Perforated Face Supply/External Supply Plenum - Accurex XBEW Installation, Operation And Maintenance Manual

Perforated Face Supply or External Supply
Plenum - Rotating Vane Method
1. Hood set up.
Turn on both exhaust and supply air. If the make-up
air unit has temperature control, it should be used to
keep the supply air at the desired room discharge air
temperature.
2. Measure velocities.
Divide the first perforated face panel or air supply
plenum perforated panel into a grid of equal areas,
each approximately 4 in. (101.6 mm) square.
Measure the velocity at the center of each grid
area. A digital 2.75 in. (69.85 mm) rotating vane
anemometer or equivalent is suggested. The center
of the anemometer should be held tight to the
face of the panel. Both squareness and distance
are important for accuracy. Calculate the average
velocity of the panel.
3. Measure the length and height of the perforated
panel.
Example: Face supply hood with three 28 inch (.711 m) by 16 inch (.406 m) perforated panels
Measured velocities in ft/min. for one perforated panel
Average Velocity =
=
(Imperial)
=
(Metric)
Measure length and height. 28 inches (.711 m) long perforated panel by 16 inches (.406 m) high
Volume for one panel = Conversion Factor x
=
(Imperial)
=
(Metric)
Total system volume =
=
(Imperial)
=
(Metric)
20 Kitchen Hoods • Type I and Type II
Sum of Velocity Readings
Number of Readings
260 + 250 + ... + 265 + 260
28
4755 + 4572 + ... + 4846 + 4755
28
Average Velocity
0.005 x
0.72 x
(Panel 1 Volume) + (Panel 2 Volume)
606.4 +
1029 +
4. Calculate the perforated panel volume using the
following formula:
CFM = avg. velocity x length (in.) x height (in.) x 0.005
3
m /hr = avg. velocity x length (m) x height (m) x 0.72
5. Calculate the system's volume by repeating the
process for the remaining perforated panels and
adding the individual panel volumes together.
Filter Readings (ft/min.)
260 250
270 275
290 285
285 275
4755 4572
4938 5029
5304 5212
5212 5029
= 270.7 ft/min.
= 4951 m/hr
x Length
270.7 ft/min. x 28
4951 m/hr x .711
+ (Panel 3 Volume)
614.3 +
1044 +
255 260 250 255
270 280 265 265
280 280 275 290
280 260 270 265
Filter Readings (m/hr)
4663 4755 4572 4663
4938 5121 4846 4846
5121 5121 5029 5304
5121 4755 4938 4846
x Height
x 16 = 606.4 cfm
x .406 = 1029 m
593.8 = 1814.5 cfm
1009 = 3082 m
265
270
295
260
4846
4938
5395
4755
3
/hr
3
/hr