MBA MLA1000 User manual

Operating Instructions
MLA1000
Conductivity Meter for Flowing Light Oil
Description
Installation
Operation
EN

Document information
Described product
Product name: MLA1000
Document identification
Title: MLA1000 Operating Instructions
Order number: 8011607
Version: 1.0
Date: 2019-10
Publisher
MBA Instruments GmbH
Friedrich-List-Str. 3-725451 Quickborn · Germany
Phone: [phone]
Fax: [phone]
Email: [email protected]
Warranty information
The stated product characteristics and technical data do
not constitute warranty declarations.
© MBA Instruments GmbH. All rights reserved.
Glossary
ATEX Atmosphères explosibles: Abbreviation for
European standards relating to safety in explosion-
endangered areas
DC Direct current
IP xy International protection (also: Ingress Protection);
protection class for a device pursuant to IEC/DIN
EN 60529.
PE Polyethylene
PUR Polyurethane
PVC Polyvinyl chloride
TPE Thermoplastic elastomer
Warning symbols
Hazard (general)
Hazard from electrical voltage
Hazard in explosion-endangered areas
Hazard from explosive substances/ substance
mixtures
Hazard from noxious substances
Warning levels/signal words
WARNING
Hazard situation for people that could result in serious
injuries or death.
CAUTION
Hazard that could result in less serious or minor injuries
and/or risk of damage to property.
IMPORTANT
Hazard possibly resulting in damage to property.
Information symbols
Important technical information for this product
Important information about explosion-
endangered areas
Tip
Additional information
Reference to information elsewhere

Content
1Safety Instructions .........................................................................................................................................................................................5
1.1 Important instructions for safe usage .......................................................................................................................................5
1.2 Principal installation instructions ..............................................................................................................................................5
1.3 Principal operating instructions ................................................................................................................................................5
1.4 Responsibilities of the user .......................................................................................................................................................6
1.4.1 Only allow installation and use by specialist technicians ..........................................................................................................6
1.4.2 Correct use ................................................................................................................................................................................6
1.4.3 Consideration of local conditions..............................................................................................................................................6
1.4.4 Safekeeping of the documentation ...........................................................................................................................................6
2Product Description .......................................................................................................................................................................................7
2.1 Intended usage..........................................................................................................................................................................7
2.1.1 Intended scope of application...................................................................................................................................................7
2.1.2 Application restrictions .............................................................................................................................................................7
2.1.3 Certification for explosion-endangered areas...........................................................................................................................7
2.2 Operating principle....................................................................................................................................................................8
2.3 Product components.................................................................................................................................................................9
2.3.1 MLA1000-S measuring probe ....................................................................................................................................................9
2.3.2 MLA1000-A display unit ............................................................................................................................................................9
2.3.3 MLA1000-K probe cable ............................................................................................................................................................9
2.3.4 Options......................................................................................................................................................................................9
2.4 Scope of delivery .....................................................................................................................................................................10
3Installation of the Measuring Probe ...........................................................................................................................................................11
3.1 Selecting the installation location for the measuring probe ...................................................................................................11
3.1.1 Requirements for the measuring liquid at the installation location........................................................................................11
3.1.2 Requirements for the installation location..............................................................................................................................11
3.2 Preparing the piping system....................................................................................................................................................12
3.3 Installation of the measuring probe with immersion pipe ......................................................................................................12
4Installation of the Display Unit....................................................................................................................................................................14
4.1 Mounting the display unit .......................................................................................................................................................14
4.1.1 Criteria for the mounting location...........................................................................................................................................14
4.1.2 Securing the display unit without a mounting bracket ...........................................................................................................14
4.1.3 Securing the display unit with a mounting bracket.................................................................................................................14
4.2 Connecting the potential equalisation ....................................................................................................................................15
4.3 Opening the housing ...............................................................................................................................................................15
4.4 Installing the cables.................................................................................................................................................................16
4.4.1 General information about installing the cables .....................................................................................................................16
4.4.2 Connecting the probe cable ....................................................................................................................................................16
4.4.3 Connecting the measurement reading outputs ......................................................................................................................16
4.4.4 Connecting the supply voltage ................................................................................................................................................17
4.4.5 Closing the cable glands and housing......................................................................................................................................17
5Operation.......................................................................................................................................................................................................18
5.1 Putting the MLA1000 into operation ......................................................................................................................................18
5.2 Checking the operating status.................................................................................................................................................18
5.2.1 Indications for a safe operating status ....................................................................................................................................18
5.2.2 Indications for an unsafe operating status..............................................................................................................................18
5.3 Display screens........................................................................................................................................................................18
5.3.1 Screen after switching on........................................................................................................................................................18
5.3.2 Operating screen.....................................................................................................................................................................18
5.3.3 Malfunction screens................................................................................................................................................................19
6Maintenance..................................................................................................................................................................................................21
6.1 Removing the immersion pipe (with measuring probe)..........................................................................................................21
6.2 Testing the measuring function...............................................................................................................................................21
6.3 Cleaning the measuring probe ................................................................................................................................................22
6.4 Reinstalling the measuring probe............................................................................................................................................22
7Troubleshooting ...........................................................................................................................................................................................23
7.1 If the MLA1000 does not function at all ... ..............................................................................................................................23
7.2 If the measurement readings are obviously incorrect... .........................................................................................................23
8Appendix .......................................................................................................................................................................................................24
8.1 Technical data .........................................................................................................................................................................24
8.1.1 MLA1000-S measuring probe ..................................................................................................................................................24
8.1.2 MLA1000-A display unit ..........................................................................................................................................................24
8.1.3 MLA1000-K probe cable ..........................................................................................................................................................24
8.2 Certification/suitability test.....................................................................................................................................................24
8.3 Disposal Information ...............................................................................................................................................................25

