Accurex XB Installation, Operation And Maintenance Manual page 17

Baffle Filter - Shortridge Method
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. Measure velocities
• Set up the Shortridge meter.
• For 20 in. (500 mm) wide filters, position the
grid as shown in Fig. 8 and 9. Average the two
measurements.
• For 16 in. (400 mm) wide filters, position the grid as
shown in Fig. 10.
• Take velocity readings for each filter.
3. Calculate each filter's volumetric flow rate as follows:
Calculate each filter's average velocity by summing
the velocity readings and dividing by the number of
readings for each filter.
Multiply the average velocity by the conversion factor
to obtain the volumetric flow rate for each filter.
4. Calculate the hood's total volumetric flow rate by
summing the volumetric flow rate of each individual
filter in the hood as calculated in Step 3.
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 a 20 x 20 filter = 185 and 189 ft/min.
Sum of Velocity Readings
Average Velocity =
185 + 189
=
(Imperial)
3383 + 3456
=
(Metric)
Flow rate for one filter =
=
(Imperial)
=
(Metric)
Total hood flow rate = (Filter 1 Flow Rate) +
= 448.8 + 457.8 + 437.5 + 444.8 =
(Imperial)
= 763 + 778 + 743 + 756
(Metric)
Number of Readings
= 187.0 ft/min.
2
= 3420 m/hr
2
Conversion Average
x
Factor Velocity
2.40 x 187.0 ft/min.
.223 x 3420 m/hr
...
Place standoff spacers against
face of outlet or inlet grill,
filter, coil, etc.
Maintain 1½ inch
(38.1 mm) margin
Swivel bracket
Tubing connectors
Extension rods
Captive knob screws
Nominal Filter Size (H x L)
Inches Millimeters
16 x 16 400 x 400
16 x 20 400 x 500
20 x 16 500 x 400
20 x 20 500 x 500
= 448.8 cfm
3
= 763 m /hr
+ (Filter x Flow Rate)
1788.9 cfm
3
= 3040 m /hr
Kitchen Hoods • Type I and Type II
Edge of outlet/inlet
active face area
Maintain 1½ inch
(38.1 mm) margin
Tubing harness
Pressure input ports
Neckstrap
External read jack
Pushbutton handle and plug
Handle bracket
Imperial Metric
Conversion Conversion
Factor Factor
1.66 .154
2.10 .195
1.96 .182
2.40 .223
14 in. 14 in.
(355.6 mm) (355.6 mm)
2.75 in. 2.75 in.
(69.85 mm) (69.85 mm)
Fig. 8
17.25 in. 17.25 in.
(2978.15 mm) (2978.15 mm)
6 in. 6 in.
(152.4 mm) (152.4 mm)
Fig. 9
14 in. 14 in.
(355.6 mm) (355.6 mm)
2.75 in. 2.75 in.
(69.85 mm) (69.85 mm)
Fig. 10
10 in. 10 in.
(254 mm) (254 mm)
10 in. 10 in.
(254 mm) (254 mm)
10 in. 10 in.
(254 mm) (254 mm)
17