A complete pneumatics toolkit in one place: pipe diameter sizing, maximum flow rate, pressure drop, air receiver sizing, leakage detection, compressed air consumption and cost, plus unit converters. Every calculation runs in your browser - no data is sent anywhere.
Finds the minimum inner diameter for a given allowable pressure drop (Darcy-Weisbach model, friction factor after Swamee-Jain).
The result is for a straight run (inner diameter). With many elbows, tees, quick couplings and filters, use an equivalent length greater than the geometric one.
How much compressed air will flow through your pipe at a given pressure drop.
Pressure loss over a given section as a function of flow rate, diameter and pipe length.
All three flow calculators (diameter, maximum flow, pressure drop) use the same Darcy-Weisbach model, so they are mutually consistent: a diameter sized for a given drop returns exactly that drop here.
Minimum receiver volume that keeps the number of compressor starts within the allowed limit.
Pressure-decay method: from a receiver of known volume it derives the average air leakage.
Air consumption of double-acting cylinders and the annual compressed air cost.
Converts the volumetric flow rate between metric and imperial units (at the same reference conditions).
This converts volumetric units only - it does not convert m³ to Nm³ (normal air), which requires the pressure and temperature. Use the "Air density" or "FAD ↔ Nm³/h" tab for that.
Ratio of absolute discharge pressure to absolute suction pressure: σ = p₂(abs) / p₁(abs).
For compression ratios above about 3.5, reciprocating compressors usually use multi-stage compression with intercooling.
How much free air (at atmospheric pressure) a vessel / cylinder holds. Boyle's law, isothermal process.
Dry air density from the ideal gas equation: ρ = p(abs) / (R·T), R = 287.05 J/(kg·K).
Values are for dry air. Humid air is slightly less dense - accounting for it requires the water vapour pressure.
Converts actual delivery (FAD - air drawn in at ambient conditions) to normal air (Nm³/h) and back, conserving mass (ideal gas).
FAD (Free Air Delivery) is the volume at the compressor inlet conditions. Nm³ refers to normal conditions - in industry most often 0 °C and 1.01325 bar (DIN 1343); ISO 1217 for compressors uses 20 °C and ISO 2533 for the atmosphere uses 15 °C. Pick the definition that matches your data. Dry air.
Converts the pressure dew point (at working pressure) to the atmospheric dew point (after expansion) and back. Magnus formula over water.
Dew point is given over water (WMO definition, valid roughly -45...+60 °C). Below 0 °C this is the dew point over supercooled water; the frost point over ice would be a few degrees higher.
Volumetric flow is the product of the pipe cross-section and the flow velocity: Q = A · v, where A = π·d²/4. For compressed air the diameter is sized so the pressure drop across the network stays below about 0.1 bar, and the velocity stays in the 6-10 m/s range in the main line and up to about 15 m/s in branches. Use the "Max. flow rate" tab to compute the flow for a specific diameter.
"Bar" is a unit of pressure, not volume, so there is no single conversion. The meaningful question is the stored free air: a vessel of V litres at p bar(g) holds roughly V·(p+1.013) litres of free air (at atmospheric pressure). Example: a 50 l vessel at 10 bar(g) is about 550 litres of free air. Compute it in the "Bar-liters / stored air" tab.
A bar-liter is the product of volume in litres and absolute pressure in bar: bar-liters = V[l] · p(abs)[bar]. To convert it to free air volume, divide by atmospheric pressure (about 1.013 bar). The "Bar-liters / stored air" tab does both automatically.
The diameter is sized for an allowable pressure drop (typically below 0.1 bar for the whole network) at the maximum flow. The data needed are: flow rate (FAD), pipe length including local losses, working pressure and pipe material. The pipe diameter calculator uses the Darcy-Weisbach model and returns the nearest nominal size.
The compression ratio is the ratio of absolute discharge pressure to absolute suction pressure: σ = p₂/p₁. For a compressor delivering 8 bar(g) and drawing in atmospheric air, σ ≈ (8+1.013)/1.013 ≈ 8.9. Compute it in the "Compression ratio" tab.
The mass depends on pressure and temperature. Dry air at 1.013 bar(a) and 20 °C has a density of about 1.204 kg/m³, so 1 litre is about 1.2 grams. At 7 bar(g) and 20 °C a litre already weighs about 9.5 grams. Compute the value for your conditions in the "Air density" tab.
FAD (Free Air Delivery) is the air volume at the compressor inlet conditions (e.g. 20 °C, 1.013 bar). Nm³ refers to normal conditions, most often 0 °C and 1.01325 bar per DIN 1343. The conversion conserves mass: Nm³/h = FAD[m³/h] · (p_amb·T_norm)/(p_norm·T_amb). For example 10 m³/min FAD at 20 °C is about 559 Nm³/h at 0 °C. Use the "FAD ↔ Nm³/h" tab.
On expansion of compressed air the water vapour partial pressure falls in proportion to the total pressure, so the atmospheric dew point is lower than the pressure dew point. For example a dew point of +3 °C at 7 bar(g) corresponds to about -23 °C after expansion to atmosphere. The "Dew point" tab converts both ways.
The CPP-PREMA calculator set lets you quickly and accurately design and audit a pneumatic installation. You can size pipe diameters, check the maximum flow and pressure drop, size the air receiver, assess leakage, and compute compressed air consumption and cost. Additional converters (flow units, compression ratio, bar-liters, air density) replace lookup tables and manual formulas.
For compressed air system designers, maintenance teams, automation engineers, and purchasing departments comparing compressor running costs. The calculations are based on established relations (Darcy-Weisbach, Boyle's law, the ideal gas equation) and are indicative - for critical installations we recommend verification with our engineering team.
