Flow fiber-optic

Void distribution measurement. The local void fraction is an important parameter in the reduction and analysis of hydraulic test data in two-phase flow. In addition to photographic visualization and fiber optic video probes for observation (Donaldson and Pulfrey, 1979), the following other methods are currently available, each with its own unique set of attributes and drawbacks (Delhaye et al., 1973 Delhaye, 1986 Andreychek et al., 1989). 

Capacitance or conductance measurement This method is applied where the working fluid acts as a capacitive or conductive element in a circuit (Jones et al., 1981). Use of fiber optics sensors has been developed recently (Moujaes and Dougall, 1987, 1990). These methods are used to measure film thickness in annular flow. Further discussion appears in Section 3.3.4.4. For other regimes, the use of the electrical impedience imaging method has also been introduced (Lin et al., 1991). 

Kirkbright G.F., Narayanaswamy R., Welti N.A., Studies with immobilized chemical reagents using a flow-cell for the development of chemically sensitive fiber-optic devices. Analyst 1984 109 15. 

Dremel B.A., Schaffar B.P., Schmid R.D., Determination of glucose in wine and fruit juice based on a fiber-optic glucose biosensor and flow-injection analysis, Anal. Chim. Acta 1989 225 293. 

Gautier S.M., Blum L.J., Coulet P.R., Multifunction fiber-optic sensor for the bioluminescent flow determination of ATP or NADH, Anal. Chim. Acta 1990 235 243. 

Xie X., Suleiman A.A., Guilbault G.G., Yang Z., Sun Z., Flow-injection determination of ethanol by fiber-optic chemiluminesecnce measurement, Anal. Chim. Acta 1992 266 325-329. 

Blum L.J., Chemiluminescent flow injection analysis of glucose in drinks with a bienzyme fiber optic biosensor, Enzyme Microb. Technol. 1993 15 407-411. 

Identical olfactory neurons are located in different places in the cavity, and therefore occupy different positions in the flow path. By using a nasal cavity model, we investigated the influence of the dynamic flow on the sensors response14. The responses from identical fiber optic sensors located... 

Cavity size (volume) Approx. 50 L Delivered power 1500 W Max. output power 1200 W Temperature control Outside IR remote sensor Immersed fiber-optic probe (optional) Pressure measurement Pneumatic pressure sensor (optional) Cooling system Air flow through cavity 100 m3 h1 External PC Optional not required as integrated key panel is standard equipment ... 

The reactor has facilitated a diverse range of synthetic reactions at temperatures up to 200 °C and 1.4 Pa. The temperature measurements taken at the microwave zone exit indicate that the maximum temperature is attained, but they give insufficient information about thermal gradients within the coil. Accurate kinetic data for studied reactions are thus difficult to obtain. This problem has recently been avoided by using fiber optic thermometer. The advantage of continuous-flow reactor is the possibility to process large amounts of starting material in a small volume reactor (50 mL, flow rate 1 L hr1). A similar reactor, but of smaller volume (10 mL), has been described by Chen et al. [117]. 

Further sensitivity enhancements of PDA are likely to stem from advanced flow-cell design using fiber-optic technology to extend the... 

Newer techniques for measuring the refractive index allow for instantaneous, real-time measurement in process streams, or alternatively, a special continuous-flow sample well can be installed on bench top instruments. Small, pocket-sized refractometers also make held measurement very simple and reliable. Fiber optic sensors find uses in biomedical applications. 

Fiber-optic-coupled spectrophotometers (single beam and double beam) are the best choice for on-line analyses. The advent of nonsolarizing optical fiber has made possible on-line analyses in which the spectrophotometer may be located remotely from the process and light is carried to/from the process by the optical fiber. A rugged probe or flow cell provides the sample interface. 

Design and selection of the sample interface is vital to provide the best-quahty data for an analysis. The sample interface may be located in the sample cavity of a spectrophotometer, as in the cases of laboratory cuvettes, vials, and flow cells. The sample interface may also be fiber-coupled and located closer to the process. Fiber-optic sample interfaces include flow cells, insertion probes, and reflectance probes. 

Flow cells are used in fiber-optic applications. They may be plumbed directly into a process, or onto a sidesampling loop. They typically have two opposing lenses with a sample gap in between. The flow path is usually the Z configuration (Figure 4.2). The volumes of the flow cells may vary widely depending upon the sampling requirements. 

A dissolution testing apparams consists of a set of six or eight thermostatted, stirred vessels of an established geometry and volume from the USP guidelines. The dissolution apparatus provides a means to dissolve each sample, but does not provide a means to determine the concentration of the aetive ingredient in the bath. In the most well-established scheme, sipper tubes withdraw samples from each dissolution vessel and send them through a multiport valve to a flow cell sitting in the sample chamber of a UV-vis spectrophotometer. In recent years, moves have been made to make in situ measurements in the dissolution baths by means of fiber-optic probes. There are three possible probe implementations in situ, down shaft, and removable in situ (see Table 4.2). 

Local Extractive Fiber-Optic Flow Cell Sample Systems... 

Figure 5.24 Example fiber-optic-coupled flow cell sample system.

---