metal bellow pump
A metal bellow pump is a type of positive displacement pump that utilizes the axial expansion and contraction of a metal bellows to convey fluid.
Due to the characteristics of its core component-the metal bellows-this type of pump offers irreplaceable advantages in specific applications. A detailed analysis is provided below.

Working Principle
The working principle of metal bellow pump is similar to that of an accordion or a syringe, belonging to the positive displacement pump category. Its operating cycle typically consists of four steps, controlled by a drive mechanism that actuates the bellows:
- Suction Stroke: The drive mechanism (e.g., a cam or pneumatic actuator) extends the bellows, increasing its internal volume and creating a negative pressure (vacuum). Due to the pressure difference, the inlet valve opens, and fluid is drawn into the pump chamber. The outlet valve remains closed.
- End of Suction / Beginning of Compression: The bellows reaches its fully extended position, completing the suction phase.
- Discharge Stroke: The drive mechanism compresses the bellows, decreasing its internal volume and increasing the pressure inside. The inlet valve closes to prevent backflow. The outlet valve is forced open, and the fluid is discharged from the pump.
- End of Discharge / Preparation for Next Suction: The bellows returns to its initial compressed position, completing the discharge. The cycle then repeats.
Core Characteristics (Determined by the Metal Bellows)
Absolute Sealing / Zero Leakage:
This is its most prominent advantage. The metal bellows itself provides a all-metal, dynamic seal-less barrier. The pump's driving components (e.g., push rod) are completely isolated from the conveyed medium, fundamentally eliminating the possibility of leakage through a pump rod or shaft seal.
Applications: Extremely suitable for handling highly toxic, expensive, radioactive, highly corrosive, or ultra-pure media.
High Corrosion Resistance and Temperature Tolerance:
The bellows can be manufactured from different metal materials (e.g., 316L stainless steel, Hastelloy, titanium, tantalum) based on the medium's properties, enabling resistance to various strong acids, strong alkalis, and organic solvents.
The all-metal structure allows for an extremely wide operating temperature range, from cryogenic temperatures to several hundred degrees Celsius (depending on the material).
High Cleanliness and Contamination-Free:
The absence of rubber or plastic seals avoids the risk of media contamination by wear particles from sealing materials or reactions with elastomers.
The smooth inner wall of the pump chamber, with no dead legs, facilitates thorough cleaning and sterilization.
Applications: Ideal for occasions demanding high cleanliness, such as in the semiconductor, biopharmaceutical, and food industries.
Good Self-Priming Capability and Metering Accuracy:
As a positive displacement pump, it possesses good self-priming capability and a constant displacement per cycle. It operates stably even at low flow rates, making it suitable for use as a metering pump.
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