User's Manual
Hygro Thermo-Anemometer
Model 407412
2
EXTECH INSTRUMENTS CORPORATION warrants this instrument to be free of defects
in parts and workmanship for one year from date of shipment (a six month limited
warranty applies on sensors and cables). If it should become necessary to return the
instrument for service during or beyond the warranty period, contact the Customer
Service Department at (781) 890-7440 for authorization. A Return Authorization (RA)
number must be issued before any product is returned to Extech. The sender is
responsible for shipping charges, freight, insurance and proper packaging to prevent
damage in transit. This warranty does not apply to defects resulting from action of the
user such as misuse, improper wiring, operation outside of specification, improper
maintenance or repair, or unauthorized modification. Extech specifically disclaims any
implied warranties or merchantability or fitness for a specific purpose and will not be
liable for any direct, indirect, incidental or consequential damages. Extech's total liability
is limited to repair or replacement of the product. The warranty set forth above is
inclusive and no other warranty, whether written or oral, is expressed or implied.
Introduction
WARRANTY
Congratulations on your purchase of Extech's Hygro Thermo-Anemometer. This Heavy
Duty meter measures and displays Air Velocity + Temperature and Relative Humidity +
Temperature. Air flow can be displayed in the following units of measure: feet per minute,
meters per second, miles per hour, kilometers per hour, and knots. Temperature and RH
units are displayed in oC/oF and % units respectively. Careful use of this meter will provide
years of reliable service.
Specifications
General Specifications
Display Dual function, 3-1/2 digit (2000 count) LCD display
Units of measure m/s (meters per second), km/hr (kilometers per hour), ft/min (feet per
Data hold Holds reading on the LCD display when button is pressed
Sensors Air velocity sensor: Twisted vane arm with low friction ball bearing;
Max/Min Record Records highest and lowest readings for later recall
Data Output RS-232 serial PC interface
Operating Temp. 32°F to 122°F (0°C to 50°C)
Operating Humidity Max. 80% RH.
Power Supply 9V battery
Power Consumption Approx. 8.3 mA DC
Weight 0.77 lbs. (350g)
Dimensions Meter: 7.1x2.8x1.3" (180 x 72 x 32mm);
Accessories Anemometer/temperature and RH Probes, 9V battery, & case
minute), knots (nautical miles per hour), mile/hr (miles per hour);
Temperature: °C/°F; Humidity: %RH
Temperature: Precision thermistor; Humidity: Thin film capacitor
Anemometer Probe: 0.7" (17mm) Diameter x 6.7" (170mm)
Model 407412 May 2001 Rev. 1.6
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RH Probe head
Range Specifications
Air velocity
Measurement Range Resolution Accuracy
ft/min 80-4930 ft/min 1 ft/min
m/s 0.4 - 25.0 m/s 0.1 m/s
km/hr 1.4 - 90.0 km/hr 0.1 km/hr
±(2% + 20ft/min)
±(2% +2digits)
mile/hr 0.9-55.9 mile/hr 0.1 mile/hr
knots 0.8 - 48.6 knots 0.1 knots
Temperature
Range Resolution Accuracy
32oF to 122oF / 0oC to 50oC / 0.1oC/oF ±1.5oF / ±0.8oC
Relative Humidity
Range Resolution Accuracy
10 to 70% RH 0.1% ±3% RH
70 to 95% RH 0.1% ±4% RH
Meter Description
1. LCD Display
2. POWER button
3. Data Hold button
4. °C/°F Selection button
5. Function switch
6. Data Record button
7. Data Recall button
8. Units select button
9. RS-232 output jack
10. Probe input socket
11. Battery compartment
9 10
1
3
2
6
4
5
7
8
11
(rear)
Vane
Probe head
Probe
Handles
Probe
Plugs
Model 407412 May 2001 Rev. 1.6
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Anemometer and Temperature Operation
1. Insert the Vane sensor into the meter's input jack at the top of the meter.
2. Press the POWER button to turn the instrument on.
3. Select 'Anemometer' operation by placing the function slider switch to the vane icon.
4. Select the temperature units by pressing the °C/°F button. The LCD display will
indicate '°C' or '°F' as selected.
5. Select the air velocity unit of measure by pressing the
UNIT button. With each press the display scrolls
through the units (m/s, km/hr, ft/min, knots, & mile/h).
6. Hold the probe by its handle and position the vane so
that the yellow dot is on the exhaust side of the vane.
The meter will then indicate Air Velocity + Temperature
(See diagram at right).
Yellow
Dot
airflow
Relative Humidity and Temperature Operation
1. Insert the Relative Humidity probe in the input jack at the top of the meter.
2. Press the POWER button to turn on the instrument.
3. Select the Humidity mode of operation by placing the function slider switch to the
%RH position.
4. Select the temperature units by pressing the °C/°F button. The LCD display will
indicate '°C' or '°F' as selected.
5. Hold the probe by the handle and point it in the area to be measured. The meter will
display Relative Humidity + Temperature.
