Valve design materials ratings

Process material, pressures, temperatures and flow rates will have a major impact of valve type chosen. Matching process needs, including the need for tight shut-off and other safety requirements must also be done. Valve manufacturers often customize the valve design to match specific needs. It is recommended to consult with experts from the valve manufacturer to assure a well-designed final element. 

Cardiac valves with components fabricated from low temperature isotropic carbons (pyrolytic carbon) are successfully used clinically [23]. These materials are appropriate for such applications as mechanical valves which require long-term chemical inertness, smoothness, and wear-resistance. The reasons for the marked improvement in the performance (reduced thrombosis and thromboembolic stroke rates) of these newer vs. older style heart valves are not entirely understood, but are undoubtedly multifactorial and related to improved patient management and valve design, as well as to the nature of the carbon surface. The specific benefits conferred by pyrolytic carbons with respect to blood cell and protein interactions, resulting in a very low frequency of clinical complications, remain to be defined. The use of carbon coatings has been proposed for other devices, i.e., vascular grafts, although such devices have not yet been used clinically. 

This represents a significant flow rate. Assuming a 15-min emergency response period to stop the release, a total of26,000 kg of hazardous waste will be spilled. In addition to the material released by the flow, the liquid contained within the pipe between the valve and the rupture will also spill. An alternative system must be designed to limit the release. This could include a reduction in the emergency response period, replacement of the pipe by one with a smaller diameter, or modification of the piping system to include additional control valves to stop the flow. 

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