## 020

Note: l = thickness of perforated plate or length of bars, ft (m); Dh, Ar, A0, and Ax are as defined following Eq. 37.

Source: Reference 7.

Note: l = thickness of perforated plate or length of bars, ft (m); Dh, Ar, A0, and Ax are as defined following Eq. 37.

Source: Reference 7.

D, where Re = Reynolds number referred to hydraulic diameter VO = velocity through area of opening, ft/s (m/s)

: hydraulic diameter (= diameter if openings are round holes), ft (m) kinematic viscosity, ft2/s (m2/s) : area of single opening, in2 (mm2) perimeter of single opening, in (mm) diameter of hole, in (mm) percentage of open area : horizontal spacing of holes, in (mm) vertical spacing of holes, in (mm) diameter of approach, in (mm) Sh = horizontal apace between vertical bars, in (mm) Sv = vertical space between horizontal bars, in (mm)

t = thickness of plate laths or bars, in (mm) AO = total area of openings, ft2 (m2) A1 = total area of approach, ft2 (m2)

Sb = space between single vertical or horizontal bars, in (mm)

The loss of head through perforated plates may also be calculated by using an orifice coefficient C, as suggested by Smith and Van Winkle10 and Kolodzie and Van Winkle.11 Test results using air and other gases with equilateral-triangle pitch perforated plates are shown in Table 10 for Reynolds numbers 400 to 20,000. Using single-orifice relations, the following expression equates flow rate to pressure drop: ## Survival Treasure

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