The Grundfos 77S50-8 (product number 98924481) is a SP14 stainless steel submersible well pump rated 73.5 US gpm at 158.1 ft across 8 stages, supplied complete with a 5 HP three-phase Grundfos MS4000 submersible motor.
Performance Curve
Official Grundfos curve — 60 Hz, water at 68 °F. Head (H) and efficiency (η) against flow (Q); lower chart shows power and NPSH required.
Performance & Hydraulic Data
| Rated flow | 73.5 US gpm |
| Rated head | 158.1 ft |
| Stages | 8 |
| Pump speed (data basis) | 3450 rpm |
| Pump type | SP14 |
| US designation | SP14-8 |
| Maximum operating pressure | 870.23 psi |
| Maximum outlet pressure | 102.98 psi |
| Built-in return valve | Yes |
| Maximum axial load | 992 lb |
| Curve tolerance | ISO9906:2012 3B |
Materials of Construction
| Pump housing | Stainless steel — EN 1.4301 — AISI 304 |
| Impellers | Stainless steel — EN 1.4301 — AISI 304 |
| Motor shell | Stainless steel — EN 1.4301 — AISI 304 |
| Motor shaft seal | HM/Ceramics |
Installation & Connections
| Discharge connection | 2 NPT(F) |
| Motor diameter | 4 inch |
| Minimum borehole diameter | 4.13 in |
| Overall length | 55.7 in |
| Liquid temperature range | 5 °F to 104 °F |
Motor & Electrical Data
| Motor type | Grundfos MS4000 submersible |
| Rated power (P2) | 5 HP |
| Voltage & phase | 208-220-230 V, three-phase |
| Frequency | 60 Hz |
| Rated speed | 3450-3470-3480 rpm |
| Rated current | 17.0-16.4-16.1 A |
| Locked-rotor current | 490-540-590 % |
| Power factor (cos φ) | 0.86-0.84-0.76 |
| Service factor | 1.15 |
| Method of starting | Direct-on-line (DOL) |
| Thermal protection | External |
| Enclosure class | IP68 |
| Insulation class | F |
| Grundfos motor number | 92959951 |
Approvals, Weights & Identification
| Approvals | CULDWUS,CCSAUS |
| Drinking water | PROP65 |
| Grundfos product number | 98924481 |
| EAN | 5712603664064 |
| Net weight (pump + motor) | 70.8 lb |
| Gross (shipping) weight | 164.1 lb |
| Country of origin | United States |
| HS / customs tariff code | 8413.70.2004 |
Typical Applications
Well and borehole water supply • groundwater abstraction • irrigation • pressure boosting • livestock and rural water • industrial process water.
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