Types of traps

The decision of what type of trap to use is typically more likely made by what one is familiar with, what is available, and/or what is economically viable. For example, you may be inclined to use liquid nitrogen in a situation where dry ice would be adequate if you re in a facility that has a lot of liquid nitrogen available. On the other hand, you might try to get by with dry ice when you don t have access to liquid nitrogen. Alternatively, perhaps there is a situation where a molecular sieve trap would be optimum. If you are not familiar with that type of trap, it is less likely to be used. 

There are four basic foreline trap designs (and one post-pump trap)  

Cold traps that rely on condensation or freezing to trap a condensable vapors. 

Particulate traps that physically block the passage of large pieces ( 2 microns) of materials from getting into mechanical pump. 

Molecular sieves primarily used to trap hydrocarbon oils—they also trap water vapor to a limited extent. 

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In many oil and gas fields throughout the world hydrocarbons are found in fault bound anticlinal structures. This type of trapping mechanism is called a combination trap. 

The most widely used type of trap for the study of ion-molecule reactivity is the ion-cyclotron-resonance (ICR) [99] mass spectrometer and its successor, the Fourier-transfomi mass spectrometer (FTMS) [100, 101]. Figure A3.5.8 shows the cubic trapping cell used in many FTMS instmments [101]. Ions are created in or injected into a cubic cell in a vacuum of 10 Pa or lower. A magnetic field, B, confines the motion in the x-y... 

Fig. 3. Types of traps for tar sand deposits, where 0 represents a stratigraphic trap, x, an intermediate between stratigraphic and stmctural/stratigraphic traps H, a stmctural/stratigraphic trap , an intermediate between stmctural/stratigraphic and stmctural traps and A, a stmctural trap.

The groupings then may be described as mechanical, which will include both ball float and inverted bucket steam traps thermostatic, which will include both balanced pressure and bimetallic elements and thermodynamic or disc pattern traps (Figure 22.13). Each type of trap has its own characteristics, and these will make one pattern of trap more suitable for use on a given application than another. In practice, it is usual to find that the applications in any given plant fall into a small number of categories, and it often is possible to standardize on a quite small number of trap types. 

A new-field wildcat is a well located on a structural feature or other type of trap which has not previously produced oil or gas. In regions where local geological conditions have little or no control over accumulations, these wells are generally at least two miles from the nearest productive area. Distance, however, is not the determining factor. Of greater importance is the degree of risk assumed by the operator, and his intention to test a structure or stratigraphic condition not previously proved productive. 

A new-pool test (new-pool wildcat) is a well located to explore for a new pool on a structural feature or other type of trap already producing oil or gas, but outside the known limits of the presently producing area. In some regions where local geological conditions exert an almost negligible control, explor-... 

The values of t and in fact must vary from contact to contact, as dictated by the conditions on the surface, depth position, and physical nature of traps, i.e. averaging is required for all metal-semiconductor microcontacts and all types of traps. We shall assume that all barriers and all traps are similar. If that is the case, one can write coefficient A... 

There are two general types of multidimensional chromatography separation schemes those in which the effluent from one column flows directly on to a second column at some time during the experiment, and those in which some type of trap exists between the two columns to decouple them (off-line mode). The purpose of a trap is often to allow collection of a fixed eluate volume to reconcentrate the analyte zone prior to the second separation step, or to allow a changeover from one solvent system to another. The use of offline multidimensional techniques (conventional sample cleanup) with incompatible mobile phases, is common in the literature, and replacing these procedures with automated on-line multidimensional separations will require continuous development efforts. 

Bachu et al. proposed a theoretical approach to C02 storage estimation considering each type of trapping mechanism in deep saline aquifers [26]. They introduced a simple time-independ-... 

Eggs must be protected, or the adults will eat them. An egg trap designed for small system tanks can be placed into the bottom of the tank late in the afternoon prior to the day eggs are needed. Other types of traps can be used in the bottom of larger system tanks or stand-alone aquaria. 

