KRAL OMG Series User manual

Operating instructions
KRAL flowmeters.
Series OMG
OIO 14en-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.....................................................4
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 ......................................................5
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.............................................10
4.5 Sound pressure level...................................................10
4.6 Dimensions and weights..............................................10
4.6.1 Pipe thread (BSPP thread) .............................10
4.6.2 DIN flange .......................................................11
4.7 Pressure bearing capacity ...........................................12
4.7.1 Pressure bearing capacity OMG-013..............12
4.7.2 Pressure bearing capacity OMG-020..............13
4.7.3 Pressure bearing capacity OMG-032..............14
4.7.4 Pressure bearing capacity OMG-052..............15
4.7.5 Pressure bearing capacity OMG-068..............16
4.7.6 Pressure bearing capacity OMG-100..............17
4.7.7 Pressure bearing capacity OMG-140..............18
5 Function description.................................................... 19
5.1 Structure ......................................................................19
5.2 Functional principle......................................................19
5.3 Rolling bearings...........................................................19
5.4 Signal generation.........................................................20
5.5 Linearization ................................................................20
5.6 Temperature compensation.........................................20
5.7 Recognition of flow direction........................................20
6 Transportation, storage............................................... 21
6.1 Dangers during transportation .....................................21
6.2 Dangers during storage ...............................................21
6.3 Unpacking and checking the state of delivery .............21
6.4 Transporting flowmeters ..............................................21
6.5 Storing the flowmeter...................................................22
7 Preservation ................................................................. 22
7.1 Preservation table........................................................22
7.2 Preserving the inner surfaces......................................22
7.3 Preserving the outer surfaces......................................23
7.4 Removing the preservation..........................................23
8 Installation, removal .................................................... 24
8.1 Dangers during installation ..........................................24
8.2 Dangers during removal...............................................24
8.3 Installing the flowmeter ................................................24
8.3.1 Protecting the flowmeter against soiling ..........24
8.3.2 Installation types..............................................24
8.3.3 Installation recommendation............................25
8.3.4 Installing the flowmeter....................................26
8.4 Removing the flowmeter ..............................................27
9 Connection.....................................................................27
9.1 Dangers during connection work .................................27
9.2 Connecting the flowmeter to the pipe system ..............28
9.3 Connecting the pick up ................................................28
10 Operation........................................................................29
10.1 Dangers during operation ............................................29
10.2 Commissioning ............................................................29
10.2.1 Cleaning the pipe system ................................29
10.2.2 Checking the function ......................................29
10.2.3 Commissioning the flowmeter .........................30
10.3 Decommissioning.........................................................30
10.3.1 Switching off the flowmeter..............................30
10.4 Recommissioning.........................................................30
10.4.1 Recommissioning the flowmeter......................30
11 Maintenance...................................................................31
11.1 Required maintenance.................................................31
11.2 Maintaining flowmeters ................................................31
11.3 Recalibration of the flowmeter .....................................31
12 Servicing ........................................................................32
12.1 Dangers during servicing .............................................32
12.2 Replacing seals and ball bearings ...............................32
12.2.1 Removing seals and ball bearings OMG-013
.........................................................................32
12.2.2 Installing seals and ball bearings OMG-013....32
12.2.3 Removing seals and ball bearings OMG-020/
OMG-032.........................................................33
12.2.4 Installing seals and ball bearings OMG-020/
OMG-032.........................................................34
12.2.5 Removing seals and ball bearings OMG-052/
OMG-068.........................................................36
12.2.6 Installing seals and ball bearings OMG-052/
OMG-068.........................................................37
12.2.7 Removing seals and ball bearings OMG-100/
OMG-140.........................................................38
12.2.8 Installing seals and ball bearings OMG-100/
OMG-140.........................................................39
13 Disposal..........................................................................41
13.1 Dangers during disposal ..............................................41
13.2 Dismantling and disposing of the flowmeter ................41
14 Troubleshooting ............................................................42
14.1 Possible faults..............................................................42
14.2 Troubleshooting ...........................................................42
15 Spare parts.....................................................................44
15.1 Overview OMG-013 .....................................................44
15.2 Overview OMG-020/OMG-032 ....................................45
15.3 Overview OMG-052/OMG-068 ....................................46
15.4 Overview OMG-100/OMG-140 ....................................48
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Table of contents
16 Accessories .................................................................. 49
16.1 Heating ........................................................................49
16.1.1 Possible types of heating ................................49
16.1.2 Technical data of the electrical heating system
........................................................................49
16.1.3 Technical data of the fluid heating system......49
16.1.4 Installing the heating system...........................49
16.2 Junction box ................................................................51
16.2.1 Function description........................................51
16.2.2 Technical data.................................................51
16.2.3 Installing the junction box................................51
16.3 Extension cable ...........................................................52
16.3.1 Function description........................................52
16.3.2 Technical data.................................................52
16.3.3 Connecting the extension cable......................52
17 Appendix....................................................................... 54
17.1 Tightening torques for screws with metric screw threads
with and without wedge lock washers .........................54
17.2 Tightening torques for screw plugs with thread meas-
ured in inches and elastomer seal...............................54
17.3 Tightening torques and widths for threaded rings .......54
17.4 Contents of the Declaration of Conformity...................55
Operating instructions OIO 14en-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 person-
nel
Delegated task Personnel trained by the operator-owner who know the task deleg-
ated to them and the possible dangers arising through improper be-
haviour.
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
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.
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2 Safety
1.4 Associated documents
Meaning Source and possible consequences of non-observance
Risk of slipping Discharging pumped liquid and oils on the foundation or tread surfaces
can cause falls with serious physical injury or death.
Flammable
substances
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"
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.
Operating instructions OIO 14en-GB Edition 2020-01 5

