What is Dirt Holding Capacity in Filtration?
Dirt holding capacity (DHC) is the total weight of contaminant, in grams, that a filter element can capture before reaching its terminal differential pressure. It is measured per ISO 16889 using standardized test dust. Higher DHC means longer element life between replacements and lower total operating cost.
How DHC is Measured
During the ISO 16889 multi-pass test, test dust is continuously injected upstream while ΔP is monitored. The test runs until the element reaches terminal ΔP (typically the bypass valve setting). The total grams of dust injected equals the DHC. Values range from under 5 grams for small elements to over 100 grams for large, high-capacity elements.
Factors Affecting DHC
Media surface area (larger elements hold more), media type (glass fiber typically outperforms cellulose), pleat count and geometry, and micron rating (finer elements fill faster). Element length and diameter directly affect DHC, which is why longer elements and elements with more pleats last longer in service.
DHC in Cross-Referencing
When cross-referencing filter elements, matching DHC ensures equivalent service life. An element with lower DHC at the same micron rating will need more frequent replacement. If OEM element change intervals are critical to your maintenance schedule, verify that the replacement element offers comparable DHC.
Reference Table
| Element Length | Typical DHC (grams) | Approx. Service Life |
|---|---|---|
| 4–6 inches | 5–15g | 500–1,000 hours |
| 8–10 inches | 15–35g | 1,000–2,000 hours |
| 13–16 inches | 35–60g | 2,000–3,000 hours |
| 20–24 inches | 60–90g | 3,000–4,000 hours |
| 36+ inches | 90–130g | 4,000–6,000 hours |
Frequently Asked Questions
How long does a hydraulic filter last?
Does micron rating affect dirt holding capacity?
Related Specifications
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