What is the minimum connection size for a sight glass?

The minimum connection size for a sight glass is typically 1/2". This size is required to ensure adequate flow and visibility of the fluid within the sight glass, allowing for an accurate reading of the fluid level or status. A 1/2" connection size balances sufficient fluid movement while providing clear visibility of the fluid, which is essential for the function of the sight glass. Smaller connection sizes may restrict flow or impede the ability to see the fluid, leading to ineffective monitoring. Therefore, when considering the operational requirements and the purpose of sight glasses in piping systems, the 1/2" connection size stands out as the minimum necessary to achieve reliable performance.