Description
MEGAVF7000 Series is a Vortex flowmeter based on Von Karman principle of vortices generated by a bluff body in the pipe. The number of vortices are linearly proportional to the volumetric flow in the pipe.
MEGAVF7000 Series is versatile flowmeter widely used for Gases, Steam Liquid applications. There are no moving parts and comes with either flange or wafer connection.
- Simplified setup and self-diagnostic functions
- Auto. Temperature & Pressure compensation
- Either 4-20mA or Pulse output for your selection
- Available with Modbus and HART protocol
- Wide temperature range up to 320℃
- Available in wafer, flanged, and high pressure designs.
Vortex Flow Meters - Principle of Operation
Vortex Flow Meters use the Von Karman Effect to measure the rate of flow of a fluid or gas.What is the Von Karman Effect?
Early in the 20th century, a Hungarian-American mathematician and physicist, Theodore von Karman, discovered that a fluid or gas flowing perpendicularly pass a bluff body would generate alternating vortices on both sides of the body. The path of these vortices is called the Von Karman Street.
Von Karman found that if the frequency of these vortices was measured, that the frequency is proportional to the flow velocity that is generating the vortices. This frequency is called the Karmen Vortex Frequency. The relationship of the fequency and the flow velocity can be mathematically expressed with the following formula:
From the equation, we can see that the frequency is proportional to the velocity. If we can measure the frequency (f), know the Strouhal number (St), know the shedder bar width (d); we can solve for v (velocity).
What are the advantages of using Vortex Flow Meters?
- High Accuracy
The accuracy of the vortex flow meter is ±1~1.5% (pulse output) of the indicated value for both liquids and gases and is higher compared to orifice flow meters. For liquids, an accuracy of ±0.75% is available depending on the fluid type and their conditions.
- Wide Rangeability
Rangeability is defined as the ratio of maximum value to min. value of the measureable range. It is braod rangeability the allows vortex flow meters to operate in processes where the measuring point may fluctuate greatly.
- Output is Proportional to Flow Rate
Since the output is directly proportional to the flow rate (flow velocity), no square root calculation is needed, while orifice flow meters require square root calculations.
- No Zero-point Fluctuation
Since frequency is poutput from the sensor, zero-point shift does not occur.
- Minimal Pressure Loss
Since only the vortex shedder is placed in the pipe of the vortex flow meter, the fluid pressure loss due to the small restriction in the flow piping is small compared with flow meter a having an orifice plate.
Specifications
| Medium | Liquid, Gas, Steam |
| Size | 15, 20, 25, 32, 40, 50, 65, 80, 100, 125, 150, 200, 250, 300 |
| Nominal Pressure | 1.6MPa, 2.5MPa, 4.0MPa, High pressure can be customized |
| Accuracy |
Liquid: ±1.0% reading Gas, Steam: ±1.5% reading/±1.0% reading |
| Range ratio | 1:10；1:15；1:20 |
| Sensor Material | SS304 (Standard), SS316/SS316L (Option) |
| Use environment |
Medium temperature: -40℃～+250℃ / -40℃～+320℃ Ambient temperature: -20℃～+60℃ Relatively humidity: 5%~95% Atmospheric pressure: 86Kpa ~ 106 Kpa |
| Power Supply |
24VDC Built in 3.1V10AH lithium battery |
| Output Signal |
Pulse signal Two-wire 4-20mA (HART is available) Three-wire 4-20mA (RS485 is available) |
| Electrical interface | M20x1.5 (Standard); 1/2’’NPTF (Option) |
| Ex-proof |
Flame proof: ExdIIBT6 Intrinsic safety: ExiaIICT5 |
| Protection level | IP65 |
| Compensation |
Temperature compensation Pressure compensation Temperature & Pressure compensation |
| Connection | DIN, ANSI, JIS Flanges |
Installation
Required Straight Pipe Length
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