Greenheck Canopy Hoods (452413 IOM) - Manual (Page 16)

Kitchen Hoods • Type I and Type II 16
®
Airflow
2 in.
(50.8 mm)
Rotating Vane
Anemometer
Nominal Filter Size (H x L) Imperial
Conversion
Factor
Metric
Conversion
Factor
Inches Millimeters
16 x 16 400 x 400 1.63 .157
16 x 20 500 x 400 2.13 .198
20 x 16 400 x 500 1.90 .177
20 x 20 500 x 500 2.48 .230
Total hood volume = (Filter 1 Volume) + (Filter 2 Volume) + (Filter 3 Volume)
(Imperial) = 474.6 + 455.4 + 470.1 = 1400.1 cfm
(Metric) = 809 + 880 + 799 = 2488 m 3 /hr
For a nominal filter size of 20 x 16, the conversion factor is 1.90 Imperial (.177 Metric)
Volume for one filter = Conversion Factor x Average Velocity
(Imperial) = 1.90 x 249.8 ft/min. = 474.6 cfm
(Metric) = .177 x 4568 m/hr = 809 m 3 /hr
Example: Exhaust only hood with three 20 x 16 filters
Measured velocities in ft/min. for one 20 x 16 filter
Average Velocity =
Sum of Velocity Readings
Number of Readings
(Imperial) =
255 + 250 + 256 + 248 + 240
5
= 249.8 ft/min.
(Metric) =
4663 + 4572 + 4681 + 4535 + 4389
5
= 4568 m/hr
255
(4663.44 m/h)
248
(4535.42 m/h)
256
(4681.73 m/h)
240
(4389.12 m/h)
250
(4572 m/h)
Measure and record the velocity of each location.
A digital 2.75 in. (69.85 mm) rotating vane anemometer
or equivalent is suggested. The center of the
anemometer should be held 2 in. (50.8 mm) from the
face of the filters. It is helpful to make a bracket to keep
Calculate the average velocity for the filter.
3. Determine the filter’s conversion factor from the
table.
4. Calculate the filter’s volume in CFM (m 3 /hr) by
multiplying the average velocity by the conversion
factor.
5. Calculate the hood’s volume by repeating the
process for the remaining filters and summing the
individual filter volumes.
X
X
X
H/4
H/4
H/2
H
L
X
X
Fig. 7
Nominal Filter Size
Testing Hood Air Volume
Baffle Filter - Rotating Vane Method
With all the filters in place, determine the total hood
exhaust volume with a rotating vane anemometer as
follows:
1. All cooking equipment should be on.
2. Measure the velocities. Velocity measurements
should be taken at five locations per filter. These
must be over a filter slot as in Fig. 7.
the anemometer at the 2 in. (50.8 mm) distance and
parallel to the filter. Both squareness and distance are
very important for accuracy.