What is the minimum required hole size to accommodate a 30 mm (1 in) O.D. copper pipe with a 20 mm (3/4 in) insulation?

To accommodate a 30 mm (1 in) O.D. copper pipe with 20 mm (3/4 in) of insulation, it is essential to consider the total diameter of the insulated pipe.

First, the insulation adds an additional thickness around the copper pipe. Since the insulation is 20 mm thick and it wraps around the entire diameter of the pipe, you will need to add this thickness to both sides of the copper pipe’s diameter. This leads to a calculation of the required hole size as follows:

1. The diameter of the copper pipe is 30 mm.
2. The insulation adds 20 mm on one side and 20 mm on the other side, which totals 40 mm of insulation.
3. Therefore, the total diameter of the insulated pipe becomes 30 mm + 40 mm = 70 mm.

To accommodate this overall diameter, a hole size of at least 70 mm (2 5/8 in) is necessary. This ensures that the insulated pipe can fit through the hole without being squeezed or damaged.

This is why the choice indicating a hole size of 70 mm is the correct answer. It appropriately allows for both the pipe and its insulation, ensuring proper installation and function in the residential air