Extech Instruments 407123 User manual

User's Guide
Hot Wire Thermo-Anemometer
Model 407123

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Introduction
Congratulations on your purchase of the Extech Hot Wire Anemometer. This instrument measures air flow and
temperature by placing the sensor into an airway such as a duct or a vent. The sensor is situated at the end of the
telescoping wand for convenience and has a protective sliding cover. The meter includes an RS-232 PC Interface
jack for use with the Model 407001 Data Acquisition software and interface cable kit. This meter is shipped fully
tested and calibrated and, with proper use, will provide years of reliable service.
Description
Meter Description
1. LCD display – Indicates air velocity and temperature readings,
units of measure, low battery icon, and other user alerts
2. Push-buttons:
POWER: Turn meter ON and OFF
HOLD: Freezes the displayed reading
C/F: Select the temperature units
RECORD: Press to track the
highest (MAX) and lowest (MIN) reading
RECALL: Displays MAX/MIN readings
UNIT: Air velocity units of measure
ZERO: Press to zero the display
(sensor cover must be closed)
3. Protective holster – Rubber jacket that
surrounds the meter (must be removed to
access battery compartment)
4. Battery compartment - Located on the
lower back of the meter
5. PC Interface jack – Accepts a 3.5mm plug
from a PC interface cable (cable and
data acquisition software available using part number 407001)
6. Sensor input jack – Insert the sensor plug
7. Sensor opening – Air must flow through this opening for proper measurement
8. Telescoping sensor handle – Extends to 39” (1m)
9. Sensor protective cover – Slide DOWN to open when in use and slide UP to protect sensor when
not in use (close the cover when zeroing the meter)
Sensor Tip Description
1. Air Direction indentation
2. Air Velocity Sensor
3. Sensor cover in lower (measurement) open position
4. Sensor cover in upper (zero) closed position
5. Temperature sensor
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Operation
Initialization and Zero
The meter should always be zeroed at temperature before use using the ZERO button. Do not
rely on the initial zero display.
Notes:
The meter does not display negative numbers.
Open antenna to desired length.
1. Connect the sensor to the input jack on top of the meter and open antenna to desired length.
2. Turn on the meter using the Power button. The meter will perform a self-test during which the
display will count down from 9 to 0.
3. Select the desired temperature units using the C/F select button. The LCD will reflect the
selection.
4. Select the desired air velocity units using the UNIT button. The LCD will reflect the selection.
5. Place the sensor cover in the UP (ZERO) position.
6. Place the sensor in the area to be measured and allow a short time for the sensor to reach the
temperature of the air under test.
7. Press the ZERO button to zero the meter.
Taking Measurements
1. Zero the meter as described above.
2. Slide the air velocity sensor cover down.
3. Place the sensor in the air current to be measured. Have the air flow meet the sensor head in
the direction of the indentation on the sensor head.
4. View the air velocity and temperature readings on the LCD Display. The large main LCD display
indicates the Air Velocity reading. The lower LCD sub-display indicates the temperature reading.

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MIN and MAX Function
1. To begin capturing the Minimum (MIN) and Maximum (MAX) readings, press the RECORD
button. The ‘REC’ icon will appear on the LCD.
2. Take readings as described previously.
3. Press the RECALL button to view the Maximum reading encountered since the RECORD button
was pressed. The ‘MAX’ display icon will appear along with the maximum reading.
4. Press RECALL again to view the minimum reading (MIN).
5. Press the RECORD button to exit this mode and return to normal operation.
Data Hold
To freeze the LCD display, press the HOLD button. The 'DH' display icon will appear on the LCD.
Press the HOLD button again to return to normal operation (the 'DH' hold icon will switch off).
Battery Replacement
When the low battery indicator (LBT) appears on the LCD or if the LCD does not switch on when the
POWER button is pressed, replace the batteries.
1. Remove the protective rubber holster that encapsulates the meter.
2. Open the rear battery compartment by prying the compartment off with a flat-head screwdriver
or a coin.
3. Replace the six ‘AAA’ 1.5V batteries observing polarity.
4. Replace the battery compartment cover and the protective holster.
5.
You, as the end user, are legally bound (EU Battery ordinance) to return all used
batteries, disposal in the household garbage is prohibited! You can hand over your
used batteries / accumulators at collection points in your community or wherever batteries
/ accumulators are sold!
Disposal: Follow the valid legal stipulations in respect of the disposal of the device at the
end of its lifecycle
PC Interface
The meter is equipped with an RS-232 PC Interface jack at the top of the meter (next to the sensor
input jack). For streaming of data to a PC via the RS232 Output jack, the optional 407001-USB kit
(RS232 to USB cable and driver CD) along with the 407001 software (available free at
www.extech.com) are required.

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Specifications
General Specifications
Circuit configuration Custom one-chip LSI microprocessor circuit
Display 3-1/2 digit (2000 count) dual LCD display
Measurements m/s (meters per second), km/h (kilometers per hour), ft/min
(feet/per minute), knots (nautical miles per hour), MPH (miles per
hour), Temperature: °C, °F
Data hold Freezes reading on display
Sensor Structure Air velocity sensor: Glass bead thermistor
Temperature sensor: Precision thermistor
Min/Max Recording Record and Recall Maximum (MAX) and Minimum (MIN) readings
PC Interface RS 232 PC serial interface jack for use with Model 407001
software and interface cable kit
Operating
Temperature
0 to 50 °C (32 to 122°F)
Operating Humidity Max. 80% RH
Power Supply Six (6) 1.5V ‘AAA’ batteries
Power Consumption Approx. 30 mA DC
Weight 355 g (0.78 lb) including batteries & probe
Dimensions Main instrument: 180 x 72 x 32 mm (7.1 x 2.8 x 1.3”)
Sensor: 12mm (0.5”) diameter
Telescope: 2.1m (7’) maximum length with cable
Range Specifications
Units Range Resolution Accuracy
m/s 0.2 to 20.0 m/s 0.1 m/s ±(3.0%rdg+0.3m/s)*
km/h 0.7 to 72.0 km/h 0.1 km/h ±(3.0%rdg+1.1km/h)*
ft/min 40 to 3940 ft/min 1 ft/min ±(3.0%rdg+59ft/min)*
MPH 0.5 to 45.0 MPH 0.1 MPH ±(3.0%rdg+0.67MPH)*
knots 0.4 to 38.8 knots 0.1 knots ±(3.0%rdg+0.58knots)*
*or, ±(1.0%FS+3d) whichever is greater
Temperature 0 to 50oC (32 to 122
oF)
0.1 oF and oC0.8 oC (1.5 oF)
Note: m/s: meters per second; km/h: kilometers per hour; ft/min: feet per minute; Knots: nautical
miles per hour; MPH: miles per hour

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Useful Equations and Conversions
Area equations
The volume of air flowing through a duct or vent can be determined by taking the area of the duct
in square units (i.e. square feet) and multiplying this value by the measured linear velocity (i.e., feet
per minute). This gives: ft/min x ft2= ft3/min (CFM)
Cubic equations
CFM (ft3/min) = Air Velocity (ft/min) x Area (ft2)
CMM (m3/min) = Air Velocity (m/sec) x Area (m2) x 60
Units Conversion Table
m/s ft/min knots km/hr MPH
1 m/s 1196.87 1.944 3.6 2.24
1 ft/min 0.00508 10.00987 0.01829 0.01138
1 knot 0.5144 101.27 11.8519 1.1523
1 km/hr 0.2778 54.69 0.54 10.6222
1 MPH 0.4464 87.89 0.8679 1.6071 1
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A = pi x R
2
R
A = W x H
W
H