Fluid handling systems

Teflon PEA 440 HP is a chemically modified form of PEA 340 that provides additional benefits such as enhanced purity and improved thermal stability. This product is suitable for producing tubing, pipe linings for production of ultrapure chemicals, semiconductor components, and fluid handling systems for high performance filters (31). 

With regard to terminology, we will use FI to mean flow injection as described above with an injection valve for sample introduction. Similarly, we will use SI as described above to mean sequential injection in which solutions are pulled into a holding coil via a multiposition valve, and pushed out through this valve to the separation system. The combination of a SI fluid-handling system with a separation column can be called SI chromatography. Some papers apply FI and SI terms more loosely to flow-based systems that may or may not follow these formal fluid-handling approaches as just defined. 

The demonstrator fluid handling system contains two thermal micro flow sensors illustrated in Fig. 19. Three resistors are located in the middle of the flow channel. 

The achievements discussed in this chapter also underline that such systems are more than just separation systems. They should rather be regarded as generally applicable fluid handling systems for small volume samples. In particular in the case of electric field controlled systems, the fluid handling requires only control of electric potentials and can be easily automated. Electrophoresis experiments on the level of single DNA molecules have already been demonstrated... 

A classical approach for a flow-through device with sensors is the clinical-chemical analyzer already introduced in several hospitals. Such devices use standard miniaturized electrodes and a sophisticated fluid handling system which is bulky [90]. 

Sjoelander, S., Urbaniczky, C., Integrated fluid handling system for biomolecular interaction analysis. Anal. Chem. 1991, 63, 2338-2345. 

PVDF is widely used in the chemical industry in fluid-handling systems for solid and lined pipes, fittings, valves, pumps, tower packing, tank liners (Figure 4.20), and woven filter cloth. Because it is approved by the U.S. Food and Drug Administration for food contact, it can be used for fluid-handling equipment and filters in the food. 

Hermawan et al. (2004) showed a 90% reduction in S. enteritidis inoculated into liquid whole egg with a circulation-mode fluid handling system using 200 x 2.12 ps pps at EE strength of 25 kV cm l Moreover, combinations of PEF and heat treatment at 55°C showed a synergistic effect, resulting in 4.5-log reduction of S. enteritidis. 

Sjdlander S and Urbaniczky C 1991 Integrated fluid handling system for... 

For patient monitoring as well as for extracellular microphysiometry low volume fluid handling systems with integrated microbiosensor arrays have to be developed (Trajanoski et al. 1996). A very versatile and reliable technology is the use of polymer laminate film. The laminate is based on a PCB material and provides mixed fluidic-electric platform for the assembly of a biosensor array and microfluidic channels. Subsequent lamination of dry film resist layers over previously patterned layers allows the creation of closed channels without the use of any sacrificial layer (Fig. 3). 

Figure 6.23 shows an example of PFA tubing produced by extrusion for a high-purity fluid handling system. Figure 6.24 is an example of a convoluted ETFE tubing. 

In fluid-handling systems, PVDF finds applications as gasketing material, valve diaphragms, and membranes for microporous filters and ultrafiltration. 

Microfluidic systems, where fluid is contained in channels and reservoirs on the microscale, enable sizes to be controlled by the dimensions of the fluid handling system and the types of fluid flow that predominate in such systems. Furthermore, by reducing the volumes of fluid involved in the synthesis, one achieves greater control over the homogeneity of the reaction environment. Microfluidics also allow for the exclusion of some interfering contaminants and more precise control of temperature, residence time in the reaction chamber, localized pressure and mixing, and the use of carefully maintained concentration gradients. 

Here we will address contained fluid handling systems the open-channel flow of fluids is included in Chapter 17, together with plant drainage. We will begin by addressing the transport of liquids in pipes. The transport of liquids in containers may be important outside plant limits, but it has little place in a continuous process plant and will not be discussed. 

Within the framework of the EU-funded project BIOTEX, a multiple setup was chosen to analyse human sweat. Three types of sensors were employed — a pH, a sodium and a conductivity sensor — measuring, respectively, the pH, sodium concentration and electrical resistance of the sweat. But, in order to receive a good sample of the sweat to be analysed when wearing, a fluid-handling system based on Lycra was developed (Morris et al., 2009). 

Since the middle 1970 s, KYNAR resins have also been used for the manufacture of microporous and ultrafiltration membranes. KYNAR fluoropolymer was selected for this application because it is resistant to many chemicals both at room temperature and elevated temperature. Because PVDF is approved by the Federal Drug Administration (FDA) for articles or components of articles intended for repeated use in contact with food, KYNAR filters and fluid handling systems are being used by the chemical and the food industry and are also being used by the semiconductor industry as well as in biomedical applications The latter two applications require particularly inert materials that will not contaminate the fluid with trace contaminants, and KYNAR PVDF does meet these extreme purity requirements. 

The semiconductor processing industry is one of the more recent applications for KYNAR resins. It is used for fluid handling systems for ultra-pure fluids used in the production of microchips. Resin purity and inertness, and the total absence of any additives in the fabrication process, are absolute essentials for components handling the chemicals, etchants, and rinse waters used in the making of today s state of the art integrated circuits. 

This process will require a significant amount of labor to construct all of the samples, and then conduct extensive LC-MS and solid-state analysis to determine compatibility with a given excipient. Automation can be used to speed and reduce the amount of labor required for this process. One such robotic technique utilizes a robotic platform to construct the excipient and drug mixtures. There are a number of automated platforms that can dispense and mix powders in an accurate and reproducible manner. The platform can then utilize a fluid handling system to extract and inject the samples into an HPLC system for chemical analysis, or the samples can be removed and tested by a solid-state analysis system (XRPD or SSNMR). The samples can then be stored under accelerated conditions, and returned to the automation platform and tested to determine the stability when in the presence of the excipient. Most robotic platforms are able to track the samples using barcodes, to ensure that the sample identity and storage condition are linked properly to the data generated by the analytical systems. 

Figure 15.6 High purity fluid handling system. (Courtesy Atlantic Tubing and DuPont Companies.)...

The surface-to-volume ratio of a component can be calculated as a qualitative or quantitative measure of its contribution to contamination in a fluid handling system. Extraction data needs to be on hand for a quantitative assessment.f ] The surface-to-volume ratio of a 2.5 cm diameter tubing is 1.57 cm while that of a 185 liter chemical tank is 0.075 cm k In two studies of extractable fluorides from PFA, different parts were examined. In these studies, a 1.6 cm diameter tubeb l and various pipe fittingsb l were extracted by deionized water. The results were similar after 1,000 hours of extraction (20 mg/m ) despite the differences in the surface-to-volume ratio. 

Fluid handling systems and ultra-purity water (UPW) systems are flushed with UPW, acids, or bases to extract ions and remove the loose particles from surfaces. Diluted hydrofluoric acid is effective in leaching out metals from fluoroplastics. Ultra pure water removes anions and particles. It is not unusual to flush a system with several hundred liters of water. 

In the industrial sector, the main applications for GE Plastics Ultem products are foimd in HVAC equipment and fluid handling systems. Ultem offers high modulus, mechanical strength, heat deflection temperatures and good resistance to chemicals. It is very often used as a metal replacement material. 

Engineering Uses Fluid handling systems, filters, electrical and mechanical systems under extreme conditions, conveyor belt surfaces, high temperature release films, flexible cables, coatings, bellows, laboratory ware. 

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