Tube pitch

Tubes are most commonly arranged on an equilateral triangular pitch. Tubes are arranged on a square pitch primarily for mechanical cleaning purposes in removable-bundle exchangers. 

For square pitch tubes, the shell-side equivalent diameter is... 

Tube pitch. Tube pitch (pT) is the center-to-center distance between adjacent tubes and is usually 1.25d0. 

Figure 19.7 Square, large-pitch tubes are easier to clean.

Contrast Range Slice thickness (mm) Image spacing (mm) Table speed (mm/s) Pitch Tube voltage (kV) Tube current (m.k) Rotation time (s) Scan rOV Display LOV... 

These limitations are avoided by other configurations in Figure 13.8. The floating-head imit of Figure 13.8d eliminates the differential expansion problem. Also, the pull-through design permits removal of the tube bundle from the shell so that the outside surfaces of the tubes can be cleaned. The square-pitch tube layout is preferred for cleaifing. 

Remarks Re == DmaJfi, where D is the outside diameter of tubes, G ax Mmin with is the minimum open free-flow area between tubes Xj- is the transverse pitch/tube outside diameter N is the total number of tubes in line of flow is the longitudinal pitch/tube outside diameter = 0.43 + (1.13/ ). Fluid properties for all relations are evaluated at the mean film temperature, T = 0.5 (T. + Tf,), where T. is the tube wall temperature and is the bulk temperature of fluid. See Fig. 5.5 for tube arrangement. 

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