| Cubic meters per minute (m³/min) | Liters per minute (L/min) |
|---|---|
| 1 Cubic meter per minute | 1000 L/min |
| 2 Cubic meters per minute | 2000 L/min |
| 3 Cubic meters per minute | 3000 L/min |
| 4 Cubic meters per minute | 4000 L/min |
| 5 Cubic meters per minute | 5000 L/min |
| 10 Cubic meters per minute | 10000 L/min |
| 20 Cubic meters per minute | 20000 L/min |
| 25 Cubic meters per minute | 25000 L/min |
| 50 Cubic meters per minute | 50000 L/min |
| 100 Cubic meters per minute | 100000 L/min |
| Reference | Cubic meters per minute (m³/min) | Liters per minute (L/min) |
|---|---|---|
| A domestic shower | 0.009 m³/min | 9 L/min |
| A kitchen tap | 0.01 m³/min | 10 L/min |
| A garden hose | 0.015 m³/min | 15 L/min |
| The Amazon river | 12540000 m³/min | 1.254 × 1010 L/min |
The cubic metre per minute is a unit of volumetric flow rate equal to one cubic metre passing a point every minute. Its symbol is m³/min. It occupies the middle ground of industrial air handling: large enough for a factory's compressed-air main, small enough that the number stays in two or three digits.
Compressors are its most familiar users. A workshop screw compressor delivers 1 to 10 cubic metres per minute of free air, a large industrial machine 50 or more, and the rating is always given as free air delivery — the volume measured at atmospheric conditions rather than at the compressed pressure, because that is what the tools downstream actually consume.
Sizing a compressed-air system is an exercise in adding these numbers. Each tool has a consumption figure: an impact wrench 0.6 cubic metres per minute, a spray gun 0.3, a sandblasting nozzle several. Total them, apply a duty factor because they do not all run at once, add a margin for leaks, and the result is the compressor the workshop needs.
Mine and tunnel ventilation is quoted the same way. Regulations set a minimum air quantity per person and per unit of diesel power underground, and a working face may require 20 to 50 cubic metres per minute. The main fan at the surface handles the sum of every face, which is why the unit spans four orders of magnitude within a single industry.
Blowers, dust extraction and pneumatic conveying complete the picture. A woodworking dust extractor is rated at 20 to 60 cubic metres per minute, a bag filter for a cement plant at thousands, and a pneumatic conveyor is designed around the air velocity in the pipe, which the flow and the pipe cross-section together determine.
The conversion to its neighbours is easy in both directions. Sixty cubic metres per minute is one cubic metre per second, and one cubic metre per minute is a thousand litres per minute. That last relation is why the same fan can appear in a European catalogue as 1,200 litres per second and in another as 72 cubic metres per minute.
One cubic metre per minute equals about 0.01667 cubic metres per second, 1,000 litres per minute, or about 35.31 cubic feet per minute.
The litre per minute is a unit of volumetric flow rate equal to one litre passing a point every minute. Its symbol is L/min. It is the unit of taps, showers and small pumps — the flows a person meets directly, at a rate slow enough that a minute is the natural interval to count over.
Household plumbing is specified in it almost everywhere. A modern shower head delivers 6 to 9 litres per minute, an older one 15 or more, a kitchen tap 5 to 10, and a bath filler 15 to 20. Water-efficiency regulations in many countries set maximum figures in exactly these terms, because the flow rate multiplied by a typical shower length gives the volume of water and the energy needed to heat it.
That calculation is the reason the unit matters beyond plumbing. Reducing a shower from 12 to 8 litres per minute cuts both the water and the heating energy by a third, and heating water is one of the largest energy uses in a house. A restrictor costing very little changes a household's energy bill measurably.
Medicine uses the unit for gases. Oxygen therapy is prescribed in litres per minute — 2 through a nasal cannula for mild supplementation, 15 through a mask with a reservoir in an emergency — and the flowmeter on the wall of a hospital room is calibrated in exactly this unit. Anaesthetic machines are set the same way.
Engines and compressors also appear here. A small air compressor delivers 100 to 200 litres per minute of free air; a car's cooling system circulates tens of litres per minute; a garden pump moves 20 to 60. In each case the number is the useful one because the equipment runs for minutes at a time rather than seconds.
Sixty litres per minute is one litre per second, so the two units differ by the same factor as the two time units. That makes the conversion easy to do mentally, and it explains why the same equipment is often described in litres per minute by its manufacturer and litres per second by the engineer designing the system it goes into.
One litre per minute equals about 0.01667 litres per second, 1,000 millilitres per minute, or about 0.22 imperial gallons per minute.