Wohler TA 420 User manual

The Measure of Technologie
EN
Operation manual
Thermoanemometer
Wöhler TA 420
.
Art. n°. 23457 – 2014-04-07

General Information
2
Contents
Contents
1General Information..............................4
1.1 Operation Manual Information....................... 4
1.2 Notes............................................................. 4
1.3 Intended Use................................................. 4
1.4 Scope of supply............................................. 4
1.5 Information on disposal ................................. 5
1.6 Merchant ....................................................... 5
2Technical Data.......................................6
3Design and Function ............................9
3.1 Key assignments........................................... 9
3.2 Telescopic Bar with Sensors....................... 10
4Functional Principle............................10
5Preparation for Operation..................11
6Switch On ............................................13
7Measuring the Flow Velocity and the
Temperature........................................13
8Measuring the Volume Flow..............14
8.1 Simple volume flow measuring (current value)
14
8.2 Input of Area................................................ 15
8.3 Average Value Measurement...................... 16
8.4 Volume Flow Measurement with a Measuring
Funnel ......................................................... 17
9Zero Calibration ..................................19
10 Data Hold Function.............................19
11 Record the Minimum and Maximum
Values ..................................................19
12 Adjustments........................................20
12.1 Automatic Power Off ................................... 20

General Information
3
EN
12.2 Select the Temperature Unit........................20
13 Changing the Batteries......................21
14 System Reset......................................21
15 Maintenance and Care .......................21
16 Warranty and Service.........................22
16.1 Warranty......................................................22
16.2 Service.........................................................22
17 Accessories.........................................23
18 Declaration of conformity..................23
TOC

General Information
4
1 General Information
1.1 Operation Manual In-
formation This operation manual allows you to work safely
with the Wöhler TA 420 Thermoanemometer.
Please keep this manual for your information.
The Wöhler TA 420 Thermoanemometer should
be employed by professionals for its intended use
only.
Liability is void for any damages caused by not
following this manual.
1.2 Notes
ATTENTION!
Not following this note can cause permanent
damage to the device.
NOTE!
Useful information
1.3 Intended Use
The instrument is designed for the measurement
of airspeed, flow and temperature and for the de-
termination of the volume flow in the air duct and
at air passages
1.4 Scope of supply
Device Scope of supply
Wöhler TA 420
Thermoanemometer
Telescopic probe
Plastic case
4 batteries 1,5 V type
AA

General Information
5
EN
1.5 Information on disposal
Electronic equipment does not belong into domes-
tic waste, but must be disposed in accordance
with the applicable statutory provisions.
You may hand in any defective batteries taken out
of the unit to our company as well as to recycling
places of public disposal systems or to selling
points of new batteries or storage batteries.
1.6 Merchant
Wöhler Messgeräte Kehrgeräte GmbH
Schützenstr. 41
33181 Bad Wünnenberg
Tel.: [phone]
Fax: [phone]
E-Mail: [e-mail]
Service-Hotline:
[phone]

Technical Data
6
2 Technical Data
Description
Data
Size
203 x 76 x 38 mm
Weight 515 g
Probe length
280 mm to 940 mm
Probe diameter
12 mm
Screen
LCD 58 mm x 34 mm
Simultaneous display
of the flow speed and
the temperature
Flow probe Glas-perl-thermistor
Temperature probe
Thermistor
operational conditions
0 - 50 °C; 80 % RH
Power supply
4 batteries 1,5 V type
AA
Power Consumption
ca. 70 mA
(instrument and probe)

