Air Compressor Sizing Calculation Sheet

First step is to list every piece of equipment in the shop that uses compressed air. Fill in each one's basic info: name, quantity, per-unit air consumption, working pressure, and simultaneous use factor.

No.	Equipment Name	Quantity	Per-Unit Consumption m³/min	Working Pressure bar	Simultaneous Use Factor
1
2
3
...

Simultaneous use factor is a key number. It reflects how likely equipment is to be running at the same time during actual production. Reference values: continuous-run equipment gets 1.0, these need air the whole time production is going. Intermittent equipment gets 0.5 to 0.8, like some pneumatic clamps or cyclically acting devices. Occasional-use equipment gets 0.2 to 0.4, like blow guns or temporary pneumatic tools. Not sure about a piece of equipment, use 0.7 as a safe guess.

From Step 1 data, calculate:

Multiply each piece of equipment's consumption by its quantity and use factor, add them all up. That's your total demand.

Supply pressure has to cover all equipment needs, plus pipe losses and some margin:

P_highest need is the highest pressure any equipment requires. Grab the max from Step 1: _____ bar. P_pipe loss depends on pipe length, number of bends, diameter. Usually 0.5 to 1.0 bar: _____ bar. P_margin for pressure swings and future needs. Usually 0.5 bar: _____ bar.

To make sure the system handles all conditions, multiply total demand by a safety factor:

Safety factor depends on your situation: demand doesn't swing much and no expansion plans, 1.1 is fine. Moderate swings, 1.2. Big swings or expansion coming, 1.3 to 1.5.

With that discharge volume, look up compressor catalogs and pick a model with output at least this much: _____

Quick rule of thumb for the initial stage (based on 7 bar):

This helps check if electrical supply is enough and feeds into operating cost estimates. Actual power per the selected model's nameplate.

Tank stabilizes pressure, stores air, separates condensate. Formula:

K is an empirical factor, usually 0.1 to 0.2. Demand swings big, use the higher end. ΔP is allowable pressure fluctuation, usually 1 bar.

Standard sizes: 80 gal, 130 gal, 260 gal, 530 gal. Pick the standard size above your number.

Refrigerated dryer removes moisture from compressed air. Processing capacity must exceed the compressor's output. But rated capacity is measured at standard conditions. Real use needs corrections.

Main corrections: inlet temp over 38°C, derate to 70%. Inlet pressure below 7 bar, derate proportionally. Ambient over 38°C, derate to 80%. Multiple bad conditions, corrections stack.

Filter flow must exceed compressor output. Pick filtration grade based on air quality needs:

Application	Recommended Setup
General pneumatic tools	Main line filter (3μm)
Spray painting	Main line filter + oil removal filter (0.01 ppm)
Food / Electronics	Main line filter + precision filter + activated carbon filter
Instruments / Pharma	Main line filter + precision filter + activated carbon + terminal sterile filter

Compressed air system running cost is mostly electricity, over 70% of lifecycle cost. Estimating annual electric bill helps compare options.

Fill in: Power _____ kW. Annual hours _____ h (single shift about 2,000, double about 4,000, triple about 6,000). Average load factor _____ % (not sure, use 75%). Electricity price _____ $/kWh.

Compile results for procurement and installation:

Equipment	Model/Spec	Quantity	Notes
Screw Compressor
Air Receiver Tank
Refrigerated Dryer
Filters
Piping and Valves (estimate)