Valve standards

C = standard valve coefficient from manufacturer s catalog... 

A Standard valve with integral legs used for most services, utilizing a sharp-edged orifice in the tray floor. 

Standard valve trims are defined by standards such as API 600 and API 602. Elastomer or plastic inserts may be specified to achieve bubble-tight shutoff. Valve manufacturers may be consulted for recommended trims. 

Commercial hydrofluoric acid alkylation was started in an emergency to make aviation gasoline during World War II. It was later found that maintenance on these units could be eliminated almost entirely by using standard valves and pumps with Monel trim on the moving parts. Monel-lined regenerators also eliminated corrosion from the hot hydrofluoric acid. 

Solution Table 14-12 presents measurements by Billet (loc. cit.) for ethyl-benzene-styrene under similar pressure with sieve and valve trays. The column diameter and tray spacing in Billets tests were close to those in Example 9. Since both have single-pass trays, the flow path lengths are similar. The fractional hole area (14 percent in Example 9) is close to that in Table 14-12 (12.3 percent for the tested sieve trays, 14 to 15 percent for standard valve trays). So the values in Table 14-12 should be directly applicable, that is, 70 to 85 percent. So a conservative estimate would be 70 percent. The actual efficiency should be about 5 to 10 percent higher. 

Kh = Capacity correction factor due to backpressure. For standard valves with superimposed (constant) backpressure exceeding critical see Appendix B. 

Kb = Capacity correction factor due to backpressure. For standard valves with superimposed (constant) backpressure exceeding critical values, see Appendix B for reference values, but consult the manufacturer s data also. EN 4126 requires physical testing of these values. 

For saturated steam, use Ksh = 1. For other values, see Appendix E Kn = Capacity correction factor for dry saturated steam at set pressures above 10,346 kPaA and up to 22,060 kPaA. See Appendix F Kb = Capacity correction factor due to backpressure. For standard valves with superimposed (constant) backpressure exceeding critical values, see Appendix B (Table B. 1) for reference values but consult the manufacturer s data. EN 4126 requires physical testing of these values... 

Figure 6.10. Comparison of different mechanical emulsification techniques with US assisted emulsification, (r) toothed colloid mill, ( ) standard valve, ( ) sharpened edge valve, (o) Microfluidizet and ( ) US-assisted emulsification. (Reproduced with permission of Elsevier, Ref [32].)...

Estimate the number of valves. Valve density varies between 12 and 14 per square foot depending on tray layout and geometry. Use an average of 13 valves per square foot (140 valves per square meter) or the actual number of standard valves (155 in., 39 mm diameter) to rate a tray ... 

At the present time, valve trays constitute about 70 percent of the market, sieve trays 25 percent, and bubble-cap trays 5 percent. The standard valve tray costs about 20 percent more than the standard sieve tray with - to -inch or larger holes. The cost of a bubble-cap tray is approximately 300 percent more than the corresponding valve tray. 

Valve Loading. The designer should be particularly careful in using low pressure rating valves with relatively heavy-walled pipe. The imposed moment caused by construction or by expansion may be beyond the structural capacity of the valve. For large-diameter piping, venturi ports are sometimes used on valves (particularly when motor operated). Also, standard valves one or two sizes... 

Number of Valves The standard valve density for KG A(V-l) type is 12/ft. Thus, the number of valves can be calculated by... 

Tests have usually a comparative meaning and, for this reason, it is useful to test a standard valve, the natural one for instance. The fluid used in such tests has a great importance blood would be perfect of course, but usually a 30% glycerine and 70% water solution is used because its viscosity and density characteristics are very similar to those of blood. For studying the chemical and biological blood-prosthesis interactions, in vivo tests using animals... 

SILl Switches, transmitters Relay, safety solid state, PLCs, safety PLCs Standard valves... 

Fig. 9-1. Dimensional drawing from CGA V-1—1994 of Connection CGA 540, a standard valve outlet connection.

The standard valve outlet connection assigned to diborane cylinders is Connection CGA 350. 

TB-I6 Recommended Coding System for Threaded Cylinder Outlets and Threaded Valve Inlets. Based on a number of serious incidents with valve threads not matching cylinder threads the CGA has developed a code and marking standard valve threads currently in the United States and Canada. This technical bulletin explains why a cylinder thread code is needed and also explains why both the cylinder and valve need to be so marked. It lists the CGA code, which resides in CGA V-1, along with the codes on ISO cylinders and valves (4 pages). 

The CGA has defined standard valve connections for most of the gases that are commonly shipped in cylinders. CGA V-1 defines these connections, and the recommended standards are identified and tabulated in Chapter 8 of the CGA Handbook. Along with identification of the gas, the Handbook indicates the volume and pressure of the cylinder, the type of connection, and whether the connection is for withdrawal of liquid. The "Standard" connections are always preferred these are the CG A s recommendations for the specific gases. "Limited Standard" coimections may be recommended with some limitations on their use. "Alternate Standards" were to be phased out by the beginning of 1992. CGA recommends that cylinders fitted with these valves are not acceptable, and the user should change the valves to meet the standard [30]. 

Isolation valve closure times are designed to limit the release of radioactivity and are consistent with standard valve operators, except where a shorter closure time is required. 

The nature of a squib valve body design makes it virtually leak free that is, the valve is not subj ect to internal leakage, as with standard valve designs such as globe, butterfly, gate, and nonreturn valves. This is a very important safety function, because any such leakage would be the equivalent of a small LOCA, given the location of the squib valves in the primary circuit. 

If the bore in the cylinder exceeds the maximum specified as in Table 8-2, it can result in flat crests at the point where sealing is supposed to occur. It is therefore important that the bore not be oversize and that a good bore gauge that registers off the cylinder thread crests at a depth of (L9) be used, as shown in Fig. 8-9. The first thread on a 4-thread oversize valve is the same size as the fourth thread on a standard valve, i.e., zero threads oversize. 

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