Greenheck Fan High Efficiency Grease Filters and Greenheck Filter Box for Ventilation Hoods

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 shortridge meter as follows:

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

2.Measuring Velocities

•Set up the shortridge meter. Leave all holes of Velgrid open. Do NOT tape over holes that are not over openings. The conversion factor takes this into account.

•For 20 in. (500 mm) high filters, position the grid as shown in Fig. 34 and 35. Average the two measurements.

•For 16 in. (400 mm) high filters position the grid as shown in Fig. 36.

•For 20 in. (500 mm) wide filters, position the grid over the left and right side of the filter. Average the two measurements.

•Take velocity readings for each filter.

3.*Calculate each filter’s volumetric flow rate by summing the flow rate of each individual filter in the hood.

4.*Calculate the total hood’s volumetric flow rate by summing the flow rate of each individual filter in the hood.

*Note: For best accuracy multiply the velocity of each filter by its conversion factor and sum the flow rates. Averaging the velocity measured for all filters may cause error.

Nominal Filter Size (H x L)						Imperial					Metric
Inches		Millimeters			Conversion Factor						Conversion Factor
16 x 16		400 x 400				1.53 ft2					.142 m2
16 x 20		400 x 500				2.00 ft2					.185 m2
20 x 16		500 x 400				2.25 ft2					.209 m2
20 x 20		500 x 500				3.00 ft2					.279 m2
Example:
Measured velocities for 20 x 20 in. (500 x 500 mm) filter.
Average slot velocity		=	Sum of Velocity Readings
				Number of Readings
(Imperial)		=	198 + 205			=	201.5 fpm
				2
(Metric)		=	3021 + 3749			=	3385 m/hr
				2
Flow rate for one filter	=	Conversion Factor x			Average Velocity
	=	3.0		x		201.5 fpm			=	604.5 cfm
	=	.279		x		3385 m/hr			=	944 m3/hr
Total hood flow rate	=	Filter 1	+	…	+	Filter X
		Flow Rate				Flow Rate
	=	604.5	+	600.3	+	592.4		+	613.3 =		2410.5 cfm
		944	+	1020		1006		+	1042	=	4012 m3/hr

Fig. 34

Fig. 35

2.5 in.

Fig. 36

Fig. 33

14.25in.

2.75in.

2.75 in.

3.25in.

14.75in.

14.25in.

2.75 in.

2.75 in.

23 Proximity Hood

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