6. Note that humidity measurements take several minutes to stabilize.
Data Hold
Press the DATA HOLD button to freeze the displayed reading. The DH icon will appear on
the LCD while Data Hold is engaged. Press the DATA HOLD button again to resume
normal operation.
Min/Max Record Mode
When selected, the Record mode stores the highest (Max) and lowest (Min) readings for
later recall. To use Record mode:
1. Press the RECORD button. The REC indicator will appear on the LCD display.
2. Start a measurement session.
3. After the measurement session, press the RECALL button to view the highest (Max)
reading recorded since the RECORD button was pressed. The MAX indicator will
appear to inform the user that the displayed reading is the highest value recorded.
4. Press the RECALL button again to view the lowest reading encountered since the
RECORD key was pressed (the MIN indicator will appear on the LCD to inform the
user that the reading displayed is the lowest value recorded).
5. Press RECORD again to return the meter to normal operation. All stored data will be
cleared and the REC/MIN/MAX icons will disappear from the LCD.
6. Note that putting the meter into the Record mode defeats the Auto Power Off feature.
Model 407412 May 2001 Rev. 1.6
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RS-232 PC Interface
The RS-232 serial data port (3.5mm phono jack) is located at the top of the meter next to
the sensor input jack. The PC interface hardware is intended for use with the Extech Data
Acquisition software package, Part Number 407001 which includes WindowsTM 95 / 98 /
ME / NT / 2000 compatible softw are and PC interface cable. For more information, contact
Extech or refer to the 407001 User's Manual.
Auto Power Off feature
The Auto Power Off feature automatically turns the meter off after approximately 10
minutes. To defeat this feature, place the meter in Record mode by pressing the RECORD
key once (the REC icon will appear on the LCD). The meter will remain powered as long
as the meter is in the RECORD mode.
Battery Replacement
When it is time to replace the 9V battery, the low battery indicator (LBT) appears in the lefthand corner of the LCD display. Note that reliable readings can be obtained for several
hours after the first appearance of the low battery indicator.
To replace the battery:
1. Remove the meter's protective rubber holster.
2. Pry off the battery compartment cover on the rear of the meter using a small coin or
screwdriver.
3. Replace the 9V batter and reinstall the compartment cover and holster.
Relative Humidity Calibration
1. Turn the meter on and select the Humidity mode using the slide switch.
2. Use a simulator to apply 0.0 ºC to the meter and adjust VR3 for a display of 0.0 ºC.
3. Change the input to 25.0 ºC and adjust VR1 for a display of 25.0 ºC.
4. Change the input to 50.0 ºC and verify a display of 50.0 ºC. Readjust VR3 & VR1 if
necessary.
5. Connect the humidity probe to the unit and place the probe in a controlled 33% RH
environment. Let stabilize for a minimum of 30 minutes and adjust VR5 for a reading of
33.0% RH.
6. Place the probe in a 75% RH environment for a minimum of 30 minutes and adjust “R6
for a reading of 75.0% RH.
7. Verify that the temperature reading is within the published specifications. If not, perform
calibration steps 2 and 3, above, again.
Model 407412 May 2001 Rev. 1.6
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(
Calibration and Repair Services
Extech offers complete repair and calibration services for all of the products we sell.
For periodic calibration, NIST certification or repair of any Extech product, call customer
service for details on services available. Extech recommends that calibration be performed
on an annual basis to insure calibration integrity.
Copyright © 2001 Extech Instruments Corporation.
All rights reserved including the right of reproduction in whole or in part in any form.
Tech Support Hotlines
781-890-7440 ext. 200
extech@extech.com
www.extech.com
Model 407412 May 2001 Rev. 1.6
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Appendix
Conversion Table
to convert to multiply
feet/minute cms/sec 0.508 knots feet/hr 6,080
feet/minute feet/sec 0.01667 knots kilometers/hr 1.8532
feet/minute kms/hr 0.01829 knots nautical miles/hr 1
feet/minute meters/min 0.3048 knots statute miles/hr 1.151
feet/minute miles/hr 0.01136 mph cms/sec 44.7
meters/sec feet/min 196.8 mph feet/min 88
meters/sec feet/sec 3.281 mph feet/min 88
meters/sec kilometers/hr 3.6 mph feet/sec 1.467
meters/sec kilometers/min 0.06 mph kms/hr 1.609
meters/sec miles/hr 2.237 mph kms/min 0.02682
meters/sec miles/min 0.03728 mph knots 0.8648
kilometers/hr cms/sec 27.78 mph meters/min 26.82
kilometers/hr feet/min 54.68 mph miles/min 0.1667
kilometers/hr feet/sec 0.9113
kilometers/hr knots 0.5396
kilometers/hr meters/min 16.67
kilometers/h miles/hr 0.6214
Area Equations
Rectangular Duct
Area = W x H
Circular Duct
Area = 2
(A=2x3.14xRxR)
Cubic equations
CMM (m3/min) = Air Velocity (m/sec) x Area (m
H
2
R
π
CFM (ft3/min) = Air Velocity (ft/min) x Area (ft2)
by
to convert
W
R
to multiply
2
) x 60
by
Model 407412 May 2001 Rev. 1.6
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