1. Basic Principle
Vortex flow meters operate based on the Kármán Vortex Street principle. When a fluid flows past a bluff body (called a vortex shedder), alternating vortices are formed downstream, and the frequency of these vortices is proportional to the fluid velocity.
2. Instrument Coefficient (K Factor)
The K factor, or instrument constant, indicates the number of pulses generated per unit volume of fluid (e.g., pulses/m³). It is determined through factory calibration and is primarily affected by the geometry of the vortex shedder bar.
🔸 Correct Answer: D. Geometry of the vortex shedder bar
3. Main Components of a Vortex Flow Meter
A typical vortex flow meter consists of:
A. Vortex shedder bar
B. Sensor (detects pressure fluctuations)
C. Signal converter (transforms signal into readable format)
Optional parts include:
D. Display unit
E. Signal amplifier
4. Key Advantages of Vortex Flow Meters
No zero drift, unlike analog flow meters
Digital pulse output, no need for A/D or D/A conversion
Long-distance signal transmission with minimal signal degradation
High reliability with no moving parts
Low maintenance due to simple structure
Indicated accuracy rather than full-scale accuracy
5. Typical Operating Conditions for Proper Function
The fluid must maintain sufficient velocity
Stable vortex formation must occur downstream of the shedder
The pulse or analog signal must be correctly transmitted
6. Common Failure Modes and Troubleshooting
❌ No Output & No Display
Power not connected or faulty
Cable connection error
Replace power supply or rewire
⚠️ Display Present but No Output
Flow rate below measurable threshold
Amplifier board failure
Sensor damage
Blockage or sensor jammed
🔄 Fluctuating or Unstable Output
Poor shielding or grounding
Excessive pipeline vibration
Improper installation position
Downstream valve interference
Check amplifier filter settings
7. Causes of Zero Reading or No Indication
Power failure
Internal circuit fault
Severe fouling or damage on vortex shedder
8. Real-World Failure Example: Steam System Damage
In steam measurement applications, vortex shedder damage can occur due to sudden valve opening. High-pressure steam mixed with condensate water may strike the shedder violently, leading to mechanical failure. This phenomenon is commonly known as:
Water Hammer
9. Summary Table: Troubleshooting Overview
| Symptom | Possible Cause | Suggested Action |
|---|---|---|
| No display/output | Power failure, wiring error | Check power, cable, or replace supply |
| Display only, no output | Low flow, sensor/amplifier fault | Check flow rate, replace components |
| Unstable readings | Pipeline vibration, grounding issues | Reinforce installation, check shielding |
| Sudden shedder failure | Water hammer in steam systems | Add steam traps, open valves gradually |