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MLA1000 Continuous Conductivity Measurement
1Safety Instructions
1.1 Important instructions for safe usage
Only use the MLA1000 in explosion-endangered areas if permitted by the specifications for the
zone, explosion group and temperature class (refer to the type plate on the display unit and
measuring probe).
Pay attention to and heed the "special conditions" stated on the type examination certificate.
Installation, commissioning, maintenance and testing may only be carried out by technicians who
possess requisite knowledge of the rules and regulations for explosion-endangered areas, e.g.
zoning
types of ignition protection
installation regulations, e.g. "Ordinance on electrical systems in explosion-endangered
locations (ElexV)"
Do not alter the product. Repairs may only be carried out by the manufacturer or by trained and
authorised technicians.
If the product was delivered with special information about it: Pay preferential attention to any
special information.
1.2 Principal installation instructions
IMPORTANT:
►Install the measuring probe so that the liquid flows past the probe in the required
direction (→ p.14, Fig. 3).
►Only use measuring probes and probe cables that have been approved by the
manufacturer for the intended measuring liquid.
►Only put the MLA1000 into operation when the entire housing and all the cable
glands have been correctly sealed.
1.3 Principal operating instructions
Intended usage → p.7, section 2.1.
Do not use the measurement readings if the requirements for the installation location
of the measuring probe have not been fulfilled, in particular if the flow velocity of the
measuring liquid is not within the specified range (→ p.7, section 2.1.1).
IMPORTANT:
►In explosion-endangered areas: Only open the terminal box for the display unit
(bottom part of the housing) after the supply voltage and all external power
supplies have been switched off.
►If the measuring probe could become soiled during operation: Clean the probe at
regular intervals (→ p.22, section 6.3).
►If the measurement readings cannot be correct: Check whether the measuring
probe is soiled.
►If necessary, clean the probe.

