TESTO 549 User manual

testo 549 - testo 550 . Digital manifold
Instruction manual

2

1 Contents
3
Pos: 1 /TD/Überschr iften/1. Inhalt @ 0\mod_1177 587817070_79.doc x@ 124 3 @ 1@ 1
1Contents
1Contents ...................................................................................................3
2Safety and the environment....................................................................4
2.1. About this document........................................................................4
2.2. Ensure safety...................................................................................5
2.3. Protecting the environment..............................................................5
3Specifications ..........................................................................................6
3.1. Use ..................................................................................................6
3.2. Technical data .................................................................................6
4Product description.................................................................................9
4.1. Overview..........................................................................................9
5First steps ..............................................................................................11
6Using the product ..................................................................................13
6.1. Preparing for measurement...........................................................13
6.1.1. Switching the instrument on...........................................................................13
6.1.2. Connecting the temperature sensor...............................................................13
6.1.3. Switching Bluetooth® on and off (testo 550) ..................................................15
6.1.4. Selecting the measuring mode.......................................................................15
6.2. Performing the measurement ........................................................16
7Maintaining the product ........................................................................19
8Tips and assistance...............................................................................20
8.1. Questions and answers .................................................................20
8.2. Measurement parameters .............................................................20
8.3. Error reports ..................................................................................21
8.4. Accessories and spare parts .........................................................21
9EC declaration of Conformity ...............................................................22
10 Declarations ...........................................................................................24
Pos:2 /TD/--- Seitenwechsel--- @ 0\mod_1173774430601_0. docx @ 283 @ @ 1

2 Safety and the environment
4
Pos: 3 /TD/Übersc hriften/2. Sic herheit und Umwelt @ 0\mod_11737 74719351_79.docx @ 292 @ 1 @ 1
2Safety and the environment
Pos: 4 /TD/Übersc hriften/2.1 Zu diese mD okument @ 0\mod_117377525 2351_79.docx @ 346 @ 2 @ 1
2.1. About this document
Pos: 5 /TD/Sic herheit und Umwelt/Zu diese m Dokument/Verwendung/V erwendung (Standar d) @ 0\mod_1173775068554_ 79.docx @ 337 @ 5 @ 1
Use
> Please read this documentation through carefully and
familiarize yourself with the product before putting it to use. Pay
particular attention to the safety instructions and warning advice
in order to prevent injuries and damage to the products.
> Keep this document to hand so that you can refer to it when
necessary.
> Hand this documentation on to any subsequent users of the
product.
Pos: 6 /TD/Sic herheit und Umwelt/Zu diese m Dokument/Symbole und Sc hreibkonventionen/S ymbole und Schreibkon v. [Standard_groß] 550-557 @ 16\mod_14 23129108668_79.doc x@ 207097 @ 5 @ 1
Symbols and writing standards
Representation Explanation
Warning advice, risk level according to the
signal word:
Warning! Serious physical injury may occur.
Caution! Slight physical injury or damage to
the equipment may occur.
> Implement the specified precautionary
measures.
Note: Basic or further information.
Menu Elements of the instrument, the instrument
display or the program interface.
[OK] Control keys of the instrument or buttons of
the program interface.
Pos: 7 /TD/Übersc hriften/2.2 Sic herheit gewährleisten @ 0\m od_1173780783960_7 9.docx @ 366 @ 2 @ 1

