KRAL Volumeter OMG Series.

Universal Flowmeters.

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OMG Universal
OMG.
Flowmeters for a wide range of
applications.

KRAL Volumeter
the original.
KRAL developed the
Volumeter over 20 years
ago as a solution to an
internal requirement. We
needed a precision flowmeter as part of our production test stands but
could not find a flowmeter
that would meet our demands of accuracy, rangebility and robustness. Since
we had expertise gained
from 30 years of manufacturing positive displacement pumps, we had the
idea to turn around the
working principle of the
pumps. Instead of a
motor driving the pump
spindles, we used flowing
liquid to rotate the spindles.
We found the ideal solution to assure precision,
and reduce pressure drop,
even for diverse operating
conditions. Since then
the KRAL Volumeter line
has grown to meet a wide
variety of industrial needs.

Operating conditions and materials.

Flow Range:
0,1 to 7.500 l/min.
Max. Pressure:
250 bar.
Temperature Range: -20 to 200 C.
Viscosity Range:
1 to 1 x 106 mm/s.
Liquid: chemically neutral, lightly lubricative, clean, non-abrasive.
Accuracy:
0,1% of rate.
Casing:
cast iron EN-GJS-400.
Spindles:
nitrided steel.
Ball Bearings:
bearing steel.
Seals:
Viton.

Robust and precise.

In most flow measuring
instruments robustness
and precision are mutually
exclusive, but the OMG
offers both.
At KRAL, our core competence in profiling screw
spindles guarantees precision measuring chambers
in the meter. Therefore
extremely accurate measurements are possible
and the OMGs operation
is smooth and responsive.
This is evident in quick recovery time when there is
rapid flow fluctuation and
pressure loss.
The OMG is an extremely
sturdy design and protecting it against vibrations
and mechanical loads that
are typical in industrial
plants.

Wide range of
operating conditions.
Flowmeters are often
specified for a given set
of operating parameters.
The performance of those
meters may suffer if those
operating parameters
change.
Being a precision-made
spindle PD meter, the
exact measurement of
the OMG covers a wide
range of:
liquids
viscosities
temperatures

Easy installation.
There is often limited
space available to install
a flowmeter.
KRAL Volumeter are extremely compact devices.
They are also insensitive
to flow disturbances, so
there are no upstream or
downstream installation
requirements. The OMG
is also able to measure in
any installation position,
horizontal or vertical. Even
bi-directional flow can be
measured precisely.

Any selection of an OMG

meter is therefore suitable for a wide variety of
applications.

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The solution.
No flow conditioning.
The OMG operating principle is insensitive to flow
disturbances. Flow conditioners are not required.
Valves and pipe elbows
are allowed close to the
flowmeter. That allows for
easy installation in tight
spaces.

Wide range of
applications.
As a PD meter, the OMG
covers a wide range of
liquids and viscosities.
OMG has a turn-down
ratio up to 100:1.

Compact design.
The axial arrangement of
the measurement system
allows laminar flow with
no change in direction
making it a very compact
design.

Robust and precise.

The rigid casing protects
precisely manufactured
spindles. That is why the
OMG offers both robustness and precision.

Bi-directional flow
measurement.

Fast response measurement.

Because of the operating

principle, bi-directional
flow can be measured.
With a flow direction
sensor, a change of the
flow direction or brief reverse flow can be detected and measured.

The fast response spindles can follow any rapid

fluctuations in the flow
causes by pulsations.

High accuracy.
Because of the precision
measurement chamber,
extremely accurate measurements are possible.

Minimal pressure loss.

The precision screw
design of the Volumeter
operates with minimal
friction and pressure loss.

Standard output signal.

The flow sensor output
signal is an industry
standard square wave.
A dry sleeve seals the
meter completely, for
troublefree sensor installation and verification.

Various connections.
Available are:
Pipe thread
DIN flange, ANSI, SAE
and JIS
Custom

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OMG Selection of Size

The following
questions can assist
you in selecting an
OMG meter.

Explanation.

Instructions.

Notes.

Which size is suitable

for the flow range to be
measured?

The selection of the

correct size ensures a
long service life, high
measuring accuracy
and an excellent costutilization ratio.

From the Size table, select

a size, OMG 13 - 140,
whose nominal flowrate,
Qnom, is near that of your
application, Qapp. Then
calculate flowrate in
[% of Qnom] using the
equation shown at right.

The value of flowrate

[% of Qnom] is used in the
following diagrams. Draw
a line downward from this
value to intersect the same
value in the other diagrams.
Moving the line left or
right shows the effects of
meter size on load rating
and linearity.

Does the selected

unit have the required
service life?
What is the pressure
drop?

Service life and pressure

drop are important factors
in selecting a meter size.
Verify that your selection
will meet your expectations of service life and
pressure drop. For increased service life and
reduced pressure drop,
select a larger size. This
will reduce the flowrate
[% of Qnom] for a given
application.

In the Load rating

diagram, find the intersection point of the flowrate [% of Qnom] and viscosity [mm/s] for your
application. To the left of
this point, find the pressure
drop for the nominal flow
of your application. The
color range where the
point lies signifies either
continuous operation (yellow) or short-term operation (red). A point in the
white range is not a
recommended load rating
for an OMG.

