Dostmann Electronic VA893 User manual

User'sManual
VA893
Thermo Anemometer

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Introduction
The VA893 ThermoAnemometerinstrument measures Air Velocity, Air Flow(volume)
and Temperature. The large, easy-to-read backlit LCD includes primary and secondary
displays plus numerous status indicators. The meter is shipped fully tested and
calibrated andwith proper use will provide years of reliableservice.
Meter Description
1. LCD Display
2. Meter
3. Vane
4. Temperature Buttons
5. Power On/Off
6. Airflow/VelocityButtons
7. AVG
8. Backlight
Keypad
•POWER Press to turn themeter ON or OFF
•MAX/MIN Used to record and store the highest, lowest and average airflowor
velocity readings.
(LEFT)alsoserves as change decimalpoint button in AREA mode
•UNITS Press to select the mode of operation. InFLOWmode, themeter displays
air volume. In VELOCITY mode, the meter displays air speed.
▲(UP) alsoserves as increase numberbuttonin AREA mode.
•AVG Used to Average multiplereadings inFLOWor VELOCITY mode. Up to 20
readings canbe averaged.
•HOLD Press tofreeze the displayed reading. Press again to unlock display. This
button also functions as the ►RIGHT scrollbuttonin AREA mode.
•AREA/ NEXT Press and hold to manually enter thearea of aduct in CFM or CMM
mode. In AREA mode, used to select memory locations 1-8.
•Press toturn the backlight on/off
•MAX/MIN(Temperature) Usedtorecord and store the highest, lowest readings for
air temperature.
•°C °FHOLD (Temperature) Press to freeze the displayed temperature reading.
Press again to unlock the display. Press and holdfor 3seconds toswitch between
°C and °F. Meterwill beep twice toindicate change.
Battery compartment located onthe back of theinstrument. The rubber protective jacket
must be removed from the meter to accessthe compartment.
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DisplayLayout
•MAX (top of LCD): MaxHold function engaged for the Air Temperature function
•HOLD (top of LCD): Data Hold functionengaged for the Air Temperature function
•VEL: indicates that meter is inair velocity mode
•FLOW: indicates that meter is in air flowmode
•MAX (bottom of LCD): MaxHold for the Air Velocity and Air Flow function
•HOLD (bottom of LCD): Data Holdfor the Air Velocity and Air Flow function
•oC / oF: Temperature units of measure
•CFM/CMM: airflowunits of measure
•AREA(ft2, m2): units for area dimensions
•m/s, ft/min, km/h, MPH, knots: air velocity units of measure
•X10, X100: multipliers for air flowreadings
•AVG: air averaging mode
•REC: indicates that min/maxfunction is running (top for temp, bottom for air)
•Large LCD digits at bottom of display for AirVelocity and Air Flow
•SmallerLCD digits at top, right of display forProbe Temperature
•: Lowbattery indicator

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Operation
Connectingthe Vane
1. The vane plug is insertedin the meter’s sensor jack at the top of the meter. The plug
and jack are keyed so that the plug can onlyfit inthejack oneway.
2. Turn the plugcarefully until it lines up with thejack andthen firmly push theplug in
place. Do not apply undue force ortry totwist the plug side-to-side.
3. If the vane is not connected to themeter or if the sensoris defective, the LCD display
will indicate OL in place of a Temperature reading.
Air VelocityMeasurements (Single Point)
1. Turn on themeterusingthe ON/OFF button.
2. Press UNITS buttonto select thedesired unit of
measure. NOTE: At power up the meter will
display thelast unit of measure previously
entered.
3. Placethesensor in the airstream. Ensure that
the air enters the vane as indicated by the arrow
sticker placed inside the vane.
4. Viewthe readings on theLCD Display. The
large main LCD display shows theAir Velocity
reading. The upper right LCD sub-display shows
the temperature reading.
Air VelocityAveraging Mode
1. To enter 20Point Averaging Mode, press andhold the AVG button until it beeps twice.
The AVG icon will be displayed.
2. Take ameasurement and press the AVG button. A single beep will sound and the
HOLD iconwill appear in the display.
3. The average reading will be displayed and number of readings measured willappear in
the upper right hand corner of the display. After 5seconds, the display will return to the
current reading.
4. Repeat steps 2 - 3untilthedesired number of points have been measured.
5. To return tostandard velocity measuring modepress and hold AVG button until meter
beeps twice.
Note: In thestandard velocity measuring mode, press the AVG button once to recall the
previous average. The average will be cleared when you enter the Averaging Mode
again.
airflow
Arrow
Sideview of Vane

