Tandem mechanism

Use double or tandem mechanical seal with inert seal fluid... 

Figure 3-31B. Typical seal flush arrangement for tandem mechanical seals.

The standard unpressurized dual mechaiucal seal (previously referred to as a tandem mechanical seal) shall be a balanced seal (with two flexible elements and two mating rings in series). Unpressurized dual mechanical seals shall be designed to withstand pressurization of the bnffer flnid to 275 kPa (40 psig). 

Tandem mechanical seals, lubricated and blocked by a seal gas with slightly higher pressure than the gas discharged by the compressor offer major advantages. There is no contami... 

Mesitylfhjorenyl anion (9MsF ) is unreactive towards Mel at temperatures below —78 °C.100 Above —60 °C the absorption spectrum of 9MsF in the presence of Mel is replaced by that of the corresponding 9-mesitylfluorenyl radical (9MsF), and 9-methyl-9-mesitylfluorene is formed in low yield, hi a study of the electron-transfer photochemistry of chrysanthemol, an intramolecular S 2 reaction of a vinylcycloprop-ane radical cation has been observed.101 hi a long series of studies of the reactivity of the acids of trivalent phosphorus and their derivatives, the behaviour of P—O nucleophiles towards arylmethyl bromide systems has been examined.102 Further evidence for an X-philic substitution/SET tandem mechanism has been obtained. 

It is worth noting that the radical damage to methionine-containing peptides and proteins consists of a desulfurization process, which leads to the replacement of a methionine residue with an a-aminobutyric acid in the sequence. This could be a posttranslational modification, which is linked to a postsynthetic modification of lipids by the above-reported tandem mechanism. A chemical biology approach can be proposed involving lipidomics and proteomics, in order to configure the metabolic changes related to a radical stress. 

Recently, the regio- and stereoselective allylic substitution of MBH acetates with various carbon-pronucleophiles catalyzed by l,4-diazabicyclo[2.2.2]octane (DABCO) through a tandem mechanism have been investigated by... 

Plant updates tandem mechanical seals, leak H H... 

There are three types of mechanical seals ng e, double, and landcm. The double mechanical seal has two mechanical seals mounted back to back. The tandem mechanical seal consists two mechanical seals mounted in series. Double and tandem mechanical seals arc more effective than the single mechanical seal. 

In the prostaglandin synthesis shown, silyl enol ether 216, after transmetaJ-lation with Pd(II), undergoes tandem intramolecular and intermolecular alkene insertions to yield 217[205], It should be noted that a different mechanism (palladation of the alkene, rather than palladium enolate formation) has been proposed for this reaction, because the corresponding alkyl enol ethers, instead of the silyl ethers, undergo a similar cyclization[20I],... 

Nonwoven bonding processes iatedock webs or layers of fibers, filaments, or yams by mechanical, chemical, or thermal means. The extent of bonding is a significant factor ia determining fabric strength, dexibiUty, porosity, density, loft, and thickness. Bonding is normally a sequential operation performed ia tandem with web formation, but it is also carried out as a separate and distinct operation. 

The dry gas seal is a variation of the mechanical contact seal. It differs in that it uses a microscopically thin layer of gas to separate and lubricate the faces. The seal is configured in a tandem or double-opposed seal arrangement. More complete details are covered in Chapter 5 under Dry Gas Seals. 

Maximum Allowable Working Pressure, code, 399, 405, 406, 408 Mechanical seals, 171-177 Fundamentals, 172 Inside, 172 Installations, 173 Lubrication, 174 Outside, 173 Seal flush system, 176 Tandem, 177... 

A significant recent experimental advance is the introduction of tandem mass spectrometers for studying ion-molecule reactions. Examining various isotope effects as a function of translational energy can provide detailed information about reaction mechanisms. Tandem experiments can also observe many of the possible reaction channels for a given collision complex. Such information provides valuable clues to the chemical and physical nature of the intermediates in ion-neutral interactions. 

Obviously, experiments designed to measure cross-sections as a function of energy are needed. At present, tandem experiments are not capable of high precision at low energies because one must assume details of collision mechanics and because it is difficult to estimate collection efficiencies in forward scattering geometry (15). The extension of all known techniques to lower energy (64, 65) and the further development of pulse methods (58) offer the possibility for advances in this area. 

On a larger scale, landscape development reflects those mechanisms that expose bedrock, weather it, and transport the weathering products away. Present and past tectonism, geology, climate, soils, and vegetation are all important to landscape evolution. These factors often operate in tandem to produce characteristic landforms that presumably integrate the effects of both episodic and continuous processes over considerable periods of time. 

Scheme 20 Mechanism for iron-catalyzed tandem coupling/hydroarylation of aldehyde, aromatic alkyne, and anilines...

Shi, F.-Q., Li, X., Xia, Y, Zhang, L. and Yu, Z.-X. (2007) DFT Study of the Mechanisms of In Water Au(I)-Catalyzed Tandem [3,3]-Rearrangement/Nazarov Reaction/[l,2]-Hydrogen Shift of Enynyl Acetates A Proton-Transport Catalysis Strategy in the Water-Catalyzed [l,2]-Hydrogen Shift. Journal of the American Chemical Society, 129, 15503-15512. 

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