2 Safety and the environment
5
2.2. Ensure safety
Pos: 8 /TD/Sic herheit und Umwelt/Si cherheit gewähr leisten/Gerät bei Beschädigungen ni cht in Betrieb ne hmen @ 0\mod_1186985945 375_79.docx @ 2252 @ @ 1
> Do not operate the instrument if there are signs of damage at
the housing, mains unit or feed lines.
Pos: 9 /TD/Sic herheit und Umwelt/Sicher heit gewährleisten/K eine Messung an spannu ngsführenden Teilen @ 0\mo d_1175692564164_79 .docx @ 592 @ @ 1
> Do not perform contact measurements on non-insulated, live
parts.
Pos: 10 /TD/Sic herheit und Umwelt/Si cherheit gewährlei sten/Nicht mit Lö sungsmitteln la gern @ 0\mod_11756923751 79_79.docx @ 583 @ @ 1
> Do not store the product together with solvents. Do not use any
desiccants.
Pos: 11 /TD/Sic herheit und Umwelt/Sicher heit gewährleiste n/Nur beschriebene W artungsarbeiten durc hführen @ 0\mod_11756927 05195_79.docx @ 601 @ @ 1
> Carry out only the maintenance and repair work on this
instrument that is described in the documentation. Follow the
prescribed steps exactly. Use only original spare parts
from Testo.
Pos: 12 /TD/Sic herheit und Umwelt/Sicher heit gewährleiste n/vor Ort gültige Sic herheitsbestimmungen be achten @ 0\mod_11869971 07328_79.docx @ 2298 @ @ 1
> Dangers may also arise from the systems being measured or
the measuring environment: Note the safety regulations valid in
your area when performing the measurements.
Pos: 13 /TD/Sic herheit und Umwelt/Sicher heit gewährleiste n/testo 550/Mechanisc he Belastung testo 550 @ 4\mod_12526561 21693_79.docx @ 49837 @ @ 1
> If the measuring instrument falls or another comparable
mechanical load occurs, the pipe sections of the refrigerant
hoses may break. The valve positioners may also be damaged,
whereby further damage to the interior of the measuring
instrument may occur that cannot be identified from the outside.
The refrigerant hoses must therefore be replaced with new,
undamaged refrigerant hoses every time the measuring
instrument falls or following any other comparable mechanical
load. Send the measuring instrument to Testo Customer
Service for a technical check for your own safety.
Pos: 14 /TD/Sic herheit und Umwelt/Sicher heit gewährleiste n/testo 550/Elektro statische Aufladun g testo 5502 @ 16\mod_14231292 35029_79.doc x@ 207132 @ @ 1
> Make sure that your refrigeration system is properly earthed, as
otherwise the measuring instrument might get damaged.
Pos: 15 /TD/Übersc hriften/2.3 Umwel tsc hützen @ 0\mod_117378084 3645_79.docx @ 375 @ 2 @ 1
2.3. Protecting the environment
Pos: 16.1 /TD/Si cherheit und Umwelt/ Umwelt schützen/Akkus/ Batterien entsorgen @ 0\mod_117569 3637007_79.docx @ 619 @ @ 1
> Dispose of faulty rechargeable batteries/spent batteries in
accordance with the valid legal specifications.
Pos: 16.2 /TD/Si cherheit und Umwe lt/Umwelt schützen/ Produkt entsorgen @ 0\mod_1173780 307072_79.doc x@ 357 @ @ 1
> At the end of its useful life, send the product to the separate
collection for electric and electronic devices (observe local
regulations) or return the product to Testo for disposal.
Pos: 17 /TD/Sic herheit und Umwelt/Umwel t schützen/testo 550/K ältemittel können sc haden testo 550 @ 4\mod_125 2656710421_79.doc x @ 49869 @ @ 1
> Refrigerant gases can harm the environment. Please note the
applicable environmental regulations.

