Why are by-pass valves typically installed with larger valves?

By-pass valves are typically installed with larger valves to allow the downstream pipe to warm before opening the main valve. This approach is important in systems where temperature changes can cause rapid shifts in pressure or flow dynamics. By allowing thermal expansion to occur gradually, the by-pass valve helps ensure that the main valve can operate more smoothly and safely, reducing the risk of thermal shock or damage to the system components.

In systems where liquids are heated or where there is a risk of freezing, warming the downstream pipe before fully opening the main valve can prevent significant pressure drops or surges, which can lead to stress and potential failures in the piping system. The gradual increase in temperature helps protect the integrity of the entire assembly, showcasing the strategic role of by-pass valves in maintaining system stability and efficiency.