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MLA1000 Continuous Conductivity Measurement
1.4 Responsibilities of the user
1.4.1 Only allow installation and use by specialist technicians
►Make sure that the MLA1000 is only installed and used by specialist technicians who, on account
of their specialist training and knowledge and their familiarity with the applicable regulations, are
able to assess the work assigned to them and recognise any hazards.
This applies in particular to:
–safety in explosion-endangered areas
–welding work
–handling of combustible substances
1.4.2 Correct use
►Only use the product as described in these operating instructions. The manufacturer will bear no
responsibility for any deviating usage.
►Carry out the described maintenance work.
►Do not carry out any work or repairs on the product which are not described in these operating
instructions.
►Do not remove, add or alter any components belonging to the product unless stipulated in official
information provided by the manufacturer. Otherwise,
–the manufacturer's warranty will become void,
–the product could become dangerous,
–the certification for use in explosion-endangered areas will become void.
1.4.3 Consideration of local conditions
►All local legislation, technical rules and operating regulations that apply at the location where the
product is to be used must be observed in addition to these operating instructions.
1.4.4 Safekeeping of the documentation
►These operating instructions and all the supplied documentation must be kept available for
reference purposes.
►Give the documentation to the new owner.

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MLA1000 Continuous Conductivity Measurement
2 Product Description
2.1 Intended usage
IMPORTANT:
►If the product was delivered with special information about it:
►Pay preferential attention to any special information.
2.1.1 Intended scope of application
Measuring function
The MLA1000 is designed for continuously measuring the electrical conductance and
temperature of suitable flowing measuring liquids. Suitable measuring liquids: kerosene, light
fuels, lubricants, coolants, various chemical liquids.
It can only be guaranteed that the MLA1000 will function as intended when used in
flowing light fuel at a flow velocity of at least 0.2 m/s.
Application purpose
Liquids can become electrostatically charged during filling, pumping or filtration. In the
presence of an ignitable gas mixture in the ambient environment, there is also a risk that the
gas mixture will be ignited (i.e. explode) by discharge sparks. This risk is assessed by
measuring the electrical conductance of the liquid (see DIN 51 412-T02-79 "Determining
electrical conductance, field procedure").
The conductance is stated using the physical unit "pS/m" (picosiemens per meter).
The unit "c.u." (conductivity unit), which is still frequently used in the oil industry, has
an equal value:
1 pS ⁄ m = 1 c.u.
2.1.2 Application restrictions
►Only use the MLA1000 for measuring suitable measuring liquids.
►The measuring liquid must meet certain requirements (→ p.11, section 3.1.1).
►Heed the supplied manufacturer's information regarding restrictions and suitability.
Unsuitable liquids (e.g. acids, chlorinated hydrocarbon solvents) can damage the measuring
probe and probe cable.
WARNING: Risk of incorrect measurements
The measuring liquid must fulfil the stipulated requirements for the measuring probe
at the installation location (→ p.11, section 3.1.1) as otherwise the readings will not be
reliable.
►Make sure that the measuring fluid at the installation location of the measuring
probe fulfils the stipulated requirements.
►If the conductance measurement reading is being used to monitor the safe usage
of the measuring fluid (in particular for explosion protection purposes): Make sure
that the measurement readings are recognised as being invalid if the measuring
liquid at the installation location of the measuring probe does not fulfil the
stipulated requirements. If necessary, install appropriate safety mechanisms.
Unsafe operating conditions could otherwise arise in the monitored system.
2.1.3 Certification for explosion-endangered areas
●The MLA1000-S measuring probe (→ p.9, section 2.3.1) is certified for installation in containers (e.g.
piping systems) holding combustible liquids in Zone 0 hazardous areas.
●The MLA1000-A display unit (→ p.9, section 2.3.2) is certified for use in Zone 1 hazardous areas.
Numbers of the type examination certificates → p.24, section 8.2

