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Technical Product Information

VORTEX VO ORTTEX FL FLOWMETER LOW WMETTER W WBZ BZZ 08

RMG Messtechnik GmbH

VORTEX FLOWMETER WBZ 08 Principle, applications, properties, technical data

Principle A repeating pattern of swirling vortices caused by the unsteady separation of a fluid stream over bluff bodies is called a “Kármán vortex street” and was discovered by Theodore von Kármán in1878.

2

The accuracy of the vortex meter is dependent on the length and the condition of the meter run. Upstream flow disturbances such as swirl or an asymmetric velocity profile are eliminated by a flow straightener.

The thermistor sensors are accomodated in meter head tubings above the bluff body protecting them against direct exposure to flow and the accumulation of condensate. This arrangement also allows an inspection of the sensors without taking the meters out of service.

The arrangement creates ideal conditions for signal generation. A downstream amplifier stabilizes the signals which can be processed by RMG model series ERZ 2000 flow computers or the CS 905 counter system.

Kármán Vortex Street

Vortex shedding in a fluid following around a body is periodic. The frequency at which the vortices are shed is, in certain range, proportional to the fluid velocity. Accounting for the cross-sectional area of the conduit, the number of vortices is a very exact measure of the flow rate and the volume passed through the meter.

Vortex frequency is a function of the fluid velocity, the geometry of the bluff body and the ratio between the bluff body size and the diameter of the conduit. The geometric data determine a meter factor (pulse/volume) which is independent of pressure and temperature, density and viscosity.

The vortices produced by the bluff body in the meter are the cause of velocity and pressure oscillations. These oscillations are picked up by a thermistor sensor whose resistance varies in response to the pressure oscillations.

The measurement is duplicated for high accuracy for custody transfer metering.

Applications Vortex flow meters are used for fluid resp. gas flow measurement. Gas flow at reference conditions is calculated from flow at operating conditions pressure and temperature or flow at operating conditions and density data.

The vortex meter consists of a meter body, a bluff body and a meter head with thermistor sensors and an amplifier.

Properties • • • • • • • • • •

wide range high accuracy insensibility to higher loads no influence of meter position insensibility to vibrations high reproducibility twin signal generation maintenance without taking meter out of service insensibility to dirt explosionproofed

TECHNICAL DATA Diameters

DN 40 bis DN 600

Pressure stages

PN 10 bis PN 100 / PN 160 / PN 250 ANSI 150 bis ANSI 600 / ANSI 900 / ANSI 1500

Measuring ranges

range for custody transfer metering: - calibration at atmospheric pressure - calibration at high pressure

Linearity

± 0.5 %

Reproducibility

± 0.1 %

Accuracy

± 0.5 %

Fluid

standard design for natural gas and non-corrosive gases (other gases upon request)

1 : 10/20 max. 1 : 50

VORTEX FLOWMETER WBZ 08 Dimensions, measuring ranges sensor cover flow straightener

isolating valves

inlet straight piping

Pr

DN

bluff body

2.5 DN 20 DN A

1.5 DN

outlet straight piping

vortex flowmeter

3

5 DN C

3 DN B L

MEASURING RANGES (m3/h)

DIMENSIONS DN

A

40

1½“

50

B

C**

L**

C***

L***

Size

Qn min

G 40 -------G 65 G 65 2.400 G 100

800

120

630

1.550 --------

2“

1.000

150

800

1.950 1.250

80

3“

1.600

240

560

2.400 1.350

3.190 G 250

100

4“

2.000

300

600

2.900 1.450

3.750

150

6“

3.000

450

750

4.200 1.200

4.650

200

8“

4.000

600 1.000

5.600 1.400

6.000

250

10“

5.000

750 1.250

7.000 1.550

7.300

300

12“

6.000

900 1.500

8.400 1.700

8.600

400

16“

8.000 1.200 2.000 11.200 2.000 11.200

500

20“

10.000 1.500 2.500

600

24“

12.000 1.800 3.000 16.800 3.000 16.800

14.00 2.500 14.000

Length: A = upstream straight piping, B = meter, C = downstream straight piping, L = total length *) max. flowrange of 1:50 feasible **) 2 pockets for densitometer and drier or G¾ taps for PT 100 resistance thermometer (taps spaced at 230 mm) ***) 4 densitometer + drier pockets or more than 5 taps Physics require the following minimum flow for the vortex meter:  Qn min · pn Qfl min = ---------------- (m3/h) pfl To maintain the range for custody transfer, flow may never drop below the minimum flow qfl min tabulated above.

G 400 G 650 G 1000 G 1600 G 1600 G 2500 G 2500 G 4000* G 4000 G 6500* G 6500 G 10000* G 10000 G 16000* G 16000 G 25000*

Qfl min

40

3/5/10

40

5/10/10

80

8/13/20

80

20

130

50

160

80

200

130

320

200

320

320

500

500

800

800

Qfl max 65 100 100 160 400 650 1000 1600 2500 2500 4000 4000 6500 6500 10000 10000 16000 16000 25000 25000 40000

K

F

16700

400

8000

365

2400

350

1100

370

310

220

140

260

70

130

40

110

20

90

10

70

5

60

Pressure loss of total meter run:  Qfl2 p = 2000 · fl · ------DN4 qfl min: minimum flow at flowing conditions pfl: minimum operating pressure [bar (absolute)] f: signal frequency [Hz], (fmax at qfl max) K: meter factor [pulses/m3]  f Qfl = ----- · 3600 (m3/h) K ∆p = DN = ρfl =

pressure loss (mbar) nominal size (mm) density at flowing conditions (kg/m3)

SERVING THE GAS INDUSTRY WORLDWIDE

RMG is your competent partner along the entire chain ranging from the exploration to the supply of final consumers.

Our reliable products and systems offer to you full control within the range of regulating and measuring technology.

Furthermore we plan and build plants according to your requirements and offer to you reliable and modern solutions also in station automation. Ask us - we look forward to your challenges.

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GERMANY RMG Regel + Messtechnik GmbH Osterholzstraße 45 D-34123 Kassel Fon +49 (0)561 5007-0 Fax +49 (0)561 5007-107

WÄGA Wärme-Gastechnik GmbH Osterholzstraße 45 D-34123 Kassel Fon +49 (0)561 5007-0 Fax +49 (0)561 5007-207

RMG Messtechnik GmbH Otto-Hahn-Straße 5 D-35510 Butzbach Fon +49 (0)6033 897-0 Fax +49 (0)6033 897-130

RMG Gaselan Regel + Messtechnik GmbH Julius-Pintsch-Ring 3 D-15517 Fürstenwalde Fon +49 (0)3361 356-60 Fax +49 (0)3361 356-836

ENGLAND

CANADA

Bryan Donkin RMG Gas Controls Ltd. Enterprise Drive, Holmewood Chesterfield S42 5UZ, England Fon +44 (0)1246 50150-1 Fax +44 (0)1246 50150-0

Bryan Donkin RMG Canada Ltd. 50 Clarke Street South, Woodstock Ontario N4S 7Y5, Canada Fon +1 519 53-98531 Fax +1 519 53-73339

POLAND

USA

Gazomet Sp. z o.o. ul. Sarnowska 2 63-900 Rawicz, Polen Fon +48 (0)65 54624-01 Fax +48 (0)65 54624-08

Mercury Instruments LLC 3940 Virginia Avenue Cincinnati, Ohio 45227 Fon +1 513 272-1111 Fax +1 513 272-0211

We reserve the right for technica changes

Status 12/2008

Vortex Flowmeter WBZ 08