3 Identification
2.3 Obligations of the operator-owner
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
OMG-020.CABABA.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 14en-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 013 020 032 052 068 100 140
Maximum values
Flow rate
oQmax [l/min] 15 45 150 525 1050 3000 7500
oQrated [l/min] 10 30 100 350 700 2000 5000
oQmin [l/min] 0.1 0.3 1.0 3.5 7.0 20.0 50.0
Max. pressure [bar] 250 160 100 40
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 2259.9
Rotation speed
on (Qmax)[min-1] 9120 7200 5850 4658 4182 3600 3318
on (Qrated)[min-1] 6090 4800 3900 3105 2784 2400 2214
on (Qmin)[min-1] 61 48 39 31 28 24 22
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4 Technical data
4.3 Maximum values
Unit 013 020 032 052 068 100 140
Additional maximum values when BEG 43D is used
K1
Pole number 2 4 6 8 10 14 20
K-factor [P/l] 1216.
0
640.0 234.0 71.0 39.8 16.8 8.9
Millilitre/pulse [ml/P] 0.82 1.56 4.27 14.08 25.13 59.52 112.99
Pulse frequency
of1 (Qmax)[Hz] 304 480 585 621 697 840 1106
of1 (Qrated)[Hz] 203 320 390 414 464 560 738
of1 (Qmin)[Hz] 2.0 3.2 3.9 4.1 4.6 5.6 7.4
Additional maximum values when BEG 44 is used
K2
Pole number 4 8 12 16 20 28 40
K-factor [P/l] 2432.
0
1280.0 468.0 142.0 79.6 33.6 17.7
Millilitre/pulse [ml/P] 0.41 0.78 2.14 7.04 12.56 29.76 56.50
Pulse frequency
of2 (Qmax)[Hz] 608 960 1170 1243 1393 1680 2213
of2 (Qrated)[Hz] 405 640 780 828 929 1120 1475
of2 (Qmin)[Hz] 4.1 6.4 7.8 8.3 9.3 11.2 14.8
Additional maximum values when BEG 45 is used
K3
Pole number 12 16 26 34 42 48 50
K-factor [P/l] 7296.
0
2560.0 1014.
0
302.0 167.0 57.6 22.1
Millilitre/pulse [ml/P] 0.14 0.39 0.99 3.31 5.98 17.40 45.20
Pulse frequency
of3 (Qmax)[Hz] 1824 1920 2535 2640 2927 2880 2763
of3 (Qrated)[Hz] 1216 1280 1690 1760 1949 1920 1842
of3 (Qmin)[Hz] 12.2 12.8 16.9 17.6 19.5 19.2 18.4
Observe flow range: If the value drops below Qmin,
refer to the operating instructions of the associated
pick up
Additional maximum values when BEG 47D is used
K1
Pole number 2 4 6 8 10 14 20
K-factor [P/l] 1216.
0
640.0 234.0 71.0 39.8 16.8 8.9
Millilitre/pulse [ml/P] 0.82 1.56 4.27 14.08 25.13 59.52 112.99
Pulse frequency
of1 (Qmax)[Hz] 304 480 585 621 697 840 1106
of1 (Qrated)[Hz] 203 320 390 414 464 560 738
of1 (Qmin)[Hz] 2.0 3.2 3.9 4.1 4.6 5.6 7.4
Operating instructions OIO 14en-GB Edition 2020-01 9