Technical Data
7
EN
Air velocity
Description
Data
Units
Meter per second (m/s)
Kilometer per hour (km/h)
Miles per hour (mile/h)
Knot (knot)
Feet per minute (ft/min)
Range 0.2 – 20.0 m/s
0.7 – 72.0 km/s
0.5 – 44.7 m/s
0.4 to 38.8 knot
40 – 3940 ft/min
Resolution 0.1 m/s
0.1 km/h
0.1 m/h
0.1 knot
1 Ft/min
Accuracy ± (5 % +a) of reading,
± (1 % +a) terminal value
a= 0.1m/s, 0.1 km/h,
0.1 mile/h, 0.1 knot, 10 ft/min
Flow rate
Description
Data
Units
cubic meter/minute (m3/min)
cubic foot/minute (ft3/min)
Range
0 to 36,000 m3/min
0 to 1,271,200 ft3/min
Resolution
0.001 to 1 m3/min
0.01 to 100 ft3/min
Area
0.001 to 30.0 m2
0.001 to 322.91 ft2

8
Air temperature
Description
Data
Units
Degrees Celsius (°C),
Fahrenheit (°F)
Range 0 to 50 °C
32 °F to 122 °F
Resolution 0.1 °C
0.1 °F
Accuracy ± 0.8 °C
± 1.5 °F
Additional Functions
Description Data
Data Hold
Freezes the current
readings
Memory Recall
Indicates the minimal
and the maximal read-
ings
Auto-Off function
adjustable

Design and Function
9
EN
3 Design and Function
3.1 Key assignments
Fig. 1: Keyboard
1 POWER key Switch on/off
2 HOLD/ESC key
Hold the current value
Leave the menu
3 REC/Enter key
Recording function for maximum and minimum
values
Acknowledgement of adjustments
4 UNIT/ZERO key
Selection of measuring unit
Zero-point calibration
5 FUNCTION key
Select the measuring function
6 AVERAGE key
Average determination for system measuring
7 AREA key
Manual input of cross-section
Setup
1
2
5
4
6
7
3

Functional Principle
10
3.2 Telescopic Bar with Sensors
Fig. 2: Probe
1 White dot marking which always has to be held
against the flow direction
2 Hot wire sensor
3 Temperature sensor
4 Protective sleeve
CAUTION!
When the device is not being used, always push
the protective sleeve above the sensor opening in
order to protect the sensitive hot wire sensor. The
protective cap then will be in the upper position at
the sensor head.
CAUTION!
Do not touch the hot wire and temperature sensor
with your fingers or with hard objects, e.g. tools.
4 Functional Principle
The Wöhler TA 420 measures the flow velocity via a very small glass bead thermistor.
The temperature compensation required for a precise measurement at different tempera-
tures is automatically achieved via a separate thermistor which is installed below the flow
sensor. The display will simultaneously read both values for flow velocity and tempera-
ture. The telescopic probe makes the flexible accommodation to different air duct cross-
sections possible.
For a convenient measurement at ventilation systems, the measuring device provides
different function modules:
•In order to achieve an easy volume flow measurement, the duct cross-sectional
area at the device can be flexibly input in wide ranges. This module also can be
applied for measurements at air passages with a measuring funnel.
•For system measurements in air ducts (trivial procedure), the individual measuring
points each can be recorded and condensed in a further module. The average will
directly be shown on the display.
1
2
3
4

Preparation for Operation
11
EN
5 Preparation for Operation
CAUTION!
Only use the device in the permitted temperature range. Avoid strong vibrations.
CAUTION!
Do not operate the device in the vicinity of strong electric fields.
CAUTION!
Never lay the device onto the user interface.

Preparation for Operation
12
Fig. 3: Probe with protective cap pushed
down
•In order to be able to perform a flow meas-
urement, push the protective cap (Fig. 2, part
4) completely downwards. . Both sensors
must come into contact with ambient air.
•Pull the telescopic bar to the required length
Fig. 4: Pl
ug in sensor plug, slide switch in
right-hand position
•Connect the telescopic bar with the device by
plugging the sensor plug into the appropriate
device opening. The groove at the plug must
be at the front side of the device (Fig. 4).
Fig. 5: In order to lock the sensor plug,
push the slide switch into left-hand posi-
tion
•Lock the sensor plug by pushing the slide
switch to the left into the LOOK ON position.
(Before removing the sensor plug, the slide
switch accordingly has to be pushed to the
right again.)
CAUTION!
Never pull the telescopic bar out of the device by
pulling at the cable. Regularly check the cable for
knots.

