UEi Test Instruments DAFM4 User manual

DAFM4

Digital Air Flow Meter

INSTRUCTION MANUAL

ENGLISH

DAFM4

VOL

CFM

LW

MODE

HOLD

START
STOP

EXIT

LW-D-AREA

AVG MODE]

ON / OFF

MAX / MIN

AVG

(SET)

[HOLD TO EXIT

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TABLE OF CONTENTS

Introduction ................................................................................................3

Safety ..........................................................................................................3

Controls and Indicators ..............................................................................4

Figures and Components ............................................................................5

Operating Instructions

Disable Auto Power Off ....................................................................5

Selecting Units..................................................................................5

Basic Measurement ...................................................................... 5-6

Measuring Air Volume (CFM or CMM)

Entering Duct Information ................................................................6

Timed Average Air Volume ...............................................................7

Measurement Location and Method ............................................ 7-8

Access Hole Spacing ........................................................................8

Sample Calculated Locations ...........................................................8

Diagram of Locations ........................................................................9

Round Duct Access Hole Location ...................................................9

Estimating FREE AREA (Effective area) of a Grill ....................................10

Maintenance

Low Battery ....................................................................................11

Cleaning ..........................................................................................11

Battery Replacement ......................................................................11

Specifications ...........................................................................................12

Warranty and Service Information ..........................................................15

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INTRODUCTION

The DAFM4 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 small vane probe includes
sensors for velocity, temperature and humidity all on a telescoping
extension, making in-duct and surface measurements possible.

FEATURES

• Measures air velocity, temperature, and relative humidity (RH%)

• Calculates wet-bulb temperature, dew point, and air volume
(CFM, CMM)

• 0.7” Small diameter air vane on 39” long telescoping probe

• 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

• DAFM4 Meter

• Remote telescoping mini-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.

Damage could result, reducing accuracy or functionality.

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CONTROLS AND INDICATORS

2

5

3

HOLDMODE

4

EXIT LW-D-AREA

[HOLD TO EXIT

AVG MODE]

START/

STOP

MAX / MIN

AVG

6

7

1

ON / OFF

(SET)

1. On/Off (Setup): Press briefly to power meter on. Press and hold

to turn the meter off.

• Note: When the meter is OFF, press more than two seconds

to enter SETUP mode.

2. HOLD: Freezes display reading for current parameter

3. MODE: Press to scroll through available measurements of
velocity, air flow, ambient temperature, relative humidity,
wet-bulb temperature, and dew point temperature.

4. EXIT: Use to exit setup.

• Note: Press and hold to exit timed average display

5. START/STOP: Press to begin timed average. Press a second
time to pause timed average.

6. LW-D-AREA: Press when setting up area for calculation of air
volume. Pressing repeatedly scrolls through the three options.

(LW-Length/Width, D-Diameter, A – Area)

7. MIN/MAX AVG ( ): Press to display minimum or maximum
values for any measurement. Press when in timed average to
display average, minimum or maximum air volume.

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FIGURES AND COMPONENTS

OPERATING INSTRUCTIONS

DISABLE AUTO POWER OFF

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 DAFM4 is first powered on, air velocity is the default display.
To view other parameters press “MODE” key. Each parameter will be
displayed in turn.

• VEL – Air Velocity

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OPERATING INSTRUCTIONS CONT.

• 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).

• AT – 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 DAFM4 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 (in-duct or exit) 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 manufacturer. If this is not known, the
air volume measurement will be an estimate. (See P. 9-10)

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.

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MEASURING AIR VOLUME (CFM OR CMM) CONT.

TIMED AVERAGE AIR VOLUME

1. Press MODE until VOL is showing in the upper right corner of
the display

2. Enter duct dimensions using the method described on page 6

3. Extend the probe to the width of the duct or more

4. Verify that you are aiming the “Air In” into the air flow. This
is the side opposite of the inch/cm markings on the probe
extension. The grooves of the probe should be perpendicular to
the air flow direction

5. Insert probe into duct access hole (3/4” hole required)
a. See “Measurement Location and Method” for instructions on

where to measure

6. Start with the probe inserted just inside the access hole

7. Press “START” to begin timed average

8. Slowly move probe into the duct until it crosses the duct and
contacts the far side

9. Press “STOP” to interrupt timed average. The cumulative timer
will stop when the DAFM4 is not capturing data

10. Move to the next access hole and repeat steps 6~9.

11. Press MIN/MAX AVG ( ) after capturing data on all access
holes to view average volume

a. AVG flashing and elapsed time will show when displaying
average

b. AVG flashing, elapsed time and MIN will show minimum
measured volume

c. AVG flashing, elapsed time, and MAX will show maximum
measured volume

12. Press and hold EXIT to end test

MEASUREMENT LOCATION AND METHOD

There are recommended methods to traverse a duct in order to collect
sufficient data for an accurate average. Using a timed average increases
the number of data points for a much more accurate result. It is still
recommended to use the approach taken by the Log-Tchebycheff Rule
for access hole spacing, but the number of data points is not needed. By
utilizing a timed average you will capture these locations, plus data from
the entire width of the duct being measured.

