Flexible tubing dimensions

For plastic pipes, LDPE and LLDPE are used less than HOPE. Typical applications are irrigation lines or flexible tubes with small dimensions. 

The same approach can be used to describe the tube dimensions of a system of flexible chains in both solutions and melts. The system of interest here consist of monodisperse polymers with degree of polymerization N. Letting Dg represent the tube diameter and the... 

Abstract Polyferrocenyldimethyl-silane (PFS) diblock copolymers with polyisoprene (PFS-PI) or with polydimethylsiloxane (PFS-PDMS) self-assemble in simple alkane solvents to form what appear by TEM to be dense flexible cylinders (nanowires) or nanotube-like structures. Typical widths are on the order of 20 to 30 nm, with variable lengths often greater than 10 un. The structures that form, and the dimensions of the tube-like structures or wires, depend upon the composition of the polymers and the lengths of the blocks. Light scattering experiments show that the PFS-PDMS (block ratio 1 12) solutions aged... 

Typically, a microdialysis probe consists of a small piece (2-10 mm) of a cylindrical dialysis membrane (the hollow fibre), connected to an inlet and an outlet tube of suitable dimensions. Despite the differences in design, what essentially typifies the probe is the position of the inlet and outlet tubes. Basically, two types of probes can be distinguished in the first one, the two tubes are positioned in a serial arrangement in the other type, the inlet and outlet tubes are concentric or parallel. Consequently, in the first type, which is normally termed a linear probe , the hollow fibre is glued in between. In the second one, it is affixed at the tip, and this is usually called a concentric probe . In addition to these two basic designs, other probes are available such as the loop probe , the shunt probe , and the flexible probe . Figure 12.1 shows some schematic representations of these probes. 

Modules representing equipment are written to be as general and as flexible as possible, so that they can be used for the analysis or design of a wide variety of plants. Then they can be applied to specific situations in the plant under consideration by introducing the parameters of the plant into the modules. Appropriate parameters are called upon as needed under the control of the executive program. These parameters may be physical dimensions (such as tube size in a heat ex-... 

Image dissector tubes (Fig. 26) make use of an entrance aperture behind the photocathode, by which the photoelectrons stemming from different locations of the photocathode can be scanned and measured after amplification in the dynode train, as in a conventional photomultiplier. Although used in combination with an echelle spectrometer with crossed dispersion for flexible rapid sequential analyses [59], these systems have not had any commercial breakthrough. This might be due to the limited cathode dimensions but also to stability problems. 

The capillaries are made either of borosilicate glass or fused quartz. Pyrex glass has a cutoff at about 280 nm, so fused silica is often used. The capillary tube is coated with a polyimide to enhance flexibility by preventing the hydration of strained siloxy bonds. The columns vary in internal dia-meter from 10 to 100 pm and in length from 30 to 100 cm, with 50 to 100 cm being common. The capillary side wall is usually thick by comparison, 300 to 600 pm, to act as a heat sink. A small portion (1 to 2 mm) of the coating is burned away if a photometric detector is used. Figure 31-6 shows typical dimensions. 

Immerse the sample cell in a hydrostatic medium in a high-pressure chamber that is compatible with existing spectrometers and that is connected to the pressure-generating unit by semiflexible tubing. Since spectroscopic constraints often require a transparent fluid and preclude the use of oil, incorporate a phase separator in this line. Standardize the dimensions and specifications of the high-pressure chambers where possible, but allow flexibility to accommodate different measurements. 

---