Correctly sizing compressed air piping is important to compressed air system design. Proper sizing improves efficiency, reduces pressure loss, and lowers energy costs. The right diameter delivers consistent pounds per square inch (PSI) to tools and machines without overloading the compressor. Use the chart below to see how to size compressed air piping for your system’s flow rate and layout.
How Pipe Size Impacts Compressed Air System Performance
Sizing air compressor piping comes down to two factors: how much air are you trying to move? And how far does it have to go? When compressed air pipes are not sized properly, you can experience significant inefficiencies across your system. The biggest problem is when pipes are too small, which leads to high pressure drop. Several key factors contribute to this pressure loss:
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Friction causes pressure loss: As compressed air moves through piping, friction with the pipe walls causes it to lose pressure (PSI) during travel.
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Distance amplifies the problem: The longer the air travels, the more cumulative friction it experiences.
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System complexity adds losses: Every bend, joint, and coupling in your piping system increases pressure drop.
These pressure losses translate directly into financial costs that affect your bottom line in multiple ways:
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Immediate compensation costs: When piping is too small, you must increase overall system PSI to compensate, with no more than a 3 PSI drop being ideal between your air compressor and point of use.
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Energy cost escalation: Excessive pressure drop forces you to raise system PSI so machines and tools continue working properly, with every 2 PSI increase in plant pressure raising energy costs by about 1%.
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Compounding losses: If equipment requires 100 PSI but you experience a 20 PSI drop, you must pressurize your system to 120 PSI just to maintain minimum requirements, creating a 10% increase in energy costs.
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Long-term financial drain: Over time, these increased energy costs will be many times greater than the cost of properly sized piping.
How Compressed Air Piping Is Sized
Sizing mistakes come with real costs. If your compressed air piping is too small, it creates excessive friction and pressure drop — forcing your system to run at higher PSI just to meet tool requirements. This leads to increased energy use, higher utility bills, and inconsistent performance across your facility.
On the other hand, oversized piping won’t harm system performance, but it does add unnecessary material and installation costs. Larger pipes store more air (e.g., 500 feet of 2” pipe holds over 4x more air than 1”), but they’re not an efficient substitute for proper storage. Unless you’re planning to expand your system soon, going too big may not pay off.
The best approach is to size based on actual airflow and pressure needs — not guesswork or overcompensation.
To avoid excessive pressure drop, you need to look at two important aspects of your compressed air system:
- Total airflow (CFM)
- Minimum required operating pressure (PSI)
Compressed Air Pipe Size and CFM
Compressed air piping size requirements are directly related to the maximum airflow going through the system. Your airflow is measured in cubic feet of air per minute, or CFM. The greater your CFM, the larger your pipes will need to be to avoid excessive pressure drop.
When sizing compressed air piping, it is important to look at your maximum CFM requirements. This is the CFM of your system at moments of greatest demand. These may be momentary peaks of demand generated by dust collector blow-down valves, cylinder/ram actuation, diaphragm pumps or other systems that use short, intense bursts of air.
Aire tip: Processes that require short-duration (<1 min.), intense bursts of air may be able to be accommodated by installing an air receiver tank at the point-of-use instead of increasing pipe size throughout your system.
Calculating CFM requirements for your facility can be somewhat complicated. You may want to have a study completed to calculate your overall CFM demand, peak demand and maximum air compressor output.
Compressed Air Pipe Size and PSI
You also need to understand the minimum required operating pressure for your system. Your operating pressure is measured in pounds per square inch, or PSI. Most industrial equipment and air-powered tools require between 90 and 100 PSI to operate correctly. That means that the pressure delivered at point-of-use must be maintained at this level.
You can determine the pressure drop for your system by measuring PSI at the air compressor and at the point of use. Be sure to measure the pressure at the points most distant from your air compressor. If you are seeing a drop of more than 3 PSI and do not have a significant leak problem in your system, it may be an indicator that your air compressor piping is too small.
Aire tip: Many plants are running at a higher PSI than they need. You may be able to save money by lowering the overall pressure of your plant.