3 Specifications
6
Pos: 18 /TD/Übersc hriften/3. Leistu ngsbeschreibung @ 0\mod_1 173774791554_79.d ocx @ 301 @ 1 @ 1
3Specifications
Pos: 19 /TD/Übersc hriften/3.1 Verwendun g @ 0\mod_11762110164 37_79.docx @ 695 @ 2 @ 1
3.1. Use
Pos: 20 /TD/Leis tungsbeschreibung/V erwendung/testo 5 xx/testo 5502 @ 16\mod_14231 29284591_79.doc x@ 2071 67 @ @ 1
testo 549 and testo 550 are digital manifolds for maintenance and
service work on refrigeration systems and heat pumps. They may
only be used by qualified authorized personnel.
The functions of the testo 549 and testo 550 mean they can replace
mechanical manifolds, thermometers and pressure/temperature
charts. Pressures and temperatures can be applied, adapted,
tested and monitored.
testo 549 and testo 550 are compatible with most non-corrosive
refrigerants, water and glycol. testo 549 and testo 550 are not
compatible with refrigerants containing ammonia.
The instruments must not be used in explosive environments!
Pos: 21 /TD/Übersc hriften/3.2 Techni sche Daten @ 0\mod_11762110 88437_79.docx @ 704 @ 2 @ 1
3.2. Technical data
Pos: 22 /TD/Leis tungsbeschreibung/ Technische Daten/ Technische Daten testo 5502 @ 16\ mod_1423129376492_7 9.docx @ 207202 @ 3353 @ 1
Characteristic Values
Parameters Pressure: kPa / MPa / bar / psi
Temperature: °C/°F/K
Sensor Pressure: 2 x pressure sensor, temperature:
2 x NTC
Meas. cycle 0,5 s
Measurement
channels
Quantity: 4
Interfaces Pressure connections: 3 x 7/16" UNF
NTC measurement
Measuring ranges HP/LP pressure measuring range: -100 to
6000 kPa / -0.1 to 6 Mpa / -1 to 60 bar (rel)
/ -14.7 to 870 psi
Temperature measuring range: -50 to
+150 °C / -58 to 302°F
Vacuum measuring range (rel): -1 to
0 bar / -14.7 to 0 psi
Overload 65 bar, 6500 kPa, 6,5 Mpa, 940 psi

3 Specifications
7
Characteristic Values
Resolution Pressure resolution: 0.01 bar/0.1 psi/
1 kPa/0.001 MPa
Temperature resolution: 0.1 °C/0.1 °F
Accuracy (nominal
temperature
22 °C/71.6 °F)
Pressure: ±0,5 % of full scale (±1 digit)
Temperature (-40…150°C): ±0.5 °C (±1 digit)
/0,9°F (±1 Digit)
No. of refrigerants 60
Selectable
refrigerants
No refrigerant, R11, R12, R22, R123,
R1234ze, R125, R13B1, R134a, R14,
R142B, R152a, R161, R23, R227, R290,
R32, R401A, R401B, R401C, R402A,
R402B, R404A, R406A, R407A, R407B,
R407C, R407D, R407F, R408A, R409A,
R410A, R411A, R412A, R413A, R414B,
R416A, R417A, R420A, R421A, R421B,
R422A, R422B, R422C, R422D, R424A,
R426A, R427A, R434A, R437A, R438A,
R502, R503, R507, R508A, R508B, R600,
R600a, R718 (H2O), R744 (CO2) (only in
measuring range up to 60 bar), R1234yf
Measurable media Measurable media: All media that are stored
in the testo 549 and testo 550 Not
measurable: Ammonia (R717) and other
refrigerants which contain ammonia
Ambient conditions Operating temperature: -20 to 50 °C/
-4 to 122 °F
Storage temperature: -20 to 60 °C/
-4 to 140 °F
Housing Material: ABS/PA/TPU
Dimensions: 265 x 135 x 75 mm
Weight: approx. 1000 g (without batteries)
IP class 42
Power supply Current source: Rechargeable
batteries/batteries 4x 1.5 V, type
AA/mignon/LR6
Battery life: approx. 250h
(display light off, Bluetooth off)
Display Type: Illuminated LCDResponse time: 0.5 s

3 Specifications
8
Characteristic Values
Directives,
standards and tests
EC Directive: 2014/30/EC
Warranty Duration: 2 years
Warranty conditions: see website
www.testo.com/warranty