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MEASURING AIR VOLUME CONT.

We recommend the following number of access holes depending on duct
size;

• 18” or less – Two access holes 6” apart

• 18”~30” – Five access holes

• 30”~36” – Six access holes

• Greater than 36” – Seven access holes

ACCESS HOLE SPACING

Use the Log-Tchebycheff Rule for rectangular ducts to determine spacing
for access holes.

Number of access
holes per side

5 0.074, 0.288, 0.500, 0.712, 0.926

6 0.061, 0.235, 0.437, 0.563, 0.765, 0.939

7 0.019, 0.153, 0.217, 0.361, 0.639, 0.783,

Example – for a 20” inside dimension select 5 access holes.

• Access 1, 20 x 0.074 = 1.48” from wall (use 1 ½“)

• Access 2, 20 x 0.288 = 5.76” from wall (use 5 ¾”)

• Access 3, 20 x 0.500 = 10” from wall (use 10“)

• Access 4, 20 x 0.712 = 14.24” from wall (use 14 ¼“)

• Access 5, 20 x 0.926 = 18.52” from wall (use 18 ½“)

SAMPLE CALCULATED LOCATIONS

Access

Holes

Width 24 Width 30 Width 36

0.074 1.8 0.061 1.8 0.053 1.9

0.288 6.9 0.235 7.1 0.203 7.3

0.500 12.0 0.437 13.1 0.366 13.2

0.712 17.1 0.563 16.9 0.500 18.0

0.926 22.2 0.765 23.0 0.634 22.8

5 Access

Position relative to inner wall
(multiplier)

0.847, 0.923, 0.981

Holes

0.939 28.2 0.797 28.7

6 Access

Holes

0.947 34.1

8

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DIAGRAM OF LOCATIONS

1.8”

6.9”

12”

17.1”

22.2”

24”

24”

DAFM4

CFM

LW

MODE

HOLD

EXIT

LW-D-AREA

MAX / MIN

[HOLD TO EXIT

AVG MODE]

ON / OFF

(SET)

Access Hole Location

ROUND DUCT ACCESS HOLE LOCATION

For round ducts drill three holes at 60 degrees separation. This will
allow you to cover all locations recommended using the log-Tchebycheff
method for round ductwork.

Locate all access holes in a straight section of ductwork.

D (<10”)

60º

Access
Holes

VOL

START
STOP

AVG

60º

Log-Tchebycheff Rule for Round ducts

9

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ESTIMATING FREE AREA (EFFECTIVE AREA) OF A GRILL

To obtain air volume on a grill with unknown effective or free area
you must estimate the free area. This is difficult, but can 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 known.

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 DAFM4)

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.

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MAINTENANCE

LOW BATTERY

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.

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SPECIFICATIONS:

English Metric

Air Velocity Range 99 ~ 3937 ft/min 0.5 ~ 20 m/s

Air Velocity Resolution 0.1 ft/min 0.1 m/s

Air Velocity Accuracy ±(3% or reading +

Temperature Range -4 ~ 140°F -20 ~ 60°C

Temperature Resolution 0.1°F 0.1°C

Temperature Accuracy ±1.1°F(-4 ~ 122°F);

RH% Range 0.1 ~ 99.9% RH

RH% Resolution 0.1% RH

RH% Accuracy ±3% RH at 77°F(25°C) and 10 ~ 90%RH;

Wet bulb range -4 ~ 158°F -20 ~ 70°C

Wet bulb resolution 0.1°F (°C)

Air volume display 0 ~ 99999 CFM (m3/s)

Air volume resolution 0.1 (0 ~ 9999.9), 1 (10000 ~ 99999)

LCD Size (HxW) 1.38 x 2.13

Operating temperature
range

Operating RH% Less than 80% (handset)

Storage temperature
range

Storage RH% Less than 90%

Dimension 7.1 x 2.9 x .5 inches 180 x 73 x 38 mm

Weight .37 lbs 170g

Battery 9V battery (1)

39 ft/min)

±2.2°F at others

±5% at others

inches

32 ~ 122°F 0 ~ 50°C

-4 ~ 122°F -20 ~ 50°C

±(3% or reading +

0.2m/s)

±0.6°C(-20 ~ 50°C);
±1.2°C at others

35.2 x 54 mm

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