Ball Valve Applicators

Petrochemical plant engineers seem to be accepting ball valve applications at a much greater rate than oil refiners or gas processing plant operators. The fire hazard in process areas seems to be the deciding factor. 

PAFRA Ball Valve Applicators (or Similar Ball Valves from Other Suppliers)... 

Suppliers of ball valve applicators Besides Paffa, UK (Fig. 77), we may mention Robatech, Switzerland, and Valeo, USA. 

Figure 77 Example of ball valve application for small jobs (by courtesy of PAFRA).

For top-feed applications, the most convenient assembly is that shown in Fig. 18-95. The depth of the dam must, of course, be sufficient to contain the total quantity of feed shiny required for the test. Since the test leaf is mounted on top of the vacuum receiver, it is nec-essaiy to provide a valve between the test leaf and the receiver so that the desired operating vacuum may be obtained in the receiver before the start of a test run. It is imperative, however, that there be no restriction in this valve. The preferred choice is a ball valve with the full bore of the drainage piping. 

All of these advantages make Mg-PSZ ceramics applicable to many industrial fields such as in the construction of oil extraction pump ball valves in the petroleum industry, milling... 

Multiport This term refers to any valve or manifold of valves with more than one inlet or outlet. For throttling control, the three-way body is used for blending (two inlets, one outlet) or as a diverter (one inlet, two outlets). A three-way valve is most commonly a special globelike body with special trim that allows flow both over and under the plug. Two rotary valves and a pipe tee can also be used. Special three-, four-, and five-way ball valve designs are used for switching applications. 

The simplest valve function is on-off service. Examples of this valve type are gate and ball valves, shown in Figure 8.2. A ball valve is used for tight shutoff. One application is a drain valve on a tank, where it is required to have the... 

Because of its elastic recovery properties, PTFE, a self-lubricating compound, is used in sealing and flexing applications such as sanitary seals, valve diaphragms, o-rings in mechanical seals, and seals and seats of stem and rotary valves such as ball valves. It is also commonly used as a liner or coating material for valves and pumps for the pharmaceutical industry. 

Decreased maintenance and noncontamination of the fluid stream with lubricants are cited as additional advantages. The valve is cheaper and easier to make than other type valves, and it is easier to obtain a tighter seal with a sphere than with other shapes. Manufacturers have estimated that the ball valve is suitable for one out of five present valve applications. 

Another advantage cited for ball valves is their value for application in remote operation because they open and close so easily with only one quarter turn. With the trend to increased automatic control, this is an advantage indeed. 

The primary use for ball valves in the hydrocarbon processing industry is for valve applications under 400°F and pressures less than 4,000 psi, although with graphite seats they could be operated at temperatures as high as 1,000°F. 

The most common applications for ball valves in refineries and chemical plants at present are for loading valves on both tank car and truck racks, utility air service connections, utility water service connections, gas bleed-off valves, sample connection valves, low pressure steam service connections, fire systems, etc. 

Other recent applications of ball valves include the replacement of plug valves in chemical loading racks in 1-1/2-inch sizes and also in safety showers. They also replace gate and plug valves in caustic service. 

The failure rates of a floating ball valve have been estimated for different application conditions based on a detailed FMEDA of a ball valve. 

Although the FMEDA technique was developed for electronic circuits, the analysis can be adopted to mechanical instruments (Ref. 14). This technique has been used successfully to estimate the failure rates for various failure mode solenoids, ball valves, control valves, various t)rpes of pneumatic and hydraulic actuators, and the mechanical portion of smart valve positioners. Many of the parts must be characterized for the mechanical stress of the particular application but when that is done, the results can be realistic. 

Fig. 2 Diagram of the twin-chamber injector with a needle in position of sample application. 1 - quartz sinter, 2 - steel core, 3 - magnet, 4 - quartz tube, 5, 6 - lower and upper housing, 7, 10, 12 - ball valve, 8 - injecting cylinder, 9 - solvent evaporating chamber, 11 - analyte evaporating chamber, 13, 14 -electric heater, 15, 16, 17 - radiator, 18, 25, 26, 32 - needle valve, 19, 27, 28, 31 - solenoid valve, 20, 23 - carrier gas inlet, 21 - chromatographic column port, 24 - six-way valve, 29, 30, 33 - auxiliary gas inlet, 34 - connector pipe for sample introduction, 35 - micro-syringe needle channel, 36 - membrane, 37 - auxiliary gas outlet.

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