To Calculate:
Minimum hole-size diameter (D) through which to detect*

Given:
L = distance of hole from sensor in inches BS = beam spread in degrees S = safety factor

Formula:
S x 2 x L x tan(BS/2) = D inches

Example:
L = 4 inches BS = 7 degrees (SM600) S = 1.2 (20% safety factor)

Calculation:
1.2 x 2 x 4 tan(7/2) = 0.587 inch diameter

Note:
Since the beam spread in degrees changes with distance from the sensor, this calculation is approximate. For more accurate information, ask your distributor or the SCC for a beam plot.