Conversion from Milliliters per second to Cubic centimeters per minute

Information about the Milliliter per second (mL/s)

The millilitre per second is a unit of volumetric flow rate equal to one millilitre of fluid passing a point every second. Its symbol is mL/s. Since a millilitre is a cubic centimetre, the unit is identical to the cubic centimetre per second, and the two names are used interchangeably depending on whether the fluid is thought of as a liquid or as a volume of space.

Volumetric flow rate is a volume divided by a time, so it has the dimensions of length cubed per second. That makes it convertible to any other flow unit by a single multiplication, and it also means that a flow rate multiplied by a duration gives the total volume delivered — the arithmetic that underlies every dosing calculation and every water bill.

A millilitre per second is a small but visible flow. A tap dripping steadily produces perhaps a tenth of this; a thin stream from a partly opened tap is a few millilitres per second; a garden hose at full flow is several hundred. In household terms it is the rate at which a teaspoon fills in about five seconds.

The unit belongs to the laboratory and to small machinery. Peristaltic pumps, dosing systems, fuel injectors and analytical instruments all work in this range, and their specifications are written in millilitres per second when the process is fast and in millilitres per minute when it is slow. Where a pump must deliver a precise quantity, the rate and the running time together define the dose.

Human physiology gives useful comparisons. Resting cardiac output is about eighty millilitres per second, urine production averages under a fiftieth of that, and saliva production is around a hundredth. The flow through a single capillary is far smaller still and is measured in cubic millimetres per hour.

Converting to the SI base unit requires care with the powers of ten. One millilitre per second is a millionth of a cubic metre per second, because a millilitre is a millionth of a cubic metre. That factor of a million between the practical unit and the base unit is why flow rates are almost never quoted in cubic metres per second outside hydrology and heavy engineering.

One millilitre per second equals 0.001 litres per second, 60 millilitres per minute, or about 0.0000353 cubic feet per second.

Information about the Cubic centimeter per minute (cm³/min)

The cubic centimetre per minute is a unit of volumetric flow rate equal to one cubic centimetre passing a point every minute. Its symbol is cm³/min, and since a cubic centimetre is a millilitre, mL/min means the same thing. It is the standard unit of controlled gas flow in laboratories and in the semiconductor industry.

That industry gave it an abbreviation of its own: sccm, standard cubic centimetres per minute. The word standard matters, because a gas expands and contracts with temperature and pressure, so a volume flow means nothing until the conditions are pinned down. A mass flow controller set to 50 sccm delivers a fixed number of molecules per minute regardless of what the downstream pressure does, which is precisely what a deposition or etching process requires.

A silicon wafer passing through a plasma etcher meets several such controllers at once — argon at a few hundred sccm, a reactive fluorine compound at tens, oxygen at a handful — and the recipe that defines the process is essentially a list of these numbers against time. Repeating a process in another factory means reproducing the same flows.

Chromatography and gas analysis use the unit at the low end. Helium carrier gas through a capillary column runs at one or two cubic centimetres per minute, a flame detector burns hydrogen at thirty and air at three hundred, and a mass spectrometer's inlet is designed around a flow the vacuum pumps can cope with.

Liquids appear here as well, particularly in analytical chemistry and medicine. A high-performance liquid chromatography pump runs at 0.2 to 2 cubic centimetres per minute, and an intravenous infusion of 100 millilitres over an hour is 1.67 cubic centimetres per minute. In both cases the small, steady rate is what allows the result to be reproduced.

Sixty cubic centimetres per minute is one cubic centimetre per second, and a thousand is a litre per minute. So a typical mass flow controller set to 500 sccm is delivering half a litre of gas a minute — about the volume of a soft-drink bottle, which is a helpful way to picture what an invisible gas line is actually carrying.

One cubic centimetre per minute equals one millilitre per minute, about 0.01667 cubic centimetres per second, or 0.001 litres per minute.