Switch On
13
EN
6 Switch On
•Switch on the device by pressing the POWER
key.
The device will perform a self-diagnosis. After-
wards the main display will show the flow data
and - in the lower left-hand part - the temperature.
7 Measuring the Flow
Velocity and the
Temperature
•When switched on, the device is automatically
in the measuring mode for the flow velocity.
•Press the UNIT key and you can select the
requested measuring unit for the flow velocity.
•Now hold the telescopic bar into the air flow to
be measured.
TO BE NOTED!
There is a mark (white dot) at the sensor head.
This mark has to be held against the air flow to be
measured.
The main display will show the flow velocity, the
air temperature is shown in the lower left-hand
part, and the unit in the lower right-hand part.

Measuring the Volume Flow
14
8 Measuring the Volume Flow
8.1 Simple volume flow
measuring (current
value)
•After switching on, press the FUNCTION key
until the device is in the volume flow measur-
ing mode. The display will read CMM (cubic
meter per minute) or CFM (cubic feet per mi-
nute).
•Select the unit by pressing the UNIT key.
•Hold the telescopic bar into the air flow to be
measured.
TO BE NOTED!
There is a mark (white dot) at the sensor head.
This mark has to be held against the air flow to be
measured.
Now, the main display will show the volume flow
and the lower part the entered cross-sectional
area (refer to item 6.2)
193.6
CMM
0929 Area Meter 2
Volume flow
Area size
Fig. 6: Display during volume
flow measurement

Measuring the Volume Flow
15
EN
8.2 Input of Area
In order to facilitate the volume flow measure-
ment, you can manually input the cross-sectional
area of the pipe opening or pipe to be measured
in.
To do so, proceed as follows:
•Press the AREA key in the air volume flow
mode (CMM or CFM).
•The value can be adjusted with the
UNIT/ZERO key (upwards) and the FUNC-
TION key (downwards), with the AVERAGE
key you go to the next figure.
TO BE NOTED!
As a matter of fact, the area can only be input in
the previously selected unit (m² or ft²).
CMM: Cross-section input from 0.001 to 30.000
m² possible.
CFM: Cross-section input from 0.01 to 322.92 ft²
possible.
•Acknowledge your input with the REC key and
leave the menu with the ESC key.
03.0000
Area Meter 2
^,v,>
Fig. 7: Display during input of
cross-sectional area s

Measuring the Volume Flow
16
8.3 Average Value Meas-
urement
The individual measuring points each can be rec-
orded for system measurements in air ducts (trivi-
al procedure) and the average value can be calcu-
lated automatically. The average will directly be
shown on the display.
•Press the FUNCTION key until AVG, CMM (or
CFM) appears in the lower part of the display.
With the average value measurement, the aver-
age value of the volume flow can be calculated
from up to 20 measuring points.
•Press the AVERAGE key.
The lower left part of the display will now read 1,
the main display the first measured value.
•Once again press the AVERAGE key.
The lower left part of the display will now read 2,
the main display the calculated average value
from both measured values.
This process can be repeated up to 20 times.
In order to exit the average value measurement,
hold and keep the AVERAGE key pressed for at
least 2 seconds. In this way, the stored values for
the average value measurement are deleted.
0.000
0 AVG CMM
Number of
measuring
Fig. 8: Display during average
value measurement

Measuring the Volume Flow
17
EN
8.4 Volume Flow Meas-
urement with a Measur-
ing Funnel
Fig. 9: Schematic representation of a
measurement with a funnel
Measuring funnels (see accessories), can be used
both with the determination of the current value
(refer to item 8.1 and with the determination of the
average (refer to item 8.3). In this case, the aver-
age value measurement is to compensate fluctua-
tions during measurement.
•Insert the measuring probe into the funnel as
shown in the graphic representation.
TO BE NOTED!
There is a mark (white dot) at the sensor head.
This mark has to be held against the air flow to be
measured.
Fig. 10: Position of sensor in the funnel
TO BE NOTED!
During measurement, the hot wire (and not the
sensor tip) has to be exactly in the centre of the
funnel circular area (refer to Fig. 10).

