KRAL OMH Series User manual

Operating instructions
KRAL flowmeters.
Series OMH
OIO 08en-GB
Edition 2020-01
Original instructions
www.kral.at

Table of contents
1 About this document ..................................................... 4
1.1 General information .......................................................4
1.2 Target groups ................................................................4
1.3 Symbols.........................................................................4
1.3.1 Danger levels ....................................................4
1.3.2 Danger signs.....................................................5
1.3.3 Symbols in this document .................................5
1.4 Associated documents ..................................................5
2 Safety .............................................................................. 5
2.1 Proper use .....................................................................5
2.2 Foreseeable misuse ......................................................6
2.3 Obligations of the operator-owner .................................6
2.4 Safety instructions .........................................................6
2.4.1 Fundamental safety instructions .......................6
3 Identification................................................................... 6
3.1 Type code......................................................................6
3.2 Rating plate ...................................................................8
4 Technical data ................................................................ 8
4.1 Operating limits..............................................................8
4.2 Pressure pulsation.........................................................8
4.3 Maximum values............................................................8
4.4 Substitute operating data...............................................9
4.5 Sound pressure level.....................................................9
4.6 Dimensions and weights..............................................10
4.6.1 Pipe thread (BSPP thread) .............................10
4.6.2 DIN flange .......................................................10
4.6.3 SAE flange ......................................................11
4.7 Pressure bearing capacity ...........................................12
4.7.1 Pressure bearing capacity OMH-013..............12
4.7.2 Pressure bearing capacity OMH-020..............13
4.7.3 Pressure bearing capacity OMH-032..............14
4.7.4 Pressure bearing capacity OMH-052..............15
4.7.5 Pressure bearing capacity OMH-068..............16
4.7.6 Pressure bearing capacity OMH-100..............17
5 Function description.................................................... 18
5.1 Structure ......................................................................18
5.2 Functional principle......................................................18
5.3 Rolling bearings...........................................................18
5.4 Signal generation.........................................................19
5.5 Linearization ................................................................19
5.6 Recognition of flow direction........................................19
6 Transportation, storage............................................... 20
6.1 Dangers during transportation .....................................20
6.2 Dangers during storage ...............................................20
6.3 Unpacking and checking the state of delivery .............20
6.4 Transporting flowmeters ..............................................20
6.5 Storing the flowmeter...................................................21
7 Preservation ................................................................. 21
7.1 Preservation table........................................................21
7.2 Preserving the inner surfaces......................................22
7.3 Preserving the outer surfaces......................................22
7.4 Removing the preservation..........................................22
8 Installation, removal .................................................... 23
8.1 Dangers during installation ..........................................23
8.2 Dangers during removal...............................................23
8.3 Installing the flowmeter ................................................23
8.3.1 Protecting the flowmeter against soiling ..........23
8.3.2 Installation types..............................................23
8.3.3 Installation recommendation............................24
8.3.4 Installing the flowmeter....................................25
8.4 Removing the flowmeter ..............................................26
9 Connection.....................................................................26
9.1 Dangers during connection work .................................26
9.2 Connecting the flowmeter to the pipe system ..............27
9.3 Connecting the pick up ................................................28
10 Operation........................................................................28
10.1 Dangers during operation ............................................28
10.2 Commissioning ............................................................28
10.2.1 Cleaning the pipe system ................................28
10.2.2 Checking the function ......................................29
10.2.3 Commissioning the flowmeter .........................29
10.3 Decommissioning.........................................................29
10.3.1 Switching off the flowmeter..............................29
10.4 Recommissioning.........................................................30
10.4.1 Recommissioning the flowmeter......................30
11 Maintenance...................................................................30
11.1 Required maintenance.................................................30
11.2 Maintaining flowmeters ................................................30
11.3 Recalibration of the flowmeter .....................................31
12 Servicing ........................................................................31
12.1 Dangers during servicing .............................................31
12.2 Replacing seals and ball bearings ...............................31
12.2.1 Removing seals and ball bearings OMH-013 ..31
12.2.2 Installing seals and ball bearings OMH-013 ....32
12.2.3 Removing seals and ball bearings OMH-020/
OMH-032 .........................................................32
12.2.4 Installing seals and ball bearings OMH-020/
OMH-032 .........................................................33
12.2.5 Removing seals and ball bearings OMH-052/
OMH-068 .........................................................34
12.2.6 Installing seals and ball bearings OMH-052/
OMH-068 .........................................................35
12.2.7 Removing seals and ball bearings OMH-100 ..36
12.2.8 Installing seals and ball bearings OMH-100 ....37
13 Disposal..........................................................................38
13.1 Dangers during disposal ..............................................38
13.2 Dismantling and disposing of the flowmeter ................38
14 Troubleshooting ............................................................39
14.1 Possible faults..............................................................39
14.2 Troubleshooting ...........................................................39
15 Spare parts.....................................................................41
15.1 Overview OMH-013 .....................................................41
15.2 Overview OMH-020/032 ..............................................42
15.3 Overview OMH-052/068 ..............................................43
15.4 Overview OMH-100 .....................................................44
16 Appendix ........................................................................45
16.1 Tightening torques for screws with metric screw threads
with and without wedge lock washers..........................45
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Table of contents
16.2 Tightening torques for screw plugs with thread meas-
ured in inches and elastomer seal...............................45
16.3 Tightening torques and widths for threaded rings .......46
16.4 Contents of the Declaration of Conformity...................46
Operating instructions OIO 08en-GB Edition 2020-01 3