Other Factors in Compressed Air Pipe Sizing
Pressure drop is also related to compressed air piping material and the length of your runs. Longer runs will require a larger diameter pipe than shorter runs. Smoother pipe materials, such as aluminum, reduce friction and pressure drop allowing greater airflow compared to more textured materials like rubber hose.
The flow coefficient of your pipe is a measure of its efficiency in allowing air or fluid flow. It is expressed mathematically as:
Where:
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Q — Flow rate, typically measured in US gallons per minute (GPM).
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SG — Specific gravity of the fluid (for air, SG = 1).
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ΔP — Pressure drop across the valve or piping, measured in pounds per square inch (PSI).
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Cv — The resulting flow coefficient.
The layout of your compressed air distribution system also matters. Loop-type compressed air systems allow the air to flow in any direction to get to the demand in the path of least resistance. Typically, you can multiply the capacity of straight-line piping by 1.5 for loop type compressed air distribution systems. For example: If a 2” aluminum pipe is rated for 500 CFM at 125 PSI, that same length of pipe in a loop system would be rated for 750 CFM at 125 PSI.
Compressed Air Pipe Sizing Calculation
There are many tools available to help you with compressed air pipe sizing. You can calculate your pipe size requirements using a formula. You can also find tables online that show the CFM ratings of compressed air through traditional pipe based on PSI and distance.
When calculating compressed air sizing requirements, be sure to look at both current and future needs. If your calculation puts you at the upper range of the CFM ratings for a particular pipe size, you may want to consider sizing up, especially if you anticipate an expansion in the future. Also, remember to consider the number of turns and connections in your compressed air system; if your system has many joins and turns, you need to take that into account when calculating your compressed air piping size.
The basic formula for calculating compressed air pipe size is:
You can see the variables explained in a table below:
| Variable | Meaning | Calculation | Units |
|---|---|---|---|
| A | Pipe cross-sectional area | 3.14𝑑²4 | in² |
| Q | Flow rate | As measured or given in SCFM | SCFM |
| Pd | Pressure drop across system | Compressor PSI − Pa | Pounds per Square Inch |
| Pa | Absolute pressure at sea level | 14.7 PSI at sea level | Pounds per Square Inch |
| V | Air velocity in pipe | 20–40; max recommended: 40 | ft/sec |
Recommended air velocity ranges:
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Ideal: up to 20 ft/s (minimal turbulence).
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Acceptable: up to 30 ft/s (industry limit).
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Avoid: above 40 ft/s (risk of high pressure drop and noise).
How to Size Compressed Air Piping Step-by-Step
If that calculation looks daunting, don’t worry. You don’t have to solve it alone. Some tables can help you determine the right air compressor pipe diameter based on your CFM and the total length of the pipe in your system. And if you’d rather leave the math to the pros, compressed air services like system audits or design consultations can ensure your piping is correctly sized from the start.
Here are the steps to determine correct compressed air pipe sizing using the chart:
- Determine the max CFM for your system.
- Draw a piping schematic that includes all of the lengths of pipe and all of the fittings, valves and bends in your piping system.
- Measure and add together all of the straight runs in the piping system in feet.
- Then, add in some extra “equivalent length” for each bend, fitting or valve. As a general rule of thumb, you can add 5’ in length for every bend or tee. For a more accurate estimate, use the “Equivalent Length of Pipe for Pipe Fittings” table (Table 2 below).
- Add your total length and equivalent lengths of fittings together to get your total “Equivalent Length of Pipe” for your system.
- Using the Max CFM and Equivalent Length of Pipe, use Table 1 below to find the recommended pipe diameter for your compressed air system.
