Conversion from Milliliters per second to Cubic centimeters per second

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 second (cm³/s)

The cubic centimetre per second is a unit of volumetric flow rate equal to one cubic centimetre passing a point every second. Its symbol is cm³/s, and because a cubic centimetre is exactly a millilitre, the same rate is often written mL/s. It sits in the gap between the laboratory and the workshop: small enough to measure with a syringe, large enough to see.

Physiology uses it constantly. Resting cardiac output of five litres a minute is about 83 cubic centimetres per second, urine production is roughly 0.017, and a quiet breath moves perhaps 500 cubic centimetres over two seconds. Because the human body deals in volumes of this order, medical devices from ventilators to infusion pumps are calibrated in it.

Gas flow measurement adopted it early. A rotameter — the tapered glass tube with a float that appears on every laboratory bench — is graduated in cubic centimetres per second or per minute, and the float position gives the flow directly. Since a gas expands, such readings are meaningful only when the temperature and pressure are stated, which is why standard conditions accompany them.

Engines make an instructive example. A four-stroke engine of 2,000 cubic centimetres running at 3,000 revolutions per minute draws air through its intake at 1,500 cubic centimetres per revolution, or 75,000 cubic centimetres per second at 100 per cent volumetric efficiency. The mass air-flow sensor in the intake measures a quantity closely related to this, and the fuelling calculation depends on it.

Laboratory chromatography and analysis are specified here as well. A gas chromatograph column carries carrier gas at one to two cubic centimetres per minute, while a detector's make-up flow may be twenty or thirty, and the ratio between them determines the shape of the peaks the instrument reports.

The unit's convenience comes from the size of the cubic centimetre itself. A thousand of them make a litre, so a thousand cubic centimetres per second is a litre per second — a bath filling in about two minutes. Anything a person can pour by hand lies within a factor of a hundred of this rate.

One cubic centimetre per second equals one millilitre per second, 0.001 litres per second, or 60 cubic centimetres per minute.