Cubic centimeter per hour (cm³/h)

The cubic centimetre per hour is a unit of volumetric flow rate equal to one cubic centimetre passing a point every hour. Its symbol is cm³/h, and because a cubic centimetre is a millilitre, mL/h means the same rate. It describes flows slow enough that nothing appears to move, yet fast enough to matter over a shift or a night.

Hospital infusion is its most common setting. A syringe driver or volumetric pump is programmed in millilitres per hour: maintenance fluid at 80 to 120 for an adult, a sedative at 5, a neonatal feed at less than 1. The nurse setting the pump and the pharmacist calculating the dose both work in this unit, and the dose in milligrams per hour follows from it and the concentration of the bag.

Leak testing uses the unit as a pass-or-fail criterion. A hydraulic fitting, a fuel connector or a refrigeration joint is given an allowable leakage of so many cubic centimetres per hour, measured by collecting what escapes over a long period rather than by watching for a drip. Regulations on refrigerant loss and on vehicle fuel-system emissions are written this way.

Lubrication systems are rated here as well. A centralised oil-drip system on a machine tool delivers a few cubic centimetres per hour to each bearing, and an air-line oiler set correctly gives one drop every few minutes. Too much and the oil contaminates the workpiece; too little and the bearing fails, which is why the rate is specified rather than left to judgement.

Evaporation and drying processes are quantified in the same terms. A solvent evaporating from an open dish, water lost from a laboratory culture, or condensate produced by a small dehumidifier are all naturally described per hour, because the observation period is an hour or a day rather than a second.

The relation to bigger units keeps the scale clear. A thousand cubic centimetres per hour is a litre per hour, and a full day at one cubic centimetre per hour yields 24 cubic centimetres — about a tablespoon and a half. That is the honest measure of what a slow flow accomplishes while nobody is watching.

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

Cubic centimeter per hour conversion table