The range of short-term

operation can be
purposely used for short
times, such as a load
reserve or safety factor.

What is the measuring

accuracy of the selected
unit?

High accuracy is expected

from PD meters. The
OMG delivers excellent
accuracy over a wide
range of flows. For the
highest accuracy, linearization is possible. The
KRAL BEM 500 can linearize the meters performance curve for a defined
viscosity. Special calibration may be required.

With the flowrate [% of

Qnom] and viscosity [mm/s]
you can obtain the meter
accuracy curve from the
Linearity diagram.

The OMG begins measuring at an extremely low

flowrate, due to very low
slippage past the spindles.
As viscosity increases, so
does the linear region of
the accuracy curve.

Yellow range signifies:

The device operates within
the range of maximum
accuracy of 0,1% of
rate.
Orange range signifies:
The meter accuracy is
within the limits of
0,3% of rate.

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Qnom

Size.

Qanw
[% von Qnenn] =
x 100
Qnenn

1 10

50

[l/min]

10

OMG 13

30

OMG 20

100
350

OMG 32
OMG 52

700

OMG 68

2000
5000

OMG 100
OMG 140

100

150 Flowrate [% of Qnom ]

Load rating.
5000 mm2/s

Pressure drop [bar]

100000 50000 10000

20

2000 mm2/s

15

1000 mm2/s

10

500 mm2/s
short-term operation

5
continuous operation
0
1 10

50

100

200 mm2/s
100 mm2/s
50 mm2/s
10 mm2/s
5 mm2/s
150 Flowrate [% of Qnom]

Linearity.
Linearity [%] related to measure value

+1,0

+0,3
+0,1

200 mm2/s
20 mm2/s
2 mm2/s

-0,1
-0,3

-1,0
1 10

50

100

150 Flowrate [% of Qnom]

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The OMG combines

service life and accuracy
to produce a measuring
range of unmatched
magnitude. Since normal
flow conditions are never
static, a wide range of
acceptable viscosities and
flows is important for
precise measurement.

Are precision and

sturdiness of the
KRAL Volumeter fully
utilized?

1 This is where accurate

operation of the OMG
starts.

Yellow range signifies:

Best combination of
accuracy and service life.

2 The OMG can be

operated continuously up
to this line.

Orange range signifies:

The meter is suitable for
continuous operation with
an accuracy of 0,3%
of rate.

Notice the wide range of

conditions where the
OMG will measure with
a linearity of 0,1%
of rate.

The Measuring range

diagram provides a visual
impression of the wide
measurement range available with a Volumeter.

Red range signifies:

Short-term operation.
The linearity will be
within 0,1% of rate.

Measuring range.
100000
10000
1000

short-term operation

200
100

0,1 %

Viscosity [mm/s]

continuous operation
20
10
5
1

0,3 %

0,3 %

linearity 0,1%

1,0 %
2

1
1

10

50

150

100

Flowrate [% of Qnom]
The measuring range diagram is copyright protected internationally.

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Technical data.
OMG 13 OMG 20 OMG 32 OMG 52 OMG 68 OMG 100 OMG 140
Flow
Qmax
l/min
15
45
150
525
1050
3000
Qnenn
l/min
10
30
100
350
700
2000
Qmin
l/min
0,1
0,3
1
3,5
7
20

7500
5000
50

Pressure
bar
250
250
250
160
100
40
pmax

40

Temperature
C -20to+200 -20to+200 -20to+200 -20to+200 -20to+200 -20to+200 -20to+200
tmin to tmax
Viscosity
mm/s 1 to1x106 1 to1x106 1 to1x106 1 to1x106 1 to1x106 1 to1x106 1 to1x106
min to max
K1 pulses/l
K2 pulses/l
K3 pulses/l

1216
2432
7296

640
1280
2560

234
468
1014

71
142
302

39,8
79,6
167

16,8
33,6
57,6

8,85
17,7
22,1

f1 at Qnenn Hz
f2 at Qnenn Hz
f3 at Qnenn Hz

203
405
1216

320
640
1280

390
780
1690

414
828
1760

464
929
1949

560
1120
1920

738
1475
1842

K-Factor


Frequency

Dimensions/Weights.

1/2
250

3/4
250

1
250

1 1/2
160

2
100

4
40

6
40

l
mm
145
145
d mm 90 74
l1 mm 94
145

215
104
215

295
118
240

355
138
295

480
188
400

645
267
537

11

18

29

70

180

kg

4,6

4,1

OMG 52 OMG 68 OMG 100 OMG 140

DN mm 15 15 15 20 15 15 32 25 25 40 40
PN bar 40 160 250 40 160 250 40 160 250 40 160

M18x1
D

OMG 32

DN

L1

M18x1
d

OMG 20

G inch
p
bar

l1

OMG 13

50 50 100 100 150 150

40 100 16 40 16 40

L mm 145 145 145 185 185 195 265 265 275 285 295 340 355 450 460 600 610
D mm 95 105 130 105 105 130 140 140 150 150 170 165 195 220 235 285 300
L1 mm 94 94 94 145 145 145 215 215 215 240 240 295 295 400 400 537 537
m

kg 4,7 4,8 6,0 6,0 6,0 8,1 16 16 19

21

23

31

37

65

70 170 180

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KRAL Electronics.

