High pressure glass capillary

Figure 2.6 High pressure glass capillary and autoclave system as developed by Ludemann [19] on the basic design of Yamada. The dimensions of the high pressure capillary are inner diameter 1 mm, outer diameter 5 mm, length 35 to 40 mm.

Gla.ss Ca.pilla.ry Viscometers. The glass capillary viscometer is widely used to measure the viscosity of Newtonian fluids. The driving force is usually the hydrostatic head of the test Hquid. Kinematic viscosity is measured directly, and most of the viscometers are limited to low viscosity fluids, ca 0.4—16,000 mm /s. However, external pressure can be appHed to many glass viscometers to increase the range of measurement and enable the study of non-Newtonian behavior. Glass capillary viscometers are low shear stress instmments 1—15 Pa or 10—150 dyn/cm if operated by gravity only. The rate of shear can be as high as 20,000 based on a 200—800 s efflux time. 

The use of glass and quartz capillaries is, in principle, not restricted to what nowadays are medium frequencies (400-600 MHz). This type of high pressure NMR equipment will certainly be further improved, mainly to study biological samples by high-field H NMR. To overcome the serious sensitivity problem inher-... 

This type of pumping is frequently employed in separation chemistry for capillary electrophoresis, traditionally in fused silica capillaries, but recently more and more in planar quartz structures [32-34]. It should be noted that this type of pump is of the current-source type. This means that the pressures that can be obtained depend on the internal resistance in wide glass tubing, with little resistance, very little pressure can be built up, and a very small hydrostatically induced differential in/outlet pressure immediately overrules the electro osmotic-pumping. However, in very small capillaries, relatively high pressures can be obtained (up to tens of bars). 

All variations of the ESI use the pressure gradient, countercurrent gas with glass capillary, heated capillary (or heated chamber) and previous high-pressure liquid chromatography (HPLC). Several ionization methods have been developed. In an... 

An experiment with a dilute ceramic suspension was made as follows A very small quantity of silicon carbide particles (d 6 /xm) was dissolved in silicon oil ( 350mPas). The suspension was pumped at high pressure through a glass capillary (d = 0.6 mm). The experimental setup is shown in Fig. 3. The velocities of the silicon carbide particles in the capillary are detected by an optical sensor. From these data, the statistics of the particles velocities is calculated. Due to the optical properties of the sensor, the particles are only detected in a wedge-like sector of the cross-section of the capillary. The measured velocity distribution of the particles (Fig. 4) depends on the shape of this sector and, additionally, on the measuring tolerances of the sensor. 

Crystals that are unaffected by air, moisture, or light are usually mounted directly on a quartz or glass fiber, which is inserted into a goniometer head (Figure 14.3). If the crystal is sensitive to moisture or air, a sealed capillary tube may be used. Suitable apparatus can be used when nonambient temperatures and pressures are needed. The diamond anvil has been developed for high pressure. 

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