Metering pumps are widely used for accurate liquid dosing in pharmaceutical, lithium battery, semiconductor, fine chemical and laboratory industries. Even high-performance ceramic metering pumps may encounter abnormal flow, leakage, noise and inaccurate dosing during long-term operation. Most failures are caused by improper operation, lack of cleaning or delayed replacement of wearing parts. This article sorts out common problems of metering pumps and corresponding fast solutions to reduce downtime and extend pump service life.

Many operators spend a lot of time troubleshooting without finding root causes. This guide systematically classifies typical faults, analyzes trigger reasons and gives operable solutions, which applies to ceramic plunger, valveless and stainless steel metering pumps.

1. Overview of frequent metering pump failures

The core vulnerable components of metering pumps include plungers, check valves and sealing rings. After continuous operation, medium sediment, abrasion and aging will trigger various abnormal phenomena.

Main common faults:
• Insufficient flow or no liquid discharge
• Dosing error exceeding standard tolerance
• Seepage and leakage on pump head
• Loud noise and violent vibration
• Flow channel blocked by crystal deposits
• Seals wear out rapidly and need frequent replacement

Timely troubleshooting and standardized daily maintenance can keep metering pumps running with ±0.1% precision for a long time and cut maintenance costs greatly.

2. Low flow or no liquid output & solutions

Root Causes

• Air enters the suction pipeline and forms air lock
• Filter at inlet is blocked by particles and crystals
• Valve ball stuck by residue leading to backflow
• Ceramic plunger surface scratched causing sealing failure
• Liquid level of material tank is too low

Targeted Solutions

1. Check pipeline joints for air leakage and re-seal all connections
2. Disassemble and clean inlet filter regularly
3. Take apart pump head to clean valve seat and valve ball thoroughly
4. Replace scratched ceramic plunger to restore matching clearance
5. Keep liquid level above suction port to avoid air inhalation

3. Inaccurate dosing & unstable flow

Unstable dosing directly affects product qualification rate in battery, pharmaceutical and semiconductor production.

Main Triggers

• Accumulated bubbles inside pump cavity not fully exhausted
• Medium viscosity changes with temperature
• Check valve poor sealing causing liquid backflow
• Pump hasn’t been calibrated for more than 3 months
• Abrasion of plunger and sealing ring increases clearance

Handling Methods

• Run pump idle to completely drain all internal air bubbles
• Adjust compensation parameters according to real-time liquid temperature
• Clean or replace worn ceramic valve components
• Conduct full flow calibration with standard pure water
• Replace aging sealing rings to reduce internal clearance

4. Liquid leakage of pump head

Leakage Reasons

• Sealing ring aging, deformation or crack damage
• Hard impurities scratch ceramic plunger surface during operation
• Seals installed twisted or unevenly stressed
• Excessive working pressure exceeds pump rated parameter

Fix Solutions

1. Dismantle pump head and install brand-new matching seals correctly
2. Softly polish minor scratches on ceramic plunger or replace damaged plunger
3. Follow standard installation steps to avoid twisting sealing components
4. Adjust system pressure within the pump’s rated working range

5. Abnormal noise and vibration

Failure Causes

• Foreign hard particles trapped between plunger and pump cavity
• Pump body installed unbalanced without fixed support
• Insufficient lubrication of transmission mechanism
• Cavitation generated by severe air suction

Elimination Measures

• Disassemble pump head and fully clean internal flow channel
• Reinstall pump horizontally and lock all fixing brackets tightly
• Add special lubricant to transmission parts regularly
• Optimize suction pipeline to eliminate cavitation and air lock

6. Crystallization and pipeline blockage

This fault frequently occurs when transporting electrolyte, salt solution and easily crystallized pharmaceutical reagents.

Causes → Pump not cleaned immediately after shutdown, low ambient temperature, volatile medium precipitating solid crystals
Solutions → Flush pump cavity with compatible cleaning liquid after each batch production; disassemble pump head weekly to remove crystal deposits with soft brush; control storage temperature of liquid raw materials to reduce crystallization

7. Short service life of wearing parts

Many users frequently replace seals and plungers due to improper operation habits.

• Do not use metal hard tools to scrape ceramic surfaces during cleaning
• Select seals matched with transported medium (FKM, PTFE etc.)
• Clean flow channel completely to avoid abrasive particles wearing friction pairs
• Calibrate pressure regularly to prevent overload operation accelerating wear

8. Fault summary table for quick lookup

Most metering pump failures are avoidable through standardized daily inspection, timely cleaning and regular replacement of wearing parts. Mastering these common problems and corresponding solutions can guarantee stable long-term operation of ceramic metering pumps, maintain ±0.1% high precision and lower overall equipment operation cost.