Pumps vacuum type

Figure 5.2. Two of the more common types of low pressure CVD reactor, (a) Hot Filament Reactor - these utilise a continually pumped vacuum chamber, while process gases are metered in at carefully controlled rates (typically a total flow rate of a few hundred cubic centimetres per minute). Throttle valves maintain the pressure in the chamber at typically 20-30 torr, while a heater is used to bring the substrate up to a temperature of 700-900°C. The substrate to be coated - e.g. a piece of silicon or molybdenum - sits on the heater, a few millimetres beneath a tungsten filament, which is electrically heated to temperatures in excess of 2200 °C. (b) Microwave Plasma Reactor - in these systems, microwave power is coupled into the process gases via an antenna pointing into the chamber. The size of the chamber is altered by a sliding barrier to achieve maximum microwave power transfer, which results in a ball of hot, ionised gas (a plasma ball) sitting on top of the heated substrate, onto which the diamond film is deposited.

These factors affect the number and type of extraction wells, vacuum level, pumping rate, type of aboveground-water and off-gas treatments, and length of time required for treatment.34... 

The main components of a vacuum system are the pumps. The types of pumps most commonly used in low-temperature experiments are ... 

A miniature cylindrical ion trap mass spectrometer with APCI and ESI capabilities was developed [22], The system includes a three-stage, differentially pumped vacuum system and can be interfaced to many types of atmospheric pressure ionization sources. 

Of the six diffusion pump oil types, none has all of the above properties. In general, lighter oils pump faster than heavier oils, but heavier oils can achieve lower ultimate pressure. When your work demands varying pump oil requirements, it sometimes is easier to have separate vacuum systems than to simply change pump oils because the pump oils are seldom compatible, and mixing may impair potential peak performance. 

Piston Type of Mechanical Vacuum Pump, Vacuum, 19, 17-22 (1969). 

CHAPTER 10. VACUUM TECHNIQUE Types of Pumps Vacuum Gauges... 

Aromatic isocyanates, particularly those containing electron-attracting substituents, react noticeably more easily than aliphatic isocyanates. In the former case it often suffices to leave the components for some hours at room temperature in a water-pump vacuum, whereas for aliphatic compounds boiling under reflux is usually necessary and sometimes use of a higher-boiling solvent such as decalin. The best catalysts are cyclic phosphine oxides of type (1) (phospholene oxides)862 and cyclic phosphonic diamides of type (2) (1,3,2-diazaphospholidine oxides).863 The best results were obtained with compound (1, R = C2H5) (for its preparation see Campbell et a/.862) the phenyl compound, although more readily prepared,864 is somewhat less reactive. The amounts of catalyst needed are 0.1% for (1) or 0.5% for (2). 

Vacuum type c/s including vessel, pump, motor, drive and vacuum equipment. 

Two basic types of pneumatic conveying systems have been adopted for railcar unloading service the vacuum system and the combination negative-positive pressure system. Each possesses certain advantages which make it useful for different types of applications. Figure 7.15 shows schematically a straight vacuum type of loader that utilizes a silo-mounted vacuum chamber. In this type system, the vacuum pump... 

Use of the FC crystallizer is preferred for evaporative crystallization. The directed and controlled recirculation is carried out with an axial flow pump (elbow-type). This design can also be used for vacuum cooling crystallization, so that then the heat exchanger is no longer required ((J)). The use of this version is recommended if due to the lack of barometric cover in the draft tube crystallizer the incoming solution would boil out of the feed-in point. 

The most frequently utilised type of vacuum pump in these areas of application - even since the broad utilisation mechanical vacuum pumps - was and still is today in the area of industrial chemical process engineering, the so-called water ring pump or liquid ring vacuum pump. This type of vacuum pump is covered in-depth in chapter 3 of this book. 

In accordance with DIN 28 400 (Part 2) a dry compressing vacuum pump is a positive displacement vacuum pump which operates without an oil seal (as the liquid seal). A diaphragm vacuum pump is a dry compressing pump, a type of pump which chiefly has its role in connection with laboratory apphcations. Here the diaphragm vacuum pump replaces the universal laboratory water jet pumps, the water consumption of which and thus the high operating costs due to the generation of contaminated waste water are factors which are not desired. 

Water pumps A type of equipment used to move water through a piping system. They rely upon principles of displacement, gravity, suction, and vacuums to move water. They can be either positive displacement or centrifugal pumps. 

Adsorption pump, vacuum (vacuum technology) A capture-type vacuum pump that pumps by cryocondensation or cryotrapping on a surface of temperature less than — 150°C. See also Vacuum pump. 

Holding pump (vacuum technology) A small-capacity pump used to maintain the foreline pressure of certain types of high vacuum pumps when the use of the main backing pump is not justified. See also Backing pumps. 

Mechanical pump (vacuum technology) A compression-type vacuum pump with moving parts. The term is generally applied to pumps used for roughing or backing (Example oil-sealed mechanical pump, piston pump, diaphragm pump, etc.) and not high vacuum pumps (Example turbomolecular pumps). See also Vacuum pump. 

Dirbomolecular pump (vacuum technology) A compression-type vacuum pump with a... 

It is recommended that pilot testing be used in developing design criteria for the site-specific conditions and MF/UF product selection. Both pressure-type MF/UF systems, where the membranes are encased in pressiue vessels, and vacuum-type systems, where the membrane are immersed in tanks open to atmosphere and use fUtrate/permeate pumps to create the driving force, may be used for seawater pretreatment. 

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