1 About this document
1.1 General information
1 About this document
1.1 General information
These instructions form part of the product and must be kept for future reference. Furthermore please
observe the associated documents.
1.2 Target groups
The instructions are intended for the following persons:
oPersons who work with the product
oOperator-owners who are responsible for the use of the product
Persons who work with the product must be qualified. The qualification ensures that possible dangers
and damage to property that are connected to the activity are detected and avoided. These persons
are qualified personnel who carry out the work properly due to their training, knowledge and experience
and on the basis of the relevant provisions.
Information on the required qualification of the personnel is provided separately at the beginning of the
individual chapters in these instructions. The following table provides an overview.
Target group Activity Qualification
Transport
personnel
Transporting,
unloading,
setting up
Qualified personnel for transport, mobile crane operators, crane
operators, forklift operators
Fitter Mounting,
connection
Qualified personnel for mounting
Electrician Electrical
connection
Qualified personnel for electric installation
Trained
personnel
Delegated task Personnel trained by the operator-owner who know the task
delegated to them and the possible dangers arising through
improper behaviour.
Tab.1: Target groups
1.3 Symbols
1.3.1 Danger levels
Signal word Danger level Consequences of non-observance
DANGER Immediate threat of danger Serious personal injury, death
WARNING Possible threat of danger Serious personal injury, invalidity
CAUTION Potentially dangerous situation Slight personal injury
ATTENTION Potentially dangerous situation Material damage
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2 Safety
1.4 Associated documents
1.3.2 Danger signs
Meaning Source and possible consequences of non-observance
Electrical voltage Electrical voltage causes serious physical injury or death.
Raised load Falling objects can result in serious physical injury or death.
kg
Heavy load Heavy loads can result in serious back problems.
Risk of slipping Discharging pumped liquid and oils on the foundation or tread surfaces
can cause falls with serious physical injury or death.
Flammable sub-
stances
Discharging pumped liquid and oils can be easily inflammable and can
result in serious burns.
Hot surface Hot surfaces can cause burns.
1.3.3 Symbols in this document
Meaning
Warning personal injury
Safety instruction
Request for action
1.
2.
3.
Multi-step instructions for actions

