Hydraulic Filter Collapse: Why It Happens & How Bypass Valves Prevent It
Overview
A collapsed hydraulic filter element-where the metal inner tube crushes inward-is caused by excessive differential pressure (ΔP) across the filter media.
──────────────────► [ Filter Media ] ──► Low Outlet (P2)
│
Extreme Delta P (ΔP)
CRUSHES INNER TUBE
2 Main Causes of Filter Collapse
1. Cold Start Viscosity:
Cold hydraulic oil thickens. When starting up, thick fluid cannot pass through micro-glass pores fast enough, creating a massive upstream pressure spike.
2. Hydraulic Pressure Surges:
Sudden cylinder movements or heavy load drops send high-flow surges slamming directly into the filter pleats.
The Critical Role of the Bypass Valve
The Bypass Valve acts as a safety relief valve:
- How It Works:
- When ΔP hits a safe limit (e.g., 3.5 bar), the valve opens to bypass oil around the media, preventing structural destruction.
- Incorrect Setting Risks:
- Set Too High / Stuck Closed: Oil cannot bypass during cold starts, causing immediate structural collapse.
- Set Too Low: The valve opens under normal driving, letting dirty oil damage downstream pumps.
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