Operating Principle of PTFE Pneumatic Diaphragm Pump: Achieving Efficient and Reliable Conveying Through Synergy Between Material and Pneumatic Systems
I. Core Structure of PTFE Pneumatic Diaphragm Pump: Laying the Foundation for the Implementation of the Operating Principle
To understand its operating principle, it is essential to first clarify the functions of its core components. The main body of a PTFE pneumatic diaphragm pump consists of the following parts:
1.Dual Diaphragm Assembly:
Two PTFE elastic diaphragms connected by a central connecting rod, symmetrically arranged on both sides of the pump chamber. PTFE’s high chemical stability enables it to resist corrosion from strong acids, alkalis, and organic solvents, while its low friction coefficient minimizes medium adhesion.
2.Pneumatic Valve System:
Includes an air inlet and a reversing valve (often a ball valve or rotary vane valve), responsible for controlling compressed air to alternately enter the back chambers of the two diaphragms, driving their reciprocating motion.
3.Inlet/Outlet Valve Sets:
Each side of the pump chamber is equipped with independent check valves (typically ball valves or butterfly valves), consisting of an inlet valve (suction side) and an outlet valve (discharge side), ensuring unidirectional liquid flow.
4.Pump Body and Connection Flanges:
Mostly made of metal or reinforced plastic, providing a sealed chamber and connecting pipelines.
II. Operating Principle: "Breathing-Type" Conveying Driven by Pneumatic Power and Diaphragm Reciprocation
The operation of a PTFE pneumatic diaphragm pump can be simplified into a cyclic process of "compressed air drive → diaphragm reciprocation → valve set flow control," divided into four stages:
1.Compressed Air Input and Initial State
Before startup, compressed air enters the pump’s pneumatic valve system through the air inlet. In the initial state, the reversing valve directs airflow into the back chamber of the left diaphragm (the cavity between the diaphragm and the pump body), while the back chamber of the right diaphragm is vented to the atmosphere. At this point, the left diaphragm extends outward (away from the pump chamber) under air pressure, while the right diaphragm contracts toward the pump chamber as its back chamber depressurizes.
2.Liquid Suction Phase: Left Diaphragm Extends, Right Diaphragm Contracts
As the left diaphragm extends, the volume of the left pump chamber increases, reducing internal pressure below that of the inlet pipeline. This opens the left inlet valve, drawing liquid into the left pump chamber under atmospheric pressure. Meanwhile, the contraction of the right diaphragm reduces the volume of the right pump chamber, increasing internal pressure and pushing open the right outlet valve to discharge previously suctioned liquid into the outlet pipeline.
3.Pneumatic Valve Reversal: Driving Reverse Diaphragm Motion
When the left diaphragm reaches the end of its stroke, it mechanically triggers or pneumatically feedbacks to actuate the reversing valve in the pneumatic system. The reversing valve switches the airflow direction, directing compressed air into the back chamber of the right diaphragm, while the left diaphragm’s back chamber vents to begin depressurization.
4.Simultaneous Liquid Discharge and Suction: Right Diaphragm Extends, Left Diaphragm Contracts
The right diaphragm extends under air pressure, increasing the volume of the right pump chamber, opening the right inlet valve to suction liquid. Concurrently, the left diaphragm contracts as its back chamber depressurizes, reducing the volume of the left pump chamber and opening the left outlet valve to discharge the previously suctioned liquid. This completes one full cycle, after which the reversing valve actuates again, repeating the process.
III. The Critical Role of PTFE Material: A Core Element Determining Performance Boundaries
The properties of PTFE directly influence the pump’s operational efficiency and applicable scenarios, with its material advantages reflected in three key aspects during principle implementation:
•Corrosion Resistance: PTFE reacts with almost no chemicals (except molten alkali metals, fluorine, and other rare media). Even when conveying highly corrosive liquids like concentrated sulfuric acid or aqua regia, the diaphragm will not swell, dissolve, or fail, ensuring long-term sealing performance.
•Low Friction and Anti-Adhesion: PTFE has an extremely low surface energy (≈18 dyn/cm), preventing media (e.g., colloidal slurries, resins, particle-containing slurries) from adhering to the diaphragm surface. This reduces scaling-induced flow attenuation and lowers diaphragm movement resistance, extending service life.
•Wide Temperature Tolerance: PTFE’s long-term operating temperature range is -20°C to 260°C, making it suitable for high-temperature steam purging or low-temperature medium conveyance, broadening applications in chemical reactors, waste heat recovery, and other scenarios.
IV. Unique Advantages Derived from the Operating Principle
Based on the above principles and material characteristics, PTFE pneumatic diaphragm pumps offer irreplaceable value in practical applications:
•No Electrical Drive, Inherently Safe: Powered solely by compressed air, it is suitable for explosion-proof areas (e.g., gas stations, oil and gas pipeline maintenance).
•Self-Priming and Anti-Cavitation: Diaphragm contraction can create a vacuum (self-priming height up to 5-7 meters), and it tolerates gas entrainment in media (e.g., aeration tank effluent), resisting damage from cavitation.
•Adjustable Flow and Pressure: By regulating compressed air pressure (0.1-0.8 MPa), output pressure (up to 0.8 MPa) and flow (typically 0-1000 L/min) can be linearly controlled to adapt to varying pipeline resistance requirements.
•Maintenance-Free Design: With no rotating parts (e.g., impellers, shaft seals), only the diaphragms and valve balls need replacement when worn, minimizing downtime and maintenance costs.
