Pneumatic Sanitary Diaphragm Pumps (AODD) are conveying equipment specially designed for clean and sterile working conditions such as food, pharmaceutical, daily chemical, and bioengineering industries. Their core features include no dead corners, quick disassembly, and compatibility with CIP (Cleaning In Place) and SIP (Sterilization In Place). With the advantage of compressed air drive, they achieve leak-free and low-shear sanitary medium conveying. Their structural design and working principle are centered around the core of "hygiene, efficiency, and safety."
I. Core Structural Composition
The structure of a pneumatic sanitary diaphragm pump must meet the requirements of no residue, easy cleaning, and pollution prevention. It is mainly composed of 6 core components, which work together to ensure the hygiene and stability of conveying:
1. Pneumatic Motor Assembly
As the power core of the pump, it mainly includes an air inlet valve, a reversing valve, an air distribution chamber, and a piston. Its function is to receive external compressed air, control the direction of air flow through the reversing valve, drive the piston to reciprocate, and then drive the diaphragm to move synchronously, serving as the "power source" of the entire pump. This assembly adopts a sealed design to prevent impurities in the compressed air from entering the pump body and ensure the cleanliness of the conveyed medium.
2. Diaphragm & Diaphragm Shaft
This is a key component to ensure hygiene, adopting a double-diaphragm structure (food-grade materials, commonly PTFE Teflon, EPDM ethylene-propylene-diene monomer rubber, or composite sanitary materials), with the two diaphragms fixedly connected by a central connecting shaft. Its core function is to isolate compressed air from the conveyed medium, prevent air from mixing into the medium to cause pollution, and avoid medium leakage, ensuring sterile and cross-contamination-free conveying process.
3. Pump Chamber & Sanitary Housing
Both the pump chamber and the housing are made of 316L stainless steel, with the inner wall polished to a mirror finish (roughness Ra≤0.8μm), free of any dead corners and burrs, which can effectively avoid medium residue and facilitate subsequent cleaning and sterilization. The housing adopts a quick-clamp (Tri-Clamp) connection method, which can be quickly disassembled, greatly improving cleaning and maintenance efficiency and adapting to the strict requirements of the hygiene industry.
4. Check Valve Assembly
It includes two upper and lower one-way ball valves or flap valves, all made of sanitary-grade materials, with no dead corners and easy cleaning. Its core function is to control the one-way flow of the medium, realize the alternating "suction-discharge" action, prevent medium backflow, avoid contamination of the conveyed clean medium, and ensure the stability of the conveying pressure.
5. Inlet & Outlet Ports
Adopting standard sanitary quick-clamp interfaces, it can be directly matched with general pipelines in the food and pharmaceutical industries, with convenient installation and disassembly without additional tools. The interface seal uses food-grade sealing rings (EPDM, PTFE materials) to ensure no medium leakage and further improve hygiene and safety.
6. Silencer & Air Regulator
The silencer is used to reduce the noise generated when the pneumatic motor exhausts, avoiding interference with the production environment; the air regulator can adjust the air intake pressure and air intake volume, thereby accurately controlling the flow rate and conveying pressure of the pump, adapting to sanitary media with different viscosities and different conveying needs (such as syrup, liquid medicine, fermentation broth, etc.).
II. Working Principle
The pneumatic sanitary diaphragm pump is powered by compressed air. Through the reversing control of the pneumatic motor assembly, it drives the two diaphragms to perform synchronous reciprocating motion, alternately completing the "suction" and "discharge" actions to realize continuous and stable conveying of the medium. The entire process is free of mechanical friction and leakage, fully meeting the sanitary requirements. The specific working process is as follows:
Compressed air enters the pneumatic motor assembly through the air inlet, is distributed by the air distribution chamber and the reversing valve, pushes the internal piston to move to one side, and then drives one side of the diaphragm to compress inward.
The volume of the pump chamber on this side decreases accordingly, and the internal pressure increases, forcing the inlet check valve on this side to close and the outlet check valve to open. The medium in the pump chamber is discharged to the subsequent pipeline through the outlet interface under pressure.
At the same time, the diaphragm on the other side is stretched outward under the drive of the diaphragm shaft, the volume of the pump chamber on this side increases, and negative pressure is formed inside, causing the outlet check valve on this side to close and the inlet check valve to open. The sanitary medium to be conveyed (such as liquid medicine, fruit juice, etc.) is sucked into the pump chamber through the inlet interface under negative pressure.
When the piston moves to the limit position, the automatic reversing valve in the pneumatic motor assembly triggers reversing, switching the direction of compressed air flow and changing the movement direction of the piston.
The two diaphragms instantly reverse their movement direction: the side that originally discharged the medium starts to suck the medium, and the side that originally sucked the medium starts to discharge the medium, completing one "suction-discharge" cycle.
The above cycle is carried out alternately at high frequency to realize continuous, stable and low-shear conveying of sanitary media. The entire process does not require motor drive, no oil pollution, and is suitable for sterile and explosion-proof production environments.
III. Supplementary Core Sanitary Advantages
Fully Sealed Isolation Design: The diaphragm completely isolates the power source (compressed air) from the conveyed medium, with no leakage and no oil pollution, avoiding medium cross-contamination, and meeting the requirements of hygiene certifications such as FDA, 3A, and EHEDG.
Low-Shear Conveying: Without rotating parts, the reciprocating movement of the diaphragm exerts extremely low shear force on the medium, which is suitable for conveying shear-sensitive sanitary media such as yogurt, serum, biological agents, and essence, without damaging the original characteristics of the medium.
Adaptation to Strict Working Conditions: It can run dry, has strong self-priming ability, can be started without priming the pump, and has explosion-proof characteristics, fully adapting to the sterile, explosion-proof and clean production needs of food, pharmaceutical, daily chemical and other industries.
Easy Cleaning and Maintenance: With a quick-installation structure design, it is easy to disassemble, has no dead corners on the inner wall, can quickly complete CIP online cleaning and SIP online sterilization, reduce maintenance costs, and improve production efficiency.