Without proper intake design per HI 9.8, common issues include:
ANSI/HI 9.8 is the definitive industry standard for the hydraulic design of pump intakes for rotodynamic (centrifugal, mixed-flow, and axial-flow) pumps. It provides critical guidance on preventing intake-related problems such as vortices, uneven flow distribution, air entrainment, and pre-swirl—conditions that lead to cavitation, vibration, reduced efficiency, and premature pump failure.
Overall Assessment: Highly recommended as the primary reference for engineers designing pump sumps, wet wells, and suction piping. However, its conservative nature and complexity can challenge inexperienced users. ansi hi 9.8 rotodynamic pumps for pump intake design
If the incoming channel is longer than 5x the sump width, HI 9.8 mandates flow conditioning. This includes:
A single pump is easy. When you put two or more pumps side-by-side, the hydraulics interact. HI 9.8 mandates: Without proper intake design per HI 9
Before you can design against vortices, you must identify them. HI 9.8 provides a standardized Vortex Scale (Type 1 to Type 6):
| Type | Name | Description | Acceptability | | :--- | :--- | :--- | :--- | | 1 | Surface dimple | A shallow depression, no rotation | Acceptable | | 2 | Surface swirl | Rotating string, extends < 50% to bell | Marginal | | 3 | Swirl with dye trail | Dye streak visible, no air core | Not acceptable for critical service | | 4 | Funnel vortex | Air core reaches bell but not pump | Unacceptable | | 5 | Air-entraining vortex | Air enters the pump | Prohibited | | 6 | Full air core | Continuous air column | Prohibited | A single pump is easy
Design goal: Achieve Type 1 or 2 at minimum NPSH available and maximum flow.