Troubleshooting guide

21
14 in.
10 in.
2.75 in.
Fig. 32
Fig. 33
Fig. 34
Nominal Filter Size (H x L)
Imperial
Conversion Factor
Metric
Conversion Factor
Inches Millimeters
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
Testing Hood Air Volume
17.25 in.
6 in.
10 in.
2.75 in.
14 in.
10 in.
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.
Example: Measured velocities for 20 x 20 filter = 185 and 189 fpm
Average Velocity =
Sum of Velocity Readings
Number of Readings
(Imperial)
=
185 + 189
2
= 187.0 fpm
(Metric)
=
3383 + 3456
2
=
3420 m/hr
Flow rate for one filter =
Conversion
Factor
x
Average
Velocity
= 2.40 x 187.0 fpm = 448.8 cfm
= .223 x 3420 m/hr = 763 m
3
/hr
Total hood flow rate =
(Filter 1
Flow Rate)
+ … +
(Filter X
Flow Rate)
= 448.8 + 457.8 + 437.5 + 444.8 = 1788.9 cfm
= 763 + 778 + 743 + 756 = 3040 m
3
/hr
Fig. 31