Greenheck Fan PN 458294 manual Volume with a rotating vane anemometer as follows

Fig. 32

2 in.

1/2 Height

Fig. 31

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		1/2 Width
volume with a rotating vane anemometer as follows:	1/4 Width	1/4 Width

1. All cooking equipment should be off. If the hood has internal short circuit make-up air, it should be turned off.

2.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 2.75 in.

(70 mm) rotating vane anemometer or its equivalent is suggested. The center of the anemometer should be held

2 in. (50 mm) from the face of the filters as in Fig. 32. It is helpful to make brackets to keep the anemometer at the 2 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.

Rotating Vane Anemometer

Nominal Filter Size (H x L)		Imperial	Metric
Inches	Millimeters	Conversion Factor	Conversion Factor
16 x 16	400 x 400	1.31 ft2	.122 m2
16 x 20	400 x 500	1.65 ft2	.153 m2
20 x 16	500 x 400	1.23 ft2	.114 m2
20 x 20	500 x 500	1.65 ft2	.153 m2

Example: (Imperial)

Hood Length = 7 feet 0 inches with four 20 x 20 filters.

Measure the velocities in fpm for each 20 x 20 filter (six readings per filter)

	Filter 1	225	201		187
		210	238		197
	Filter 2	228	222		226
		237	240		220
	Filter 3	230	245		240
		250	223		219
	Filter 4	225	265		219
		245	221		200
Average slot velocity for Filter 1				=	Sum of Velocity Readings
					Number of Readings
				=	1258	= 209.7 fpm
					6

(repeat for each filter)

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 ft2	x	209.7 ft./min.
=	346.0 cfm (repeat for each filter)

Total hood volume

=Filter 1 + Filter 2 + Filter 3 + Filter 4 Volume Volume Volume Volume

=346.0 + 377.6 + 386.9 + 378.1 = 1488.6 cfm

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)

	Filter 1	4114.80	3675.88		3419.86
		3840.48	4352.54		3602.74
	Filter 2	4169.66	4059.94		4133.08
		4334.26	4389.21		4023.36
	Filter 3	4420.12	4480.56		4389.12
		4572.00	4078.22		4005.07
	Filter 4	4114.80	4846.52		4005.07
		4480.56	4041.65		3657.60
Average slot velocity for Filter 1				=	Sum of Velocity Readings
					Number of Readings
				=	23006	= 3834 m/hr
					6

(repeat for each filter)

For a nominal filter size of 500 x 500, the conversion factor is .153

Volume for Filter 1 = Conversion Factor		x	Average Velocity
=	.153 m2	x	3834 m/hr
=	586.7 m3/hr (repeat for each filter)

Total hood volume

=Filter 1 + Filter 2 + Filter 3 + Filter 4 Volume Volume Volume Volume

= 587 + 642 + 657 + 642 = 2528 m3/hr

22 Proximity Hood

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