TESTO 425 User manual

Bedienungsanleitung de
Instruction manual en
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Contents
General notes ....................................................18
1. Safety advice .....................................................18
2. Intended purpose...............................................19
3. Product description............................................20
3.1 Display and control elements........................................ 21
3.2 Voltage supply.............................................................. 22
4. Commissioning ..................................................22
5. Operation...........................................................23
5.1 Connecting a probe...................................................... 24
5.2 Switching the instrument on / off .................................. 24
5.3 Switching the display light on / off ................................ 24
5.4 Performing settings ...................................................... 24
6. Measuring..........................................................26
7. Care and maintenance.......................................30
8. Questions and answers......................................31
9. Technical data ...................................................32
10. Accessories/spare parts.....................................32
testo 425
Thermal anemometer

General notes18
General notes
This chapter provides important advice on using this
documentation.
The documentation contains information that must be
applied if the product is to be used safely and efficiently.
Please read this documentation through carefully and
familiarise yourself with the operation of the product before
putting it to use. Keep this document to hand so that you
can refer to it when necessary.
Identification
Representation Meaning Comments
Note Offers helpful tips and information.
, 1, 2 Objective Denotes the objective that is to be
achieved via the steps described. Where
steps are numbered, you must always
follow the order given!
Condition A condition that must be met if an action
is to be carried out as described.
>, 1, 2, ... Step Carry out steps. Where steps are
numbered, you must always follow the
order given!
Text Display text Text appears on the instrument display.
Button Control button Press the button.
- Result Denotes the result of a previous step.
Cross-reference Refers to more extensive or detailed
information.

1. Safety advice 19
1. Safety advice
This chapter gives general rules which must be followed
and observed if the product is to be handled safely.
Avoid personal injury/damage to equipment
>Do not use the measuring instrument and probes to
measure on or near live parts.
>Never store the measuring instrument/probes together
with solvents and do not use any desiccants.
Product safety/preserving warranty claims
>Operate the measuring instrument only within the
parameters specified in the Technical data.
>Always use the measuring instrument properly and for its
intended purpose. Do not use force.
>Do not expose handles and feed lines to temperatures in
excess of 70 °C unless they are expressly permitted for
higher temperatures.
Temperatures given on probes / sensors relate only to
the measuring range of the sensors.
>Open the instrument only when this is expressly
described in the documentation for maintenance and
repair purposes.
Carry out only the maintenance and repair work that is
described in the documentation. Follow the prescribed
steps when doing so. For safety reasons, use only
original spare parts from Testo.
Ensure correct disposal
>Take faulty rechargeable batteries/spent batteries to the
collection points provided for them.
>Send the product back to Testo at the end of its
useful life. We will ensure that it is disposed of in an
environmentally friendly manner.
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2. Intended purpose20
2. Intended purpose
This chapter gives the areas of application for which the
product is intended.
Use the product only for those applications for which it was
designed. Ask Testo if you are in any doubt.
testo 425 is a compact instrument for measuring flow
velocities and temperatures by means of a permanently
connected flow/temperature probe (hot wire probe).
The product was designed for the following tasks/
applications:
· Measuring volumetric flow rates in ducts
· Measuring flow velocities in rooms
· Measuring the temperature of flows
The product should not be used in the following areas:
· Areas at risk of explosion.
· Diagnostic measurements for medical purposes

3. Production description 21
3. Product description
This chapter provides an overview of the components of
the product and their functions.
3.1 Display and control
elements
Overview
Probe
Display
Control buttons
Battery compartment (rear)
Service compartment (rear)
Button functions
Button Functions
Switch instrument on;
switch instrument off (press and hold)
Switch display light on / off
Keep reading, display maximum/
minimum value
Open/leave configuration mode (press
and hold);
In configuration mode:
Confirm input
In configuration mode:
Increase value, select option
In configuration mode:
Reduce value, select option
Multi-point and timed mean calculation
Volumetric flow
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3. Production description22
Important displays
Display Meaning
Battery capacity (bottom right in display):
·4 segments in the battery symbol are lit: Instrument battery is fully
charged
·No segments in the battery symbol are lit: Battery is almost spent
3.2 Voltage supply
Voltage is supplied by means of a 9V monobloc battery
(included in delivery) or rechargeable battery. It is not
possible to run the instrument from the mains supply or
charge a rechargeable battery in the instrument.

