Stainless Steel Deep‑Well Submersible Pump

Stainless steel deep‑well pump is a multi‑stage submersible pump. The whole unit is submerged in underground water. It is mainly used to draw groundwater from deep wells. All wetted parts are made of stainless steel, differing from cast‑iron deep‑well pumps.

1. Main Features

• Corrosion‑resistant material
  Wetted components (pump casing, impeller, diffuser, shaft) adopt 304 / 316 stainless steel, resisting corrosion of groundwater and minor sand abrasion. 316 is suitable for salt‑containing and corrosive groundwater, while 304 for ordinary well water.
  Compared with cast‑iron pumps: less rust and scale buildup, cleaner water quality, suitable for drinking‑water extraction.
• Multi‑stage impeller structure for high head
  It is a multi‑stage centrifugal pump. Multiple impellers are connected in series to deliver high head. It can lift water from dozens to hundreds of meters underground to the ground surface, with moderate flow rate, ideal for deep wells, not for large‑flow low‑head applications.
• Submerged operation with low noise
  Motor and pump body are integrated and immersed in water. No ground pump house is required, with very low operating noise. The motor is cooled by well water.
• Slender profile for deep well casings
  Slender and compact outer shape with small outer diameter, fits small‑diameter well casings (common well diameter 100‑150 mm) and occupies little installation space.
• Good sealing for drinking‑water applications
  Food‑grade stainless steel is applicable for domestic drinking‑water supply. It is not suitable for wells with large amounts of coarse sand and mud, as sand particles will rapidly wear impellers.
• Drawbacks
  • Sensitive to sand content in well water; high sand content will accelerate wear and shorten service life.
  • The motor must be fully submerged underwater and cannot run exposed to air.
  • Installation and maintenance underground are complicated, requiring hoisting and lifting operations.

2. Overall Structure

A stainless steel deep‑well pump consists of submersible motor, pump body (multi‑stage pump head), intake strainer, discharge pipe, power cable and rising main pipe.

1. Submersible Motor (lower section)

• Water‑filled or oil‑filled submersible motor with stainless‑steel housing and waterproof sealing.
• Motor shaft connects upward to pump shaft.
• Built‑in thrust bearing to bear axial thrust of the pump.
  Oil‑filled type: better sealing for water with impurities. Water‑filled type is mostly used for drinking‑water applications.

2. Multi‑stage Pump Head (upper core unit)

From top to bottom: intake strainer → multi‑stage impellers & diffusers (multi‑stage centrifugal units) → discharge connector.

• Impeller: Stainless‑steel centrifugal impeller, rotating to pressurize water step‑by‑step.
• Diffuser (guide casing): Each impeller is matched with one diffuser, guiding water from previous stage into next‑stage impeller to raise pressure progressively.
• More stages deliver higher head.

3. Intake Strainer

Located at the bottom of pump, prevents large sand particles and debris from entering pump interior to protect impellers.

4. Rising Main Pipe (discharge pipe)

Connected to pump outlet, extends all the way to ground surface to deliver high‑pressure water above ground.

5. Submersible Power Cable

Water‑resistant aging‑resistant waterproof cable leads from motor to ground control cabinet.

Assembly sequence down the well: rising main pipe → pump head → submersible motor.

3. Working Principle

Stainless‑steel deep‑well pump is a multi‑stage centrifugal submersible pump.

1. Motor drives pump shaft to rotate at high speed, which drives multi‑stage impellers to rotate synchronously.
2. Well water passes through bottom intake strainer into first‑stage impeller. Centrifugal force generated by rotating impeller pressurizes water, which flows through diffuser into second‑stage impeller.
3. Water passes through multiple impellers for step‑by‑step pressure boosting. Each impeller adds partial pressure.
4. After passing all impeller stages, high‑pressure water exits pump outlet and is conveyed upward to ground via rising main pipe.

Simple analogy: multiple centrifugal pumps connected in series to stack pressure for deep‑well water lifting.
Important note: The motor must be fully submerged in water for cooling. Running out of water will burn out motor quickly.

4. Application Scenarios

1. Domestic Water Supply (most common)

Draw groundwater for household drinking and daily use. 304 stainless‑steel is preferred for clean water quality.
Requirement: low sand content in well water.

2. Farmland Irrigation

Deep‑well water for orchard and farmland irrigation. Select head according to well depth. Install sediment filtration for high‑sand‑content wells.

3. Livestock Farm Water Supply

Large‑volume water intake for livestock breeding. Stainless‑steel material resists corrosion and scale buildup.

4. Small‑scale Factory & Construction‑site Water Supply

Temporary water supply for construction sites and small manufacturing plants.
Note: Ordinary 304 is not suitable for industrial wastewater or highly corrosive liquids; select 316 stainless‑steel instead.

5. Landscaping & Greening Irrigation

Deep‑well water for green‑plant watering.

6. Hot‑spring & Saline‑water Wells

For salt‑containing groundwater, use 316 stainless‑steel deep‑well pump; 304 is prone to corrosion.

❌ Unsuitable Scenarios

• Wells with large quantities of coarse sand and muddy water (rapid impeller wear).
• River‑water extraction requiring large flow and low head.
• Liquids with strong acid or alkali corrosion.
• Wells with casing diameter smaller than pump outer diameter.

5. Operation & Maintenance Precautions

🔹Installation Guidelines

• Well‑casing inner diameter must be larger than pump outer diameter with sufficient clearance to avoid pump rubbing against well wall.
• Installation depth: motor must be fully submerged below minimum water level.
  Do not place pump on bottom silt. Keep at least 3‑5 m away from well bottom to avoid sucking sediment.
• Secure rising‑main pipe connections. Fix underwater cable to prevent abrasion against pipe and electric leakage.
• Equip with control cabinet with overload, phase‑loss and low‑water‑level protection. Never connect directly to mains power.
• All cable joints must be waterproof sealed and must not be immersed in water.

🔹Operation Practices

• Never run dry (without water): Motor relies on water cooling; dry running will burn motor instantly.
• Confirm sufficient water level and full submergence before startup.
• Avoid frequent start‑stop. Keep several‑minute interval between shutdown and restart.
• Shut down immediately if water output contains large amount of sand, as sand will wear impellers and bearings.
• Do not operate beyond rated head; excessive head causes reduced flow and motor overload.

🔹Routine Maintenance

• Regularly check water quality. Stop operation promptly if output water turns turbid.
• Inspect cable outer sheath for damage every year.
• For long‑term idle storage: hoist pump out of well for sediment cleaning, or run briefly periodically to prevent rust and seizure.
• Inspect control cabinet regularly to verify protection relays and earth‑leakage protection function properly.

🔹Common Fault Diagnosis

• No water output: low water level, worn impellers, clogged strainer by sediment, motor reverse rotation.
• Reduced flow rate: worn impellers, clogged strainer, falling well water level.
• Motor tripping: motor water ingress, damaged bearings, phase loss, overload.
• Excessive noise: sand‑caused bearing wear, pump hitting well wall.

🔹Maintenance Prohibitions

• Do not run pump for long hours in muddy water inside well.
• Do not disassemble submersible motor internally.
• Do not power‑on motor when pump is exposed above water level due to water‑level drop.

🔹Selection Tips

• Ordinary drinking water: 304 stainless‑steel.
• Saline water, hot springs, corrosive groundwater: 316 stainless‑steel.
• Well depth determines required head. Rated pump head must exceed well depth plus pipeline losses.
• High‑sand‑content wells: prefer sand‑resistant deep‑well pumps or implement well sediment treatment.