What is the standard size of the pipe that connects to a drain valve in water column applications?

In water column applications, the standard size of the pipe that connects to a drain valve is typically 3/4 inch. This diameter is commonly used because it allows for effective drainage without causing excessive back pressure or flow restriction. The 3/4 inch pipe size provides a balance between adequate drainage capacity and ease of installation, making it a preferred choice for most applications involving drain valves.

Using a smaller diameter, like 1/2 inch, may not provide sufficient flow rate for drainage, while larger sizes, such as 1 inch or 2 inches, could be overkill and lead to unnecessary complications in plumbing design and installation. Hence, 3/4 inch is commonly seen as the industry standard.