1. Description of the problem and scope of application
Hydraulic pump cavitation is a critical condition caused by the formation and subsequent collapse of vapor bubbles in a liquid when the local pressure drops below the saturated vapor pressure of the liquid at the current temperature. This phenomenon leads to intensive erosive wear of internal components, destruction of seals and a catastrophic decrease in system efficiency.
This manual is intended for diagnosing cavitation on piston, gear and vane pumps of industrial hydraulic systems. Criticality classification: Critical (requires immediate intervention to prevent complete destruction of the pump).
2. Safety measures
CAUTION: Hydraulic system under pressure is dangerous to life. Before starting work, perform the LOTO (Lockout/Tagout) procedure. Reduce the residual pressure in the system. Use PPE: safety glasses, oil-resistant gloves, special shoes. Be aware of the danger of hot hydraulic fluid (>60°C).
3. Necessary diagnostic tools
| Tool | Specification/Model | Measuring range | Purpose |
|---|---|---|---|
| Vacuum gauge (analog) | Class 1.6, membrane | -1.0 ... 0 bar | Pressure measurement in the suction line |
| Vibroanalyzer | Accelerometer type | 10 Hz ... 10 kHz | Detection of high-frequency vibration (gravel characteristic) |
| Thermal imager | Resolution ≥160x120 | -20 ... +150°C | Localization of overheating of the pump housing |
| Viscometer (portable) | Rotary or capillary | 10 ... 500 cSt | Control of working fluid viscosity |
| Ultrasonic leak detector | Frequency range 20-100 kHz | - | Detection of air suction in suction lines |
4. Initial assessment checklist
| Criterion | What to check / Write down |
|---|---|
| Terms of use | Current working pressure, liquid temperature, pump load |
| Fluid level | Does the level in the hydraulic tank correspond to the recommended level (taking into account expansion) |
| Filter status | Last replacement date, pressure drop indicator |
| Alarm history | Have there been previous reports of overheating or unusual noise |
| Changes in the system | Have components been replaced or reconfigured? |
5. Systematic diagnosis diagram
- Assess the nature of the noise:
- If you hear a "gravel" or "crack" sound that gets louder with increased pressure or revs: Go to step 2.
- If the sound is stable and monotonous: Probably a mechanical failure (bearings), not cavitation.
- Checking the suction line:
- Measure the pressure at the pump inlet. If the pressure is below 0.2 bar (vacuum): Go to step 3 (restriction).
- Use an ultrasonic leak detector on the connections of the suction line: If a signal is detected, eliminate the air leak.
- Viscosity and temperature evaluation:
- If fluid temperature > 65°C: Check cooler (heat exchanger).
- If the viscosity is higher than the specified one for the given temperature range: Replace the fluid.