4. Commissioning 23
4. Commissioning
This chapter describes the steps required to commission
the product.
Inserting a battery/rechargeable battery:
1To open the battery compartment on the rear of the
instrument, push the lid of the battery compartment in
the direction of the arrow and remove it.
2Insert a battery/rechargeable battery (9V monobloc).
Observe the polarity!
3To close the battery compartment, replace the lid
of the battery compartment in position and push it
against the direction of the arrow.
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5. Operation24
5. Operation
This chapter describes the steps that have to be executed
frequently when using the product.
5.1 Connecting a probe
The necessary probes are permanently connected or
integrated. It is not possible to connect any additional
probes.
5.2 Switching the instrument
on / off
Switching the instrument on:
>Press .
- The thermal sensor is heated up (5s).
- Measurement view is opened: The current reading
is displayed, or ----- lights up if no reading is
available.
Switching the instrument off:
>Press and hold (for approx. 2s) until the display
goes out.
5.3 Switching the display
light on / off
Switching the display light on/off:
The instrument is switched on.
>Press .

5. Operation 25
5.4 Performing settings
1To open configuration mode:
The instrument is switched on and is in measurement
view. Hold, Max or Min are not activated.
>Press and hold (for approx. 2s) until the display
changes.
- The instrument is now in configuration mode.
You can change to the next function with .
You can leave configuration mode at any time. To do
so, press and hold (for approx. 2s) until the
instrument has changed to measurement view. Any
changes that have already been made in configuration
mode will be saved.
2To set the area:
Configuration mode is opened, AREA is lit.
>Set the cross-sectional area with / and
confirm with .
3To set the absolute pressure:
The absolute pressure is required for the pressure
compensation of the flow velocity measurement value.
The absolute pressure must be measured using a
separate instrument or obtained from the local
weather station.
Configuration mode is opened, HPA or InHG is lit.
>Set the absolute pressure with / and confirm
with .
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5. Operation26
4To set Auto Off:
Configuration mode is opened, AutoOff is flashing.
>Select the desired option with / and confirm
with :
· on: The measuring instrument switches off
automatically if no button is pressed for 10min (Hold
or Auto Hold is lit).
· oFF: The measuring instrument does not switch
itself off automatically.
5To set the unit of measurement:
Configuration mode is opened, UNIT is lit.
1With / set the required unit for the top line
(m/s, fpm) and confirm with .
2With / set the required unit for the bottom
line (m3/h, l/s, cfm) and confirm with .
6To reset:
Configuration mode is opened, RESET is lit.
>Select the desired option with / and confirm
with :
· no: Instrument is not reset.
· Yes: Instrument is reset. The instrument is reset to
the factory settings.
- The instrument returns to measurement view.

6. Measuring 27
6. Measuring
This chapter describes the steps that are required to
perform measurements with the product.
Taking a measurement:
The instrument is switched on and is in measurement
view.
>Put the probe in position.
The arrow mark on the probe head must point in the
direction of flow. The correct measurement value
is determined by rotating the probe slightly in both
directions until the maximum value is displayed.
- Read off the readings.
Changing the measurement channel display:
>To change between displaying the temperature (°C, °F)
and the calculated volumetric flow rate (m3/h, l/s, cfm):
Press .
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6. Measuring28
Holding the reading, displaying the maximum/minimum
value:
The current reading can be recorded. The maximum and
minimum values (since the instrument was last switched
on) can be displayed.
>Press several times until the desired value is
displayed.
- The following are displayed in turn:
· Hold: the recorded reading
· Max: Maximum value
· Min: Minimum value
· The current reading
Resetting the maximum/minimum values:
The maximum/minimum values of all channels can be
reset to the current reading.
1Press several times until Max or Min lights up.
2Press and hold (approx. 2s).
- All maximum or minimum values are reset to the
current reading.
Performing a multi-point mean calculation:
Hold, Max or Min are not activated.
1Press .
- Mean is lit.
- The number of readings recorded is displayed
in the upper line, while the current reading is
displayed in the lower line.
Option:
>To change between displaying the temperature (°C,
°F), flow velocity (m/s, fpm) and calculated
volumetric flow rate (m3/h, l/s, cfm): Press .
2To include readings (in the desired quantity):
Press (several times).

