Brochure

Engineering Data
Instructions for use of Drop Chart
The drop of the air stream is determined by
using the throw and velocity of the register
selected. On the drop chart, lay a straight edge
connecting these values. The total drop of the
air stream will be the sum of the drop due to
temperature (D
t
) and the drop due to spread
(D
s
).
Example: The drop for a 92 Series register “C”
deflection 16x5 size has an 800 fpm velocity
and a 16 foot throw. Connect these two points
on the chart and read the drops as follows:
D
t
= 2.7’ D
s
= 2’
D total = 2.7 + 2 = 4.7’
D
t
= Drop along line of throw due to
temperature difference.
D
s
= Drop resulting from vertical spread.
Engineering Data
133
Recommended Noise Criteria and Face Velocity Ranges are on page 75
Drop Chart, Use with size selection charts
821, 831, 92 Series, 98VOH, H and V Series (Page 7-16)