How to avoid contamination risk with zero dead angle diaphragm valve?

Zero dead leg diaphragm valves are designed to eliminate “dead legs” or stagnant areas in piping systems where liquids can accumulate, which can lead to microbial growth and contamination. In addition to the valve’s design, attention must also be paid to its materials, reliable sealing, proper operation, regular inspection and maintenance, regular CIP cleaning and SIP sterilization to avoid microbial growth and contamination.

Here’s how to avoid contamination risks with zero dead leg diaphragm valves:

1. Leverage the valve’s design (how it works)

• No dead leg design: The core principle of a zero dead leg (or zero dead leg) sanitary diaphragm valve is that its weir (the part of the diaphragm that closes) is located directly on the inside diameter of the pipe. This eliminates any depressions or recessed areas that can cause liquid to stagnate.
• Automatic full drainage: The design ensures that the flow path is smooth and unobstructed when the valve is open. When closed, it helps the valve cavity drain completely without any residue.
• Diaphragm barrier: The flexible diaphragm seals the process media from the external environment and the valve actuator. This physical barrier is essential for aseptic applications.
• Smooth internal surface: The highly polished internal surface of the valve body and diaphragm (low Ra value, usually electropolished) prevents microbial adhesion and biofilm formation. DONJOY hygienic diaphragm valves can be polished to Ra0.4um by conventional internal polishing, and can be polished to Ra0.25um by electrolysis.

2. Material selection:

Choose materials that meet food grade or pharmaceutical grade standards. This ensures that the fluid will not be contaminated by the valve itself and meets strict hygiene requirements.

DONJOY diaphragm meet EHEDG requirements and are certified by 3A, CE and FDA.

3. Aseptic design:

Hygienic diaphragm valves perform well in aseptic environments due to their simple structure, good sealing and the fact that the medium only contacts the diaphragm. The aseptic design principle is mainly reflected in its unique structure and material properties, ensuring that the medium is not contaminated during the flow process.

4. Reliable sealing:

Choose a corrosion-resistant and high-temperature resistant diaphragm to prevent the diaphragm from degrading and contaminating the fluid. Ensure that the diaphragm is in close contact with the sealing surface of the valve to prevent external contamination.

5. Actuator integrity:

Ensure that pneumatic actuators use clean, dry, instrument-grade air to prevent contaminants from entering the actuator and possibly damaging the diaphragm in the event of a pinhole leak.

6. Controllability:

Diaphragm valves can be controlled manually or automatically, offering flexibility in operation and ensuring proper flow control to minimize contamination.

7. Correct installation:

Install the valve in the correct direction (usually vertical or slightly tilted) to ensure optimal drainage and prevent product accumulation in the valve or adjacent pipe sections. Please refer to the manufacturer's instructions. Excessive force or improper installation may damage the diaphragm, causing contamination or leakage.

8. Correct operating specifications:

Ensure that the valve is fully open or fully closed during operation to avoid partial retention due to half-open state.

Frequent dry friction of the diaphragm may generate particles. The medium must be kept lubricated to avoid dry operation and textile contamination.

9. Regular inspection and replacement of diaphragms:

The diaphragm is a wearable part. Regularly check the diaphragm for signs of wear, cracking, blistering or discoloration. Even if there is no obvious damage, follow the manufacturer's recommended replacement schedule to maintain the integrity of the valve and prevent contamination.

10. Cleaning and sterilize:

The smooth surface of the valve is easy to CIP clean and SIP disinfect, ensuring the safety and hygiene of its products. Regular CIP cleaning and SIP disinfection ensure that product residues are thoroughly removed and microorganisms are inactivated/eliminated.