14.5 in.
.75 in.
.75 in.
.5 in.
3.5 in.
14.75 in.
14.5 in.
.75 in.
.75 in.
Fig. 34
Fig. 36
Fig. 35
Nominal Filter Size (H x L)
Imperial
Conversion Factor
Metric
Conversion Factor
Inches
Millimeters
16 x 16
400 x 400
1.53
ft
.14
m
16 x 0
400 x 500
.00
ft
.185
m
0 x 16
500 x 400
.5
ft
.09
m
0 x 0
500 x 500
3.00
ft
.79
m
Grease-X-Tractor™ High Efficiency Filters or Grease Grabber™ Multi-Filtration System
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.
• For 0 in. (500 mm) high filters, position the grid
as shown in Fig. 34 and 35. Average the two
measurements.
• For 16 in. (400 mm) high filters position the grid as
shown in Fig. 36.
• For 0 in. (500 mm) wide filters, position the grid over
the left and right side of the filter. Average the two
measurements.
• 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.
3
Flow rate for one filter = Conversion Factor x
Average Velocity
=
3.0
x
01.5 fpm
=
604.5 cfm
=
.79
x
3385 m/hr
=
944 m
3
/hr
Total hood flow rate
=
Filter 1
Flow Rate +
…
+
Filter X
Flow Rate
=
604.5
+
600.3
+
59.4
+
613.3
=
410.5 cfm
944
+
100
1006
+
104
=
401 m
3
/hr
Example:
Measured velocities for 0 x 0 in. (500 x 500 mm) filter.
Average slot velocity
=
Sum of Velocity Readings
Number of Readings
(Imperial)
=
198 + 05
= 01.5 fpm
(Metric)
= 301 + 3749
= 3385 m/hr
Fig. 33
