What is the Sieve designation standard (in mm) equivalent to the alternate US standard for 0.425 mm?

The Sieve designation standard corresponds to the size of particles that can pass through a given mesh opening. In this case, the question pertains to the equivalent sieve designation for a size of 0.425 mm under the alternate US standard.

The No. 40 sieve has a mesh opening that allows particles of approximately 0.425 mm in diameter to pass through, which aligns perfectly with the size specified in the question. This means that any material that is finer than this sieve will be intercepted, while material that is coarser will not pass.

This standardization is essential as it ensures consistency across various applications, especially in materials engineering, where the size and distribution of particles can significantly affect the properties of materials. Establishing the equivalency with a recognized sieve designation provides a universal reference point in both engineering and construction contexts.

The other options correspond to different mesh openings that do not align with the size of 0.425 mm. This establishes No. 40 as the correct designation based on the relationships between particle sizes and the corresponding mesh sizes.