Sensor selection.
You have the choice
between a PNP sensor for
standard applications and
an -sensor for use in
explosive areas.

Industry standard
signals.

KRAL Electronic
BEM 300 and BEM 500.

KRAL Industrial PC
BEM 900.

For display of flowrate

and consumption, the
BEM 500 is an effortless
solution. The compact
unit is designed by KRAL
to support the Volumeter
as well as our various
applications. BEM 300
is the economy single
flowmeter device.

For complex applications

with up to 16 KRAL
Volumeter connected, the
pre-programmed BEM 900
is a perfect complement
to OME. Beside flow and
consumption measurement, this solution offers
monitoring and data acquisition and evaluation.

The BEG 40 sensor supplies

PNP square wave signal.
The BEG 41 -sensor
produces a Namur signal.
Both of these can be
processed by standard
industrial interfaces.

Sensors.
BEG 43D
BEG 44
Amplifier.

BEG 45
BEV 13

BEG 47D

Design
M18x1

Signal

PNP square wave

inductive

PNP square wave

inductive

PNP square wave

inductive

Namur sine wave

inductive

Material

Arcap / Ceramic

Arcap

Arcap

1.4401/ Ceramic

K-Factor

K1

K2

K3

K1

bar

250

420

420

40

-20 to 100

- 40 to 150

- 40 to 250

-25 to 100

Pressure
pmax
Temperature
tmin to tmax

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Successful applications with the

KRAL Volumeter OMG.

p
[bar]

200

100
Boring

10

20

30

Return stroke

t [ms]

Fuel consumption
measurement in boilers.

Flow measurement in
polyurethane blending.

Tunnel-boring
hydraulics.

Returnability of
measurement.

Liquid: heavy fuel oil.

Flowrate: 1,6 to 19 l/min.
Pressure: 40 bar.
Temperature: 130 to 150 C.
Viscosity: 10 to 15 mm/s.
Measuring device:
two OMG 20s.

Liquid: polyol, isocyanate.

Flowrate: 3,5 to 42 l/min.
Pressure: 250 bar.
Temperature: 10 to 80 C.
Viscosity: 20 to 2.000 mm/s.
Measuring device:
OMG 32.

The fuel consumption of

the boiler is measured by
determining the difference
between the flow in the
supply and return lines in
order to:
adjust the engine
performance to an
optimum
continuously monitor
the fuel consumption.

Measuring task: Accurate

flow measurement of
components to maintain
the proper blend.

Liquid: hydraulic oil.

Flowrate: 0,3 to 45 l/min
bi-directional.
Pressure: pulsating up to
250 bar.
Temperature: 40 to 80 C.
Viscosity: 60 to 3.000 mm/s.
Measuring device:
OMG 20.

Each KRAL Volumeter is

tested and calibrated on
our in-house test bed.
Depending on customer
requirements, we perform
either a factory calibration
or a calibration in compliance to KD (Austrian
Calibration Service).

The flowrate to the

hydraulic cylinder of a
tunnel-boring machine is
measured in order to be
able to determine the
exact position of the
boring bit. As the bit digs
through dirt and rocks, the
vibration is transmitted to
the hydraulic cylinder as
fluid pulsations. A diagram
of these pulsations is
shown above.

The factory calibration is

KRAL Standard. Special
standards requirements
are also possible. As example, by adding further
measurement points.
KD calibrated Volumeters are delivered to ISO
IEC EN 17025 standards.
The measured values
are traceable to national
standards. The measurement uncertainty of
national standard to test
unit is specified.

Since the fuel consumption makes up the greatest

part of operating costs,
high accuracy is important.
Also at high temperatures,
heavy fuel oil is aggressive
and forms deposits.
The accurate and selfcleaning OMG is perfect
for this application.

Blend errors can result in

flawed product, such as car
dashboards that are sensitive to heat and sunlight.
Problems such as these,
which are not discovered
until the product is delivered
to the customer, can be
avoided with accurate
measurement before of
the blending head. Precise,
reliable measurements
ensure proper, consistent
blends, and no subsequent
claims. The OMG meets
these requirements.

The OMG is trusted for

reliable measurement in
both flow directions although extreme vibrations
and impacts occur during
boring.

Our certified QA-system,

in accordance with EN
ISO 9001:2000, guarantees the highest quality
and delivery reliability.

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6285-05 KRAL VolumOMG 8s+2 en.in10 10

nderungen vorbehalten 11/06.

KRA L AG, B i l d g a s s e 4 0 , I n d u s t r i e N o r d , 6 8 9 0 L u s t e n a u , Au s t r i a , Te l . : + 4 3 / 5 5 7 7 / 8 6 6 4 4 - 0
Fa x : + 4 3 / 5 5 7 7 / 8 8 4 3 3, w w w. k r a l . a t , E - m a i l : k r a l @ k r a l . a t

28.11.2006 10:00:24 Uhr