The DAFM3B Anemometer/Psychrometer is designed with 6 HVAC/R
parameters in one instrument. These are included in a portable, batteryoperated instrument for measuring humidity, air temperature, dew point,
wet bulb, air velocity and air volume. The vane probe includes
sensors for velocity, temperature and humidity.
FEATURES
• Measures Air Velocity, Temperature, and Relative Humidity (RH%)
• Calculates Wet-bulb temperature, dew point, and air volume
(CFM, CMM)
• 3” diameter air vane
• Timed accumulative average for air volume with one hour maximum
• Min/Max and Hold
• English/Metric Scales
• Fast response
• Auto-power off (can be disabled)
• Low battery indicator
INCLUDED
• DAFM3B Meter
• Air vane probe
• Battery (1 x 9V)
• User manual
• Hard carrying case
SAFETY NOTES
Before using this meter, read all safety information carefully. In this
manual the word “WARNING” is used to indicate conditions or actions
that may pose physical hazards to the user. The word “CAUTION” is
used to indicate conditions or actions that may damage the instrument.
CAUTION! Do not strike the fan portion of the probe.
With the meter off, press and hold ON/OFF and HOLD for more than two
seconds. The display will show an “n” indicating that auto power off is
disabled.
SELECTING UNITS
• With the meter off press and hold ON/OFF (Set) button for more
than two seconds.
• Press MIN/MAX AVG ( ) to select unit (P10)
• Press or to switch units
• Press MIN/MAX AVG ( ) to select choice
• Press EXIT to return to normal operation
BASIC MEASUREMENT
When the DAFM3B is first powered on, air velocity is the default display.
To view other parameters press “MODE” key. Each parameter will be
displayed in turn.
• VOL – Air volume in CFM or CMM, based on dimensions entered
Note: Icon at bottom of screen will indicate the method used to
calculate volume (LW-Length/Width, D-Diameter, A – Area).
• TA – Ambient Temperature measured at the probe tip
• RH – Relative Humidity measured at the probe tip
• WBT – Wet Bulb Temperature calculated from measured
temperature and RH%
• DP – Dew Point Temperature calculated from measured
temperature and humidity
MEASURING AIR VOLUME (CFM OR CMM)
Measuring air volume with the DAFM3B has two steps. The first step is
to enter the characteristics of the area being measured. There are three
methods to enter this and depend on the location of your measurement.
If measuring square duct work you would enter Length and Width (LW). For round duct you would enter Diameter (D). If measuring the
exit with a grill it is recommended to use the effective area or free
area (A) from the grill manufacture. If this is not known, the air volume
measurement will be an estimate.
Note: Grill manufacturers often provide engineering data on
effective or free area. This is indicated as the Ak value.
ENTERING DUCT INFORMATION
1. Press MODE until VOL is showing in the upper right corner of the
display
2. Press LW-D-AREA until the desired method is showing in the
lower left corner of the display
3. Press MIN/MAX AVG ( ) to select this mode
a. Press (HOLD) to increase the value
b. Press (LW-D-AREA) to decrease the value
c. Press MIN/MAX AVG ( ) to accept the displayed value
Note: Press and hold to scroll through the values quickly.
Release and then press briefly to increase or decrease one
digit at a time.
After entering the duct characteristics you will be taken back to the
display for Air Volume. Hold the probe in the area to be measured for a
direct display of air volume.
To obtain air volume on a grill with unknown effective or free area you
must estimate the free area. This is difficult, but can be used to provide
an estimate of the volume for comparison testing. If multiple grills of the
same design are compared using this method, you will have an accurate
relative comparison, although the actual value may not be exact.
Method 1
• Measure length and width in inches.
• Obtain overall area in square inches by multiplying length
times width.
• Divide square inches by 144 to convert to square feet.
• Multiply the result by 0.70 (70%) to estimate the actual
open area.
Note: For return registers that are more open, increase the factor to
0.9 (90% open). For louvered registers with much more covered area
decrease to 0.5 or 0.6 (50~60% open).
Example – 4”x10” residential floor register
•Step 1 – 4” and 10”
•Step 2 – 4 x 10 = 40 square inches
•Step 3 – 40 ÷ 144 = 0.2777 square feet
•Step 4 – 0.277 x 0.70 = 0.194 square feet
(use this when entering free area “A” on the DAFM3B)
Method 2
Measure the grill area inside the frame of the register, calculate area in
square inches and convert to square feet using the method 1 steps. You
do not need to perform step 4.
Example – 4”x10” floor register
•Step 1 – actual louver area dimensions are 9” x 3.5”
•Step 2 – 9 x 3.5 = 31.5 square inches
•Step 3 – 31.5 ÷ 144 = .219 square feet
Note: This method may result in a slightly elevated result as it does not
fully remove the louvers that are in the air path.
When the low battery “ ” icon appears on the display, all readings will
change to “ “ to prevent inaccurate results. Change the 9V battery
located in the inner compartment on the rear of the instrument.
CLEANING
Periodically clean your meters case using a damp cloth (not wet) only.
DO NOT use abrasive, flammable liquids, cleaning solvents, or strong
detergents as they may damage the finish, impair safety, or affect the
reliability of the structural components.
BATTERY REPLACEMENT:
Remove screw from the battery compartment cover on the back of your
meter and remove cover. Replace battery with a fresh 9 Volt battery
paying attention to polarity. Replace cover and secure with screw.
The DAFM3B is warranted to be free from defects in materials and
workmanship for a period of one year from the date of purchase. If
within the warranty period your instrument should become inoperative
from such defects, the unit will be repaired or replaced at UEi’s option.
This warranty covers normal use and does not cover damage which
occurs in shipment or failure which results from alteration, tampering,
accident, misuse, abuse, neglect or improper maintenance. Batteries
and consequential damage resulting from failed batteries are not
covered by warranty.
Any implied warranties, including but not limited to implied warranties
of merchantability and fitness for a particular purpose, are limited
to the express warranty. UEi shall not be liable for loss of use of the
instrument or other incidental or consequential damages, expenses, or
economic loss, or for any claim or claims for such damage, expenses
or economic loss.
A purchase receipt or other proof of original purchase date will be
required before warranty repairs will be rendered. Instruments out of
warranty will be repaired (when repairable) for a service charge.
For more information on warranty and service:
This warranty gives you specific legal rights. You may also have other
rights which vary from state to state.