Ansi Hi 9.8 Rotodynamic Pumps For Pump Intake Design ((better)) Info

The most recent edition, , supersedes the 2018 edition and introduces several important updates: revision to the physical model study requirement for closed‑bottom suction can pumps; improved guidance on pump operating conditions that influence intake design; updates and additions to terms and definitions; and updates to content and figures that clarify or improve existing materials.

If the incoming channel is longer than 5x the sump width, HI 9.8 mandates flow conditioning. This includes:

Studies have shown that installing proper floor-type flow separators can reduce swirl angles by approximately 60%, bringing many designs into compliance with the 5-degree limit. Application and Compliance ANSI/HI 9.8 applies to a wide range of industries: Water and wastewater treatment plants Power generation plants Flood control pumping stations Industrial process water systems

Adhering to is not merely a regulatory step; it is an investment in the hydraulic efficiency and mechanical longevity of the pumping system. By carefully managing sump dimensions, minimizing swirl, and eliminating vortices, engineers can prevent costly downtime and premature failure. ansi hi 9.8 rotodynamic pumps for pump intake design

Pre-swirl occurs when the fluid enters the pump suction bell with an inherent rotational component.

It restricts entrained air to less than 1% to 2% by volume. Air bubbles reduce pump capacity, cause mechanical shock waves, and trigger localized cavitation. 2. Standard Intake Geometries Governed by ANSI/HI 9.8

The distance from the center of the pump column to the back wall is tightly controlled to prevent trailing vortices. 2. Formed Suction Intakes (FSI) The most recent edition, , supersedes the 2018

Circular footprints are highly cost-effective for deep excavations. However, they naturally induce swirling flow patterns. ANSI/HI 9.8 provides guidelines on utilizing splitters, baffles, and specific inlet pipe positioning to break up the internal swirl before it reaches the vertical turbine or submersible pumps. 3. Strict Hydraulic Performance & Acceptance Criteria

The standard covers several types of intakes, including wet pits, suction tanks, and closed-conduit inlets. However, the core principles remain the same. 1. Minimizing Swirl

The primary goal of the ANSI/HI 9.8 standard is to ensure that the fluid arriving at the pump suction eye is uniform, steady, and free from harmful rotational components. Specifically, the standard establishes guidelines to achieve three major hydrodynamic milestones: Application and Compliance ANSI/HI 9

✅ Intake flow velocity < 0.5 m/s ✅ Submergence ≥ 1.5D (verify with HI 9.8 curve) ✅ Bottom clearance 0.3D – 0.5D ✅ No free-surface vortices visible during operation ✅ Straight approach length ≥ 5× bay width ✅ CFD or physical model for complex geometries

“Physical modeling is recommended for flow rates exceeding 10,000 gpm (2,300 m³/h) or where NPSHa margin is less than 50%.”