Valve technology

The Cv Concept. From a quantitative standpoint, steam loss can be estimated through the application of the C, concept. A familiar term in control valve technology, C, expresses the flow capability of a fluid-controlling device—in this case, a steam trap. A large C,. means a high flow rate a low C, means a low flow rate. 

The HP 6890 series GC gas-samphng valve technology, in conjunction with programmed interval sampling, makes this type of GC-based quahty-control automation a reahty. The GC can control and sense the position of multi-position valves to make it possible to automate sample-stream selection. Each sample, which is downloaded automatically, can then be analysed by a different method. Automated analysis of multiple process streams is especially attractive and cost-effective for complex chemical and petrochemical operations in which raw materials for product streams need to be assessed at regular intervals. 

Figure 14.5 The nanoflex valve used by the Topaz system from Fluldigm. A Fluldigm chip contains 48 sets of wells as represented in (a). Three subwells are designed so as to test various ratios of solution to crystallize versus screening solution. The process of feeding the wells Is controlled by the nanoflex valve technology (b). Pressure Is applied to the upper channel to Inflate the valve, resulting In closing the Input lower channel.

Control of a fluid within an integrated analytical microchip is an important task. Fluid control tasks include acquisition of the sample by the microchip from a specimen container or reservoir, movement of the sample to different regions of the microchip for processing and distribution of the sample to multiple processing or test sites. A range of microfabricated pump and valve technologies have been described and these may ultimately provide the fluid control elements anticipated to be required for integrated microchips. 

Misuse of a product by the consumer, such as using a product inverted, results in the discharge of the vapor phase instead of the liquid phase. Most of the propellant is contained in the vapor phase and therefore some of the propellant will be lost and the spray characteristics will be altered. Additionally, the sprays produced using compressed gases are very wet. However, recent developments in valve technology have reduced the risk of misuse by making available valves which will spray only the product (not propellant) regardless of the position of the container. Additionally, barrier systems will also prevent loss of propellant. 

Currently, the CoreValve still awaits FDA approval for an investigational device exemption (IDE) to initiate a clinical trial in the United States. In the meantime, Medtronic, Inc. (Minneapolis, MN) announced acquisition of CoreValve on February 23, 2009. Given Medtronic s longstanding involvement in the prosthetic valve technology, this transaction will certainly further help facilitate future clinical program developments of the CoreValve Revalving system in the coming years. 

Although early clinical outcomes with the current percutaneous valve technologies indeed offer considerable promise to those high-risk patients who are not deemed to be operative candidates, conventional open heart surgery should still be the method of choice for... 

In writing this chapter, the intent of the authors was to provide the reader with a rudimentary knowledge of the practical aspects associated with elastomeric valving technology—one that could be directly implemented in the laboratory. At this point, the reader should have a basic understanding of the mechanics of actuation for the two featured valving methods, as well as an understanding... 

Schultz RK, Dupont RL, Ledoux KA. Issues surrounding metered dose valve technology past, present and future perspectives. In Respiratory Drug Delivery IV. Buffalo Grove, IL Interpharm Press, 1994 211-219. 

Up to now, the development of microneedles has focused on microfabrication techniques for Si and other biocompatible materials. Currently, there are several commercially available microneedle products, such as MTS (Microstructured Transdermal System) by 3 M, Macroflux by ALZA, and Micro-Trans by Bio Valve Technologies, and most of them are designed to increase skin permeability and adopt passive delivery methods (i.e., capillary force). As the feasibility of microneedles is well established, the next step is to understand the characteristics of fluid transport by microneedles,... 

If the commercially available valve prostheses have proven to be efficient, they all present some limits. Actually, the replacement of a diseased valve remains a huge challenge due mainly to the high stress undergone in the body. The development of the trans-catheter procedure generates even additional stress at implantation time. These issues need to be known and addressed in order to develop a new valve technology. 

Gerhard-Multhaupt, R. 1991. Light valve technologies for HDTV projection displays a summary. Proceedings of the International Television Symposium. ITS, Montreux, Switzerland. 

Figure 3.14 Design comparison with (a, V series) and without (b, VG series) dead spaces and valve technology.

With valve control, the actual and target vacuum is adjusted by influencing the suction rate through valve technology. For this, one or multiple vacuum pumps are operated constantly at a fixed speed. 

Figure 7.17 Cone valve (ISL Cone Valve Technology).

ISL Cone Valve Technology (2006) Cone Valves for Bulk Bag Discharge, http //www.conevalve.com/. Accessed 21 November 2006. 

Having identified optimum syringe or valve technology, successful application relies on choosing the most appropriate control system. 

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