What is the largest inside diameter copper tube for a 1 inch nominal size?

To determine the largest inside diameter copper tube for a 1-inch nominal size, we need to understand the classifications of copper tubing expressed by Types L, K, and M. These types refer to the wall thickness, which consequently affects the inside diameter of each tube.

Type K copper tubing has the thickest walls among the three types, followed by Type L and then Type M, which has the thinnest walls. Due to the thinner wall thickness in Type M, this type offers the largest inside diameter for a nominal size compared to the other types. Thus, for a 1-inch nominal size, Type M copper tubing will have the most significant internal capacity.

It's important to consider the applications for which each type is typically used. Type K is often used for underground and high-pressure applications, Type L is for general plumbing and heating purposes, and Type M is usually used for lighter commercial applications and residential work.

In summary, Type M provides the largest inside diameter for a 1-inch nominal size due to its thinner wall thickness relative to Types K and L.