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MLA1000 Continuous Conductivity Measurement
1089 pS/m
20.1 °C
V0.95 5-2000
No.: xxxxxxx
xxxxATEXxxxx
2.2 Operating principle
●The measuring probe of the MLA1000 is installed in the container through which the measuring
liquid flows (e.g. a piping system). The measuring liquid must meet certain requirements (→ p.11,
section 3.1.1).
●The probe measures the conductance by sending an electrical current through the measuring
liquid by means of low auxiliary voltage. The greater the conductance, the stronger is the electrical
current. The electronics in the probe convert the measured current into a digital measurement
signal.
●The display unit supplies the probe with auxiliary voltage and processes the measurement signals
using a microprocessor. The measurement readings are displayed numerically and outputted as
an analogue signal.
Fig. 1 Product components
13
4
2
1
MLA1000-A display unit
2
MLA1000-S measuring probe
3
MLA1000-K probe cable
4
Immersion pipe (optional)

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MLA1000 Continuous Conductivity Measurement
2.3 Product components
2.3.1 MLA1000-S measuring probe
The measuring probe consists of two parts:
●Probe body (hexagonal) with core electrode and connection for the probe cable
●Sheathed electrode (cylindrical) with inlet and outlet opening
The sheathed electrode can be unscrewed for cleaning purposes.
The probe body has a screw thread for attaching the measuring probe.
The temperature sensor and probe electronics are integrated in the sensor body.
●Technical data → p.24, section 8.1.1.
●Functional test with ring magnet → p.21, section 6.2.
2.3.2 MLA1000-A display unit
The display unit housing consists of two parts:
●Top housing: Display section –contains the electronic components.
●Bottom housing: Terminal box –contains the connection terminals.
The top and bottom parts of the housing are separated by a gas-tight seal.
The electronic connection to the measuring probe is intrinsically safe.
IMPORTANT:
The connection between the housing parts must be supported (certification requirement).
►Secure both housing parts of the display unit on a solid subsurface such as a
mounting panel (instructions → p.15, section 4.1.2).
●Technical data → p.24, section 8.1.2
●Certification for explosion-endangered areas → p.7, section 2.1.3.
2.3.3 MLA1000-K probe cable
●Length: The probe cable is available in different lengths. The cable ends are ready for use:
–Ferrules for connection terminals
–Receptacle for the measuring probe plug connector
●Material: The sheath material used for the selected version of the probe cable must be chemically
resistant to the intended measuring liquid. The right type of probe cable is therefore dependent
upon the specific application.
Technical data → p.24, section 8.1.3.
2.3.4 Options
Option
Notes
Immersion pipe
–for the measuring probe
–with securing chain
Mounting bracket
–for the display unit
Sliding sleeve
–for the immersion pipe
Ball valve
–as sluice for the immersion pipe

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MLA1000 Continuous Conductivity Measurement
2.4 Scope of delivery
Basic components
●Measuring probe (→ p.9, section 2.3.1)
●Display unit (→ p.9, section 2.3.2)
●Probe cable (→ p.9, section 2.3.3)
●Ring magnet for functional testing (→ p.21, section 6.2)
Options / accessories
As ordered (→ p.9, section 2.3.4).
Standard delivery:
●If delivery includes an immersion pipe: The immersion pipe, measuring probe and
probe cable are already assembled.
●If delivery includes the mounting bracket: The immersion pipe and display unit are
already assembled.
Documentation
●Certificate of conformity
●Type examination certificate BVS 14 ATEX E047 X (for MLA1000-S probe)
●Type examination certificate BVS 14 ATEX E026 X (for MLA1000-A display unit)
●Operating instructions
●If delivery includes a ball valve: Directions for use from the manufacturer of the ball valve
●If delivery includes a sliding sleeve: Directions for use from the manufacturer of the sliding sleeve

