What Is a Deep Well Long-Shaft Fire Pump?
The XBD-GJ series deep well long-shaft fire pump (also referred to as a vertical turbine fire pump or deep well fire protection pump) is a specialized fire water supply system designed for applications where the water source is located at significant depth below ground level. Unlike standard surface-mounted fire pumps, this pump is engineered to draw water directly from deep wells, underground reservoirs, or open water bodies, making it indispensable for fire protection systems that cannot rely on municipal water pressure.
The pump assembly consists of three primary sections: the submerged working section (containing multi-stage centrifugal impellers and diffuser shells), the column pipe section (housing the transmission shaft), and the above-ground section (including the pump base, electric motor, and motor bracket). The motor, mounted at ground level, drives the submerged impellers through a concentrically arranged long shaft inside the column pipe, delivering the required flow and pressure for fire suppression systems.
This guide covers the complete installation process, commissioning procedures, and long-term maintenance requirements for the XBD-GJ series, helping engineers and contractors achieve reliable fire water supply from deep sources.
Key Technical Specifications
| Parameter | Specification |
|---|---|
| Flow Rate (Q) | 5 – 110 L/s |
| Head (H) | 32 – 200 m |
| Motor Power (N) | 3 – 200 kW |
| Rated Speed (n) | 2900 / 2850 r/min |
| Water Source | Deep wells, underground reservoirs, open water bodies |
| Medium Temperature | ≤ 40°C |
| pH Range | 6.5 – 8.5 |
| Solid Content | ≤ 0.01% by weight |
| H₂S Content | ≤ 1.5 mg/L |
| Compliance | GB 6245 Fire Pump Performance Standards |
Pre-Installation Requirements
Site & Well Preparation
Before the pump arrives on site, ensure the following conditions are met:
- Well Diameter: Confirm the well casing inner diameter accommodates the pump’s submerged section with adequate clearance (minimum 25 mm on each side).
- Well Verticality: Excessive well deviation will cause shaft wear and vibration. If the well is significantly off-vertical, consider using a smaller pump size or re-drilling.
- Dynamic Water Level: Verify the dynamic water level during pumping to ensure the pump’s submerged section remains below the lowest expected water level.
- Water Quality: Confirm pH is between 6.5–8.5, solid content ≤ 0.01%, H₂S ≤ 1.5 mg/L, and temperature ≤ 40°C.
Foundation & Mounting
- Base Leveling: The pump base must be level to within 2 mm/m. Use precision spirit levels during installation.
- Anchor Bolts: Tighten all anchor bolts securely and re-check periodically before startup to prevent loosening-induced vibration.
- Pipe Support: Never allow piping weight to rest on the pump. Provide independent supports for inlet and outlet lines.
Installation Steps
Step 1: Submerged Section Assembly
The working section (impellers, diffuser shells, bearings) is factory-assembled. Before lowering into the well, rotate the shaft by hand to confirm there is no binding or friction between impellers and shells. Inspect wear rings for proper fit.
Step 2: Column Pipe & Shaft Connection
Connect column pipe sections using flanged joints with proper gaskets. The transmission shaft (available in 2Cr13 stainless steel or standard steel) must be centered within each pipe section. Use alignment gauges to verify concentricity — misalignment at this stage is the most common cause of premature bearing failure.
Step 3: Above-Ground Section Installation
Mount the pump base, motor bracket, and electric motor. Connect the motor shaft to the transmission shaft using the provided coupling. The coupling must be aligned within 0.05 mm radial and 0.05 mm angular tolerance. Misalignment beyond this range will cause excessive vibration, noise, and accelerated bearing wear.
Step 4: Instrumentation & Valve Installation
- Discharge Valve: Install a gate valve or butterfly valve on the outlet pipe for flow regulation.
- Pressure Gauges: Install pressure gauges near both the inlet and outlet to monitor operating conditions.
- Check Valve: For high-head applications, install a check valve upstream of the discharge valve to prevent water hammer during power loss events.
Commissioning Procedures
Pre-Start Checklist
- Manual Rotation: Turn the motor shaft by hand. The impeller should rotate freely without binding or scraping sounds.
- Rotation Direction: Jog the motor briefly to confirm rotation is counter-clockwise (when viewed from the motor end). If reversed, swap any two power supply phases.
- Insulation Test: Measure motor insulation resistance — it must be ≥ 50 MΩ before energizing.
- Lubrication: Verify rubber bearings are properly pre-lubricated with clean water.
Startup Sequence
- Close the discharge valve to reduce starting load.
- Energize the motor and allow the pump to reach rated speed.
- Gradually open the discharge valve to reach the desired operating point.
- Monitor all readings: Motor current, discharge pressure, bearing temperature, and vibration levels should all be within specified ranges.
- Record baseline data for future comparison during routine inspections.
Shutdown
Gradually close the discharge valve, then cut power. If ambient temperature is below 0°C, drain all water from the pump to prevent freezing damage.
Maintenance & Troubleshooting
Routine Maintenance Schedule
- Daily: Monitor motor current, pressure, and vibration during operation.
- Monthly: If the pump is not in regular use, start it at least once per month for a minimum of 15 seconds to prevent bearing seizure and ensure readiness.
- Annually: Perform a full inspection — check bearing wear, shaft alignment, impeller clearance, and motor insulation.
Common Issues & Solutions
Pump Does Not Deliver Water
Causes: Dynamic water level dropped below the strainer; broken transmission shaft; ruptured column pipe.
Solutions: Add additional column pipe sections to lower the pump; inspect and replace damaged shaft or pipe sections.
Significant Flow Reduction
Causes: Clogged strainer; worn seal rings; excessive impeller-to-housing clearance; low power frequency.
Solutions: Clean strainer; replace seal rings; reassemble and adjust axial clearance; verify power supply frequency.
Excessive Vibration
Causes: Impeller-to-housing friction; bent motor/transmission shaft; worn rubber bearings; misaligned coupling; well deviation.
Solutions: Stop pump and adjust axial clearance; straighten or replace shaft; replace bearings; realign coupling; consider a smaller-diameter pump for deviated wells.
Motor Overheating or High Current
Causes: Low supply voltage; bearing damage; impeller-to-housing friction; sand ingress.
Solutions: Stop pump, boost voltage, then restart; inspect and replace bearings; adjust axial clearance; clean or repair the well.
Why Choose Chaodun Pump for Deep Well Fire Pumps?
Chaodun Pump manufactures XBD-GJ deep well long-shaft fire pumps in compliance with GB 6245 fire pump performance standards, with every unit undergoing hydrostatic testing and performance verification before shipment. Our pumps are deployed in industrial complexes, high-rise buildings, and municipal fire protection networks across China and internationally.
We provide complete technical documentation including installation drawings, commissioning checklists, and maintenance manuals in both Chinese and English. Contact our engineering team for a custom configuration based on your well depth, flow requirements, and fire protection system design.