Action result

Cross-reference
1.4 Associated documents
oCalibration certificate
oDeclaration of conformity according to EU Directive 2006/42/EC
oManufacturer's declaration according to EU Directive 2014/68/EU
oCorresponding operating instructions for accessories
2 Safety
2.1 Proper use
oFlowmeter solely for flow measurement of lubricating liquids that are chemically neutral and that do
not contain gas or solid components.
oFlowmeters require the operation with clean liquids. If coarse soiling, solid particles in the liquid or
abrasive fine particles occur during operation, the flowmeter has to be protected additionally by a
correspondingly dimensioned operating filter in the pipe system.
oUse the flowmeter only within the operating limits specified on the rating plate and in the chapter
"Technical data". Deviating operating data can result in damage to the flowmeter. In the case of op-
erating data that do not agree with the specifications on the rating plate, please contact the manu-
facturer.
oStrong changes in the flow rate (for example rapid shutdown, pulsations, etc.) cause marked pres-
sure differences in the flowmeter and can damage the measuring unit. The pressure loss of the
flowmeter must not exceed the values shown in the chapter "Technical data"
Operating instructions OIO 08en-GB Edition 2020-01 5

3 Identification
2.2 Foreseeable misuse
2.2 Foreseeable misuse
oAny use that extends beyond the proper use or any other use is misuse.
oThe product is not suitable for pumping liquids outside the operational limits.
oAny bypassing or deactivation of safety equipment during operation is prohibited.
2.3 Obligations of the operator-owner
The operator-owner is the person who operates the product commercially or permits a third party to
use it and who bears the legal responsibility for the product, the protection of the personnel and third
parties during its operation.
The product is used in industrial applications. The operator-owner is therefore subject to the statutory
obligations concerning occupational health and safety.
In addition to the safety instructions in these instructions, the regulations on safety, accident prevention
and environmental protection respectively valid for the range of application of the product are to be ob-
served.
2.4 Safety instructions
2.4.1 Fundamental safety instructions
The following safety instructions must be observed strictly:
oRead these operating instructions carefully and observe them.
oRead the operating instructions for the electronic unit and the sensors carefully and observe them.
oHave work only carried out by qualified personnel / trained personnel.
oWear personal protective equipment and work carefully.
oPumped liquids can be subject to high pressure and can result in personal injury and damage to
property in case of incorrect operation or damaged components.
oPumped liquids can be hot, poisonous, combustible and caustic.
oObserve the associated data sheets and safety regulations when handling dangerous materials.
oAvoid skin contact with system parts carrying liquids at operating temperatures exceeding 60°C.
oCollect any discharging pumped liquid safely and dispose of it in an environmentally compatible
manner in accordance with the applicable local regulations. Neutralize residues.
oKeep the mounting surfaces, scaffolding, ladders, lifting platforms and tools clean in order to pre-
vent slipping or stumbling.
oIf pressurized or energized components are damaged, shut down the flowmeter immediately. Re-
place the components or flowmeter.
3 Identification
3.1 Type code
OMH-020.CAAABA.0001
3
4
5
2
7
68
9
1
Fig.1: Type code
1Series
2Size
3Sensor equipment (pick up)
4Function of the sensor equipment
5Material of bearing
6Material of seal
7Mechanical connection
8Electrical connection
9Version index
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3 Identification
3.1 Type code
Item Designation Description
1Series OME Economy
OMG General/Universal
OMH High Pressure
OMP Performance
OMS Stainless steel
2Size Corresponds to the diameter of the measuring screw large in [mm]
3Sensor equip-
ment (pick up)
A BEG 06
B BEG 43
C BEG 44
D BEG 45
E BEG 45 + BEV 13
F BEG 47
G BEG 53
H BEG 54
I BEG 56
J BEG 60-62
X Special design
4Function of the
sensor equip-
ment
A Without recognition of flow direction
B With recognition of flow direction
C Without recognition of flow direction, with temperature compensation
D With recognition of flow direction, with temperature compensation
X Special design
5Material of
bearing
A Steel
B Hybrid
C Stainless steel
D All-ceramic
X Special design
6Material of seal A FPM (FKM)
B FFPM (FFKM)
C Low-temperature FPM
D EPDM
X Special design
7Mechanical
connection
A Thread connection BSPP
B Flange connection DIN
C Thread connection NPT
D Flange connection ANSI
E Flange connection JIS
F Flange connection SAE
X Special design
8Electrical con-
nection
A Loose cable end
B Cable gland junction box
C Cable gland compact sensor
D Fixing kit for display and processing unit
E Smart Solution version
X Special design
9Version index For internal administration
Tab.2: Type code
Operating instructions OIO 08en-GB Edition 2020-01 7

