Trykfaldet

Trykfaldet (Danish: "pressure drop") denotes the decrease in pressure experienced by a fluid as it moves through a conduit, across a component, or during a change in flow conditions. It is a central concept in hydraulics, pneumatics and process engineering because it represents energy loss that must be supplied by pumps or compressors.

Causes of trykfaldet include viscous friction along pipe walls, turbulence, changes in flow area, fittings and valves, bends, and local obstructions. In compressible flows (gases) pressure loss is additionally affected by density changes and can interact with thermodynamic processes.

Quantification and prediction rely on empirical and theoretical relations. For laminar flow, pressure drop is roughly proportional to flow rate and can be described by the Hagen–Poiseuille relation for circular pipes; for turbulent flow the drop scales approximately with the square of velocity and is commonly estimated with the Darcy–Weisbach equation using a friction factor that depends on Reynolds number and roughness. Differential pressure sensors, manometers and pressure transducers are typical measurement methods.

Practical importance of trykfaldet includes pump and compressor sizing, energy efficiency assessments, pipeline and HVAC design, and process control. Engineers mitigate excessive pressure loss by optimizing pipe diameter, smoothing flow paths, reducing unnecessary fittings, and selecting low-resistance components. Understanding trykfaldet is essential for reliable, efficient fluid transport and system design.