Hole pitch

The hole pitch (distance between the hole centres) l p should not be less than 2.0 hole diameters, and the normal range will be 2.5 to 4.0 diameters. Within this range the pitch can be selected to give the number of active holes required for the total hole area specified. 

Square and equilateral triangular patterns are used triangular is preferred. The total hole area as a fraction of the perforated area Ap is given by the following expression, for an equilateral triangular pitch  

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Decide plate layout details calming zones, unperforated areas. Check hole pitch, if unsatisfactory return to step 6 (Section 11.13.11). 

The relationship between the grid hole pitch, Lh, and the number hole density (holes per unit area of the bed), Nd, depends on whether the holes are laid out in triangular or square pitch. 

Figure 4. The relationship between hole density and grid hole pitch for triangular and square pitch.

This design results in 2,400 holes. Determine the hole pitch... 

Several equations are applied to calculate sieve tray hole area. Normally sieve tray hole individual diameters are Vie to % in. As for bubble caps, sieve tray hole pitch is the measure from center to center between sieve tray holes. The pitch may be square or triangular, each angle of the triangle being 60°. Section areas are the tray deck area of one pitch markoff area, noted as SECTAREA. For square pitch, one complete hole area is measured for triangular pitch, one-half hole area is measured, noted as SECTHA. The active area divided by SECTAREA equals the number of pitch sections on the tray deck, noted as SECTNO. Equations (3.98) through (3.103) will help clarify these statements. 

Pilch. For an equilateral triangular arrangement, the hole pitch can be calculated from the following geometrical relationships (1). 

Hole size Hole pitch Total no. holes Active holes Blanking area... 

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