4 Technical data
3.2 Rating plate
3.2 Rating plate
R
1 2 3
4567
Fig.2: Rating plate
1Serial number
2Construction year
3K-factor
4Preferred flow direction
5Max. temperature
6Series
7Max. pressure
4 Technical data
4.1 Operating limits
The values specified on the rating plate and the calibration certificate apply. The permissible operating
limits of individual values influence each other so that every application is checked individually by the
manufacturer when selecting the flowmeter.
If no operating data are provided by the orderer, standardized substitute operating data are used.
4.2 Pressure pulsation
10 3020 40 t [ms]
30
10
20
0
p
[bar]
Fig.3: Pressure pulses
Strong pressure pulsations in the system can
reduce the service life of the flowmeter.
4.3 Maximum values
The following table shows the respective maximum values that, however, may not occur simultan-
eously. In addition, the operating limits of the corresponding completion, of the sealing material and of
the pick up are to be observed.
Unit 013 020 032 052 068 100
Maximum values
Flow rate
oQmax [l/min] 15 45 150 525 1050 3000
oQrated [l/min] 10 30 100 350 700 2000
oQmin [l/min] 0.1 0.3 1.0 3.5 7.0 20.0
Max. pressure [bar] 420 420 420 420 420 250
Min.-max. temperature [°C] -20 ... +200
Min.–max. viscosity [mm2/s] 1–1000000
Measuring chamber volume [ml/U] 1.6 6.3 25.6 112.7 251.3 833.3
Rotation speed
on (Qmax)[min-1] 9120 7200 5850 4658 4182 3600
on (Qrated)[min-1] 6090 4800 3900 3105 2784 2400
on (Qmin)[min-1] 61 48 39 31 28 24
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4 Technical data
4.4 Substitute operating data
Unit 013 020 032 052 068 100
Additional maximum values when BEG 44 is used
K2
Pole number 4 8 12 16 20 28
K-factor [P/l] 2432 1280 468 142 79.6 33.6
Millilitre/pulse [ml/P] 0.41 0.78 2.14 7.04 12.56 29.76
Pulse frequency
of2 (Qmax)[Hz] 608 960 1170 1243 1393 1680
of2 (Qrated)[Hz] 405 640 780 828 929 1120
of2 (Qmin)[Hz] 4.1 6.4 7.8 8.3 9.3 11.2
Additional maximum values when BEG 45 is used
K3
Pole number 12 16 26 34 42 48
K-factor [P/l] 7296 2560 1014 302 167 57.6
Millilitre/pulse [ml/P] 0.14 0.39 0.99 3.31 5.98 17.36
Pulse frequency
of3 (Qmax)[Hz] 1824 1920 2535 2640 2927 2880
of3 (Qrated)[Hz] 1216 1280 1690 1760 1949 1920
of3 (Qmin)[Hz] 12.2 12.8 16.9 17.6 19.5 29.2
Observe flow range: If the value drops below Qmin, refer to the
operating instructions of the associated pick up
Additional maximum values when BEG 53A/BEG 54A is used
K4
Pole number 12 16 26 34 42 73
K-factor [P/l] 7296 2560 1014 302 167 87.6
Millilitre/pulse [ml/P] 0.14 0.39 0.99 3.31 5.98 11.42
Pulse frequency
of4 (Qmax)[Hz] 1824 1920 2535 2643 2923 4380
of4 (Qrated)[Hz] 1216 1280 1690 1762 1948 2920
of4 (Qmin)[Hz] 12.2 12.8 16.9 17.6 19.5 29.2
4.4 Substitute operating data
The following table shows standardized values for the flow rate, temperature and viscosity. These val-
ues can be used at the same time as maximum values without impairing the service life of the flow-
meter. In addition, the operating limits of the corresponding completion, of the sealing material of the
pick up and of the temperature sensor are to be observed.
Unit 013 020 032 052 068 100
Flow rate
oQmax [l/min] 10 30 100 350 700 2000
oQrated [l/min] 10 30 100 350 700 2000
oQmin [l/min] 0.2 0.6 2.0 7.0 14.0 40.0
Max. pressure [bar] 420 420 420 420 420 250
Min. temperature-max. [°C] -20 ... +120
Min.–max. viscosity [mm2/s] 1–200
Tab.3: Substitute operating data
4.5 Sound pressure level
The sound pressure level of the flowmeters amounts to less than 70 dB(A).
Operating instructions OIO 08en-GB Edition 2020-01 9

