What does a sieve size of No. 4 indicate?

A sieve size of No. 4 is part of a standardized sieve classification system commonly used in construction and soil testing. This particular size indicates that the sieve has openings that are 4.75 mm in diameter, which corresponds to a nominal size rather than the number of openings.

When referring to a sieve size, it indicates the size of the mesh openings rather than the number of openings in any linear or square measurement. The correct interpretation of a No. 4 sieve is that it has openings large enough to allow particles smaller than 4.75 mm to pass through while retaining larger particles, making it suitable for specific applications in construction and materials testing.

The emphasis here is on the size of the openings themselves, which is consistent with construction standards and practices for selecting materials based on size and application requirements. Instead of focusing on how many openings may exist per linear or square measurement, understanding that No. 4 refers specifically to the diameter of the openings clarifies the sieve's purpose and application.