6. Measuring 29
3To end measurement and calculate the mean value:
Press .
- Mean flashes. The calculated spot mean value is
displayed.
4To return to measurement view: Press .
Performing a mean calculation in time:
Hold, Max or Min are not activated.
1Press twice.
- Mean is lit.
- The elapsed measuring time (mm:ss) is displayed
in the upper line, while the current reading is
displayed in the lower line.
Option:
>To change between displaying the temperature (°C,
°F), flow velocity (m/s, fpm), and calculated
volumetric flow rate (m3/h, l/s, cfm): Press .
2To start measurement: Press .
3To interrupt/continue measurement: Press each
time.
4To end measurement and calculate the mean value:
Press .
- Mean flashes. The calculated mean value in time
is displayed.
5To return to measurement view: Press .
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7. Care and maintenance30
7. Care and maintenance
This chapter describes the steps that help to maintain the
functionality of the product and extend its service life.
Cleaning the housing:
>Clean the housing with a moist cloth (soap suds) if
it is dirty. Do not use aggressive cleaning agents or
solvents!
Changing the battery/rechargeable battery:
The instrument is switched off.
1To open the battery compartment on the rear of the
instrument, push the lid of the battery compartment in
the direction of the arrow and remove it.
2Remove the spent battery/rechargeable battery and
insert a new battery/rechargeable battery
(9 V monobloc). Observe the polarity!
3To close the battery compartment, replace the lid
of the battery compartment in position and push it
against the direction of the arrow.

8. Questions and answers 31
8. Questions and answers
This chapter gives answers to frequently asked questions.
Question Possible causes Possible solution
is lit (bottom right · Instrument battery is · Replace instrument
in display). almost spent. battery.
Instrument switches · Auto Off function · Switch function off.
itself off automatically. is switched on.
· Residual capacity · Replace battery.
of battery is too low.
Display: ----- · Probe break. · Please contact your
dealer or Testo
Customer Service.
Display reacts slowly · Ambient temperature · Raise ambient
is very low. temperature.
Display: uuuuu · Permitted measuring · Keep to permitted
range was undershot. measuring range.
Display: ooooo · Permitted measuring · Keep to permitted
range was exceeded. measuring range.
If we are unable to answer your question, please contact
your dealer or Testo Customer Service. For contact data,
see back of this document or web page www.testo.com/
service-contact
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9. Technical data32
9. Technical data
Characteristic Value
Parameters Flow velocity (m/s, fpm)
Temperature (°C / °F)
Measuring range 0...+20 m/s
-20...+70 °C / -4...+158 °F
Resolution 0.01 m/s
0.1 °C / 0.1 °F
Accuracy ±0.03 m/s+5% of reading
(±1 Digit) ±0.5 °C / ±0.9 °F (0...+60.0 °C / +32...+140 °F)
±0.7 °C / ±1.3 °F (rest of range)
Probe Telescopic flow velocity/temperature probe (hot wire probe)
with NTC temperature sensor (permanently connected)
Measuring rate 2/s
Operating temperature range -20...+50 °C / -4...+122 °F
Storage temperature -40...+85 °C / -40...+185 °F
Voltage supply 1x 9 V monobloc battery/rech. battery
Battery life approx. 20 h
Protection class with TopSafe (accessory part): IP 65
EC Directive 2004/108/EEC
Warranty 2 years
10. Accessories/spare
parts
Name Part no.
TopSafe testo 425, protects from impact and dirt particles 0516 0221
For a complete list of all accessories and spare parts,
please refer to the product catalogues and brochures or
look up our website: www.testo.com