1. Causes of Gear Pump Shutdown: Mechanical Seal Failure
Gear pumps, known for their compact structure and excellent performance, are widely used in petroleum, chemical, and machinery industries. However, unexpected shutdowns may still occur during operation, primarily caused by mechanical seal failure. The most common symptom is leakage, with the main causes summarized as:
- Compensation ring O-ring leakage: due to deformed gland, uneven preload, improper installation, incorrect material, or incompatible selection.
- Dynamic and static ring face leakage: caused by insufficient flatness or roughness, surface scratches, particle intrusion, or incorrect assembly.
2. Gear Pump Operation and Advantages
A gear pump uses a pair of meshing gears to isolate the suction and discharge chambers. Driven by a motor, gear rotation causes suction on one side (due to expanding gear space) and discharges fluid on the other side (due to shrinking space). Key benefits include:
- Stable flow with <1% pressure pulsation;
- Enhanced extrusion line stability;
- Reduced material shear, residence time, temperature, and pressure fluctuations;
- High viscosity liquid handling;
- Flow rate up to 300 m³/h, pressure up to 30 MPa.
3. Installation & Maintenance Space Requirements
To ensure operation and maintenance safety, leave:
- ≥1.2–1.5 m clearance between pump and wall;
- ≥2 m spacing between dual-row pumps;
- Sufficient top clearance for lifting during overhaul;
- Maintenance access on at least one side of the pipeline layout.
4. Cleaning & Replacement of Filter Elements
Filter elements protect gear pumps from impurities and blockages. Here are recommended cleaning steps for different types:
- Sintered metal filter:
Brush clean → Solvent degrease / bake <400°C → Back-flush with water/gas (0.4–0.5 MPa) → Acid wash → Final blow-dry. - Paper filter:
Non-washable. Replace when clogging indicator triggers. - Mesh / wedge wire filter:
Degrease → Brush → Water flush → Air dry → Reassemble in a clean area.
Use original specifications for all replacements, including sealing rings, to avoid leaks or air intake.
5. The Role and Importance of Filter Screens
If the pump runs without a filter screen at the inlet, solid particles can enter, leading to internal blockages and flow reduction. Particularly when transporting unrefined crude oil, solid debris may clog suction/discharge ports.
Prevention:
- Install an appropriate mesh filter at the inlet;
- Regularly inspect and clean filters;
- Monitor pressure drop to detect early signs of clogging.
Conclusion
Gear pump shutdowns are often due to seal failures or impurity blockages. Implementing proper sealing installation, routine inspection, and timely filter maintenance can greatly enhance operational reliability and service life.