| Cubic centimeters per hour (cm³/h) | Cubic inches per hour (in³/h) |
|---|---|
| 1 Cubic centimeter per hour | 0.0610237440947 in³/h |
| 2 Cubic centimeters per hour | 0.122047488189 in³/h |
| 3 Cubic centimeters per hour | 0.183071232284 in³/h |
| 4 Cubic centimeters per hour | 0.244094976379 in³/h |
| 5 Cubic centimeters per hour | 0.305118720474 in³/h |
| 10 Cubic centimeters per hour | 0.610237440947 in³/h |
| 20 Cubic centimeters per hour | 1.22047488189 in³/h |
| 25 Cubic centimeters per hour | 1.52559360237 in³/h |
| 50 Cubic centimeters per hour | 3.05118720474 in³/h |
| 100 Cubic centimeters per hour | 6.10237440947 in³/h |
| Reference | Cubic centimeters per hour (cm³/h) | Cubic inches per hour (in³/h) |
|---|---|---|
| A domestic shower | 540000 cm³/h | 32952.8 in³/h |
| A kitchen tap | 600000 cm³/h | 36614.2 in³/h |
| A garden hose | 900000 cm³/h | 54921.4 in³/h |
| The Amazon river | 7.524 × 1014 cm³/h | 4.59143 × 1013 in³/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.
The cubic inch per hour is a unit of volumetric flow rate equal to one cubic inch passing a point every hour. Its symbol is in³/h. Since a cubic inch is a little over a tablespoon, an hour at this rate produces a small puddle — which is exactly why the unit belongs to slow losses, slow doses and slow wear rather than to transfers.
Seepage and weeping are its natural subject. A mechanical seal on a pump is allowed a small permanent leakage to lubricate its faces, and the specification is written in cubic inches per hour on American equipment. A packed gland on a valve stem is similar: a few drops an hour is correct operation, and a dry gland is a gland about to score its stem.
Oil consumption in engines is quoted this way in the imperial world. A large stationary engine's cylinder lubrication is metered at a few cubic inches per hour per cylinder, and the acceptable rate of oil loss past the rings on a diesel is expressed the same way. Because such engines run for thousands of hours between overhauls, an hourly figure is what turns into a drum of oil on the purchase order.
Slow-fill and top-up systems live here too. An automatic battery-watering system, a coolant make-up line, a header tank feeding a boiler and a chemical dosing pump on a cooling circuit all move volumes of this size, and their design lifetime is set by the reservoir divided by the hourly rate.
Corrosion, erosion and permeation figures convert into it when a rate must be given as a volume. A seal that permits so many cubic inches of refrigerant per hour, or a hose whose wall passes so much fuel vapour, is compared against a regulatory limit written as an annual figure, and the hourly rate is what the test bench actually measures.
The relation to larger units frames it clearly. There are 231 cubic inches in a US gallon, so one cubic inch per hour fills a gallon in about ten days, and 61 cubic inches per hour is roughly a litre per hour. A flow that takes a week and a half to fill a milk jug is the very definition of a rate you watch rather than use.
One cubic inch per hour equals about 16.39 cubic centimetres per hour, about 0.01667 cubic inches per minute, or about 0.004329 US gallons per hour.