4 Product description
9
Pos: 23 /TD/Übersc hriften/4. Produkt beschreibung @ 0\mod_1 173774846679_79.doc x@ 310 @ 1 @ 1
4Product description
Pos: 24 /TD/Übersc hriften/4.1 Übersi cht @ 0\mod_11763799460 03_79.docx @ 733 @ 2 @ 1
4.1. Overview
Pos: 25 /TD/Produk tbeschreibung/ Übersicht/Übersicht t esto 5502 @ 17\mod_142312 9444087_79.doc x@ 20723 7 @ 5 @ 1
Display and control elements
1Mini-DIN probe socket for NTC temperature probe, with socket
cover
2Foldable suspension device (on rear)
3Display. Instrument status icons:
Icon Significance
Battery capacity
Bluetooth®, (see Switching Bluetooth® on and
off (testo 550), page 15)
//
Select measuring mode (see Selecting the
measuring mode, page 15)
4Battery compartment. It is not possible to charge rechargeable
batteries in the instrument!

4 Product description
10
5Control keys:
Key Function
[Set] Set units
[R, ►, ■] Select refrigerant/ Start/stop / Tightness
test
[Mode] Switching measuring mode
[Min/Max/Mean] Display min./max./mean values
[▲] Up key: Change display view
[P=0] Pressure zeroing
Esc Switches to the measurement/home view
[▼] Down key: Change display view
[/] Switching the instrument on/off
Switch the display illumination on/off.
6Sight glass for refrigerant flow
72 x valve positioner
83 x hose parkers for refrigerant hoses
93 x connections 7/16" UNF, brass
Left/right: Low pressure/high pressure, for refrigerant hoses
with quick connect fitting, passage can be locked via valve
positioner. Centre: for refrigerant bottles, for example, with
sealing cap.
10 On the back below the battery compartment cover, mini-USB
connection for firmware update.
Pos: 26 /TD/Übersc hriften/5. Erste Sc hritte @ 0\mod_1173774895 039_79.docx @ 319 @ 1 @ 1

5 First steps
11
5First steps
Pos: 27 /TD/Erst e Schritte/testo 550/ Erste Schritte testo 55 02 @ 17\mod_142313136780 9_79.docx @ 207272 @ 555 @ 1
Inserting batteries/rechargeable batteries
1. Fold out the suspension device and open the battery
compartment (clip lock).
2. Insert batteries (included in delivery) or rechargeable batteries
(4x 1.5 V, type AA/Mignon/LR6) in the battery compartment.
Observe the polarity!
3. Close the battery compartment.
- After inserting the batteries, the instrument switches on
automatically and goes into the settings menu.
When not in use for long period: Remove
batteries/rechargeable batteries.
Performing settings
1. Press [Set] repeatedly,
2. Press [▲]or [▼]to select the unit/parameter.
−The settings will be accepted once the last selection has been
made.
Key functions
Representation Explanation
[▲]or [▼]Change parameter, select unit
[Set] Select units/parameters
Adjustable parameters
Representation Explanation
°C, °F Set temperature unit.
bar, kPa, MPa, psi Set unit of pressure.
Pabs, Prel or psig Depending on the selected unit of pressure:
Switch between absolute and relative
pressure display.
14.7 psi
1.013 bar
Set current absolute pressure
/ / Select measuring mode
AUTO OFF Automatic switch-off time, instrument
switches off after 30 minutes if no
temperature probe is connected and there is
no pressure apart from ambient pressure.

5 First steps
12
Representation Explanation
Tfac Temperature compensation factor, icon is
shown on the display if the function is
disabled.
− Settings will be applied following the final selection.
Operating valve positioner
The digital manifold acts like a conventional two-way manifold with
regard to the refrigerant path: The passages are opened by
opening the valves. The adjacent pressure is measured with valves
closed as well as with them open.
> Open valve: Turn valve positioner anticlockwise.
> Close valve: Turn valve positioner clockwise.
WARNING
Valve positioner tightened too tightly.
• Damage to the PTFE seal (1).
• Mechanical deformation of the valve piston (2) leading to the
PTFE seal (1) falling out.
• Damage to the thread of the threaded spindle (3) and the valve
screw (4).
• Broken valve knob (5).
Tighten the valve positioner only hand-tight. Do not use any tools
to tighten the valve positioner.

