Do you know self-priming water pump?

1. Basic structure and composition

The core structure of the self-priming water pump includes the following parts:

Pump body

Design features: A water storage chamber is provided in the pump body to store a small amount of liquid to achieve the self-priming function.

Material: cast iron (low cost), stainless steel (corrosion resistant) or engineering plastic (lightweight).

Impeller

Type: closed impeller (high efficiency) or open impeller (allowing particles to pass through).

Material: cast iron, stainless steel or bronze, selected according to the properties of the liquid.

Mechanical seal

Function: Prevent liquid leakage and ensure a negative pressure environment in the pump.

Type: single-end seal (ordinary scenario) or double-end seal (corrosive liquid).

Gas-liquid separation chamber

Function: Separate gas and liquid during the self-priming process to ensure that the liquid enters the impeller smoothly.

Inlet and outlet pipelines

Design: The inlet pipeline is usually equipped with a check valve to prevent liquid backflow.

2. Working principle

The self-priming function of the self-priming water pump is achieved through the following steps:

Initial start-up

A small amount of liquid is pre-injected into the water storage chamber in the pump body (manual filling is required for the first use).

When the impeller rotates, the liquid is thrown to the edge of the pump casing, forming a low-pressure area.

Gas discharge

The gas in the inlet pipeline is sucked into the pump body, mixed with the liquid and then enters the gas-liquid separation chamber.

The gas is discharged through the exhaust port, and the liquid flows back to the center of the impeller.

Liquid circulation

The liquid circulates in the pump body, gradually discharging the gas in the inlet pipeline to form a negative pressure.

The negative pressure sucks the liquid from the water source into the pump body, completing the self-priming process.

Normal operation

After the self-priming is completed, the water pump enters the normal working state and the liquid is continuously transported.

3. Main types

According to the power source

Electric self-priming pump:

Advantages: stable operation, low noise, suitable for fixed places.

Disadvantages: dependent on power supply, not suitable for areas without electricity.

Fuel self-priming pump:

Advantages: independent operation, suitable for field or emergency scenarios.

Disadvantages: high noise, regular maintenance required.

According to the structure

Internal mixing self-priming pump:

Features: gas-liquid mixing is completed in the pump body, and the self-priming speed is fast.

Applicable scenarios: clean water or slightly contaminated liquids.

External mixing self-priming pump:

Features: The gas-liquid mixing is completed externally, and the self-priming height is relatively large.

Applicable scenarios: Liquids containing more gas.

By use

Clean water self-priming pump:

Features: Suitable for clean liquids without particles.

Examples: Household water supply, agricultural irrigation.

Sewage self-priming pump:

Features: Allows small particles to pass through, suitable for sewage discharge.

Examples: Construction site drainage, municipal sewage treatment.

IV. Core performance indicators

Self-priming height

Definition: The maximum vertical height that the pump can automatically absorb water without assistance, in meters.

Example: A pump with a self-priming height of 6 meters can directly absorb water from a well 6 meters deep.

Flow rate (Q)

Definition: The volume of liquid delivered by the pump per unit time, in cubic meters/hour (m³/h) or liters/minute (L/min).

Example: The flow rate of a certain model of water pump is 20m³/h, which means that 20 tons of water can be delivered per hour.

Head (H)

Definition: The maximum vertical height to which a pump can lift a liquid, in meters.

Example: A pump with a head of 30 meters can deliver water to a height of 30 meters.

Power (P)

Definition: The driving power of a pump, in kilowatts (kW) or horsepower (HP).

Example: A 5.5kW self-priming pump can meet the needs of a flow rate of 15m³/h and a head of 20 meters.

Maximum particle diameter

Definition: The maximum solid particle diameter that a pump can pass, in millimeters (mm).

Example: The maximum particle diameter of a sewage self-priming pump is 10mm, which is suitable for discharging impurity-containing liquids.

V. Application scenarios

Agricultural irrigation

Applicable pump type: clean water self-priming pump, flow rate 20-50m³/h, head 20-40 meters.

Case: A farm uses an electric self-priming pump to pump water from a river to irrigate 100 acres of farmland.

Building drainage

Applicable pump type: sewage self-priming pump, flow rate 30-100m³/h, head 10-20 meters.

Case: A construction site uses a diesel self-priming pump to remove water from the foundation pit, with an average daily drainage of 500 cubic meters.

Household water supply

Applicable pump type: small clean water self-priming pump, flow rate 1-5m³/h, head 10-20 meters.

Case: A rural family uses a self-priming pump to pump water from a well to meet daily water needs

Industrial circulating water

Applicable pump type: corrosion-resistant self-priming pump, flow rate 10-50m³/h, head 20-50 meters.

Case: A chemical plant uses a stainless steel self-priming pump to transport cooling water, with an average daily circulating water volume of 1,000 cubic meters.

VI. Selection Guide

Clear requirements

Determine the flow rate, head, liquid properties (clean water, sewage, corrosive liquid) and use environment (temperature, altitude).

Matching parameters

Choose the appropriate pump type and power according to the needs.

Example: Irrigation of 20 mu of farmland requires a flow rate of 20m³/h and a head of 30 meters. A 5.5kW electric self-priming pump can be selected.

Consider the self-priming height

Choose a pump with a suitable self-priming height according to the depth of the water source.

Example: To pump water from a 6-meter-deep well, a pump with a self-priming height ≥ 7 meters must be selected.

VII. Maintenance and care

Daily inspection

Check the sealing of the pump body to ensure that there is no leakage.

Clean the inlet filter to prevent clogging.

Regular maintenance

Replace the mechanical seal and lubricating oil every 500 hours of operation.

Check the wear of the impeller and replace it if necessary.

Long-term storage

Drain the liquid in the pump body to prevent freezing or corrosion.

Store the pump in a dry and ventilated place to avoid rust.

VIII. Advantages and limitations

Advantages

Self-priming function: no need to fill water, easy to start.

Wide range of application: suitable for clean water, sewage and corrosive liquids.

Simple structure: easy maintenance and long service life.

Limitations

Limited self-priming height: usually not more than 8 meters.

Slightly lower efficiency: Compared with ordinary centrifugal pumps, self-priming pumps are 5%-10% less efficient.