4 Technical data
4.6 Dimensions and weights
4.6 Dimensions and weights
4.6.1 Pipe thread (BSPP thread)
L1
D
G
T
T
M18x1
L2
Fig.4: Dimensional drawing pipe thread connection
GPipe thread
M18x1 Pick up hole
DOuter diameter
L1 Total length
L2 Length of the flowmeter without
connections
TMax. screw-in depth
Unit 013 020 032 052 068 100
G [inch] 1/2 3/4 1 1 1/2 2 4
Pressure stage [bar] 420 420 420 420 420 250
D [mm] 100 145 180 220 235 247
L1 [mm] 150 185 255 320 385 500
L2 [mm] 94 115 175 240 295 400
T [mm] 15 16 22 34 36 44
Weight [kg] 7.0 12.0 28.0 54.5 80.5 148.0
Tab.4: Dimensions and weights - pipe thread connection
4.6.2 DIN flange
L2
L1
D
L3
L3
TK
D
DN
M18x1
Fig.5: Dimensional drawing DIN flange connection
DN Nominal diameter flange
M18x1 Pick up hole
DOuter diameter
L1 Total length
L2 Length of the flowmeter without
connections
L3 Flange thickness
TK Pitch circle
Unit 013 020 032 052 068 100
DN 15 15 25 40 50 100
Pressure stage [bar] 400 400 400 400 400 250
D [mm] 145 145 180 220 235 300
L1 [mm] 150 185 255 320 385 500
L2 [mm] 94 115 175 240 295 400
L3 [mm] 28 35 40 40 45 50
TK [mm] 100 100 130 165 180 235
Weight [kg] 9.5 12.0 28.0 54.0 80.0 170.0
Tab.5: Dimensions and weights – DIN flange connection
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4 Technical data
4.6 Dimensions and weights
4.6.3 SAE flange
L3 L3L2
L1
D
DN
M18x1
Fig.6: Dimensional drawing SAE flange connection
DN Nominal diameter flange
M18x1 Pick up hole
DOuter diameter
L1 Total length
L2 Length of the flowmeter without
connections
L3 Flange thickness
Unit 013 020 032 052 068
DN [inch] 1/2 3/4 1 11/2 2
Class 6000 6000 6000 6000 6000
D [mm] 100 145 180 220 235
L1 [mm] 150 185 255 320 385
L2 [mm] 94 115 175 240 295
L3 [mm] 28 35 40 40 45
Weight [kg] 7.0 12.0 28.0 54.0 80.0
Tab.6: Dimensions and weights – SAE flange connection
Operating instructions OIO 08en-GB Edition 2020-01 11

