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Hydraulic Pump Cavitation Diagnostics: Detection of Inlet Restriction, Reservoir Level, Fluid Viscosity, and Suction Tube Air Leakage

Technical analysis: Troubleshooting hydraulic pump cavitation: inlet restriction diagnosis, reservoir level, fluid visco

Діагностика кавітації гідравлічного насоса: виявлення обмеження на вході, рівня резервуара, в’язкості рідини та витоку повітря у всмоктувальну трубку - UNITEC-D Industrial MRO
Цей гайд вирішують проблеми, пов’язані з кавітацією гідравлічного насоса, включаючи виявлення обмеження на вході, рівня резервуара, в’язкості рідини та витоку повітря. Діагностика виконується з викори

1. Description of the problem and the size of the impact

This guide addresses problems related to hydraulic pump cavitation, which results in system malfunction, noise, detonation, and improper power output. The problem can occur in various types of industrial equipment: hydraulic presses, cutting machines, transport mechanisms and control systems. According to the requirements of DSTU 4641:2005, cavitation is considered critical because it can cause damage to the pump, increase in system temperature and loss of efficiency.

2. Safety and Warnings

Warning: Before diagnosis, shut down system, apply procedural lockout/tagout (LOTO), use protective clothing (PPE) and turn off power to avoid accident. If there is no liquid in the tank, gas may escape, leading to an explosion.

3. Necessary diagnostic tools

Name of the tool Model/specification Measuring range The goal
Multimeter Megger M335 0-2000 ohms Checking electrical resistance
Thermal camera FLIR T1020 -20°C to 650°C Detection of thermal anomalies
Vibration analyzer LDI VIBROSCAN 2000 0-100000 mm/s Measurement of the vibration level
Pressure sensor Testo 510 0-10 bar Checking the pressure in the suction line

4. First review and control

Indicator Meaning
Fluid temperature ≤ 50°C
Liquid level in the tank ≥ 70% of the volume
Pressure in the suction line ≥ 0.5 bar
Liquid viscosity ISO VG 46
Vibration index ≤ 2.5 mm/s

5. Systematic diagnostic scheme

  1. Symptom: Pump hums, does not make power.
    1. Check the fluid level in the tank.
    2. If the level is less than 70%, check for leaks.
    3. Check the suction line pressure with a gauge.
    4. If the pressure is less than 0.5 bar, check the inlet restriction.
  2. Symptom: Explosions in the system.
    1. Use the thermal camera to detect thermal anomalies.
    2. If abnormalities are found, check the viscosity of the liquid.
    3. If the viscosity is higher than ISO VG 46, replace the fluid.
    4. Check the suction tube for air leaks.
  3. Symptom: High vibration.
    1. Use a vibration analyzer to measure the vibration.
    2. If the vibration is greater than 2.5 mm/s, check the fluid level.
    3. Check the suction tube for restrictions.

6. Matrix of echo causes

Symptom Reasons (in order of probability) Diagnostic test Expected result
Humming of the pump
  1. Low fluid level
  2. Air leak
  3. Low pressure in the suction line
  1. Checking the fluid level
  2. Checking the suction line for leaks
  3. Pressure measurement in the suction line
  1. Level less than 70%
  2. An air leak has been detected
  3. The pressure is less than 0.5 bar
Explosions
  1. High viscosity of liquid
  2. Incorrect system pressure
  3. Low fluid level
  1. Checking liquid viscosity
  2. Pressure measurement in the system
  3. Checking the fluid level
  1. Viscosity higher than ISO VG 46
  2. The pressure is higher than 30 bar
  3. Level less than 70%
High vibration
  1. Low fluid level
  2. Entry restrictions
  3. Incorrect fluid viscosity
  1. Checking the fluid level
  2. Check entry for restrictions
  3. Checking the viscosity of the liquid
  1. Level less than 70%
  2. Entry restrictions
  3. Viscosity higher than ISO VG 46

7. Analysis of root causes

7.1. Low liquid level in the reservoir

Low fluid levels can cause cavitation because the pump cannot properly suck in the fluid. This is due to leaks, incorrect tank matching, or incorrect matching of system capacity. If this is not corrected, an explosion or damage to the pump may occur. Check fluid level and leaks.

7.2. Air leakage in the suction line

Air leakage in the suction line leads to cavitation, as air can create voids in the system. This can be caused by improper connections, air leaks, or leaks. If this is not corrected, an explosion or damage to the pump may occur. Use a thermal imager or vibration analyzer to detect leaks.

7.3. Low pressure in the suction line

Low suction line pressure can be caused by inlet restriction, power mismatch, or fluid viscosity mismatch. This can cause cavitation, explosion or damage to the pump. Check suction line pressure and compliance.

7.4. High viscosity of the liquid

High fluid viscosity can cause cavitation because it reduces the speed of fluid movement through the system. This can be caused by improper fluid selection, fluid aging, or improper storage. If this is not corrected, an explosion or damage to the pump may occur. Check fluid viscosity and compliance with standards.

8. Troubleshooting steps

8.1. Low fluid level

  1. Dose the liquid to the tank up to 70% of the volume.
  2. Check all connections for leaks.
  3. Check for leaks or blockages.
  4. Use a thermal camera to detect leaks.
  5. Use a vibration analyzer to check the vibration.

8.2. Air leak

  1. Wrap all connections.
  2. Check all points for leaks.
  3. Use a pressure gauge to check the pressure in the suction line.
  4. Use a thermal camera to detect leaks.
  5. Bleed the system to remove air.

8.3. Low pressure in the suction line

  1. Check all connections for restrictions.
  2. Use a pressure gauge to check the pressure.
  3. Check the fluid level in the reservoir.
  4. Use a thermal camera to detect leaks.
  5. Use a vibration analyzer to check the vibration.

8.4. High viscosity of the liquid

  1. Replace fluid with ISO VG 46.
  2. Check for aging or clogging.
  3. Use a viscosity sensor to check.
  4. Check fluid storage.
  5. Use a vibration analyzer to check the vibration.

9. Prevention

The root cause Prevention strategy Control method Recommended interval
Low fluid level Periodic check of the fluid level Thermal camera, pressure sensor Every day
Air leak Periodic check of connections Thermal camera, vibration analyzer Every week
Low pressure in the suction line Periodic pressure check Pressure sensor, thermal camera Every week
High viscosity of the liquid Periodic check of viscosity Viscosity sensor, vibration analyzer the moon

10. Replacement parts and components

Description of the component Specification When to replace UNITEC-D category
Reservoir Volume 200 l After clogging or leaks Category 123
Oil seals ISO 3404 After the leaks Category 124
Suction tube Diameter 20 mm After leaks or blockages Category 125
liquid ISO VG 46 After aging or clogging Category 126

Contact UNITEC-D for exact components: https://www.unitecd.com/e-catalog/

11. Links

  • DSTU 4641:2005 – Hydraulic systems
  • ISO 10426:1996 – Hydraulic pumps
  • EN 12125:2005 – Hydraulic systems
  • UNITEC-D technical manuals
  • UNITEC-D maintenance guides

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