6 Using the product
13
Pos: 28 /TD/Übersc hriften/6. Produkt verwenden @ 0\mod_ 1173774928554_79. docx @ 328 @ 1 @ 1
6Using the product
Pos: 29 /TD/Produk t verwenden/testo 557/An schließen, nulle n, einstellen 5502 @ 17\mo d_1423131416357_79.doc x @ 207307 @ 235355355 @ 1
6.1. Preparing for measurement
6.1.1. Switching the instrument on
> Press [].
Zeroing the pressure sensors
Zero the pressure sensors before every measurement.
✓There must be ambient pressure at all connections. >.
> Press for 3 seconds key [P=0] and execute zeroing.
6.1.2. Connecting the temperature sensor
Sensors must be connected before the measuring
instrument is switched on, so that they are recognised by
the instrument.
Surface temperature sensor
An NTC temperature sensor (accessory) must be connected for
measuring the pipe temperature and for automatic calculation of
superheating and subcooling.
Deactivating the surface compensation factor for insertion and
air temperature sensor
A surface compensation factor has been set in the measuring
instrument to reduce the measuring errors in the main field of
applications. This reduces measuring errors when using surface
temperature sensors.
If the measuring instrument testo 550 is used in combination with
insertion or air temperature sensors (accessories), this factor must
be deactivated:
1. Press [Set] repeatedly until Tfac is displayed.
2. Press [▲]or [▼]to set Tfac to Off.
3. Press [Set] to continue through the settings menu until the
measurement/home view is displayed.
- Tfac is shown on the display if Tfac is disabled.

6 Using the product
14
Connecting the refrigerant hoses
Before each measurement check whether the refrigerant
hoses are in flawless condition.
✓ The valve actuators are closed.
1. Connect the refrigerant hoses for low-pressure side (blue) and
high-pressure side (red) to the measuring instrument.
2. Connect the refrigerant hoses to the system.
WARNING
The measuring instrument dropping down or any other comparable
mechanical load can cause breakage of the pipe pieces in the
refrigerant hoses. The valve actuators may also suffer damage,
which in turn could result in further damage inside the measuring
instrument, which may not be detectable from outside.
> For your own safety you should return the measuring
instrument to the Testo Service for technical inspection.
> You should therefore always replace the refrigerant hoses with
new ones after the measuring instrument has dropped down or
after any comparable mechanical loading.
Setting the refrigerant
1. Press [R, ►, ■].
- This opens the refrigerant menu and the currently selected
refrigerant flashes.
2. Setting the refrigerant:
Key functions
Representation Explanation
[▲]or [▼]Changing the refrigerant
[R, ►, ■] Confirm the setting and exit the refrigerant
menu.
Available refrigerants
Representation Explanation
R... Refrigerant number of refrigerant acc. to
ISO 817
--- no refrigerant selected.

6 Using the product
15
Example: Setting refrigerant R401B
1. Press [▲]or [▼]several times, until R401B flashes.
2. Press [R, ►, ■]to confirm the setting.
Quitting the refrigerant selection
> Press [R, ►, ■]or automatically after 30 s, if no other key has
been pressed.
Pos: 30 /TD/Produk t verwenden/testo 550/B luetooth Übersc hrift 550 @ 16\mod_14210585 14340_79.docx @ 206201 @ 3 @ 1
6.1.3. Switching Bluetooth® on and off (testo 550)
Pos: 31 /TD/Produk t verwenden/testo 557/B luetooth ein-aussc halten @ 16\mod_141873 2441244_79.docx @ 2054 97 @ @ 1
In order to be able to establish a connection via Bluetooth,
you need a tablet or smartphone with the Testo app
Refrigeration already installed on it.
You can get the App for iOS instruments in the App Store
or for Android instruments in the Play Store.
Information about compatibility can be found in the relevant
app store.
1. Press [▲]and [▼]simultaneously and hold down for
3 seconds.
- Once the Bluetooth icon is shown on the display, Bluetooth is
switched on.
Display Explanation
flashes There is no Bluetooth connection, or a
potential connection is being searched for.
is permanently
displayed
There is a Bluetooth connection.
is not displayed Bluetooth is disabled.
2. Press [▲]and [▼]simultaneously and hold down for
3 seconds.
- Once the Bluetooth icon is no longer shown on the display,
Bluetooth is switched off.
Pos: 32 /TD/Produk t verwenden/testo 550/ Messmodus testo 5502 @ 17\ mod_1423131750000_7 9.docx @ 207342 @ 3 @ 1
6.1.4. Selecting the measuring mode
1. Press [Set] several times.
2. Select function with [▲] or [▼].
3. Save setting: press [Set].
- Measuring mode is dsplayed.
Display Mode Function

