| Cubic meters per minute (m³/min) | Cubic inches per second (in³/s) |
|---|---|
| 1 Cubic meter per minute | 1017.06240158 in³/s |
| 2 Cubic meters per minute | 2034.12480316 in³/s |
| 3 Cubic meters per minute | 3051.18720474 in³/s |
| 4 Cubic meters per minute | 4068.24960632 in³/s |
| 5 Cubic meters per minute | 5085.31200789 in³/s |
| 10 Cubic meters per minute | 10170.6240158 in³/s |
| 20 Cubic meters per minute | 20341.2480316 in³/s |
| 25 Cubic meters per minute | 25426.5600395 in³/s |
| 50 Cubic meters per minute | 50853.1200789 in³/s |
| 100 Cubic meters per minute | 101706.240158 in³/s |
| Reference | Cubic meters per minute (m³/min) | Cubic inches per second (in³/s) |
|---|---|---|
| A domestic shower | 0.009 m³/min | 9.15356 in³/s |
| A kitchen tap | 0.01 m³/min | 10.1706 in³/s |
| A garden hose | 0.015 m³/min | 15.2559 in³/s |
| The Amazon river | 12540000 m³/min | 1.2754 × 1010 in³/s |
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 cubic inch per second is a unit of volumetric flow rate equal to one cubic inch passing a point every second. Its symbol is in³/s. A cubic inch is 16.387 cubic centimetres, a little over a tablespoon, so this unit describes the modest but visible flows of imperial engineering practice.
Hydraulics is where it survives most strongly. American hydraulic pumps and cylinders are still catalogued in inches, and a cylinder's speed follows directly from the flow divided by the piston area: a 2-inch bore cylinder has an area of 3.14 square inches, so 31.4 cubic inches per second extends it at 10 inches per second. Working in inches throughout avoids converting the bore, the stroke and the flow separately.
Machining uses the same idea for material removal. A milling cutter taking a 0.1-inch depth at 0.5 inch width and 20 inches per minute of feed removes one cubic inch per minute, and a modern machining centre roughing aluminium can exceed twenty. Tool manufacturers publish removal rates in these units because their customers' machines are dimensioned that way.
Small engines and pumps carry the unit too. An engine's displacement in cubic inches, multiplied by its speed, gives the air it swallows: a 350 cubic inch V8 at 3,000 revolutions per minute ingests 525,000 cubic inches a minute, or about 8,750 per second, ideal efficiency assumed. The old American habit of naming engines by cubic inches is the same measurement standing still rather than flowing.
Metering and dispensing in imperial industries follow. Adhesive dispensers, lubricators and grease systems on American plant are specified in cubic inches per second or per minute, and a shot of grease from an automatic lubricator is quoted in cubic inches per cycle, which the cycle time converts into a rate.
For a sense of scale, 61 cubic inches per second is about a litre per second, and one cubic inch per second fills a US gallon in a little under four minutes. That is roughly the rate of a garden tap opened a quarter turn, which makes the unit easy to picture despite its unfamiliarity outside the imperial trades.
One cubic inch per second equals about 16.39 cubic centimetres per second, 0.01639 litres per second, or about 0.2597 US gallons per minute.