Hydrogen Pipeline Calculator

No -- this calculator sizes Pipe Diameter purely to hit a fixed 15 m/s target flow velocity for the given Flow Rate, and Compression Power depends only on Flow Rate and the ratio between Inlet Pressure and Outlet Pressure. Pipeline Length only feeds into Pressure Drop Per Km, a derived display figure; it has no effect on Pipe Diameter, Flow Velocity, Pressure Drop, Compression Power, or Annual Compression Cost anywhere else in this calculator.

No -- Pressure Drop is simply Inlet Pressure minus Outlet Pressure as you enter them; the calculator does not derive that drop from a friction equation applied to a given length and diameter. A real pipeline design (typically using the Weymouth or a similar gas-flow equation) works the other direction -- computing how much pressure a specific pipe would lose over a specific length -- which this simplified planning tool does not attempt. Because these are two independent inputs, you can enter an Outlet Pressure equal to or above Inlet Pressure, which is physically impossible for passive flow -- hydrogen can't flow "uphill" in pressure without an inline compressor this calculator doesn't model. When that happens, Flow Configuration Status flags it as "Invalid," and Pressure Drop, Pressure Drop Per Km, Compression Power, and Annual Compression Cost all show "N/A" instead of a misleadingly small or zero number.

It's the theoretical isentropic power to compress hydrogen from Outlet Pressure up to Inlet Pressure at the given Flow Rate -- essentially the compressor work needed to establish the pipeline's stated inlet boundary condition, not ongoing power to push gas that's already moving through the pipe. It uses a fixed hydrogen-specific heat ratio (gamma = 1.41) and does not account for real compressor efficiency losses, which would raise the actual electrical power draw above this theoretical figure. Annual Compression Cost then multiplies that power by an assumed 8,760 continuous operating-hours/year and an illustrative $0.06/kWh electricity rate -- substitute your actual duty cycle and local rate for a real facility cost estimate.

It's computed from the ideal gas law at the average of Inlet and Outlet Pressure and a fixed 20°C (293 K), with no real-gas compressibility correction. Hydrogen behaves closer to an ideal gas than many other gases at typical pipeline pressures, so the error is smaller than it would be for, say, natural gas, but this is still a simplified estimate rather than a laboratory-grade equation of state.

No -- treat it strictly as an early planning estimate. Real hydrogen pipeline design must follow ASME B31.12 code requirements, account for hydrogen embrittlement of candidate pipe materials (hydrogen can degrade certain steels' fatigue and fracture resistance over time), and run detailed friction-loss and stress calculations this simplified tool does not perform. Consult a qualified pipeline engineer and the applicable code edition before specifying any real hydrogen pipeline.