4 Technical data
4.4 Substitute operating data
Unit 013 020 032 052 068 100 140
Additional maximum values when BEG 53A/BEG 54A is used
K4
Pole number 12 16 26 34 42 73 102
K-factor [P/l] 7296.
0
2560.0 1014.
0
302.0 167.0 87.6 45.1
Millilitre/pulse [ml/P] 0.14 0.39 0.99 3.31 5.99 11.42 22.17
Pulse frequency
of4 (Qmax)[Hz] 1824 1920 2535 2643 2923 4380 5638
of4 (Qrated)[Hz] 1216 1280 1690 1762 1948 2920 3758
of4 (Qmin)[Hz] 12.2 12.8 16.9 17.6 19.5 29.2 37.6
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 013 020 032 052 068 100 140
Flow rate
oQmax [l/min] 10 30 100 350 700 2000 5000
oQrated [l/min] 10 30 100 350 700 2000 5000
oQmin [l/min] 0.2 0.6 2.0 7.0 14.0 40.0 100.0
Max. pressure [bar] 250 160 100 40
Min.–max. temperature [°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).
4.6 Dimensions and weights
4.6.1 Pipe thread (BSPP thread)
L1
L2
D
G
M18x1
G1/4"
T T
Fig.4: Dimensional drawing pipe thread connection
GPipe thread
M18x1 Pick up hole
G1/4″ Temperature sensor hole
DOuter diameter
L1 Total length
L2 Length of the flowmeter without
connections
TMax. screw-in depth
Unit 013 020 032 052 068 100 140
G [inch] 1/2 3/4 1 1 1/2 2 4 6
Pressure stage [bar] 250 250 250 160 100 40 40
D [mm] 90 74 104 118 138 188 267
L1 [mm] 145 145 215 295 355 480 645
L2 [mm] 94 145 215 240 295 400 537
T [mm] 16 16 18 27.5 30 40 54
Weight [kg] 4.6 4.1 11 18 29 70 180
Tab.4: Dimensions and weights - pipe thread connection
10 OIO 14en-GB Edition 2020-01 Operating instructions

