Greenheck Fan 452413 manual Testing Hood Air Volume

Testing Hood Air Volume

Baffle Filters Style Hoods with the Shortridge Meter 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.

•For 20 in. (500 mm) wide filters, position the grid as shown in Fig. 32 and 33. Average two measurements.

•For 16 in. (400 mm) wide filters position the grid as shown in Fig. 34.

•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	1.66	.154
16 x 20	400 x 500	2.10	.195
20 x 16	500 x 400	1.96	.182
20 x 20	500 x 500	2.40	.223

Example: Measured velocities for 20 x 20 filter = 185 and 189 fpm
Average Velocity	=	Sum of Velocity Readings					Fig. 32
		Number of Readings
(Imperial)	=	185 + 189	=	187.0 fpm
		2
(Metric)	=	3383 + 3456 =		3420 m/hr
		2
Flow rate for one filter	=	Conversion	x	Average			Fig. 33
		Factor		Velocity
	=	2.40	x	187.0 fpm	=	448.8 cfm
	=	.223	x	3420 m/hr	=	763 m3/hr
		(Filter 1		(Filter X
Total hood flow rate	=	Flow Rate)	+	… + Flow Rate)
	=	448.8 + 457.8 + 437.5 + 444.8 =				1788.9 cfm	Fig. 34
	=	763 + 778 + 743 + 756			=	3040 m3/hr

21Canopy Hood

Fig. 31

14in. 2.75 in.

10 in.

17.25 in.

6 in.

10 in.

14in.

2.75 in.

10 in.

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