National Pump Company (NPC), a recognized market leader in vertical turbine pumps, highlights its line of low Net Positive Suction Head Required (NPSHR) impellers to support reliable performance in challenging suction conditions. The line includes 12 low NPSH first-stage impeller options in 2-inch size increments, giving engineers and end users more flexibility to match hydraulics to specific applications.
NPSHR is a critical parameter in pump selection, and overlooking it can lead to reduced performance, cavitation, and premature failure. Because NPSHR is measured only at the first stage of a vertical turbine pump, NPC’s low NPSH impellers are engineered specifically for the first stage to reduce NPSHR while maintaining efficient hydraulic performance. These impellers are well suited for installations where available NPSH (NPSHA) is limited or where operating conditions may vary over time.
A key feature of the product line is the ability to combine a low NPSH first-stage impeller with other impeller designs for the remaining stages in the bowl assembly. For example, L8HC-S first stages can be teamed with L8MC and L8HC impellers, L10HC-S with L10LC, L10MC, and L10HC, M12HC-S with M12LC, M12MC, and M12HC, M14XXHC-S with M14MC, M14HC, and M14XXHC, H14XHC-S with H14LC, H14MC, and H14XHC, K20HC-S with K20LC, K20MC, and K20HC, and H24MC-S with H24LC and H24MC. This configuration allows users to achieve optimum flow and efficiency while still meeting NPSHA requirements, reducing the risk of cavitation at the pump inlet.
Traditionally, marginal NPSHA conditions have been addressed by increasing pump setting depth or using canned pumps, with each additional foot of setting providing approximately one additional foot of NPSHA. While effective, this approach can significantly increase equipment and installation costs. Low NPSH first-stage impellers provide an engineered alternative that can reduce the need for deeper settings, helping owners balance capital and operating costs with long-term reliability.
To further expand design flexibility, NPC is developing additional low NPSH first-stage models scheduled for release in 2026 and 2027, including KK10LS, compatible with K10LC stages, and DH16FS, compatible with H16MC and H16XHC stages. These offerings will extend the available hydraulic coverage for more flow and head combinations and enable users to address an even broader range of suction-limited applications. NPC’s teams are available to assist customers in evaluating system conditions and selecting appropriate low NPSH impeller options and stage combinations.