Accurex 470400 Installation, Operation And Maintenance Manual page 22

Grease-X-Tractor™ High Efficiency Filters or Grease Grabber™ Multi-Filtration System
A. Exhaust
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 off. If the hood has internal
short circuit make-up air, it should be turned off.
. Measuring Velocities
• Measurement should be taken at six locations per filter.
They must be over the inlet opening as shown in Fig. 31.
• Measure the velocity of each location. A digital .75 in.
(70 mm) rotating vane anemometer or its equivalent is
suggested. The center of the anemometer should be held
 in. (50 mm) from the face of the filters as in Fig. 3. It is helpful to make brackets to keep the
anemometer at the  in. (50 mm) distance and parallel to the filter. Both squareness and distance
are important for accuracy.
3. Calculate the average velocity for the filter.
4. Determine the filter's conversion factor from the table.
5. Calculate each filters volume in CFM by multiplying the average velocity
by the conversion factor.
Nominal Filter Size (H x L)
Inches Millimeters
16 x 16 400 x 400
16 x 0 400 x 500
0 x 16 500 x 400
0 x 0 500 x 500
Example: (Imperial)
Hood Length = 7 feet 0 inches with four 0 x 0 filters.
Measure the velocities in fpm for each 0 x 0 filter
(six readings per filter)
5
Filter 1
10
8
Filter 
37
30
Filter 3
50
5
Filter 4
45
Average slot velocity for Filter 1
For a nominal filter size of 0 x 0, the conversion factor is 1.65
Volume for Filter 1 = Conversion Factor x Average Velocity
=
= 346.0 cfm (repeat for each filter)
Total hood volume
Filter 1 Filter  Filter 3
= + +
Volume Volume Volume
= 346.0 + 377.6 + 386.9 + 378.1 = 1488.6 cfm

1/4 Width
Imperial
Conversion Factor
1.31
1.65
1.3
1.65
01 187
38 197
 6
40 0
45 40
3 19
65 19
1 00
Sum of Velocity Readings
=
Number of Readings
158
= = 09.7 fpm
6
(repeat for each filter)

1.65 ft x 09.7 ft./min.
Filter 4
+
Volume
1/4 Width
1/2 Width
1/4 Width
1/2 Height
Metric
Conversion Factor

ft m
.1

ft m
.153

ft m
.114

ft m
.153
Example: (Metric)
Hood Length = .13 meters, with four 500 x 500 mm filters.
Measure the velocities in m/hr for each 500 x 500 mm filter
(six readings per filter)
4114.80
Filter 1
3840.48
4169.66
Filter 
4334.6
440.1
Filter 3
457.00
4114.80
Filter 4
4480.56
Average slot velocity for Filter 1
For a nominal filter size of 500 x 500, the conversion factor is .153
Volume for Filter 1 = Conversion Factor x Average Velocity
=
= 586.7 m
Total hood volume
Filter 1 Filter 
= + +
Volume Volume
= 587 + 64 +
1/2 Width
Rotating Vane
Anemometer




3675.88 3419.86
435.54 360.74
4059.94 4133.08
4389.1 403.36
4480.56 4389.1
4078. 4005.07
4846.5 4005.07
4041.65 3657.60
Sum of Velocity Readings
=
Number of Readings
3006
= =
6
(repeat for each filter)

.153 m x 3834 m/hr
3
/hr (repeat for each filter)
Filter 3 Filter 4
+
Volume Volume
657 + 64 = 58 m
1/4 Width
1/2 Height
Rotat
Anem
Fig. 31
2 in.
Fig. 3
3834 m/hr
3
/hr