UEi Test Instruments DAFM3 - Manual (Page 9)

A register example is 4” by 10”. The area of
this in square inches is 4 x 10 = 40 square
inches. Next convert that to square feet
dividing by 144 results in 0.278 square feet.
This would give the total area if it were open,
but because the grill covers a portion of this
we need to estimate the amount of area that is
really open.
Below is an example of the steps needed to determine this area:
On a grill, the overall dimensions are not open, or “Free Area.” Entering
dimensions on this would cause a large error. For best results use the
Ak specification from grill manufacturer.
If needed an estimation may be used for comparison
First calculate the total free area of the grill, then take a percentage of
that to enter into the instrument.
On this 4x10 grill, we had calculated the total area At 0.278 square feet.
If we estimate only 70% of the area is truly open, the are would be
0.278 x 0.70 = 0.195 sq. feet
One estimation method would be to measure the area of the louvers
and use length x width. There will still be errors using this approach,
but in comparison analysis the error will be small.
Entering Information into the DAFM3
The first thing to notice is the keypad
labels have two different items under
most buttons. The top line is the activity
that occurs on a short press of the button.
The second (in brackets) line is the activity
that occurs on a long press. This is key to
understanding how to navigate through
the DAFM3 during use.
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10”
10”
On a grill, the overall dimensions are not open, or “Free Area”
Entering dimensions on this would cause a large error
For best results use the Ak specification from grill manufacture.
If needed an estimation may be used for comparison
First calculate the total free area of the grill, then take a
Percentage of that to enter into the instrument.
On this 4x10 grill, we had calculated the total area
At 0.278 square feet. If we estimate only 70% of the area
Is truly open, the are would be
0.278 x 0.70 = 0.195 sq. feet
One estimation method would be to measure the area of the louvers
and
use length x width. There will still be errors using this approach, but in
comparison analysis the error will be small.
*note 4x10 floor register from Hart and Cooley engineering data
shows this register has a free area of 0.20 square feet
4”
12”
12
”
Area is length x width
12”x12”=144 sq. inches
Converting to sq. ft.
144 sq inches/144=1 sq
ft
Area is length x width
12”x12”= 144 sq. inches
Converting to sq. ft.
144 sq. inches = 1 sq ft.
4”
10”