Measuring the Volume Flow
18
Depending on which funnel is used for measuring,
the areas stated below are to be input in the TA
420 in accordance with Chapter 8.2:
Measuring
funnel Item number Area to be input
K 150 53788 0.005 m2
K 120 53789 0.035 m2
K 75 53793 0.011 m2
K 35 53794 0.005 m2
TO BE NOTED!
The area to be input depends on the air intake
opening of the measuring funnel. Since it is the
same with the measuring funnels K 150 and K35,
the area to be input is the same as well.

Zero Calibration
19
EN
9 Zero Calibration
•Press the FUNCTION key in order to get into
the flow velocity measuring mode. The dis-
play will read the unit for the air velocity (m/s,
ft/min, knots or mile/h).
•Push the protective cap at the sensor head
over the hot wire sensor until it is completely
covered. (The protective cap then will be in
the upper position.)
•Keep the key UNIT/ZERO pressed for 2 se-
conds until the display reads 0.
10 Data Hold Function
•Press the HOLD key during the measuring
process.
The current measuring value will be held in the
display and the upper part will read HOLD.
•Press the HOLD key once again to return to
the normal measuring mode.
11 Record the Mini-
m
um and Maximum
Values
The minimum and maximum values can be rec-
orded in RECORD mode.
•Press the REC key in order to get into the
RECORD mode. The display will read REC.
•Once again press the REC key. The display
will show the highest value that has been
measured since activating the RECORD func-
tion. The upper part of the display will read
MAX REC.
•Press the HOLD key to delete the maximum
value. The upper part of the display will now
only read REC.
•Press the REC key twice. The display will
show the lowest value that has been meas-
ured since activating the RECORD function.
The upper part of the display will read MIN
REC.
•Press the HOLD key to delete the minimum
value. The display will now only read REC.
•Keep the REC key pressed for 2 seconds in
order to leave the RECORD mode. Now, all
recorded minimum and maximum values are
deleted.

Adjustments
20
12 Adjustments
Before being able to make any adjustments at the device, the HOLD function and the
REC function have to be deactivated as described in the relevant chapters. This means
that the display must neither show HOLD nor REC.
•Keep the AREA key pressed for 2 seconds in order to get into the adjustment
mode.
•Consecutively press the AREA key to get to the following options:
Auto power off
Temp. Unit
ESC > Finish
Activate/deactivate the automatic power off.
Select temperature unit
(Leave adjustment mode)
•Press the ESC key and you will leave the adjustment mode.
12.1 Automatic Power Off In this mode you have the possibility to change
between the options 1 (= power off activated) and
0 (= power off deactivated). When the automatic
power off is activated, the device will automatically
switch off, if no key has been pressed for 10
minutes. Shortly before power off, an acoustic
warning signal will sound.
•Press the UNIT key or the FUNCTION key in
order to activate or deactivate power off.
•Acknowledge your selection with the ENTER
key and leave the adjustment menu with the
ESC key.
12.2 Select the Temperature
Unit
In this mode you have the possibility to change
between the options 1 (= degree Fahrenheit) and
0 (= degree Celsius).
•Press the UNIT key or the FUNCTION key in
order to switch between the units °F and °C.
Acknowledge your selection with the ENTER key
and leave the adjustment menu with the ESC key.
1 = Auto power on.
0 = Auto power off.
1 = °F.
0 = °C.
Fig. 11: Display during
setup "Automatic power
off".
Fig. 12: Display for select-
ing the temperature unit.