1450 First Ave.
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(800) 283-1141 or (715) 723-1141
Fax: (715) 723-7890
DTA4000 User Manual
Pacer Instruments, Inc
Rev 1.0
www.pacer-instruments.com
11-Aug-2007
Phone: 1-800-283-1141
APPENDIX D – AIRFLOW VOLUME CALCULATIONS
Theory:
To calculate cubic feet per minute (CFM) from a measured air velocity (FPM), you need the
calculated cross-sectional area of the airflow stream:
Volume Flow (CFM) = Velocity (FPM) X Area (sq ft).
In rectangular ductwork this cross sectional area equals the Width times the Height.
W x H=A (cross-sectional area)
In circular ductwork this cross section area equals the radius squared times
π
(3.14).
R x R x 3.14=A (cross-sectional area)
To convert an area calculated in square inches to an area calculated in square feet (which is
required for the Volume Flow equation above) divide by 144: (area in sq in.)/144 = (area in sq
ft.).
Example:
The air duct is rectangular, the width is 24 in. and the height is 12 in. The air velocity reading
through the duct is 450 FPM. Calculate the Volume Flow.
Step 1:
Cross-sectional area = 24 in. x 12 in. = 288 sq in.
Step 2:
288 sq in /144 = 2 sq ft.
Step 3:
Volume flow = Air Velocity x Area, therefore, Volume flow rate = 450 FPM x 2 sq ft. = 900
CFM.
APPENDIX E – ERROR CODES
“E-02”
Data logger is filled to maximum capacity of 999 SAVED measurements.
“E-03”
Storage is empty. No measurements have been SAVED since last time memory was cleared.
“E-04”
No communication is occurring through the RS232 data link with the printer or PC.
“E-08”
Temperature is below range (<-99.9 ºC or ºF).
“E-09”
Temperature is above range (>300.0ºC or >575ºF).
“E-XX”
Error codes of 50 or higher are internal errors. In this case, contact the manufacturer.
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