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MLA1000 Continuous Conductivity Measurement
3 Installation of the Measuring Probe
3.1 Selecting the installation location for the measuring probe
3.1.1 Requirements for the measuring liquid at the installation location
Criterion
Action
The measuring liquid should flow at the
installation location as homogeneously
and evenly as possible.
►If possible, install the measuring probe in
a long, straight piece of tubing.
►After a pipe bend, select a distance
equivalent to at least five times the
inside diameter of the pipe (5d).
The measuring liquid at the installation
location should have an homogeneous
composition (fully mixed).
►Do not install the measuring probe
immediately after the mixing stations.
The flow velocity must lie between 0.2
and 7 m/s (→ p.24, section 8.1).
►Specifications → p.24, section 8.1.
Temperature and pressure must be
within
the permitted ranges (→ p.24, section 8.1).
3.1.2 Requirements for the installation location
Criterion
Action
The probe cable between the measuring
probe and display unit can have a
maximum length of 24 m.
►Check the length of the supplied probe
cable.
The immersion pipe may have to be
removed after a certain number of
operating hours for cleaning or replacing
the measuring probe.
►Take into account the space required for
the piping system.
►As required: Install auxiliary devices for
disassembling the probe while the piping
system is in operation (sliding sleeve[1],
ball valve[1]).
[1] Optional (→ p.9, section 2.3.4).
WARNING: Risk of incorrect measurements
The measuring liquid must fulfil the stipulated requirements at the
measuring probe as otherwise the readings will not be reliable.
►Make sure that the measuring fluid at the installation location of the
measuring probe fulfils the stipulated requirements.
►If the conductance measurement reading is being used to monitor the
safe usage of the measuring fluid (in particular for explosion
protection purposes): Make sure that the measurement readings are
recognised as being invalid if the measuring liquid at the installation
location of the measuring probe does not fulfil the stipulated
requirements. If necessary, install appropriate safety mechanisms.
Unsafe operating conditions could otherwise arise in the monitored system.

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MLA1000 Continuous Conductivity Measurement
No.: xxxxxxx
xxxxATEXxxxx
No.: xxxxxxx
xxxxATEXxxxx
3.2 Preparing the piping system
►Prepare the installation location so that the work can take place in a safe manner.
►On the piping system, mount the devices that are required for installing the immersion pipe.
►If delivery includes a ball valve: Install the ball valve in the piping system as described in the directions for
use provided by the manufacturer of the ball valve (separate document).
If delivery includes the optional immersion pipe, the measuring probe is installed in
the pipe.
WARNING: Danger of explosion
In explosion-endangered areas:
►Before beginning with the installation, carry out all the measures that are
necessary to safeguard against explosion during the installation work.
WARNING: Danger of explosion/fire hazard
Before welding:
►Completely empty the piping system.
►Remove all remaining measuring liquid from the piping system.
Vapours can otherwise occur during welding work that will produce an explosive
gas mixture; residues of the measuring liquid could catch fire.
3.3 Installation of the measuring probe with immersion pipe
Preparations for the installation → p.12, section 3.2.
IMPORTANT:
►Install the measuring probe so that the required direction of flow for the probe is
given.
Otherwise the measurement readings will not be reliable.
Marking the direction of flow
►Set the marker arrow on the immersion pipe so that it points in the direction of flow for the
measuring probe (→ Fig. 2).
Fig. 2 Marker arrow for the direction of flow
1
3
2
1
Marker arrow
2
Outlet
3
Direction of flow

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MLA1000 Continuous Conductivity Measurement
No.: xxxxxxx
xxxxATEXxxxx
Marking the installation depth
►On the immersion pipe, mark how far it has to be inserted in the slide fitting so that the
measuring probe is correctly positioned in the flowing media.
Slide a sealing ring onto the immersion pipe as marker.
Installing the immersion pipe
1Carefully insert the immersion pipe (with measuring probe) over the device in the piping
system up to the marker for the immersion depth.
2Turn the immersion pipe so that the marker arrow points in the direction of flow (→ Fig. 3).
3Affix the immersion pipe in this position.
Connecting the probe cable
►Connect the probe cable. Secure the plug connector with the coupling nut on the
connector.
Fig. 3 Installed measuring probe

