Sanitary pneumatic diaphragm valveThe core principle can be summarized as follows:Using compressed air as power, a flexible diaphragm is driven to deform, thereby achieving the opening and closing of the valve, and ensuring that the medium flow path is isolated from all driving components, achieving the purpose of easy cleaning and pollution prevention.

Below, we will decompose its technical principles from several levels:

1、 Core structure composition

1. valve body: Usually used316L stainless steelThe surface is polished with high precision (such as mirror polishing or electrolytic polishing with Ra ≤ 0.8 μ m) to form a smooth, seamless, and internal cavity, preventing microbial adhesion and residue.

2. diaphragmThis is the most critical component. fromFood grade or pharmaceutical grade elastic materialsMade from materials such as EPDM, silicone rubber, fluororubber, PTFE coated rubber, etc. It divides the valve chamber into two isolated parts: upper and lower

• Upper chamberConnected to compressed air and control components.

• Lower flow channelDirect contact with the process medium.

3. Valve cover/pneumatic actuator: IncludesCylinder, piston, push rodWaiting for components. Compressed air is controlled by a pneumatic solenoid valve and enters the cylinder to push the piston and push rod up and down.

4. valve seatLocated in the flow channel, it is the part where the diaphragm tightly adheres when closed, ensuring sealing.

2、 Working principle (action process)

1. Closed state:

• Compressed air is introduced through a pneumatic solenoid valveUpper chamber of actuator cylinder.

• Driven by air pressurePiston moves downwardsDriven by the pistonputterPress down.

• The push rod transmits force toDiaphragm center, causing it to undergo elastic deformation, protrude downward, and press tightly againstOn the sealing surface of the valve seat.

• At this point, the medium flow channel is blocked and the valve is closed. Sealing is achieved through the elasticity of the diaphragm material and the continuous action of air pressureDouble sealed(Between diaphragm and valve seat, valve body and valve cover).

2. Open status:

• Pneumatic solenoid valve changes direction, cuts off the air path to the upper chamber of the cylinder, andCompressed air is introduced into the lower chamber of the cylinderAt the same time, exhaust the upper chamber.

• Driven by air pressureThe piston moves upwardsDrive the push rod upwards.

• The pressure of the push rod on the center of the diaphragm is released,The diaphragm relies on its own elasticity to retract and protrude upwardsDetach from the valve seat.

• At this point, the medium can flow around the valve seat (full bore design) with minimal flow resistance, and the valve opens.

3、 Implementation of core technology and hygiene grade characteristics

1. Leaving and：

• This is the most core advantageThe flexible diaphragm acts as a reliable barrierDrive components (piston, spring, air) are 100% physically isolated from the process mediumThe medium only contacts the inner cavity of the valve body and the lower surface of the diaphragm, avoiding the risk of contamination of the medium by lubricating oil, metal debris, etc., and also preventing the medium from corroding the actuator.

2. CIP/SIP capability：

• The flow channel is smooth and arc-shaped, without any grooves, threads, or gaps. When the diaphragm is opened, its surface smoothly transitions with the contour of the flow channel, forming a complete cleaning channel.

• Online Cleaning (CIP)The valve can be kept in the open or closed state, allowing the cleaning solution to pass through at high speed and with a large flow rate, flushing all surfaces in contact with the medium and achieving cleaning.

• Online Sterilization (SIP)Valves and piping systems can withstand sterilization with high temperature saturated steam (typically ≥ 121 ° C, ≥ 30 minutes). The diaphragm and sealing material must have corresponding temperature resistance performance. The actuator part is usually designed with heat sinks to protect the internal seals.

3. Reliable sealing：

• When closed, the diaphragm is widely pressed against the valve seat, formingFace sealingIt has a certain tolerance for particulate matter and good sealing effect.

• Even if there is a slight damage to the diaphragm, the leaked medium will still leak from the valve bodyLeak detection holeDischarging to the outside without contaminating the pneumatic system or another medium (especially important in double diaphragm valves), providesFault safety warning.

4. Advantages of Pneumatic Drive：

• quick responseQuick opening and closing, suitable for processes that require frequent switching or automated control.

• adjustment function: By equippingvalve positionerandPneumatic pressure reducing valveIt can accurately control the air pressure entering the cylinder, thereby controlling the downward stroke and force of the push rod, and achieving control over the flow rateProportional adjustment(However, the adjustment accuracy and linearity are not as good as specialized control valves).

• Safe Failure ModeCan be designed according to process safety requirementsAir open type (spring reset closed)orGas closed type (spring reset open)Automatically return to a safe position in case of gas interruption or malfunction.

4、 Typical application scenarios

• Food and beverage industryTransportation, filling, and CIP circuits for liquids such as milk, juice, beer, wine, soy sauce, vinegar, etc.

• pharmaceutical industryInjection water (WFI), purified water, drug solution, intermediate pipeline, and bioreactor system.

• BioengineeringTransfer of cell culture medium, culture medium, and buffer solution.

• cosmetics industry: Production pipeline of lotion, paste and other products.