Conversion from Cubic centimeters per minute to Cubic meters per hour

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.

Information about the Cubic meter per hour (m³/h)

The cubic metre per hour is a unit of volumetric flow rate equal to one cubic metre passing a point every hour. Its symbol is m³/h. It is the commercial unit of flow: the one that appears on water bills, gas meters, pump curves and ventilation schedules, because a cubic metre per hour multiplied by the hours of operation gives the volume that is actually paid for.

Domestic water and gas meters read in cubic metres, and the meter's rating is a flow in cubic metres per hour — typically 1.5 or 2.5 for a house, meaning the maximum continuous flow it can measure accurately. A gas meter marked G4 passes 6 cubic metres per hour, which at the calorific value of natural gas is roughly 63 kilowatts, comfortably more than a domestic boiler needs.

Pumps are sold by their curve, and the curve's horizontal axis is almost always cubic metres per hour. A domestic booster pump delivers 2 to 5, a swimming-pool pump 10 to 20, an irrigation pump 50 to 200, and a large water-supply pump thousands. Reading the curve at the required flow gives the head the pump can produce and the power it will draw.

Ventilation is scheduled in the same unit across much of Europe. A dwelling requires roughly 0.5 air changes an hour, so a 250 cubic metre flat needs about 125 cubic metres per hour of fresh air; a restaurant kitchen hood may need 3,000, and a laboratory fume cupboard around 1,000 each. Since the room volume is in cubic metres, using the hour as the time base makes the arithmetic immediate.

Industrial process flows are quoted here whether the fluid is liquid or gas. Cooling towers, boiler feedwater, effluent treatment and compressed-air dryers all carry ratings in cubic metres per hour, and district heating substations are sized from the flow needed to carry the heat at a given temperature difference.

Its relation to the SI unit is a division by 3,600. One cubic metre per second is 3,600 cubic metres per hour, which is why river flows look enormous in this unit and why hydrologists avoid it. The hour is the right base for equipment that runs continuously and is billed monthly.

One cubic metre per hour equals about 0.000278 cubic metres per second, 1,000 litres per hour, or about 4.403 US gallons per minute.