Crimp height

Foi structured packings, values correspond to crimp height. 

Eor noncircular apertures, the equivalent hydraulic diameter should be used. Eor crimped metal ribbon elements, the equivalent hydraulic diameter of a right isosceles triangle is 0.83 times the crimp height, and the thickness (width) should be at least 0.5 inches (EISE 1980). 

Eor crimped metal ribbon arresters it provides the following equation for the maximum flame speed obtained by Cubbage (1959) for the stoppage of town gas-air mixture detonations by arresters with a crimp height of 0.017 inches ... 

Pressure drop for both AS (0.5-in. crimp height) and AS (0.375-in. crimp height) packings is acceptable for the crude tower operation. 

B. Gempak pressure drop, Series AS, with 0.50-in. crimp height. Used by permission of Glitsch, Inc., Bull. 5140. 

Figures 9-63A and -63B illustrate for a specific packing the hydraulic flood and mass-transfer efficiency limitations. The differences in crimp height can influence the results. Figure 9-63B shows the effect of a higher flow parameter taken using larger columns the system apparendy was approaching its critical, but the cause of the performance is not yet known.

Harrison and France (52) presented the only published rule of thumb for structured packings efficiency. This rule states that HETP is 9 in for Winch crimp height, 18 in for 1/2-inch crimp, and 33 in for 1-in crimp. The author found this rule to do well when the crimp angle is 45°, but to be less satisfactory for other angles. Basad on data in Chap. 11, the author proposes an alternative rule of thumb. 

Crimp heights and specific surface area are listed in Table 8.1. The 4 in added in Eq. (9.35) gives this rule a conservative bias. Eliminating the 4 from Eq. (9.35) will improve the fit of this rule to data, and for a crimp angle of 45° will make it practically identical to Harrison and France s. However, the author feels that just like in the Porter and Jenkins rule (above), the conservative bias is needed to render the rule suitable for design. 

Figure 13 Schematic identifying five rules for crimping. (1) Well-adapted shape of crimp collet, (2) well-adapted depth stop, (3) crimping diameter, (4) crimp height, (5) sufficient vertical force. 

Depth Stop. Use a depth stop adapted to various kinds of valves and pumps. The shape of the depth stop must be designed according to the external shape of the valve ferrule. The depth stop has three functions. It transmits the necessary force to compress the sealing gasket it enables adjustment of the crimping height and it positions the valve ferrule correctly inside the crimp collet. The result is a good concentric crimp. 

Crimping Height. Calculate the theoretical crimping height to determine the position of the depth stop in the crimp collet. Knowledge of the theoretical... 

Figure 23 Recommended crimp dimensions for a 20-mm FEA standard glass bottle. H is crimp height, and d is the diameter beneath the neck as measured with a caliper gauge. 

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