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Air FlowMeasurements (CMM / CFM)
1. Turn on the meterusingthe ON/OFF button
2. Press the UNITS button to select the desired airflow
units: CMM (cubic meters per minute) or CFM (cubic
feet per minute). NOTE: At power up the meter will
display thelast unit of measure previously entered.
3. To begin enteringthe area in m2or ft2, press and
hold the AREA button until it beeps twice. The
leftmost digit of the bottom displaywill begin toflash.
4. Use the ▲(UP) buttontochange the flashing digit
Use the (LEFT) button to move the decimal
Use ►(RIGHT) button to select the other digits.
Afterall of the digits are entered, press and hold the
AREA button (untilmeter beeps twice) to save the area into memory and return to
CFM or CMM measuring mode.
5. Placethesensor in the airstream. Ensure that theair enters the vane as indicated by
the arrowsticker placed insidethevane. Refer to the diagram. Thelarge main LCD
display shows the Air Velocity reading. Theupper right LCD sub-display shows the
temperature reading.
The meterhas 16 memory locations (8 for CFM and 8for CMM) that can beusedtostore
commonly usedarea sizes that you can recallat anytime.
1. Press the AREA button untilmeter beeps twice. A memory locationnumberwill
appear in the top right of thedisplay indicating thememory location.
2. Pushthe NEXT button to scrollthru and select thedesiredlocation. Once you have
selected the desired memory location enter your dimension
Use the ▲(UP) buttontochange the flashing digit
Use the (LEFT) button to move the decimal
Use ►(RIGHT) button to select the other digits. After allof the digits are entered,
press andhold the AREA button (until it beeps twice) to save the area into memory
and return to CFM or CMM measuring mode.
To select and use apreviously stored dimension, press and hold the AREA button untilit
beeps twice.
Press NEXT toscroll thru the 8 memory locations. Press and holdthe AREA button until it
beeps twice to return to CFM or CMM measuringmode.
Air Flow Averaging Mode
1. To enter 20Point Averaging Mode, press andhold the AVG button until it beeps twice.
The AVG icon will be displayed.
2. Take ameasurement and press the AVG button. A single beep will sound and the
HOLD iconwill appear in the display.
3. The average reading will be displayed and number of readings measured will appear in
the upper right hand corner of the display. After 5seconds, the display will return to the
current reading.
4. Repeat steps 2 - 3untilthe desired number of points have been measured.
5. To return tostandard airflowmeasuring mode press andhold AVG button until meter
beeps twice.
Note: In thestandard velocity measuring mode, press the AVG button once to recall the
previous average. The average will be cleared when you enter the Averaging Mode
again.
airflo
w
Arrow
Sideview of
Vane

