1
High Velocity Cartridge Filters
1/ width
1/ height
Fig. 30
Nominal Filter Size (H x L)
Imperial
Conversion Factor
Metric
Conversion Factor
Inches
Millimeters
16 x 16
400 x 400
1.
ft
.113
m
16 x 0
400 x 500
1.67
ft
.155
m
0 x 16
500 x 400
1.1
ft
.11
m
0 x 0
500 x 500
1.50
ft
.139
m
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. 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 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. 9
Total hood flow rate
= (Filter 1 Flow Rate) + … + (Filter X Flow Rate)
= 43.0 + 41.8 + 40.7 + 418. = 1683.7 cfm
Flow rate for one filter
= Conversion
Factor
x
Average
Velocity
(Imperial)
=
1.50
x
8 fpm
=
43.0 cfm
(Metric)
=
.139
x 5157 m/hr =
717 m
3
/hr
Example:
Measured velocities for 0 x 0 filter = 8 fpm (5157 m/hr)
= 717 + 717 + 715 + 711
= 860 m
3
/hr
