Is water considered an uncompressible substance?

Water is often considered an incompressible substance in many practical applications, particularly in HVAC and fluid systems. This assumption is based on the fact that water's volume changes very little under pressure, making it suitable for calculations involving fluid dynamics and system design. Because liquids like water are dense and their molecules are closely packed, they do not significantly change in volume when subjected to typical pressures encountered in HVAC systems.

While extreme conditions can lead to minor compressibility, for the sake of everyday engineering and operational considerations in heating and cooling systems, water can be treated as incompressible. This simplifies the mathematical modeling of fluid flow, pressure drops, and heat transfer calculations, making it easier for engineers to design efficient systems without delving into the complexities introduced by compressibility factors.

In contrast, gases are highly compressible and can change volume significantly with changes in pressure and temperature, which is why this principle does not apply to them in the same way it does for liquids.