In general, various types of traps and recombination centers may be present, and their involvement in the reaction kinetic process will greatly change with temperature. The temperature range in which a specific range dominates must, therefore, be determined. This is most conveniently achieved with the aid of nonisothermal temperature scans, during which TSL and TSC are monitored. Of course, the microscopic physical and chemical nature of traps cannot be determined with these methods. 

In this method the moisture is carried over as an azeotrope with carbon tetrachloride into a special trap (burette). Here the water separates into a layer on top of the CCI4 and the amt distilled over is read In a graduated portion of the trap. Two types of traps, (also called "distillation craps ) are described by Pierson (Ref il, ppl289—The Hercules Powder Co type (shown here as Fig 1), known as "6-ml type , has a 6.0-ml graduated portion with the smallest intervals 0.05 ml and is numbered at each 1,0ml division, whereas the E.I. DuFbnt de Nemours Co type has a 1.0 ml portion with smallest intervals 0.02ml (See Fig la)... 

The operation of a trap at 900 lb/in.2 would also facilitate the use of a recycling system for the CO2. Several experiments designed to perform a preliminary evaluation of this type of trapping system were also promising. 

The serpentine plug, shown in Fig. 6, is an interesting type of trap, an example of which is the Hilbig Field in Bastrop County, Texas, As illustrated, a porous serpentine plug has formed a reservoir within itself by intruding into nonporous surrounding formations. 

Lens-Type Traps. These form in limestone and sand. In this type of trap the reservoir is sealed in its upper regions by abrupt changes in the amount of connected pore space within a formation. A trap formed in sand is shown in Fig, 7(a). An example is the Burbank Field in Osage County, Oklahoma. This type of trap may occur in sandstones where irregular deposition of sand and shale occurred at the time the formation was laid down. In these cases, oil is confined within the porous parts of the rock hy the nonporous parts of rock surrounding it. A lens-type trap formed in limestone is shown in Fig. 7(b). In limestone formations there are frequent areas of high porosity with a tendency to form traps. Examples of limestone reservoirs of this type are found in the limestone fields of West Texas. 

Storage has mainly been achieved in four types of traps (11 the radio frequency or Paul trap (2) the Penning trap (3) the Kingdon electrostatic trap and (4) the magnetostatic (magnetic bottle) trap. The principles, advanlages, and disadvantages of these traps are detailed by DJ. Wineland (Science, 226, 395-400, Oct. 26, 1984). 

From the overall shape of the spectrum and possible structures one can draw general conclusions about the dissociation dynamics. The A band of H2O is (almost) structureless indicating a mainly direct dissociation mechanism. The B band exhibits some weak undulations which can be attributed to a special type of trapped motion with a lifetime of the order of one internal vibration (see Section 8.2). However, the broad background indicates that the dissociation via the B state also proceeds primarily in a direct way. Finally, the C band consists of rather pronounced structures which immediately tell us that the excited H20(C1Hi) complex lives on the order of at least several internal vibrations. Although the absorption spectrum is a highly averaged quantity it contains a wealth of dynamical information more of this in Chapters 6-8. 

On the other hand, an extended model with two different types of traps appears to be much better suited to explain the experimental observations obtained by Bahnemann and coworkers [7a]. They have therefore proposed the following modification of reaction (7.3). It is... 

While both types of trapped holes will recombine with the trapped electrons within the first 200 ns after their generation following reaction (7.1), only holes excited thermally from the shallow traps have the chance to migrate to the energetically more favored h+ff(i site (cf. reaction... 

To prevent (or limit) condensable vapors from getting to a pump, traps [either of chilled or chemical design (see Sec. 7.4 on traps and foreline traps)], are used. Depending on the type of trap used, there are opportunities for vapors to pass on to the mechanical pump. Thus, one cannot depend fully on traps of any kind, and one must also deal with vapors at the pump itself. 

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