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Unit Converter

Quickly convert between the most common pressure, flow, power, and temperature units in pneumatics.

PSI, bar, kPa, atm, CFM, l/min, m³/h, HP, kW and more. Useful for engineering, purchasing, and sales.

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Air Compressor Unit Conversion Guide

Compressor specs mix pressure, flow and power units depending on the country and manufacturer. Here we explain the most common conversions for engineers, technicians and buyers, with exact conversion factors and quick-reference tables.

Pressure Units: PSI, bar, kPa, kgf/cm²

PSI to bar — Complete Reference Table

1 PSI = 0.068948 bar and 1 bar = 14.504 PSI. North American compressors are rated in PSI; European models use bar. Most CBS industrial compressors operate between 100–175 PSI (7–12 bar).

PSI	bar	kPa	kgf/cm²	atm
90 PSI	6.21	620.5	6.33	6.12
100 PSI	6.89	689.5	7.03	6.80
125 PSI	8.62	861.8	8.79	8.50
145 PSI	10.00	999.7	10.20	9.86
175 PSI	12.07	1,206.6	12.30	11.90

Exact factor: 1 PSI = 0.068948 bar = 6.8948 kPa = 0.070307 kgf/cm² = 0.068046 atm

bar to PSI — Screw Compressor Reference

The bar is standard in European-made screw compressors and most industrial gauges. 1 bar = 14.504 PSI. CBS screw compressors typically operate between 7 and 13 bar.

bar	PSI	kPa	kgf/cm²
5 bar	72.5	500	5.10
7 bar	101.5	700	7.14
8 bar	116.0	800	8.16
9 bar	130.5	900	9.18
10 bar	145.0	1,000	10.20
13 bar	188.5	1,300	13.26

Exact factor: 1 bar = 14.5038 PSI = 100 kPa = 1.01972 kgf/cm²

Flow Rate Units: CFM, m³/h, L/min, NL/min

CFM vs PCM — Same Unit, Two Names

CFM (cubic feet per minute) and PCM (pies cúbicos por minuto) are exactly the same unit — CFM in English, PCM in Spanish. 1 CFM = 1 PCM = 28.317 L/min = 0.4719 L/s = 1.699 m³/h.

CFM / PCM	L/min	L/s	m³/h	m³/min
5 CFM	141.6	2.36	8.5	0.142
10 CFM	283.2	4.72	17.0	0.283
13 CFM	368.1	6.14	22.1	0.368
21 CFM	594.7	9.91	35.7	0.595
25 CFM	708.0	11.80	42.5	0.708
50 CFM	1,415.8	23.60	84.9	1.416

Exact factor: 1 CFM = 28.3168 L/min = 0.47195 L/s = 1.69901 m³/h = 0.028317 m³/min

Liters per Minute (L/min) — Complete Conversions

L/min is the most common unit in piston compressors for workshop use. To convert L/min to CFM divide by 28.317; to get L/s divide by 60.

L/min	CFM / PCM	L/s	m³/h
46 L/min	1.62	0.77	2.76
100 L/min	3.53	1.67	6.0
250 L/min	8.83	4.17	15.0
500 L/min	17.66	8.33	30.0

Exact factor: 1 L/min = 0.035315 CFM = 0.016667 L/s = 0.06 m³/h

What is NL/min or m³(N)/h? — Normal Liters

The "N" stands for Normal conditions: 0°C and 1 atm (ISO 1217 / DIN 1343). NL/min allows standardized flow comparison regardless of altitude or ambient temperature. To convert NL/min to standard CFM: 3,950 NL/min ÷ 28.317 = 139.5 NCFM.

Frequently Asked Questions

Can you convert L/min (liters per minute) to PSI?

Not directly. L/min measures flow rate and PSI measures pressure — they are different physical quantities. In compressor specs they appear together (e.g., "250 L/min at 90 PSI") showing how much air the compressor delivers at a given pressure. Our engineers can help you size your system.

Can you convert cubic meters (m³) to PSI?

No. Cubic meters measure volume; PSI measures pressure. The relationship depends on temperature and follows PV = nRT. In compressed gas cylinders, available gas is often expressed as m³ at atmospheric pressure — but that requires knowing the tank volume and current pressure to calculate.

What does NL/min mean in compressor specs?

NL/min stands for Normal Liters per Minute — flow measured at standard conditions: 0°C and 1 atm (ISO 1217 / DIN 1343). It allows fair comparison between compressors regardless of altitude or ambient temperature. To convert NL/min to standard CFM, divide by 28.317.

What does Im³/hr (Dis) mean on a compressor datasheet?

Im³/hr (Dis) is the actual delivery flow in cubic meters per hour at discharge pressure. It’s equivalent to FAD (Free Air Delivery) per ISO 1217 — the real air volume delivered at the rated working pressure, always lower than theoretical displacement due to volumetric efficiency losses.

How many CFM does a compressor produce per HP?

There’s no universal ratio — it depends on compressor type, working pressure and volumetric efficiency. General reference for piston compressors at 90–125 PSI: 3.5–4.5 CFM per HP. High-efficiency screw compressors can achieve 4.5–5.5 CFM per HP. Always verify with the specific model datasheet. Contact a CBS specialist for sizing help.

How many HP do I need for a machine requiring 5 m³/h at 8 kgf/cm²?

With those specs (≈ 7.84 bar / 114 PSI at 5 m³/h = 2.94 CFM), a compressor of 5 to 7.5 HP is typically sufficient for single-machine use. If multiple machines run simultaneously, add up their consumption and include a 20–30% safety margin. Contact a CBS engineer for an exact model recommendation.

How long does it take to fill a 500-liter tank to 115 PSI with a 10 HP compressor?

With 40 CFM (1,132 L/min) and a 500 L tank at 115 PSI (7.93 bar), the theoretical fill time from empty is approximately 3.5 minutes. Simplified formula: T (min) = [V (L) × P (bar)] ÷ [Q (L/min) × P_atm]. Actual time varies based on volumetric efficiency, temperature and starting pressure.

How many PSI can a 5 HP compressor reach?

Horsepower determines flow rate, not maximum pressure. CBS 5 HP piston models typically reach 125–175 PSI depending on the series. Contact us to confirm the right model for your application.

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