6 Using the product
16
Display Mode Function
Refrigeration
system
Normal functionality of the digital
manifold
Heat pump Normal functionality of the digital
manifold
Automatic
mode
If the automatic mode is activated, the
testo 549 und testo 550 digital
manifold automatically changes the
display of the high and low pressure.
This automatic change occurs when
the pressure on the low-pressure side
is 1 bar higher than the pressure on
the high-pressure side. During the
change, Load (2 s) is shown in the
display.
This mode is especially suited to air
conditioning systems which cool and
heat.
Pos: 33 /TD/Produk t verwenden/testo 550/ Messung durchführ en testo 5502 @ 17\mod_142313 1786289_79.docx @ 207377 @ 2555 @ 1
6.2. Performing the measurement
WARNING
Risk of injury caused by refrigerant that is at high pressure,
hot, cold, or poisonous!
> Wear safety goggles and protective gloves.
> Before pressurizing the measuring instrument: Always fasten
the measuring instrument at the suspension device in order to
prevent it from falling (risk of breakage)
> Check if the refrigerant hoses are intact and connected
correctly before each measurement. Do not use a tool to
connect the hoses. Only tighten the hoses by hand (max.
torque 5.0 Nm/3.7 ft*lb).
> Maintain permissible measuring range (0 to 60 bar). Pay
particular attention with systems with refrigerant R744, as
these are often operated with higher pressures.

6 Using the product
17
Measuring
1. Pressurize the measuring instrument.
2. Read off readings.
With zeotropic refrigerants, the evaporation temperature
to/Ev is displayed after the complete evaporation/the
condensation temperature tc/Co is displayed after the
complete condensation.
The measured temperature must be assigned to the
superheating or the subcooling side (toh <--> tcu).
Depending on this assignment, toh/T1 or ∆toh/SH or
tcu/T2 or ∆tcu/SC is shown depending on the selected
display.
- Reading and display illumination flash:
• 1 bar before reaching the critical pressure of the refrigerant,
• upon exceeding the max. permissible pressure of 60 bar.
Key functions
> [▲]or [▼]: Change the reading display.
Possible display combinations:
Evaporation pressure
Refrigerant evaporation
temperature to/Ev
Condensation pressure
Refrigerant condensation
temperature tc/Co
or (only with connected temperature probe)
Evaporation pressure
Measured temperature toh/T1
Condensation pressure
Measured temperature tcu/T2
or (only with connected temperature probe)
Evaporation pressure
Superheating ∆toh/SH.
Condensation pressure
Subcooling ∆tcu/SC
With two connected NTC probes, ∆t is also shown.
> [Mean/Min/Max]: Record readings, display min./max. readings,
mean values (since switching on).
Tightness test/pressure drop test
Systems can be tested for tightness with the
temperature-compensated tightness test. The system
pressure and the ambient temperature are measured
over a defined period for this. A temperature probe can
be connected that measures the ambient temperature

