Preventive maintenance on metering pumps: a practical guide to extending their service life

What is preventive maintenance on metering pumps?

Preventive maintenance consists of a set of periodic actions aimed at maintaining the good condition of the dosing pump, anticipating possible failures and ensuring accurate and constant dosing.

Difference between preventive and corrective maintenance

• Preventiveis carried out before faults occur. Reduces long-term costs.
• Correctiveis applied after a breakdown. Often involves unplanned downtime and higher costs.

Why preventive maintenance is key in dosing

Metering pumps work with chemicals that can be corrosive, abrasive or viscous. A poorly maintained pump can dose incorrectly, cause overpressure or even damage the entire system.

Risks of not carrying out regular maintenance

• Irregular or non-existent dosage.
• Leaks due to wear of seals.
• Blockages in valves or pipes.
• Overheating of the engine or electronic components.
• Increased energy consumption and reduced efficiency.

Basic preventive maintenance plan

The following is a general plan, although each manufacturer may have specific recommendations. It is recommended to keep a record per installation.

1. Daily check (visual and functional)

• Check for leaks.
• Check that the pump doses the programmed volume.
• Check the condition of pipes and connections.

2. Weekly review

• Clean the suction filter.
• Check system pressure if sensor is present.
• Check the level of the chemical in the tank.
• Calibrate pH, redox or flow sensors, if connected to the system.

3. Monthly review

• Purge the system and remove possible bubbles.
• Inspect the condition of the suction and discharge valves.
• Confirm that the programmed flow rate is correct.

4. Quarterly review

• Replace seals if there are signs of wear.
• Remove the head if necessary for cleaning.
• Check control panel and electrical connections.

5. Annual review

• Replace hoses.
• Check engine and lubrication if applicable.

How does a metering pump work and which components require attention?

Understanding how a pump works helps to identify which parts need to be checked more frequently.

Major components of frequent maintenance

• Dosing head: part where the injection movement takes place. Seals, diaphragm or piston may wear out.
• Piping and valves: ducts through which the product circulates. They accumulate waste or air.
• Control panel: may fail if there is moisture, overload or bad electrical contact.
• Sensor or control system: if the system is automated, it is key to calibrate and check it regularly.

Common maintenance mistakes and how to avoid them

Do not use original spare parts

• Problem: materials may not be compatible.
• Solution: use model and chemical specific maintenance kits.

Ignoring signs of wear and tear

• Problem: small leaks turn into major breakdowns.
• Solution: check the physical condition of connections and joints on a weekly basis.

Dismantling without training

• Problem: errors in retrofitting, pressure drops or electrical faults.
• Solution: follow the manual or contact the technical service.

Case study: maintenance at a municipal water plant

A water treatment plant in Andalusia (Spain) reported a chlorine dosing failure after 6 months of use. Analysis revealed that filters were not cleaned and pumps were not purged from the installation.

After implementing a preventive maintenance protocol:

• Reduced downtime by 85% in 6 months.
• They increased the service life of the hoses by 40%.
• Improved chlorine dosing accuracy by 0.3 ppm.

This example shows how the implementation of simple but regular tasks directly impacts the effectiveness of the system.

Best practices to maximise the performance of your pump

• Always use personal protective equipment (PPE).
• Work in ventilated areas.
• Document each review.
• Do not mix chemicals in the same dosing system.
• Keep a spare pump if the installation is critical.

How to solve common problems during maintenance

1. Pump does not suck in product

• Causes: clogged suction valve, dirty filter, cracked pipe.
• Solution: clean valve and filter, check suction pipe.

2. Pump runs but does not dose

• Causes: air in the system, blocked discharge valve.
• Solution: Purge, dismantle valves and clean.

3. Error in the control panel

• Causes: internal humidity, electrical failure.
• Solution: disconnect, check connections, dry and protect with IP65 enclosures.

Frequently asked questions

How often should I flush the dosing pump?

It is recommended at least once a month, and after any prolonged shutdown, to ensure that there is no air in the circuit.

What happens if I don't clean the suction filter?

Sediment builds up and blocks the chemical inlet, which can damage the pump or prevent correct dosing.

Is it necessary to use original maintenance kits?

Yes. Using generic spare parts may cause chemical incompatibilities or pump malfunction.

What maintenance does a peristaltic pump require compared to an electromagnetic pump?

The peristaltic pump requires more attention to the tubing (due to compression wear). Electromagnetic pumps have more internal moving parts, but less wear on the tubing.

How do I know if my pump needs calibration?

If you notice that the dosed volume does not match the programmed volume or there are fluctuations, it probably requires a recalibration or sensor check.

Technical glossary

Dosing pump

Equipment designed to inject precise quantities of a chemical into a system. It is used in applications such as water treatment, industrial processes or agriculture.

Dosing head

Front part of the pump where the suction and delivery action of the liquid takes place. It usually contains the diaphragm or piston, valves and connections.

Flow rate

The volume of liquid that a pump can dispense in a given time, usually expressed in litres per hour (L/h).

Non-return valve

A device that allows the fluid to flow in one direction only, preventing the liquid from flowing backwards in the dosing system.

Suction filter

A component that prevents impurities from entering the pump from the chemical tank, protecting the valves and the pump head.

Purging

Process of removing air from the dosing circuit to ensure continuous and accurate liquid injection.

pH / ORP sensor

Instruments connected to the system allow the measurement and control of acidity (pH) or redox potential values, ensuring proper dosing according to chemical parameters.

IP65

Degree of protection of electrical enclosures against dust and water. IP65 indicates that it is fully protected against dust and low pressure water jets.