Brochure

119
Engineering Data
821, 831, 92 Series, 98VOH, H
and V Series Drop Chart, Use
with size selection charts
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