The Grundfos 16S50-38 (product number 99922004) is a 4-inch SP stainless steel submersible well pump rated 17.6 US GPM at 813.7 ft of head across 38 stages, driven by a 5 HP three-phase submersible motor. Built entirely in AISI 304 stainless steel with a built-in return valve, it is designed for deep, high-head wells and carries cUL / cCSA drinking-water listings.
Performance Curve
Official Grundfos curve — 60 Hz, water at 68 °F. Head (H) and efficiency (η) against flow (Q); lower chart shows power (P2 shaft) and NPSH required. Duty point 17.6 GPM @ 813.7 ft.
Performance & Hydraulic Data
| Rated flow | 17.6 US GPM |
| Rated head | 813.7 ft |
| Stages | 38 (no reduced-diameter impellers) |
| Pump speed (data basis) | 3,450 RPM |
| Pump type | SP3A (4-inch) |
| Maximum operating pressure | 870 psi |
| Maximum outlet pressure | 512 psi |
| Built-in return (non-return) valve | Yes |
| Curve tolerance | ISO 9906:2012 grade 3B |
| Minimum efficiency index (MEI) | ≥ 0.70 |
Materials of Construction
| Pump housing | Stainless steel — EN 1.4301 / AISI 304 |
| Impellers | Stainless steel — EN 1.4301 / AISI 304 |
| Shaft end | Cylindrical |
Installation & Connections
| Discharge connection | 1-1/4 inch NPT (female) |
| Motor diameter | 4 inch |
| Minimum borehole diameter | 4.13 in |
| Liquid temperature range | 5 °F to 140 °F |
| Pumped liquid | Water (clean, non-aggressive) |
Motor & Electrical Data
| Rated power | 5 HP (pump requires 5.5 HP at duty) |
| Voltage & phase | 3 × 380 V, three-phase |
| Frequency | 60 Hz |
| Motor type | 4-inch Grundfos submersible |
Approvals, Weights & Identification
| Drinking-water approval | cUL / cCSA (CULDWUS, CCSAUS); California Prop 65 |
| Grundfos product number | 99922004 |
| Type key | 16S50-38 — 4.0 kW, 3×380 V, 60 Hz |
| EAN | 5715114183963 |
| Net weight (pump + motor) | 79.4 lb |
| Gross (shipping) weight | 117 lb |
| Country of origin | United States |
| HS / customs tariff code | 8413.70.2004 |
Official Datasheet
📄 View the Grundfos 16S50-38 Data Sheet Grundfos product data 10110038
Typical Applications
Deep-well water supply • high-head groundwater abstraction • irrigation from deep boreholes • pressure boosting • livestock and rural water • industrial process water. The 38-stage build delivers very high head (over 800 ft) at moderate flow from narrow 4-inch and larger wells.
Need help? Contact ForeverPure Place for pricing, lead time, a matching control box, cable sizing, or help selecting the correct SP model and stage count for your well depth.