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Data Hold (Air Velocity/Air Flow)
1. Whiletaking measurements, press the HOLD button tofreeze theair velocity/airflow
reading.
2. The HOLD indicator will appear in the bottomof the LCD display.
3. Press HOLD again toreturn to normal operation.
MAX/MIN/AVG Record (Air Velocity/Air Flow)
This allows theuser to record and viewthe highest (MAX), lowest (MIN) and average
(AVG) readings.
1. Press the button MAX/MIN button. The MAX indicator and RECORD indicator along
with the Maxreading will appear on the LCD display andthe meter will begin keeping
track of theMAX, MIN and Average values.
2. Press the MAX/MIN buttonagain to viewthe minimumreading. The MIN indicator
along with the minimum reading will appear on the LCD display.
3. Press the MAX/MIN buttonagain to viewthe average reading. The AVG indicator
along with the average reading will appear on theLCD display.
NOTE: Average recording will stop automatically after 2 hours, and the upper LCD sub-
display will showa OFF (only in the average mode).
4. Press the MAX/MIN buttonagain to display current readings. NOTE: the meter will
keep recordingMAX/MIN/AVG readings.
5. To clear and stop MAX/MIN/AVG recording and return to normaloperation, press and
hold the MAX/MIN button until the meter beeps twice.
Automatic PowerOFF
To conserve battery life, themeter automatically turns off after20 minutes. Todefeat this
feature:
1. Turn the meter OFF.
2. Press and holdthe(Backlight) key while turning themeter ON.
3. “dis APO”will appear in thedisplay. The AUTO POWER OFF feature will nowbe
disabled.
4. Note that AUTO POWEROFFis re-enabled each time the meter is turned on.
5. Alsonotethat AUTO POWEROFF is disabled inCFM/CMM or Average mode.
Battery Replacement
When appears ontheLCD, the9V battery must be replaced.
1. Disconnect thesensor.
2. Remove the meter’s rubber protective jacket
3. Use a Phillips screwdriver to open the rear battery compartment
4. Replace the9V battery
5. Close the battery compartment and replace the meter’s protective jacket

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Specifications
Air Velocity Range Resolution Accuracy
m/s (meters per sec) 0.40 - 30.00m/s 0.01 m/s ± (3% + 0.20 m/s)
km/h (kilometers/hour) 1.4 - 108.0km/h 0.1 km/h ± (3% + 0.8 km/hr)
ft/min (feet per minute) 80 – 5900 ft/min 1 ft/min ± (3% + 40ft/m)
mph(miles per hour) 0.9 – 67.0 mph 0.1 mph ± (3% + 0.4 MPH)
knots (nauticalMPH) 0.8 to58.0 knots 0.1 knots ± (3% + 0.4 knots)
Air Flow Range Resolution Area
CMM (cubic meters/min) 0-999900 m3/min 0.001 to100 0 .000 to 999.9m2
CFM (cubic ft/min) 0-999900 ft3/min 0.001 to100 0.000 to 999.9ft2
Range Resolution AccuracyAir Temperature
14 - 140oF (-10 - 60oC) 0.1oF/C 4.0oF (2.0oC)
Circuit Custom LSI microprocessor circuit
Display Dual function 0.7" (16 mm)4-digit LCD
Sampling rate 1 reading per second approx.
Sensors Air velocity/flowsensor: Conventional angled vane arms with
low-friction ballbearing
Temperature sensor: NTC-type precision thermistor
Automatic Poweroff Auto shut off after 20 minutes to preserve battery life
OperatingTemperature 32 to 122°F (0 to 50°C)
Storage Temperature 14 to 140oF(-10 to 60oC)
OperatingHumidity <80% RH
Storage Humidity <80% RH
OperatingAltitude 2000 meters (7000ft)maximum
Battery One 9 volt (NEDA 1604) battery
Batterylife 80 hours approx. (if the Backlight is used continuously, battery
life will bereduced significantly)
BatteryCurrent 8.3 mA DC approx.
Weight 1.6 lbs. (725g) includingbattery & probe
Dimensions Main instrument:: 203 x75 x 50mm
Sensor Head: 2.75” (70mm) Diameter

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Useful Equationsand Conversions
Area equation forrectangularorsquare ducts
Area equation forcircular ducts
Cubic equations
NOTE: Measurements made ininches
must be converted to feet or meters beforeusingthe 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) =
o
x r2
Where o = 3.14 and r2=radius x radius

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