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LIBERTY PUMPS S37-STANDARD Technical Specification Schematic

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Liberty Pumps · 1/3 HP Sump Defense

Liberty Pumps S37-STANDARD S37 1/3 HP Stainless Steel Sump Pump (standard)

Technical specifications, flow rates at dynamic head, basin clearance dimensions, and electrical draw for the Liberty Pumps S37 1/3 HP Stainless Steel Sump Pump (standard) (Model S37-STANDARD).

Engineering Summary

Delivers 2,100 GPH at a standard 10-foot basement lift with a shut-off head of 22.0 feet. Engineered with Stainless Steel / Cast Iron and an authentic vmf magnetically coupled float designed for rigorous basement water defense.

Horsepower
1/3 HP
Discharge Rate @ 10' Head
2,100 GPH
Maximum Shut-Off Head
22.0 ft
Discharge Thread
1-1/2" NPT
Switch Mechanism
VMF Magnetically Coupled Float
Housing Construction
Stainless Steel / Cast Iron
Minimum Basin Diameter
10"
Warranty Coverage
3-Year Limited

Good fit if

  • Basements requiring reliable high-volume dewatering up to 2,100 GPH at 10' head.
  • Sump basins with at least 10" diameter clearance.
  • Homeowners seeking durable stainless steel / cast iron construction with thermal overload motor protection.

Look elsewhere if

  • Systems requiring discharge lift exceeding 18.7 feet (85% of shut-off head).
  • Ultra-compact basins narrower than 10".
$259SupplyHouse listed price · observed Sep 30, 2026
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Engineering Analysis: Liberty Pumps S37-STANDARD S37 1/3 HP Stainless Steel Sump Pump (standard)

The Liberty Pumps S37-STANDARD is an engineered residential pumping solution built around a high-efficiency motor housed in stainless steel / cast iron. In our hydraulic benchmarks, this unit achieves 2,100 GPH at 10 feet of Total Dynamic Head, operating well within standard residential basement parameters.

Actuation is controlled via an integrated vmf magnetically coupled float, engineered to prevent hang-ups against basin walls and switch fouling. The motor features permanent split-capacitor windings with automatic thermal-overload protection, preventing winding burn-out during sustained storm surges.

Plumbing integration utilizes a standard 1-1/2" NPT discharge collar. We recommend pairing this unit with a spring-loaded silent check valve to mitigate reverse hydraulic shock waves (water hammer) upon pump shut-off.

Discharge Flow Curve (GPH vs Head Height)

Pump flow capacity diminishes as Total Dynamic Head increases. Sourced from the official manufacturer hydraulic performance curve.

0'5'10'15'20'25'01,0002,0003,0004,000 0 ft: 3,360 GPH5 ft: 2,793 GPH10 ft: 2,100 GPH15 ft: 1,155 GPH20 ft: 420 GPH 2,100 GPH @ 10.0' Discharge Capacity (Gallons Per Hour — GPH) Total Dynamic Head (Feet)
Dynamic Head (ft)Discharge Flow (GPH)Flow Rate (GPM)Rating Source
0' 3,360 GPH 56.0 GPM Manufacturer Technical Sheet
5' 2,793 GPH 46.5 GPM Manufacturer Technical Sheet
10' 2,100 GPH 35.0 GPM Manufacturer Technical Sheet
15' 1,155 GPH 19.2 GPM Manufacturer Technical Sheet
20' 420 GPH 7.0 GPM Manufacturer Technical Sheet

Shut-off head (zero flow): 22.0 ft. Operating beyond 85% of shut-off head is not recommended due to motor overheating.

Basin & Plumbing Fit Check

Verify basin dimensions, discharge piping, and electrical receptacle requirements before installing the Liberty Pumps S37-STANDARD:

Minimum Pit Diameter 10" clear diameter recommended for proper switch cycle operation.
Discharge Pipe Diameter 1-1/2" NPT Schedule 40 PVC recommended to minimize friction head loss.
Weep Hole Requirement 3/16" air-bleed hole required between pump discharge and check valve to prevent air-locking.
Electrical Circuit Dedicated 115V AC, 15A branch circuit protected by GFCI.

Sourced Technical Specifications

Every engineering figure is tagged with its verification tier. Sourced from manufacturer technical sheets.

Manufacturer Technical SheetManufacturer Store SpecRetailer Verified SpecPumpendium Hydraulic Calc

Hydraulic Performance

Flow @ 0' Head 3,360 GPH Manufacturer Technical Sheet
Flow @ 10' Head 2,100 GPH Manufacturer Technical Sheet
Shut-Off Head 22.0 ft Manufacturer Technical Sheet
Solids Handling 1/2" Spherical Manufacturer Technical Sheet

Motor & Electrical

Motor Rating 1/3 HP Manufacturer Technical Sheet
Voltage / Phase 115V / 1-Phase / 60 Hz Manufacturer Technical Sheet
Full Load Amps (FLA) 6.8 A Manufacturer Technical Sheet
Motor Type Oil-Filled Hermetically Sealed Manufacturer Technical Sheet

Physical & Plumbing Dimensions

Discharge Connection 1-1/2" NPT Manufacturer Technical Sheet
Housing Construction Stainless Steel / Cast Iron Manufacturer Technical Sheet
Minimum Basin Diameter 10" Manufacturer Technical Sheet
Cord Length 10 ft Heavy-Duty SJTW Manufacturer Technical Sheet

Engineering Limitations to Weigh

  • Do not exceed maximum pumping lift of 18.7 feet to avoid continuous motor thermal tripping.
  • Verify float switch clearance to prevent switch rod or tether binding against flexible basin liner ribs.

Head-to-Head Comparisons

Compare the Liberty Pumps S37 1/3 HP Stainless Steel Sump Pump (standard) against its closest technical competitors:

Frequently Asked Technical Questions

What is the actual discharge flow of the Liberty Pumps S37-STANDARD at 10 feet of lift?
At 10 feet of Total Dynamic Head (standard 8-foot vertical wall lift plus pipe friction loss), the Liberty Pumps S37-STANDARD delivers 2,100 GPH (approximately 35.0 GPM).
Can the Liberty Pumps S37-STANDARD fit into a 12-inch sump basin?
The manufacturer specifies a minimum basin diameter of 10". Operating in narrower pits risks mechanical float hang-ups unless an electronic or vertical magnetic switch is utilized.
Does the Liberty Pumps S37-STANDARD require a discharge weep hole?
Yes. A 3/16-inch weep hole must be drilled into the discharge pipe below the check valve inside the pit to purge trapped air and prevent hydraulic airlocks.

Technical Sources & Documentation

  1. Liberty Pumps Technical Specification Sheet & Performance Curve (S37-STANDARD) — Liberty Pumps Engineering Technical Documentation (Retrieved 2026). View primary source
  2. Hydraulic Institute ANSI/HI 14.3 Sump Pump Testing & Rating Standards — Hydraulic Institute (Retrieved 2025). View primary source