4 Technical data
4.7 Pressure bearing capacity
4.7 Pressure bearing capacity
4.7.1 Pressure bearing capacity OMH-013
20
18
16
14
12
2
4
6
8
10
0
A
B
1000 h
30000 h
10000 h
5000 h
100000
5
10
50
200
500
1000
2000
5000
10000
50000
100
[mm2/s]
C
[bar]
[bar]
C2
3
0
1
100000
5000
10000
50000
5
10
50
200
500
1000
2000
100
[mm2/s]
23 4 109
8
7
65
0,1 115
14
13
12
11
E
D
[l/min]
10050 150
D
[l/min]
50
45
40
30
25
20
1510
51 35
3,52,5
1,50,5
0,1 4,5 5
1 2 3 4
[%] [%]
1
AShort-term operation
BContinuous operation
CPressure loss
DFlow rate
EQrated
Notice The values apply for lubricating liquids at temperatures up to120°C. Abrasive and aggressive liquids
reduce the service life.
12 OIO 08en-GB Edition 2020-01 Operating instructions

4 Technical data
4.7 Pressure bearing capacity
4.7.2 Pressure bearing capacity OMH-020
20
18
16
14
12
2
4
6
8
10
0
A
B
1000 h
30000 h
10000 h
5000 h
100000
5
10
50
200
500
1000
2000
5000
10000
50000
100
[mm2/s]
C
[bar]
[bar]
C
2
3
0
1
100000
5000
10000
50000
5
10
50
200
500
1000
2000
100
[mm2/s]
69 12 3027
24
21
1815
0,3 345
42
39
36
33
E
D
[l/min]
10050 150
D
[l/min]
50
45
40
30
25
20
1510
51 35
10,57,5
4,51,5
0,3 13,5 15
3 6 9 12
[%] [%]
1
AShort-term operation
BContinuous operation
CPressure loss
DFlow rate
EQrated
Notice The values apply for lubricating liquids at temperatures up to120°C. Abrasive and aggressive liquids
reduce the service life.
Operating instructions OIO 08en-GB Edition 2020-01 13

4 Technical data
4.7 Pressure bearing capacity
4.7.3 Pressure bearing capacity OMH-032
20
18
16
14
12
2
4
6
8
10
0
A
B
1000 h
30000 h
10000 h
5000 h
100000
5
10
50
200
500
1000
2000
5000
10000
50000
100
[mm2/s]
C
[bar]
[bar]
C
2
3
0
1
100000
5000
10000
50000
5
10
50
200
500
1000
2000
100
[mm2/s]
20 30 40 10090
80
70
6050
110 150
140
130
120
110
E
D
[l/min]
10050 150
D
[l/min]
50
45
40
30
25
20
1510
51 35
3525
155
1 45 50
10 20 30 40
[%] [%]
1
AShort-term operation
BContinuous operation
CPressure loss
DFlow rate
EQrated
Notice The values apply for lubricating liquids at temperatures up to120°C. Abrasive and aggressive liquids
reduce the service life.
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4 Technical data
4.7 Pressure bearing capacity
4.7.4 Pressure bearing capacity OMH-052
20
18
16
14
12
2
4
6
8
10
0
A
B
1000 h
30000 h
10000 h
5000 h
100000
5
10
50
200
500
1000
2000
5000
10000
50000
100
[mm2/s]
C
[bar]
[bar]
C2
3
0
1
100000
5000
10000
50000
5
10
50
200
500
1000
2000
100
[mm2/s]
70 105 140 350315
280
245
210175
3,5 35 525
490
455
420
385
E
D
[l/min]
10050 150
D
[l/min]
50
45
40
30
25
20
1510
51 35
122,587,5
52,517,5
3,5 157,5 175
35 70 105 140
[%] [%]
1
AShort-term operation
BContinuous operation
CPressure loss
DFlow rate
EQrated
Notice The values apply for lubricating liquids at temperatures up to120°C. Abrasive and aggressive liquids
reduce the service life.
Operating instructions OIO 08en-GB Edition 2020-01 15

