When selecting valves for a secondary battery (rechargeable battery) production line, the essential requirement comes down to this: keeping the fluid uncontaminated while stably maintaining the target pressure and flow rate. From electrode coating to electrolyte filling, the fluids handled in each process can suffer yield losses from even the slightest ingress of foreign matter, moisture, or metal ions. For this reason, rather than simply reusing general-purpose piping valves as-is, the starting point for clean fluid control and yield maintenance is to make your decision based on the wetted-part materials, the sealing structure, internal stagnation and particle generation, and ease of cleaning.
Key points of this article
Valve selection for secondary battery manufacturing becomes easier to organize when viewed through three lenses: the material and cleanliness of the wetted parts, the stability of pressure and flow rate, and the minimization of particle generation and stagnation. Because the required cleanliness and fluid characteristics differ from one application to the next, rather than standardizing every process with a single specification, it is effective to adopt an approach that separates the criteria according to each process’s characteristics.
Criteria required of valves for clean fluid control
Wetted-part materials and cleanliness
Secondary battery processes handle fluids with differing properties, such as pure water, chemical solutions, inert gases (e.g., N2), and solvents. What matters across all of them is that the parts in contact with the fluid (the wetted parts) do not release foreign matter or metal ions. Generally, stainless steel and fluororesin-based sealing materials are candidates, but the suitable combination varies with the type and concentration of the chemical solution handled. Rather than uniformly deciding that “stainless steel is safe,” a realistic approach is to narrow down the material using the fluid’s corrosivity and the required cleanliness as conditions.
Stability of pressure and flow rate
In processes such as coating, drying, and filling, slight fluctuations in pressure or flow rate can lead to variations in coating film thickness or fill quantity. Control measures such as using a pressure reducing valve to keep the secondary-side pressure constant, or a constant flow valve to suppress flow rate fluctuations, contribute to stable quality. What deserves attention here is whether the valve can control stably not only the maximum flow rate but also down into the minimum flow range. When pressure tends to fluctuate under throttled-flow conditions, a review of the bore size or valve type may be necessary.
A structure with minimal particle generation and stagnation
In clean environments, particle generation from the sliding of moving parts, and fluid stagnating in recesses along the flow path, can also become quality risks. A flow-path shape with little dead space that is easy to clean and purge, and a structure with few sliding parts, are advantageous in curbing such risks. Evaluating factors down to the frequency of disassembly cleaning and ease of maintenance makes it easier to reduce trouble after startup.
Frequently asked questions
Q1. Can general piping valves be repurposed for a secondary battery line?
A1. It may be possible for applications with low fluid cleanliness requirements. However, for chemical solutions or high-cleanliness fluids, the wetted-part materials or sealing structure may be unsuitable, so we recommend confirming this in advance.
Q2. Is stainless steel always a safe choice for the material?
A2. It cannot be said unconditionally. Depending on the corrosivity and concentration of the chemical solution handled, another material may be more suitable, so the decision must be made on the premise of the fluid conditions.
Q3. Which valve is a candidate when I want to keep pressure constant?
A3. For applications that keep the secondary-side pressure constant, a pressure reducing valve is a candidate. Because the suitable size varies with the flow rate conditions, it is effective to consider this including the minimum flow range.
Q4. How can particle generation be suppressed?
A4. A structure with few sliding parts and a flow path with little dead space are one guideline. Selecting these together with the cleanliness class of the installation environment makes the decision easier.
Q5. What information is needed for selection?
A5. The main information is the fluid type, temperature, pressure, flow rate (maximum/minimum), cleanliness requirements, and installation environment. The more firmly these conditions are set, the easier it is to narrow down an appropriate choice.
Summary
For valve selection in secondary battery manufacturing, the shortcut to protecting yield is to separate the criteria for each process from the perspectives of wetted-part cleanliness, pressure/flow-rate stability, and minimal particle generation and stagnation. All figures are guidelines only, and actual suitability varies with the fluid conditions and installation environment.
If you have specific concerns such as “I can’t judge whether the bore size is appropriate,” “I know the maximum flow rate but the minimum flow range is unclear,” or “I want to select an equivalent to an existing valve,” please organize your conditions and make use of Yoshitake’s technical and selection consultation services. We will help you consider a selection tailored to your process characteristics.