and are coated tinplate or stainless steel. Two companies use stainless steel to prevent corrosion and leakage during storage under moist and cold conditions, or for long aging under high pressure. The liners of the caps are ground cork with vinyl disks or elastomer plastic. Cork and plastic liners appear to work equally well. 

Scheme 16. Analogous macropolycyclizations to that reported for the synthesis of 63 have been performed upon 59 using the methylene-bridged bisdiene 64 and the octadeuterated bisdiene 66 to afford the [14]cyclacene derivatives, 65 and 67, respectively. In both cases, the products are isolated in yields exceeding 80%, without the need for high pressure to promote the ring-closure reaction...

Both macropolycyclizations (59 + 64 - 65) and (59 + 66 -> 67) proceed in an equally facile manner to that described for the synthesis of the original [14]cyclacene derivative 63. Neither reaction of 64 or 66 with the 2 1 adduct 59 requires high pressure to effect the final ring closure. These facts reinforce the suggestion that the bicyclic bisdienes 64 and 66 with a bicyclo[2.2.1]heptane framework constitute a good stereoelectronic match for the reactive termini present in 59. The resonances... 

In operation containers constructed of microwave-transparent materials, (e.g. quartz or fluoropolymers), are used to hold multiple samples inside the ultraCLAVE . The interior of the stainless steel vessel is protected by a titanium nitride or multi-layer PTFE plasma coating for complete acid and chemical resistance. Sample containers may be open or covered by a lid. After the samples are loaded (manually or robotically) the ultraCLAVE cover is lowered into place by an electric motor controlled from the system s PC. The vessel closure is engaged and secured in place to seal the ultraCLAVE for high pressure operation. 

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