6 Using the product
18
for this (recommendation: NTC air probe, art. no. 0613
1712). Information about the temperature-compensated
differential pressure and about the temperature at the
beginning/end of the test exists as a result. If no
temperature probe is connected, the tightness test can
be performed without temperature compensation.
1. Press [Mode] (leakage test view).
- Leakage test view is opened. ∆P is displayed.
2. Start the leakage test: Press [R, ►, ■].
3. End the leakage test: Press [R, ►, ■].
- Result is displayed.
4. Confirm message: Press [Mode].
Pos: 34 /TD/Übersc hriften/7. Produkt i nstand halten @ 0\mod_117 3789831362_79.doc x @ 397 @ 1 @ 1

7 Maintaining the product
19
7Maintaining the product
Pos: 35 /TD/Produk t instand halten/Gerä t reinigen 5502 @ 17\mod_142 3131833893_79.doc x @ 207412 @ 2 @ 1
Cleaning the instrument
Do not use any aggressive cleaning agents or solvents!
Mild household cleaning agents and soap suds may be
used.
> If the housing of the instrument is dirty, clean it with a damp
cloth.
Pos: 36 /TD/Produk t instand halten/tes to55 0/Instandhalten testo 550 @ 4\mod_ 1253262226679_79.doc x@ 50494 @ 5555 @ 1
Keeping connections clean
> Keep screw connections clean and free of grease and other
deposits, clean with a moist cloth as required.
Removing oil residues
> Carefully blow out oil residues in valve block using compressed
air.
Ensuring the measuring accuracy
Testo Customer Service would be glad to further assist you if you
so wish.
> Check instrument regularly for leaks (recommended: annually).
Keep to the permissible pressure range!
> Calibrate instrument regularly (recommended: annually).
Changing batteries/rechargeable batteries
✓Instrument is switched off.
1. Fold out the suspension device, loosen the clip and remove the
cover of the battery compartment.
2. Remove empty batteries/rechargeable batteries and insert new
batteries/rechargeable batteries (4x 1.5 V, type AA, Mignon,
LR6) in the battery compartment. Observe the polarity!
3. Set on and close cover of the battery compartment (clip must
engage).
4. Switch the instrument on.

8 Tips and assistance
20
Pos: 37 /TD/Übersc hriften/8. Tipps und Hilfe @ 0\mod_11 73789887985_79.doc x@ 406 @ 1 @ 1
8Tips and assistance
Pos: 38 /TD/Übersc hriften/8.1 Fragen und An tworten @ 0\mod_117740 2017078_79.docx @ 1093 @ 2 @ 1
8.1. Questions and answers
Pos: 39 /TD/Tipps u nd Hilfe/Fragen und Antwor ten/testo 550/FAQ tes to 550 @ 5\mod_12651859459 86_79.docx @ 56964 @ @ 1
Question Possible causes/solution
flashes Batteries are almost empty.
> Change batteries.
The instrument switches
off automatically.
Residual capacity of the batteries is
too low.
> Change batteries.
uuuu lights up instead of
the parameter display
The permissible measuring range has
been undershot.
> Keep to the permitted measuring
range.
oooo lights up instead of
the parameter display
The permissible measuring range has
been exceeded.
> Keep to the permitted measuring
range.
Pos: 40 /TD/Tipps u nd Hilfe/Fragen und Antw orten/testo 550/Messgr ößen testo 5502 @ 17\mod_ 1423131888592_79. docx@ 207447 @ 2 @ 1
8.2. Measurement parameters
Name Description
bar, °C psi, °F
∆toh SH Superheating, evaporation pressure
∆tcu SC Subcooling, condensation pressure
to Ev Refrigerant evaporation temperature
tc Co Refrigerant condensation temperature
toh T1 Measured temperature, evaporation
tcu T2 Measured temperature, condensation
Pos: 41 /TD/Tipps u nd Hilfe/Fehlermeldun gen/Fehlermeldungen testo 5502 @ 17\ mod_1423131934429_79. docx @ 207482 @ 2 @ 1