Vacuum system components

Vacuum system. Components associated with lowering the pressure within a mass spectrometer. A vacuum system includes not only the various pumping components but also valves, gauges, and associated electronic or other control devices the chamber in which ions are formed and detected and the vacuum envelope. 

Part 7 - Vacuum metallurgy Part 8 - Vacuum systems, components and 7/78... 

Components must be stable at boiling point of mixture (probably mn under vacuum) vacuum lower than 7—13 kPa (50—100 torr) may requite specialised (scraped-film) crystalliser, more compHcated vacuum system. 

Failure of compo- Ensure all system components, including flexible nents in connectors are rated for maximum feasible subatmospheric vacuum conditions pressure convey-, Ensure adequate pressure control system and ing operations. back-up (e.g., vacuum relief devices) API 2000 CCPS G-3 CCPS G-11 CCPS G-22 CCPS G-29 CCPS G-3 9... 

When you write on a blackboard with chalk, you are not unduly inconvenienced if 3 pieces in 10 break while you are using it but if 1 in 2 broke, you might seek an alternative supplier. So the failure probability, Pf, of 0.3 is acceptable (just barely). If the component were a ceramic cutting tool, a failure probability of 1 in 100 (Pf= 10 ) might be acceptable, because a tool is easily replaced. But if it were the window of a vacuum system, the failure of which can cause injury, one might aim for a Pf of lO and for a ceramic protective tile on the re-entry vehicle of a space shuttle, when one failure in any one of 10,000 tiles could be fatal, you might calculate that a Pf of 10 was needed. 

The material properties of window glass are summarised in Table 18.1. To use these data to calculate a safe design load, we must assign an acceptable failure probability to the window, and decide on its design life. Failure could cause injury, so the window is a critical component we choose a failure probability of 10The vacuum system is designed for intermittent use and is seldom under vacuum for more than 1 hour, so the design life under load is 1000 hours. 

Air is usually the basic load component to an ejector, and the quantities of water vapor and/or condensable vapor are usually directly proportional to the air load. Unfortunately, no reliable method exists for determining precisely the optimum basic air capacity of ejectors. It is desirable to select a capacity which minimizes the total costs of removing the noncondensable gases which accumulate in a process vacuum system. An oversized ejector costs more and uses unnecessarily large quantities of steam and cooling water. If an ejector is undersized, constant monitoring of air leaks is required to avoid costly upsets. 

The technology to routinely cure applied adhesives for repairing damaged composite structures at remote repair stations is currently available. There are already systems that use portable accelerators for X-ray radiographic inspection of aircraft components [43]. Fig. 6 shows a conceptual picture of a portable accelerator unit that would contain the power unit, vacuum systems, and computer... 

Resistance to physical shocks and vibration required careful attention to selection of rugged components and to securing electrical and vacuum systems, wiring, connectors, components, and boards. Chemical ionization (Cl) was used for the first time in a fieldable military detector because of the advent of rugged turbomolecular pumps capable of handling the gas load from the Cl reagent. 

The decomposition of formic acid over evaporated Pd-Au alloy films has been studied by Clarke and Rafter (69) the same reaction on Pd-Au alloy wires was studied by Eley and Luetic (128). The alloy films were prepared in a conventional high vacuum system by simultaneous evaporation of the component metals from tungsten hairpins. The alloy films were characterized by X-ray diffraction and electron microscopy. The X-ray diffractometer peaks were analyzed by a method first used by Moss and Thomas (SO). It was found that alloys deposited at a substrate temperature of 450°C followed by annealing for one hour at the same temperature were substantially homogeneous. Electron microscopy revealed that all compositions were subject to preferred orientation (Section III). 

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

Even the simplest vacuum system like that of Fig. 1.5 consists of several separate components (vacuum vessel, pump, connecting pipe, detachable joints, valves, etc.) which are usually commercially available. 

A high-vacuum system is needed so that the components of air will not be fragmented and cause an interference. 

There are five major components of a mass spectrometer coupled to a GC. They are, vacuum system, ion source, mass filter, detector, and data system. 

Two-stage and multiple-stage vented extruders are commonly used to remove volatile components from molten resin streams prior to downstream processing. The vent ports can be open to the atmosphere, or they can be attached to elaborate vacuum systems. For very specialized systems, stripping agents such as water, nitrogen, and carbon dioxide can be added upstream of the vent, mixed into the resin stream, and then devolatilized in the vent area. This technique can be employed to remove difficult components or components at a higher rate from the resin. 

The term outgassing refers to the liberation of gases and vapors from the vralls of a vacuum chamber or other components on the inside of a vacuum system. This quantity of gas is also characterized by the product of p V, A/here V is the volume of the vessel into which the gases are liberated, and by p, or better Ap, the inaease in pressure resulting from fhe infroduction of gases into this volume. 

Production of strand breaks by very low energy electrons (5-25 eV) in thin solid DNA films using ultrahigh vacuum systems have been reported in a number of studies [107-109]. Such studies have demonstrated the efficiencies of low energy electrons and photons to induce DNA damage. In the vacuum ultraviolet (UV) region, examination of experimental data [86,110,111] shows that the induction of strand breaks depends on the absorption spectrum of the components in the medium and the sensitivity spectrum of DNA [112]. Introduction of a variable with the wavelength for the induction of SSB by OH radicals, in conjunction with a fixed value for the quantum efficiency for the production of OH radical (sensitivity spectrum for induction of SSB in aqueous system [112]. 

Fig. 4. Schematic vacuum system for metal atom reactions. X represents the stopcock or Teflon-in-glass valve. Satisfactory components (for a general discussion of vacuum line design see References 1 and 4) forepump, 25 L/min free air capacity diffusion pump, 2 L/sec main trap is removable and measures about 300 mm deep main manifold has a diameter of about 25 mm, stopcock or valve in manifold should be at least 10 mm substrate container is removable container with 1-2 mm Teflon-in-glass needle valve connected to bottom of container. Connection between this needle valve and the reactor may be 1/8 in. od. Teflon tubing is used. Alternatively, the substrate may be added as shown in Fig. 3.

Although the structure and components of high vacuum systems (h.v.s.) will be discussed in detail in Chapter 2, it is essential for an understanding of what follows to give here an outline of what is involved (see Fig. 2.1.). 

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