Common Metering Pump Issues

1. Oil Leakage in the Pump

Symptoms: The pump head appears dirty due to oil leakage, which can be observed visually during regular inspections.

Causes:

• Seal failure due to debris entering the pump
• Damaged gasket
• Torn pump diaphragm caused by contamination

Solutions:

• Inspect and replace faulty seals, gaskets, and diaphragms as these are critical components affecting pump performance.

2. Overheating of Pump Body and Motor

Symptoms: The pump body and motor generate excessive heat, which can be felt by touch. This may increase energy consumption and pose a safety risk.

Causes:

• Excessive pump pressure
• Blocked discharge line or stuck valve
• Incorrect electrical wiring or low oil levels

Solutions:

• Inspect and replace damaged components
• Reduce pump pressure if necessary
• Install safety valves
• Check and replenish oil levels
• Ensure correct electrical wiring

3. Low Pressure and Flow Rate / Pump Running but Not Delivering Liquid

Symptoms: The pump runs slowly, wasting time and energy, and may eventually fail to pump any liquid.

Causes:

• Air trapped in the suction line
• Blocked suction valve or pipeline
• Highly viscous or contaminated liquid damaging the diaphragm and valves

Solutions:

• Install a suction strainer to filter out debris
• Ensure proper sealing of the pump to prevent air ingress
• Regularly inspect and clean the suction line and valves

 

4. Pump Running but No Chemical is Being Delivered

Symptoms: The pump appears operational but does not discharge any chemical, leading to dry running, which may cause severe damage.

Causes:

• Motor running in reverse direction
• Clogged check valves due to debris
• Excessive suction depth
• Highly viscous chemical causing flow restriction

Solutions:

• Verify and correct motor rotation direction
• Clean check valves thoroughly
• Ensure proper suction depth
• Check and adjust chemical viscosity suitability for the pump

5. Excessive Noise and Vibrations

Symptoms: The pump produces loud noises and noticeable vibrations during operation.

Causes:

• Lack of regular maintenance and lubrication

Solutions:

• Regularly inspect and clean the pump
• Perform scheduled oil changes

6. Inaccurate Flow Rate

Symptoms: The actual discharge volume differs from the set flow rate, either exceeding or falling below the desired value.

Causes:

• Wear and tear from prolonged use
• Lack of maintenance and diaphragm/piston replacements

Solutions:

• Conduct regular inspections
• Replace diaphragms and pistons as needed

Precautions When Repairing Metering Pumps

• Always disconnect power before performing repairs to ensure safety.
• Only qualified technicians should conduct maintenance for optimal performance.
• Use proper safety gear and follow standard electrical insulation procedures.
• Clearly label circuit breakers with warning signs during repair work.

Installation Issues and Solutions

1. Excessive Suction Height

Problem: Improper suction height reduces pump efficiency and output flow.

Solution: Install the suction line below the recommended height and keep it as vertical as possible.

2. Air Trapped in the Suction Line

Problem: Trapped air causes unstable operation, leading to cavitation and reduced lifespan.

Solution: Design the suction line with a slight downward slope, ensuring the inlet is positioned at the tank bottom.

3. Syphon Effect

Problem: Liquid continues to flow after the pump stops, leading to unstable pressure and flow rate.

Solution: Properly install check valves to prevent unwanted flow.

4. Excessive Suction Line Pressure

Problem: High suction pressure reduces pump efficiency.

Solution: Install a pressure-reducing valve and position the suction line below the discharge line.

5. Improper Placement of Pulsation Dampener and Backpressure Valve

Problem: Poor alignment leads to vibrations and unstable performance.

Solution: Align the dampener with the discharge port for optimal stability.

6. Incorrect Installation of Safety Valves

Solution: Ensure proper positioning to prevent system failures.

7. Excessively Long Chemical Injection Line

Problem: Long lines create high resistance, reducing flow efficiency.

Solution: Optimize line length for improved performance.

Operating Principle of Metering Pumps

Metering pumps operate by varying the internal chamber volume through a series of suction, discharge, and dosing processes.

1. Priming Stage: The pump chamber automatically fills with liquid.
2. Suction Stage: The inlet check valve opens, allowing liquid to enter the chamber while the discharge valve remains closed.
3. Discharge Stage: The inlet check valve closes, and the discharge valve opens, expelling the liquid.
4. Flow Adjustment: Flow rate can be manually or automatically adjusted based on the pump model.

Top Metering Pumps Available Today

1. OBL Chemical Metering Pump (Italy)

• Compact design, easy to transport and install
• Quiet operation with precise dosing capability
• Waterproof and energy-efficient
• Environmentally friendly

2. Blue White Chemical Metering Pump (USA)

• High performance with multiple models available
• Cost-effective yet durable
• Reliable motor and gearbox for smooth operation
• Wide flow rate adjustment range
• Compact and easy to install

3. Prominent Chemical Metering Pump (Germany)

• Advanced microcontroller-based control system
• Short stroke length with solenoid drive
• Diaphragm separation technology for chemical dosing
• Ideal for non-flammable liquids

For further assistance with troubleshooting and repairs, contact us for expert consultation.