What is a Diaphragm Pump?

A diaphragm pump is a positive displacement pump that uses a flexible diaphragm to transport fluids. Its core feature is that the transport medium is completely isolated from the drive mechanism by the diaphragm, and it is suitable for handling corrosive, high-viscosity or particle-containing media. The following is a detailed introduction:

Working principle
Diaphragm reciprocating motion:
The diaphragm is driven by pneumatic, hydraulic, mechanical or electric drive to reciprocate in the pump chamber. When the diaphragm contracts inward, the cavity volume increases to form a negative pressure to inhale the fluid; when it expands outward, the cavity is compressed to discharge the fluid.

One-way valve controls the flow direction:
A one-way valve (ball valve or flap valve) is set at the inlet and outlet to ensure one-way flow of the fluid and prevent backflow.

Main types
Pneumatic diaphragm pump

Drive mode: Compressed air pushes the diaphragm, no electricity is required, explosion-proof and can run dry.

Advantages: simple structure, high safety, suitable for flammable and explosive environments.

Electric diaphragm pump

Drive mode: The motor drives the diaphragm through a crank-connecting rod mechanism, which is suitable for stable flow requirements.

Hydraulic diaphragm pump

Drive mode: Hydraulic oil pushes the diaphragm, with higher pressure, often used for high-pressure precision transportation (such as chemical processes).

Core features
Leak-free design: The diaphragm isolates the medium and the driving components to avoid sealing leakage problems.

Self-priming ability: Dry suction is possible (no need to prime the pump), and the suction range can reach 5-6 meters.

Corrosion resistance/wear resistance: The diaphragm and pump body materials are optional (such as PTFE, rubber, metal), suitable for highly corrosive or solid particle-containing media.

Flow regulation: The flow rate is adjusted by air pressure or speed, and the pulsation is smaller than other positive displacement pumps.

Application areas
Chemical industry: Conveying corrosive liquids such as acids, alkalis, and solvents.

Food/Pharmaceuticals: Sanitary design, handling high-purity or sensitive fluids.

Mining/Environmental protection: Handling slurries containing sludge and abrasive particles.

Nuclear industry: Safe transportation of radioactive media.

Advantages and disadvantages
Advantages: Good sealing, simple maintenance, strong adaptability, and can run idly.

Disadvantages: The diaphragm is prone to fatigue damage (needs to be replaced regularly), and the output pulsation is large (can be relieved by adding a pulsation damper).

Key parameters for selection
Flow and pressure: Select according to the working conditions.

Diaphragm material: Rubber, PTFE, or metal are selected according to the characteristics of the medium.

Valve type: Ball valve is suitable for granular media, and the flap valve is suitable for high-viscosity liquids.

Diaphragm pumps are a choice for special working conditions due to their safety and adaptability, especially in situations where zero leakage is required.