GDL Vertical Multistage Centrifugal Pump Water Delivery Failure – Troubleshooting Guide

Fault Background

The GDL Vertical Multistage Centrifugal Pump (also known as GDL) is widely used in high-pressure systems for cold and hot water circulation, high-rise building water supply, fire protection systems, and boiler feed applications. When this vertical multistage in-line centrifugal pump fails to deliver water, it can severely impact system performance and operational efficiency.

Fault Symptoms

When the GDL Series Pump experiences water delivery failure, you will observe the following symptoms:

• The multistage pipeline pump runs but no water is discharged from the outlet
• Outlet pressure gauge shows zero or abnormally low pressure
• The high-pressure centrifugal pump operates normally but cannot build up pressure
• Flow meter indicates zero flow rate

Root Cause Analysis

The GDL Vertical Multistage Centrifugal Pump may fail to deliver water due to the following reasons:

1. Valve and Pipeline Blockage

• Inlet or outlet valves are not fully opened
• Foreign objects (stones, iron particles, debris) block the impeller flow channel
• Pipeline obstruction prevents water flow

2. Motor and Electrical Issues

• Motor rotation direction is incorrect (should be clockwise when viewed from motor end)
• Motor phase loss causes slow rotation speed
• Insufficient power supply voltage

3. Air Leakage and Insufficient Priming

• Suction pipeline has air leakage at joints or connections
• The vertical multistage in-line centrifugal pump chamber is not fully filled with liquid
• Air trapped in the pump chamber prevents proper priming

4. Insufficient Water Supply

• Inlet water supply is insufficient for the multistage pipeline pump operation
• Suction head is too high for the pump’s capability
• Foot valve (if installed) is leaking

5. Excessive Pipeline Resistance

• Too many pipeline bends increase flow resistance
• The high-pressure centrifugal pump is improperly selected for the system requirements
• Pipeline diameter is too small for the required flow rate

Step-by-Step Troubleshooting Procedure

Step 1: Check Valve Status and Remove Blockages

1. Verify that both inlet and outlet valves are fully opened
2. Shut down the GDL Series Pump and disconnect power supply
3. Inspect the impeller flow channel for foreign objects
4. Remove any stones, iron particles, or debris found in the pump chamber
5. Check pipeline for obstructions and clear if necessary

Step 2: Verify Motor Rotation and Electrical Connections

1. Jog the motor briefly to observe rotation direction
2. The vertical multistage in-line centrifugal pump should rotate clockwise when viewed from the motor fan end
3. If rotation is incorrect, swap any two of the three power lines to correct phase sequence
4. Check motor wiring for phase loss or loose connections
5. Verify power supply voltage is within rated range (380V ±10%)

Step 3: Eliminate Air Leakage and Ensure Proper Priming

1. Inspect all suction pipeline connections for air leakage
2. Tighten all sealing surfaces and pipe joints
3. Open the exhaust valve on the multistage pipeline pump to release trapped air
4. Fill the pump chamber completely with liquid until water flows from the exhaust valve
5. Close the exhaust valve tightly after priming is complete

Step 4: Verify Water Supply and Suction Conditions

1. Check inlet water supply is adequate for the high-pressure centrifugal pump
2. Verify suction head does not exceed the GDL Vertical Multistage Centrifugal Pump’s capability
3. If a foot valve is installed, check for leakage and repair or replace if necessary
4. Ensure the inlet pipeline has minimal bends to reduce flow resistance

Step 5: Reduce Pipeline Resistance

1. Count the number of bends in the pipeline system
2. Reduce unnecessary bends to minimize flow resistance
3. Verify pipeline diameter matches the pump’s inlet/outlet specifications (DN25-DN200)
4. If pipeline resistance remains excessive, consider reselecting a pump with higher head capacity

Preventive Measures

To prevent water delivery failure in the GDL Series Pump, implement the following measures:

1. Install a strainer at the pump inlet to prevent foreign objects from entering the impeller
2. Regular inspection: Check valves, pipeline connections, and motor connections monthly
3. Proper priming: Always ensure the vertical multistage in-line centrifugal pump is fully primed before startup
4. Monitor operating parameters: Regularly check current, pressure, and temperature during operation
5. Avoid dry running: Never operate the multistage pipeline pump without liquid, as this will damage the mechanical seal
6. Seasonal maintenance: In winter, drain the pump if ambient temperature drops below 0°C to prevent freezing

When to Contact Professional Technicians

Contact qualified technicians if you encounter:

• Water delivery failure persists after completing all troubleshooting steps
• Unusual noise or vibration from the high-pressure centrifugal pump during operation
• Motor overheating or electrical faults
• Mechanical seal leakage that cannot be resolved by tightening
• Impeller or bearing damage requiring disassembly

Technical Specifications Reference

The GDL Vertical Multistage Centrifugal Pump operates within the following parameters:

• Flow Rate: 2-160 m³/h
• Head Range: 10-240 m
• Motor Power: 0.75-200 kW
• Rotational Speed: 2900 r/min
• Inlet/Outlet Diameter: DN25-DN200
• Liquid Temperature: -15°C to +80°C
• Maximum Working Pressure: <2.5 MPa