High Velocity Cartridge Filters
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
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.
•Position the grid over each filter as shown.
•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 | Fig. 37 | |
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 | 1.22 ft2 | .113 m2 |
16 x 20 | 400 x 500 | 1.67 ft2 | .155 m2 |
20 x 16 | 500 x 400 | 1.21 ft2 | .112 m2 |
20 x 20 | 500 x 500 | 1.50 ft2 | .139 m2 |
Example: Measured velocities for 20 x 20 filter = 282 fpm (5157 m/hr)
Flow rate for one filter | = | Conversion | x | Average |
|
|
|
| Factor |
| Velocity |
|
|
(Imperial) | = | 1.50 | x | 282 fpm | = | 423.0 cfm |
(Metric) | = | .139 | x | 5157 m/hr | = | 717 m3/hr |
Total hood flow rate = | (Filter 1 Flow Rate) + | … + (Filter X Flow Rate) |
= | 423.0 + 421.8 + 420.7 + 418.2 = 1683.7 cfm | |
= | 717 + 717 + 715 + 711 | = 2860 m3/hr |
1/2 width
1/2 height
Fig. 38
23 Canopy Hood
®