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MLA1000 Continuous Conductivity Measurement
1089 pS/m
20.1 °C
V0.95 5-2000
4 Installation of the Display Unit
4.1 Mounting the display unit
Not applicable if the display unit and immersion pipe were delivered already assembled.
4.1.1 Criteria for the mounting location
●The display unit may be installed in a Zone 1 explosion-endangered area. An installation in Zone
0 is not permitted.
●The possible distance between the display unit and measuring probe is dependent upon the
length of the supplied probe cable (maximum length: 24 m).
●The display unit must be attached to a wall or a stable mounting.
●The display should be visible while the unit is being operated (for checking the operating status).
4.1.2 Securing the display unit without a mounting bracket
1Secure the top housing of the display unit with 2 screws (Ø 8 mm) to a firm, flat subsurface (e.g. metal
wall, metal plate, smooth wall surface of a building).
2Secure the bottom housing with at least 2 screws (Ø 6 mm) to the same subsurface.
4.1.3 Securing the display unit with a mounting bracket
The mounting bracket is a delivery option. If the delivery includes a mounting bracket, the display unit
is already mounted on it.
►Affix the mounting bracket with the unit on the immersion pipe (→ p.13, section 3.3).
Fig. 4 MLA1000-A display unit
1089 pS/m
1
°C
1
Top housing
2
Bottom housing (terminal box)
2
1

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MLA1000 Continuous Conductivity Measurement
1089 pS/m
20.1 °C
V0.95 5-2000
4.2 Connecting the potential equalisation
►Join the two connections for the potential equalisation (→ Fig. 5) directly with the main potential (earthing).
4.3 Opening the housing
WARNING: Risk of explosion in explosion-endangered areas
►Before opening the terminal box (bottom part of the display unit): The display unit
must be disconnected from the power supply.
Otherwise there could be a risk of explosion when the terminal box is opened.
1If the display unit is already connected to the power supply: Switch off or disconnect the
power supply.
2Open the bottom housing of the display unit.
Fig. 5 Connecting terminals
1089
pS/m
20.1 °C
V0.95
5-2000
1 2 3 4 5 6 7 1 2 3 4
1
Connection for the potential equalisation
2
Connecting terminals for the probe cable (→ p.17, section 4.4.2)
3
Connecting terminals for the supply voltage (→ p. 18, section 4.4.4) and measurement
reading outputs
(→ p.17, section 4.4.3)
4
Connection for the potential equalisation
The top housing of the display unit does not need to be opened. It may only be
opened by authorised technicians for repair purposes.
►Leave the top housing closed.
2
3
4
1

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MLA1000 Continuous Conductivity Measurement
4.4 Installing the cables
4.4.1 General information about installing the cables
►Use suitable cable materials → p.24, section 8.1.2.
►Run all the cables through the cable glands in the bottom housing of the display unit (→ Fig. 2).
When connecting the conductors:
►Strip the conductor insulation to a length of 7 mm.
►Tighten the clamping screw on the connecting terminal with a torque of at least 0.3 Nm.
WARNING: Danger of explosion
The cable glands are subject to approval for explosion-endangered areas.
►Only use cable materials with a suitable outside diameter.
►If the MLA1000 is being used in an explosion-endangered area: Do not replace
the cable glands with cable glands of a different type. Otherwise the certification
for explosion-endangered areas will become void and there will be a risk of
explosion in such areas.
4.4.2 Connecting the probe cable
►Connect the probe cable to the blue 4-pole terminal block (→ Table 1).
Table 1 Connecting terminals for the probe cable
4-pole terminal block
Connecting terminal
Colour code for probe cable
1
brown
2
black
3
blue
4
white
4.4.3 Connecting the measurement reading outputs
The measurement reading outputs continually give out the actual measured values. The physical
measuring range is outputted in the signal range between 4 and 20 mA.
►Connect the measurement reading outputs as shown in the terminal diagram (→ Table 2).
Table 2 Output signals for the measurement reading outputs
Output signal
Explanation
0 mA
Electrical connection has been interrupted.
MLA1000 is malfunctioning or defective.
4 to 20 mA
Current measurement reading
24 mA
Measurement readings cannot be generated.
Possible causes:
–The true physical value is greater than the
end value of the measuring range
(overflow).
–The measuring probe is soiled.
Permitted output load → p.24, section 8.1.

