Extech Instruments 451112 User manual

1 Model 451112 Version 2.4 2/04
INSTRUCTION MANUAL
Model 451112
Vane Anemometer
•Measures Air
Velocity &
Temperature
•Degrees C/F
switchable
•6 selectable units
of measure
•Data Hold function
1. INTRODUCTION
Congratulations on your purchase of Extech’s Vane Anemometer. This professional meter,
with proper care, will provide years of safe reliable service.
Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176
FAX [phone] - TestEquipmentDepot.com
99 Washington Street
Melrose, MA 02176
Phone [phone]
Toll Free 1-800-517-8431
Visit us at www.TestEquipmentDepot.com

2 Model 451112 Version 2.4 2/04
2. SPECIFICATIONS
2.1 General Specifications
Display 0.7" (18mm) 3-1/2 digit (1999 count) LCD
Measurement m/s (meters per second), km/h (kilometers per hour), ft/min
(feet per minute), knots (nautical miles per hour), Temp. °C/°F
Data hold Freezes present value on display when selected
Sensor Structure Air velocity sensor: Conventional twisted vane arm with
balanced, low-friction ball-bearing design
Temperature sensor: Thermister
Ambient 32 °F to 122 °F (0 °C to 50 °C); <80%
Power Supply 9V battery (Heavy duty type)
Power Current Approx. 9 mA DC
Weight 12 oz. (325 g) (including battery)
Dimensions Main instrument: 6.6 x 3.2 x1.2" (180 x 72 x 32 mm)
Sensor Head: Round, 2.8" (72 mm) Dia.
Sensor Cable: 39" (1m) length
2.2 Range Specifications
Measure Range Resolution Accuracy
m/s 0.4 – 30.0 m/s 0.1 m/s ± (2% + 0.2 m/s)
km/h 1.4 – 108.0 km/ 0.1 km/h ± (2% + 0.2 km/hr)
ft/min 80 – 5910 ft/min * 10 ft/min ± (2% + 20 ft/min)
knots 0.8 – 58.3 knots 0.1 knots ± (2% + 0.2 knots)
Temp. 0 to 60oC / 32 to 140oF0.1oC / 0.1oF0.8oC / 1.5oF
* Multiply displayed ft/min readings by a factor of 10
3. FRONT PANEL DESCRIPTION
1. LCD Display
2. °C/ °F /Airflow selection
3. ON/OFF/Data Hold Switch
4. Airflow unit selection
5. Sensor-to-meter connection
6. Sensor head
7. Sensor handle

3 Model 451112 Version 2.4 2/04
4. OPERATION
4.1 Move the "OFF/ON/HOLD" switch to the ON position to apply meter power.
4.2 Select temperature or airflow via the "°C/°F /airflow" switch. The display will indicate
temperature or airflow.
4.3 Select the air velocity units using the
"Airflow Units" switch, airflow will display in
"m/s", "km/h", "ft/min", or "knots" as
selected. Note that displayed ft/min
readings must by multiplied by 10.
4.4 When measuring, the air should be
striking the vane on the side of the vane
without the yellow dot (see diagram).
4.5 Data Hold: During measurements,
moving the "OFF/ON/HOLD" switch to the
"Hold" position will freeze the displayed
value. Move the switch back to "ON" to cancel the HOLD function.
5. BATTERY REPLACEMENT
When the display indicates "BAT" (low battery), replace the battery. To replace the battery:
a. Remove rear screw (bottom, center), slide the Battery Cover off, and remove
battery.
b. Replace with 9V battery (heavy duty type) and reinstall the cover and rear screw.
c. Make sure the battery cover is secured after changing the battery.
airflow
Yellow
Dot

4 Model 451112 Version 2.4 2/04
ADDENDUM: USEFUL EQUATIONS AND CONVERSIONS
Area equation for rectangular or square ducts
Area equation for circular ducts
Cubic equations
NOTE: Measurements made in inches
must be converted to feet or meters before using the above formulae.
Unit of Measure Conversion Table
m/s ft/min knots km/h 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/h 0.2778 54.69 0.54 10.6222
1 MPH 0.4464 87.89 0.8679 1.6071 1
Width (W)
Height (H)
Area (A) = Width (W) x Height (H)
CFM (ft3/min) = Air Velocity (ft/min) x Area (ft2)
CMM (m3/min) = Air Velocity (m/sec) x Area (m2) x 60
Radius Area (A) = 6x r2
Where 6 = 3.14 and r2= radius x
radius
Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176
FAX [phone] - TestEquipmentDepot.com
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Visit us at www.TestEquipmentDepot.com