19
Testing Hood Air Volume
17.5 in.
10 in.
6 in.
.75 in.
14 in.
Fig. 4
Fig. 5
Fig. 6
10 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.
. Measuring Velocities
• Set up the shortridge meter.
• For 0 in. (500 mm) wide filters, position the grid as
shown in Fig. 4 and 5. Average two measurements.
• For 16 in. (400 mm) wide filters position the grid as
shown in Fig. 6.
• 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.
Fig. 3
Example:
Measured velocities for 0 x 0 filter = 185 and 189 fpm
Average Velocity
=
Sum of Velocity Readings
Number of Readings
(Imperial)
=
185 + 189
= 187.0 fpm
(Metric)
=
3383 + 3456
= 340 m/hr
Flow rate for one filter = Conversion
Factor
x
Average
Velocity
=
.40
x
187.0 fpm
= 448.8 cfm
=
.3
x
340 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
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 0
400 x 500
.10
.195
0 x 16
500 x 400
1.96
.18
0 x 0
500 x 500
.40
.3
14 in.
.75 in.