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MLA1000 Continuous Conductivity Measurement
4.4.4 Connecting the supply voltage
►Install a fuse in the power supply lead for the MLA1000.
Fuse rating: max. 5 A (power consumption → p.24, section 8.1.2).
►Connect the power supply as shown in the terminal diagram (→ Table 3).
►Make sure that the current fed into the power supply lead cannot exceed 5 A.
Specification for the power supply → p.24, section 8.1
Table 3 Connecting terminals for the measurement reading output and power supply
7-pole terminal block
Connecting terminal
Function
1
Power supply +24 V DC
2
Power supply GND
3
Measurement reading output for temperature (+ mA)
4
Measurement reading output for conductance (+ mA)
5
Measurement reading outputs for GND (-mA)
6
7
–no function –
4.4.5 Closing the cable glands and housing
After installing the cables:
►Seal the cable glands.
►Close the housing.
WARNING: Danger of explosion
Before putting the unit into operation in explosion-endangered areas:
►Seal all the cable glands so that they are "flame-tight" (practically gas-tight).
►Either close off any unused cable glands with a closure plug or replace them
completely with sealing caps.
–Closure plugs: Select suitable closure plugs for the permitted cable
diameters and install them instead of a cable.
–Sealing caps: Select sealing caps with thread M20 x 1.5 which are certified
for usage in explosion-endangered areas. Apply suitable adhesive to the
threads and sealing surfaces.
►Tightly close the display unit housing.
Otherwise there could be a risk of explosion.

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MLA1000 Continuous Conductivity Measurement
5 Operation
5.1 Putting the MLA1000 into operation
1Make sure that the display unit housing is tightly closed.
2Switch on the supply voltage.
3Wait for the display to light up after switching it on (→ p.19, section 5.3.1).
4Check the operating status (→ section 5.2).
5.2 Checking the operating status
5.2.1 Indications for a safe operating status
1The measuring liquid fulfils the requisite operating conditions at the measuring probe
(→ p.11, section 3.1.1, e.g. flow velocity).
2The display on the display unit shows the measurement readings (→ section 5.3.2).
3Measurement readings are returned at the measurement reading outputs.
Testing the measuring function → p.21, section 6.2.
5.2.2 Indications for an unsafe operating status
Nothing is shown on the display of the display unit.
A malfunction is shown on the display (→ p.20, section 5.3.3).
At least one measurement reading output returns "0 mA".
At least one measurement reading output returns "24 mA".
The measuring liquid does not have the required flow velocity at the measuring probe
(→ section 5.3.2).
The measuring liquid is not within the permitted temp. range at the measuring probe (→ section 5.3.2).
Measurement readings are being displayed that cannot be correct.
At least one measurement reading output returns readings that cannot be correct.
5.3 Display screens
5.3.1 Screen after switching on
MLA1000 V0.95
Conductivity
measurement
Explanation:
MLA1000 is starting up (approx. 3 seconds).
Actions:
►Wait until the operating screen appears (→ section 5.3.2).
►If the operating screen does not appear: Refer to the
information about the malfunction screens (→ section 5.3.3).
5.3.2 Operating screen
1089 pS/m
20.1 °C
V0.95 5-2000
Explanation:
MLA1000 is in the normal operating status (measuring mode).
1 = actual conductance measurement reading (sample value)
2 = actual temperature measurement reading (sample value)
3 = version number of the firmware (example)
Actions:
►Check/ensure that the requirements for safe operation are
fulfilled (see warning note).
WARNING: Requirements for safe operation
●The flow velocity of the measuring liquid at the measuring probe must be between 0.2
and 7 m/s.
●The measuring liquid temperature must be between -20 and +60 °C. Otherwise the
measurement readings will not be reliable.
1
2
3

