Q: How are the glycol or viscosity compensation curves for the vortex flow meter calculated?

Proceed as follows to determine the correction factor using an SV5051: 1. Check the glycol value and working temperature of the glycol intended for use in order to determine the kinematic viscosity (v). 2. Calculate the correction factor Qo on the basis of the calculated viscosity value and store it in the controller. 3. Use the calculated viscosity value to calculate the response threshold Q(min) and store it in the controller.

Q: What behaviour can be expected with particles, air bubbles and deposits?

If there are particles in the medium, they can cause the piezoceramic sensor to break, depending on their size. If there are only minor quantities of small particles, breakage of the components can be considered unlikely. In this case, however, a loss of accuracy is to be expected, as there may no longer be a laminar flow profile that is decisive for vortex propagation. Air bubbles have the same effect. Deposits around the bluff body also lead to less accurate measurement results because they influence the vortex propagation.

Q: What must be observed with regard to installation and must inlet and outlet pipe lengths be taken into account?

The vortex measuring principle reacts very strongly to immediate disturbances, which means that inlet and outlet pipe lengths must be taken into account. The sensor should never be installed in falling pipes. If the bends are not ideal, an inlet pile length of 5 x DN and an outlet pipe length of 1 x DN should be observed. An inlet pipe length of 25 x DN must be observed downstream of a valve or pump. After 90° bends or strong tapering of the pipe, inlet and outlet conditions of 15 x DN apply. If the inlet and outlet pipe lengths cannot be adhered to, a loss of accuracy is to be expected.

Q: Does this measuring principle cause a pressure loss?

Yes, but it is very low. There are no moving parts in the medium, as, for example, with bucket wheels. The technical data sheets of the corresponding devices contain pressure loss curves that provide information on the pressure drop in relation to the flow rate. Pressure loss curve of an SV5051:

Question 1

Which media can be measured with the vortex flow meters?

Accepted Answer

Vortex flow meters are suitable for measuring ultrapure water and other non-conductive media, water and water-based media such as glycol mixtures. The proportion of glycol in the water can be up to 60%. The technical data sheets of the corresponding devices contain characteristic curves to calculate the correction factors.

Question 2

Are bidirectional measurements possible?

Accepted Answer

Vortex flow meters cannot measure bidirectionally. The reason for this lies in the measuring principle and the associated arrangement of the bluff body and the subsequent piezoceramic sensor. The bluff body generates reciprocal turbulence, which is detected by the sensor. If the cross-section is known, the number of the vortices allows to determine the flow rate.

Question 3

What behaviour is to be expected in case of changing viscosity?

Accepted Answer

If the viscosity of the medium changes due to additives or the like, an increased measurement deviation must be expected.
After a glycol or viscosity compensation, the following measuring accuracy results:

v < 4 cSt measuring accuracy 3% MEW
4 < v < 14 cSt measuring accuracy 4% MEW

Question 4

How are the glycol or viscosity compensation curves for the vortex flow meter calculated?

Accepted Answer

Proceed as follows to determine the correction factor using an SV5051:

1. Check the glycol value and working temperature of the glycol intended for use in order to determine the kinematic viscosity (v).

2. Calculate the correction factor Qo on the basis of the calculated viscosity value and store it in the controller.

3. Use the calculated viscosity value to calculate the response threshold Q(min) and store it in the controller.

Question 5

What behaviour can be expected with particles, air bubbles and deposits?

Accepted Answer

If there are particles in the medium, they can cause the piezoceramic sensor to break, depending on their size. If there are only minor quantities of small particles, breakage of the components can be considered unlikely. In this case, however, a loss of accuracy is to be expected, as there may no longer be a laminar flow profile that is decisive for vortex propagation. Air bubbles have the same effect. Deposits around the bluff body also lead to less accurate measurement results because they influence the vortex propagation.

Question 6

What must be observed with regard to installation and must inlet and outlet pipe lengths be taken into account?

Accepted Answer

The vortex measuring principle reacts very strongly to immediate disturbances, which means that inlet and outlet pipe lengths must be taken into account. The sensor should never be installed in falling pipes. If the bends are not ideal, an inlet pile length of 5 x DN and an outlet pipe length of 1 x DN should be observed. An inlet pipe length of 25 x DN must be observed downstream of a valve or pump. After 90° bends or strong tapering of the pipe, inlet and outlet conditions of 15 x DN apply. If the inlet and outlet pipe lengths cannot be adhered to, a loss of accuracy is to be expected.

Question 7

Does this measuring principle cause a pressure loss?

Accepted Answer

Yes, but it is very low. There are no moving parts in the medium, as, for example, with bucket wheels. The technical data sheets of the corresponding devices contain pressure loss curves that provide information on the pressure drop in relation to the flow rate.

Pressure loss curve of an SV5051:

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