To determine whether the Venturi nozzle is damaged, a comprehensive evaluation should be made based on appearance inspection, performance test and working condition analysis. The following are specific methods and precautions:
1. Visual Inspection
-Cracks or Deformation: Examine the nozzle surface for cracks, dents, or deformations, particularly in the throat (critical section) and diffusion section. Metal fatigue or corrosion can easily cause structural damage.
-Abrasive Wear Signs: Observe internal flow channels for abnormal wear patterns (e.g., abrasive medium-induced erosion marks), which may affect airflow/liquid flow symmetry.
-Connection Integrity: Verify flanges, threaded joints, and other connections for looseness or seal failure to prevent external leakage that could compromise measurement accuracy.
2. Performance Testing
-Flow Deviation: Compare designed flow rate with actual measurement. Significant deviations (e.g., over 10%) may indicate changes in flow area due to throat wear or blockage.
-Pressure Difference Abnormality: Measure the pressure difference between inlet and throat (ΔP). Deviations from standard curves suggest nozzle geometry alterations or internal obstructions (e.g., scaling or foreign objects).
-Outlet Flow Pattern: Inspect outlet fluid distribution for uniformity. Vortex formation or jet divergence may indicate damage to the streamlined design.
3. Operational Conditions and Historical Analysis
-Medium Characteristics: Check for abrasive particles or corrosive components in the fluid, as prolonged use may accelerate wear.
-Maintenance Records: Review replacement schedules and historical maintenance logs, as nozzles operating beyond their service life are more prone to failure.
-System Pressure Fluctuations: Frequent pressure surges (e.g., water hammer effect) may cause structural fatigue in nozzles.
4. Auxiliary detection methods
-Endoscopic inspection: For non-removable nozzles, endoscopic observation can be used to examine internal damage.
-Ultrasonic thickness measurement: To detect whether the wall thickness of metal nozzles has thinned due to corrosion.
-Calibration comparison: Compare with calibration data of new nozzles of the same model to quantify the degree of performance attenuation.
5. Replacement Suggestions
It is recommended to replace the nozzle under the following circumstances:
-The throat diameter wear exceeds 2% of the design value.
-The flow or pressure difference error continues to exceed the allowable range.
-The structural damage cannot be restored by cleaning or repair.
Precautions:
-Avoid using hard tools to scrape the inner wall when cleaning to prevent artificial damage.
-Regularly calibrate the matching differential pressure transmitter to eliminate instrument error interference.
Through the above multi-dimensional inspection, the state of the Venturi nozzle can be accurately evaluated to ensure the reliability of its measurement or process control.