MLA1000 · Operating Instruction · 8011607 V 1.0 · © MBA Instruments
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MLA1000 Continuous Conductivity Measurement
5.3.3 Malfunction screens
High pS/m
20.1 °C
V0.95 5-2000
Explanation:
The actual conductance measurement reading is greater than
2000 pS/m.
Effects:
>> The measurement reading output for the conductance is
returning 24 mA.
Recommended actions:
►Check whether the conductance of the measuring liquid at
the measuring point could actually be so high.
►Check whether the measuring liquid is passing by the
probe properly (→ p.13, 3.3).
►Clean the measuring probe (→ p.22, section 6.3).
Low pS/m
20.1 °C
V0.95 5-2000
Explanation:
The actual conductance measurement reading is less than 5
pS/m.
Effects:
>> The measurement reading output for the conductance is
returning 0 mA.
Recommended actions:
►Check whether the measuring fluid is flowing (the flow
velocity is at least 0.2 m⁄s).
►Check whether the conductance of the measuring liquid at
the measuring point could actually be so low.
►Check whether the measuring liquid is passing by the
probe properly (→ p.13, 3.3).
Sensor
Error
V0.95 5-2000
Explanation:
The measuring probe is malfunctioning.
Effects:
>> The measurement reading outputs are returning 0 mA.
Recommended actions:
►Carefully check the electrical connection between the
display unit and the measuring probe (condition of the
connecting cable, terminals; after installation:
wiring/terminal assignment).
►If that does not help: Notify the manufacturer (have the
probe replaced).
Fatal
Error
V0.95 5-2000
Explanation:
The MLA1000 is not functioning.
Effects:
>> The measurement reading outputs are returning 0 mA.
Recommended actions:
►Shut down and disconnect the MLA1000 and then put it
back into operation.
►If that does not help: Clean the measuring probe (→ p.22,
section 6.3).
►If that does not help: Notify the manufacturer.

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MLA1000 Continuous Conductivity Measurement
6 Maintenance
6.1 Removing the immersion pipe (with measuring probe)
●The MLA1000 does not have to be shut down for this work.
●If the MLA1000 remains in operation, the measuring function can be tested using
simple means (→ section 6.2).
CAUTION: Possible danger to health
If the measuring liquid could represent a health risk:
►Before removing the immersion pipe, take the appropriate protective measures suitable
for the measuring liquid (e.g. safety goggles, protective clothing, respirator).
For installations without a ball valve
1Take the piping system out of operation (stop the liquid flow).
2Remove the immersion pipe from the unit.
For installations with a ball valve
►Follow the instructions given by the manufacturer of the ball valve (separate document).
6.2 Testing the measuring function
●This procedure tests the electronic functionality of the measuring probe and
display unit.
●The supplied ring magnet is required for this procedure.
●Adjustment (electronic adjustment of the measuring probe and display unit)
are not necessary during operation.
A measuring probe that is clean, dry and functioning correctly the device displays
"low" in atmosperetic air.
1Make sure
–that the sheathed electrode is firmly screwed onto the measuring probe,
–that the probe is clean and dry,
–that the probe is properly connected to the display unit (probe cable, plug-in connection on the
probe).
2Place the ring magnets on the surface of the measuring probe opposite the labelled area.
For the test value for electrical conductivity, please refer to the test certificate.
►If the test value is not within the tolerance range: Notify the manufacturer's customer service or
return the MLA1000 to the manufacturer for repair.