| Cubic meters per hour (m³/h) | Fluid ounces per hour (fl oz/h) |
|---|---|
| 1 Cubic meter per hour | 35195.0797279 fl oz/h |
| 2 Cubic meters per hour | 70390.1594557 fl oz/h |
| 3 Cubic meters per hour | 105585.239184 fl oz/h |
| 4 Cubic meters per hour | 140780.318911 fl oz/h |
| 5 Cubic meters per hour | 175975.398639 fl oz/h |
| 10 Cubic meters per hour | 351950.797279 fl oz/h |
| 20 Cubic meters per hour | 703901.594557 fl oz/h |
| 25 Cubic meters per hour | 879876.993196 fl oz/h |
| 50 Cubic meters per hour | 1759753.98639 fl oz/h |
| 100 Cubic meters per hour | 3519507.97279 fl oz/h |
| Reference | Cubic meters per hour (m³/h) | Fluid ounces per hour (fl oz/h) |
|---|---|---|
| A domestic shower | 0.54 m³/h | 19005.3 fl oz/h |
| A kitchen tap | 0.6 m³/h | 21117 fl oz/h |
| A garden hose | 0.9 m³/h | 31675.6 fl oz/h |
| The Amazon river | 752400000 m³/h | 2.64808 × 1013 fl oz/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.
The fluid ounce per hour is a unit of volumetric flow rate equal to one imperial fluid ounce passing a point every hour. Its symbol is fl oz/h. An imperial fluid ounce is 28.413 millilitres, so an hour at this rate delivers about two tablespoons — a rate slow enough that it is measured by what has collected, not by what is moving.
Slow feeding and slow dosing account for most of its use. A drip feeder on a bird cage, a wick humidifier, a fragrance diffuser and a slow-release fertiliser injector on a greenhouse line all move liquid at a few fluid ounces per hour, and the reservoir capacity divided by that rate gives the interval between refills.
Domestic appliances are described by it in older British literature. A paraffin heater consumes a few fluid ounces per hour, a wick lamp rather less, and an oil-filled stove was once sold with its consumption stated exactly this way so that a household could calculate how long a gallon would last through a winter evening.
Evaporation and leakage measurements fall here too. Water lost from an open tank, brake fluid seeping past a seal, or condensate collected from a small cooling coil are all quantified per hour, because that is the shortest period over which enough accumulates to measure in an ordinary graduated cylinder.
The unit's usefulness lies in matching the observation to the human timescale. Nobody watches a drip for a second; a technician checks a container after an hour, a shift or a night, and expressing the rate per hour lets the observed volume be divided by the elapsed hours with no further arithmetic.
For orientation, 160 fluid ounces make an imperial gallon, so one fluid ounce per hour fills a gallon in a little under a week. Thirty-five fluid ounces per hour is about a litre per hour, and sixty fluid ounces per hour is one fluid ounce per minute.
One fluid ounce per hour equals about 28.41 millilitres per hour, about 0.02841 litres per hour, or about 0.01667 fluid ounces per minute.