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
2.Measuring Velocities
•Set up the shortridge meter.
•For 20 in. (500 mm) wide filters, position the grid as shown in Fig. 24 and 25. Average two measurements.
•For 16 in. (400 mm) wide filters position the grid as shown in Fig. 26.
•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 |
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16 x 16 | 400 x 400 | 1.66 | .154 |
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16 x 20 | 400 x 500 | 2.10 | .195 |
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20 x 16 | 500 x 400 | 1.96 | .182 |
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20 x 20 | 500 x 500 | 2.40 | .223 |
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Example: Measured velocities for 20 x 20 filter = 185 and 189 fpm |
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Average Velocity | = | Sum of Velocity Readings |
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| Fig. 24 | |||
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| Number of Readings |
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(Imperial) | = | 185 + 189 |
| = | 187.0 fpm |
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| 2 |
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(Metric) | = | 3383 + 3456 |
| = | 3420 m/hr |
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| 2 |
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Flow rate for one filter | = | Conversion | x |
| Average |
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| Factor |
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| Velocity |
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| Fig. 25 |
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| = | 2.40 | x |
| 187.0 fpm | = | 448.8 cfm |
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| = | .223 | x |
| 3420 m/hr | = | 763 m3/hr |
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| (Filter 1 |
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| (Filter X |
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Total hood flow rate | = | Flow Rate) | + |
| … + Flow Rate) |
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| = | 448.8 + 457.8 + 437.5 + 444.8 = | 1788.9 cfm |
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| = | 763 + 778 + 743 + 756 | = | 3040 m3/hr | Fig. 26 |
Fig. 23
14in.
2.75in.
10 in.
17.25 in.
6 in.
10 in.
14in.
2.75 in.
10 in.
19 Proximity Hood
®