Greenheck Fan 452413 - Manual (Page 25)

25 Canopy Hood
®
14.25 in.
2.75 in.
2.75 in.
2.5 in.
3.25 in.
14.75 in.
14.25 in.
2.75 in.
2.75 in.
Fig. 42
Fig. 44
Fig. 43
Nominal Filter Size (H x L) Imperial
Conversion Factor
Metric
Conversion Factor Inches Millimeters
16 x 16 400 x 400 1.53 ft 2 .142 m 2
16 x 20 400 x 500 2.00 ft 2 .185 m 2
20 x 16 500 x 400 2.25 ft 2 .209 m 2
20 x 20 500 x 500 3.00 ft 2 .279 m 2
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. 42 and 43. Average the two
measurements.
• For 16 in. (400 mm) high filters position the grid as
shown in Fig. 44.
• 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.
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 m 3 /hr
Total hood flow rate =
Filter 1
Flow Rate +
… +
Filter X
Flow Rate
= 604.5 + 600.3 + 592.4 + 613.3 = 2410.5 cfm
944 + 1020 1006 + 1042 = 4012 m 3 /hr
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
2
= 201.5 fpm
(Metric)
= 3021 + 3749
2
= 3385 m/hr
Fig. 41