Glossary · Pneumatics and hydraulics
Leakage
Also known as: Leak
German: Leckage
In fluid power, leakage is the unintended escape of fluid from a component or system, either externally to the surroundings or internally across seals and gaps between chambers, causing loss of energy, performance or control.
- Fluid power
In one sentence
Leakage is fluid escaping unintentionally, externally from a system or internally across seals, costing energy and control.
Example
Internal leakage across the piston seal lets a hydraulic cylinder slowly sink under load even though the valve is closed.
How it applies
- Engineering: Some internal leakage is inherent in spool valves and pumps; designs that must hold loads use seat valves or check valves.
- Operation: Compressed air leaks are a major energy cost; hydraulic leaks cause slip hazards, fire hazards and environmental damage.
- Maintenance: Leak detection (ultrasound for air, visual inspection for oil) is part of routine maintenance.
- Documentation: Include leak checks in maintenance schedules and describe safe detection: never feel for hydraulic leaks by hand because of injection injuries. Explain the effect of internal leakage on load holding, for example drifting axes.
External vs. internal leakage
External leakage is visible and escapes to the environment. Internal leakage stays inside the system but reduces efficiency and can let actuators move or sink.