With High Efficiency Filters (Gx Series) - Greenheck Type I Installation, Operation And Maintenance Manual

Grease-X-Tractor™ High Efficiency Filters or
Grease Grabber™ Multi-Filtration System
Rotating Vane Method
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.
2. Measure velocities
Measurement should be taken at six locations per
filter. They must be over the inlet opening as shown
in Fig. 13.
Measure the velocity of each location. A digital
2.75 in. (69.85 mm) rotating vane anemometer
or its equivalent is suggested. The center of the
anemometer should be held 2 in. (50.8 mm) from
the face of the filters as in Fig. 14. It is helpful to
make brackets to keep the anemometer at the 2 in.
(50.8 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 filter's volumetric flow rate in CFM by
multiplying the average velocity for each filter by the
conversion factor.
Example: (Imperial)
Hood Length: 7 feet 0 inches with four 20 x 20 filters.
Measure the velocities in ft/min. for each 20 x 20 filter
(six readings per filter)
225 201
Filter 1
210 238
228 222
Filter 2
237 240
230 245
Filter 3
250 223
225 265
Filter 4
245 221
Average slot velocity for Filter 1
For a nominal filter size of 20 x 20, the conversion factor is 1.65
Volume for Filter 1 = Conversion Factor x Average Velocity
= 1.65 ft
= 346.0 cfm (repeat for each filter)
Total hood volume
Filter 1 Filter 2 Filter 3
= + +
Volume Volume Volume
= 346.0 + 377.6 + 386.9 + 378.1 = 1488.6 cfm
18 Kitchen Hoods • Type I and Type II
187
197
226
220
240
219
219
200
Sum of Velocity Readings
=
Number of Readings
1258
= = 209.7 ft/min.
6
(repeat for each filter)
2
x 209.7 ft/min.
Filter 4
+
Volume
Fig. 13
1/4 Width
Nominal Filter Size (H x L)
Inches Millimeters
16 x 16 400 x 400
16 x 20 400 x 500
20 x 16 500 x 400
20 x 20 500 x 500
Example: (Metric)
Hood Length: 2.13 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 3675.88
Filter 1
3840.48 4352.54
4169.66 4059.94
Filter 2
4334.26 4389.21
4420.12 4480.56
Filter 3
4572.00 4078.22
4114.80 4846.52
Filter 4
4480.56 4041.65
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
= .153 m
= 586.7 m
Total hood volume
Filter 1 Filter 2 Filter 3
= + +
Volume Volume Volume
= 587 + 642 + 657
1/2 Width
1/4 Width
1/2 Height
2 in.
(50.8 mm)
Rotating Vane
Anemometer
Fig. 14
Imperial Metric
Conversion Conversion
Factor Factor
2
ft m
1.31 .122
2
ft m
1.65 .153
2
ft m
1.23 .114
2
ft m
1.65 .153
3419.86
3602.74
4133.08
4023.36
4389.12
4005.07
4005.07
3657.60
Sum of Velocity Readings
=
Number of Readings
23006
= = 3834 m/hr
6
(repeat for each filter)
Average Velocity
2
x 3834 m/hr
3
/hr (repeat for each filter)
Filter 4
+
Volume
3
+ 642 = 2528 m /hr
2
2
2
2
®