4 Technical data
4.7 Pressure bearing capacity
4.7.5 Pressure bearing capacity OMH-068
20
18
16
14
12
2
4
6
8
10
0
A
B
1000 h
30000 h
10000 h
5000 h
100000
5
10
50
200
500
1000
2000
5000
10000
50000
100
[mm2/s]
C
[bar]
[bar]
C
2
3
0
1
100000
5000
10000
50000
5
10
50
200
500
1000
2000
100
[mm2/s]
140 210 280 700630
560
490
420350
770 1050
980
910
840
770
E
D
[l/min]
10050 150
D
[l/min]
50
45
40
30
25
20
1510
51 35
245175
10535
7 315 350
70 140 210 280
[%] [%]
1
AShort-term operation
BContinuous operation
CPressure loss
DFlow rate
EQrated
Notice The values apply for lubricating liquids at temperatures up to120°C. Abrasive and aggressive liquids
reduce the service life.
16 OIO 08en-GB Edition 2020-01 Operating instructions

4 Technical data
4.7 Pressure bearing capacity
4.7.6 Pressure bearing capacity OMH-100
20
18
16
14
12
2
4
6
8
10
0
A
B
1000 h
30000 h
10000 h
5000 h
100000
5
10
50
200
500
1000
2000
5000
10000
50000
100
[mm2/s]
C
[bar]
[bar]
C
2
3
0
1
100000
5000
10000
50000
5
10
50
200
500
1000
2000
100
[mm2/s]
400 600 800 20001800
1600
1400
12001000
20 200 3000
2800
2600
2400
2200
E
D
[l/min]
10050 150
D
[l/min]
50
45
40
30
25
20
1510
51 35
700500
300100
20 900 1000
200 400 600 800
[%] [%]
1
AShort-term operation
BContinuous operation
CPressure loss
DFlow rate
EQrated
Notice The values apply for lubricating liquids at temperatures up to120°C. Abrasive and aggressive liquids
reduce the service life.
Operating instructions OIO 08en-GB Edition 2020-01 17

5 Function description
5.1 Structure
5 Function description
5.1 Structure
123421
5
7
8
96
Fig.7: Structure of the flowmeter
1Connection 6Measuring screw large
2Bearing cover 7Ball bearing fixed bearing end
3Measuring housing 8Pick up hole
4Measuring screw small 9Pole wheel
5Ball bearing floating bearing end
5.2 Functional principle
Flowmeters belong to the group of rotating displacement meters as screw meters. The pumped liquid
makes the measuring unit rotate. The displacement effect results from the continuous filling, axial dis-
placement and discharge of the volumes that are formed by the measuring housing and measuring
unit. The measured pumped liquid flows around and lubricates all the rotating parts. Thanks to the dis-
placement principle, the flowmeter does not require inlet sections and smoothing sections at the feed
line and outlet.
Depending on the customer requirements, the flowmeters can be equipped with suitable end connec-
tions for connection to various flanges.
5.3 Rolling bearings
Thanks to precision rolling bearings the measuring unit operates contact-free and with low friction in
the housing of the flowmeter. The bearing on the side of the pole wheel is realized as a fixed bearing.
The following bearings are used depending on the size:
oSingle-row deep-groove ball bearings
oAngular-contact ball bearings arranged in pairs
oFour-point contact bearings
The bearing position on the opposite side of the measuring unit is realized for all sizes with a displace-
able deep-groove ball bearing as a floating bearing.
18 OIO 08en-GB Edition 2020-01 Operating instructions

