Milk
In milk production, sanitary valves are critical components for ensuring food safety, product consistency, and production efficiency. Milk is rich in protein and fat, making it an ideal medium for microbial growth. Furthermore, modern dairy processing involves operating across a wide temperature range—from just a few degrees Celsius to over one hundred degrees—placing extremely rigorous demands on valve design and performance.
In summary, valves used in milk production lines must possess four core capabilities: exceptional cleanliness, reliable sealing to prevent cross-contamination, gentle handling (minimizing shear stress), and resistance to harsh cleaning processes.
1. Key Application Scenarios and Valve Selection
The challenges associated with different stages of production—from raw milk reception at the farm to final product filling—dictate the choice of valves:
Raw Milk Reception and Transfer — Sanitary Mix-proof Valves or Butterfly Valves
Pain Point: Raw milk must be strictly isolated from cleaning water and dairy products of different grades (e.g., Grade A vs. non-Grade A). Any cross-contamination results in the scrapping of the entire product batch.
Solution: Use mix-proof valves or double-seat valves. These valves feature two internal seats with an atmospheric leakage chamber situated between them. If a seal fails on one side, the leaking medium is discharged through the chamber rather than contaminating the material on the other side; this ensures absolute isolation between the product and CIP (Clean-in-Place) fluids or between different product types.
Sampling Requirements: Frequent sampling and testing are required during the reception phase. Specialized sanitary sampling valves can be installed directly onto pipelines to enable aseptic sampling for parameters such as microbial counts, without contaminating the bulk milk within the tank or pipeline.
Pasteurization and UHT (Ultra-High Temperature) Sterilization — Arc-shaped Valves or UHT-specific Safety Valves
Pain Point: During high-temperature sterilization (≥135°C), the process must ensure thorough sterilization of the milk and prevent equipment hazards caused by excessive pressure, all while eliminating sanitary dead zones.
Solution: The key component is the sanitary arc-shaped valve. Its internal flow path is smooth and streamlined, free of any recesses or protrusions; this completely eliminates sanitary dead zones, ensuring that milk does not scorch or spoil due to stagnation while in the high-temperature zone. Meanwhile, sanitary safety valves specifically designed for UHT applications serve as a critical safeguard. Featuring clamp connections and flat-face sealing, they allow for internal cleaning without the need for venting, ensuring absolute safety and hygiene under high-temperature and high-pressure conditions.
Homogenization and Cooling—Full-Bore Ball Valves Are the Preferred Choice
Pain Point: After homogenization, fat globules are extremely fine. Abrupt changes in flow paths or sharp edges within standard valves can generate excessive shear forces, compromising the milk's mouthfeel and stability.
Solution: Use full-bore ball valves. The internal diameter of the flow path matches the pipeline exactly, allowing the medium to pass smoothly. This minimizes flow resistance and shear damage to the milk, thereby preserving its natural flavor and texture.
CIP (Clean-in-Place) Systems—Mix-Proof Valves/Butterfly Valves Are the Preferred Choice
Pain Point: Residual milk in pipelines after production creates a breeding ground for bacteria. CIP systems require circulating strong acids, strong alkalis, and high-temperature water (up to 150°C), placing extreme demands on the valves' corrosion and temperature resistance.
Solution: CIP systems extensively utilize mix-proof valves to isolate cleaning fluids from production lines. Additionally, sanitary butterfly valves—valued for their simple design, low pressure drop, and ease of cleaning—are frequently used to control the flow of cleaning fluids across various tanks and pipelines. They reliably withstand the high temperatures and chemical exposure inherent in CIP processes.
2. Core Technical Requirements
When selecting or maintaining milk valves, the following mandatory specifications must be met:
Materials and Surface Treatment:
Material: All components in contact with milk must be made of 304 or 316L stainless steel. 316L is the superior choice; due to its molybdenum content, it offers better resistance to corrosion from whey, salts, and CIP cleaning agents compared to 304. Seals must be made from FDA-compliant, food-grade materials such as EPDM (ethylene propylene diene monomer) or PTFE (polytetrafluoroethylene).
Surface Roughness: Internal surfaces in contact with milk must undergo precision electropolishing, with a surface roughness (Ra value) of ≤0.8 μm (high-end products may achieve 0.4 μm). This mirror-like, smooth surface prevents milk proteins and bacteria from adhering, which is key to ensuring ease of cleaning.
Structural design specifications:
No dead zones: All internal angles within the valve body measuring 135° or less must be machined with rounded corners—typically with a radius of at least 6.5 mm—to avoid creating sharp-angled areas that are impossible to clean.
Self-draining: Valves and pipelines must be installed at a slight incline (e.g., 1–3 degrees) and feature an effective drainage design; this ensures that, when the system is shut down, any residual milk drains completely via gravity, leaving no standing liquid or residue behind.
Summary: In milk production, the key to selecting sanitary valves lies in ensuring complete isolation (using mix-proof valves), a mirror-like surface finish (Ra ≤ 0.8 μm), safe materials (316L stainless steel and FDA-certified seals), and a design free of dead zones (utilizing rounded corner transitions). These factors not only impact equipment longevity but also directly determine the hygiene and quality of every glass of milk.