4 Technical data
4.6 Dimensions and weights
4.6.2 DIN flange
L3
D
TK
G1/4"
DN
M18x1
L3 L2
L1
Fig.5: Dimensional drawing DIN flange connection
DN Nominal diameter flange
M18x1 Pick up hole
G1/4″ Temperature sensor hole
DOuter diameter
L1 Total length
L2 Length of the flowmeter without
connections
L3 Flange thickness
TK Pitch circle
Unit 013 020 032
DN 15 15 15 20 15 15 32 25 25
Pressure stage [bar] 40 160 250 40 160 250 40 160 250
D [mm] 95 105 130 105 105 130 140 140 150
L1 [mm] 145 145 145 185 185 195 265 265 275
L2 [mm] 94 94 94 145 145 145 215 215 215
L3 [mm] 25.5* 25.5* 25.5 20 20 25 25 25 30
TK [mm] 65 75 90 75 75 90 100 100 105
Weight [kg] 4.7 4.8 6.0 6.0 6.0 8.1 16 16 19
Tab.5: Dimensions and weights – DIN flange connection
*Screw-in depth is not equal to L3 but is 17mm
Unit 052 068 100 140
DN 40 40 50 50 100 100 150 150
Pressure stage [bar] 40 160 40 100 16 40 16 40
D [mm] 150 170 165 195 220 235 285 300
L1 [mm] 285 295 340 355 450 460 600 610
L2 [mm] 240 240 295 295 400 400 537 537
L3 [mm] 22.5 27.5 22.5 30 25 30 31.5 36.5
TK [mm] 110 125 125 145 180 190 240 250
Weight [kg] 21 23 31 37 65 70 170 180
Tab.6: Dimensions and weights – DIN flange connection
Operating instructions OIO 14en-GB Edition 2020-01 11

4 Technical data
4.7 Pressure bearing capacity
4.7 Pressure bearing capacity
4.7.1 Pressure bearing capacity OMG-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 14en-GB Edition 2020-01 Operating instructions

4 Technical data
4.7 Pressure bearing capacity
4.7.2 Pressure bearing capacity OMG-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 14en-GB Edition 2020-01 13

4 Technical data
4.7 Pressure bearing capacity
4.7.3 Pressure bearing capacity OMG-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.
14 OIO 14en-GB Edition 2020-01 Operating instructions

4 Technical data
4.7 Pressure bearing capacity
4.7.4 Pressure bearing capacity OMG-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 14en-GB Edition 2020-01 15

4 Technical data
4.7 Pressure bearing capacity
4.7.5 Pressure bearing capacity OMG-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 14en-GB Edition 2020-01 Operating instructions

4 Technical data
4.7 Pressure bearing capacity
4.7.6 Pressure bearing capacity OMG-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 14en-GB Edition 2020-01 17

4 Technical data
4.7 Pressure bearing capacity
4.7.7 Pressure bearing capacity OMG-140
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]
1000 1500 2000 50004500
4000
3500
30002500
50 500 7500
7000
6500
6000
5500
E
D
[l/min]
10050 150
D
[l/min]
50
45
40
30
25
20
1510
51 35
17501250
750250
50 2250 2500
500 1000 1500 2000
[%] [%]
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.
18 OIO 14en-GB Edition 2020-01 Operating instructions

5 Function description
5.1 Structure
5 Function description
5.1 Structure
12/2a 345 2 3 1
6
78
9
10
Fig.6: Structure of the flowmeter
1Connection 6Ball bearing floating bearing end
2Screw plug 7Measuring screw large
2a Connection of temperature sensor 8Ball bearing fixed bearing end
3Bearing cover 9Pick up hole
4Measuring housing 10 Pole wheel
5Measuring screw small
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.
Operating instructions OIO 14en-GB Edition 2020-01 19

5 Function description
5.4 Signal generation
5.4 Signal generation
A pole wheel10 whose pole is sampled by a pick up is affixed at the fixed bearing end of the measur-
ing screw large7. 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
oNAMUR
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:
oInductive pick ups
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 of the flowmeter. 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 Temperature compensation
Flowmeters of the OMG series can be equipped additionally with temperature sensors for sizes
OMG-013 to OMG-100. For size OMG-140 the installation of a temperature sensor is recommended. If
the flowmeter is equipped with a temperature sensor, the current density of the flowing liquid can be
calculated from the measured values by using a density table stored in the electronic unit. This allows
standardised volume measurement in which the displayed values are converted to a reference temper-
ature that can be selected freely. This ensures that measuring errors caused by changes in the density
due to temperature variations are avoided.
5.7 Recognition of flow direction
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.
20 OIO 14en-GB Edition 2020-01 Operating instructions