This compressed air pipe sizing chart shows the minimum pipe diameter (mm) based on SCFM and distance to the furthest outlet, assuming 100 PSI and up to 4% pressure loss.
| Nl/min | Nm³/h | CFM | Distance (Feet) | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 80' | 160' | 320' | 500' | 650' | 1000' | 1300' | 1600' | 3200' | 4900' | 6500' | |||
| 230 | 14 | 8 | 20 | 20 | 20 | 20 | 20 | 20 | 20 | 20 | 25 | 25 | 25 |
| 650 | 39 | 23 | 20 | 20 | 20 | 25 | 25 | 25 | 32 | 32 | 32 | 40 | 40 |
| 900 | 54 | 32 | 20 | 20 | 25 | 25 | 32 | 32 | 32 | 32 | 40 | 40 | 40 |
| 1200 | 72 | 42 | 25 | 25 | 25 | 32 | 32 | 32 | 32 | 40 | 40 | 50 | 50 |
| 1750 | 105 | 62 | 25 | 25 | 32 | 32 | 32 | 40 | 40 | 40 | 50 | 50 | 65 |
| 2000 | 120 | 71 | 32 | 32 | 32 | 40 | 40 | 40 | 40 | 50 | 50 | 65 | 65 |
| 2500 | 150 | 88 | 32 | 32 | 32 | 40 | 40 | 40 | 50 | 50 | 65 | 65 | 65 |
| 3000 | 180 | 106 | 32 | 32 | 40 | 40 | 40 | 50 | 50 | 50 | 65 | 65 | 65 |
| 3500 | 210 | 124 | 40 | 40 | 40 | 40 | 50 | 50 | 50 | 50 | 65 | 65 | 80 |
| 4500 | 270 | 159 | 40 | 40 | 40 | 50 | 50 | 50 | 65 | 65 | 65 | 80 | 80 |
| 6000 | 360 | 212 | 50 | 50 | 50 | 50 | 50 | 65 | 65 | 65 | 80 | 80 | 80 |
| 7000 | 420 | 247 | 50 | 50 | 50 | 50 | 50 | 65 | 65 | 65 | 80 | 80 | 100 |
| 8500 | 510 | 300 | 50 | 50 | 50 | 50 | 65 | 65 | 65 | 80 | 80 | 100 | 100 |
| 12000 | 720 | 424 | 65 | 65 | 65 | 65 | 65 | 80 | 80 | 80 | 100 | 100 | 125 |
| 15000 | 900 | 530 | 80 | 80 | 80 | 80 | 80 | 100 | 100 | 100 | 125 | 125 | 150 |
| 18000 | 1080 | 636 | 100 | 100 | 100 | 100 | 100 | 125 | 125 | 125 | 150 | 150 | 200 |
| 21000 | 1260 | 742 | 125 | 125 | 125 | 125 | 125 | 150 | 150 | 150 | 200 | 200 | 200 |
| 26000 | 1560 | 918 | 150 | 150 | 150 | 150 | 150 | 200 | 200 | 200 | 250 | 250 | 250 |
| 31000 | 1860 | 1095 | 200 | 200 | 200 | 200 | 200 | 250 | 250 | 250 | 300 | 300 | 300 |
| 33000 | 1980 | 1165 | 200 | 200 | 200 | 200 | 200 | 250 | 250 | 250 | 300 | 350 | 350 |
| 44000 | 2640 | 1554 | 250 | 250 | 250 | 250 | 250 | 300 | 300 | 300 | 400 | 400 | 450 |
| 50000 | 3000 | 1766 | 300 | 300 | 300 | 300 | 300 | 350 | 350 | 350 | 450 | 450 | 500 |
| 58000 | 3480 | 2048 | 350 | 350 | 350 | 350 | 350 | 400 | 400 | 400 | 500 | 500 | 550 |
| 67000 | 4020 | 2368 | 400 | 400 | 400 | 400 | 400 | 450 | 450 | 450 | 550 | 550 | 600 |
| 75000 | 4500 | 2648 | 450 | 450 | 450 | 450 | 450 | 500 | 500 | 500 | 600 | 600 | 600 |
| 83000 | 4980 | 2931 | 500 | 500 | 500 | 500 | 500 | 550 | 550 | 550 | 600 | 600 | 600 |
| 92000 | 5520 | 3249 | 550 | 550 | 550 | 550 | 550 | 600 | 600 | 600 | 600 | 600 | 600 |
Getting your pipe sizing right is essential for keeping pressure consistent, energy costs down, and your system running smoothly.
Let’s take the guesswork out of pipe sizing. Schedule a consultation with Fluid-Aire Dynamics for expert help designing a compressed air system that meets your needs with maximum efficiency.