5 Function description
5.4 Signal generation
5.4 Signal generation
A pole wheel9 whose pole is sampled by a pick up is affixed at the fixed bearing end of the measuring
screw large6. This pick up generates a specific number of pulses per flow volume unit - depending on
the size and working point. This device-specific characteristic is called the K-factor (unit: Pulse/litre)
and is specified on the rating plate as well as the enclosed calibration certificate.
Possible formats of the signals are:
oPNP
oPush-pull
Depending on the version of the pick up, cylindrical pole wheels with embedded magnets or toothed
metal disks with different tooth densities can be used (higher pole number = higher K-factor). Depend-
ing on the application (operating temperature, required frequencies) pick ups of different types can be
used:
oPick ups based on the Hall effect
oMagnetic pick ups
A preferred flow direction for which the pick up is located on the downstream side is specified on the
rating plate. This preferred direction results from the goal to position the pick up in case of a blockage
of the flowmeter on the low-pressure side.
5.5 Linearization
The calibration certificate of the flowmeter contains a mean K-factor that has been determined for the
flow range 10:1 and that can therefore be used across a wide flow range. However, the K-factor shows
slightly different values at different flow rates. These are also documented in the enclosed calibration
certificate. If highest measuring precision is required, it is therefore advisable, especially at strongly
varying flow rates, to take these different values into consideration by means of a "Linearization". The
K-factors are therefore stored in a suitable electronic unit by means of several interpolation values of
the flow rate. The K-factor relevant for the flow rate being measured is then determined by means of
linear interpolation between the two nearest interpolation values.
The viscosity dependence of the K-factors must also be taken into account. These are determined dur-
ing calibration at a viscosity of approximately 4.2 mm²/s. The influence of the flow rate on the K-factor
decreases at higher viscosities so that the mean K-factor can then also be used in a considerably lar-
ger flow range without noteworthy errors.
5.6 Recognition of flow direction
Notice At the flowmeter OMH-100 recognition of the flow direction is not possible since the connection of a
second pick up is not possible due to the design.
Systems with a changing flow direction require the usage of a second pick up to recognize the change
in direction. In the case of systems with pressure pulsation a reversal of the flow direction can also oc-
cur briefly.
The flow direction can be determined by means of the additional phase-shifted signal and the incre-
mental encoder positions available in the KRALelectronic unit and then taken into account for the cal-
culation of the total values.
Operating instructions OIO 08en-GB Edition 2020-01 19

6 Transportation, storage
6.1 Dangers during transportation
6 Transportation, storage
6.1 Dangers during transportation
The following safety instructions must be observed:
oHave all work only carried out by authorized transport personnel.
oUse intact and correctly dimensioned hoisting equipment.
oEnsure that the means of transport is in a flawless state.
oEnsure that the centre of gravity of the load is taken into consideration.
oDo not stand under raised loads.
6.2 Dangers during storage
The following safety instructions must be observed:
oObserve the storage conditions.
6.3 Unpacking and checking the state of delivery
1. Upon delivery unpack the flowmeter and check it for damage during transportation.
2. Report damage during transportation immediately to the manufacturer.
3. Store the supplied sensors for the installation.
4. Dispose of packaging material in accordance with the locally applicable regulations.
6.4 Transporting flowmeters
WARNING
Risk of injury and damage to equipment through falling and toppling parts.
► Use intact and correctly dimensioned hoisting equipment in accordance with the total weight to be
transported.
► Select the lift points for the hoisting equipment in accordance with the centre of gravity and the
weight distribution.
► Use at least two load ropes.
► Do not stand under raised loads.
ATTENTION
Damage to equipment through improper transportation.
► Protect the flowmeter against damage, heat, sunlight, dust and moisture.
Requirement:
üSufficiently dimensioned hoisting equipment
üThe used hoisting equipment corresponding to the local rules and regulations for the prevention of
accidents
20 OIO 08en-GB Edition 2020-01 Operating instructions