| Fluid ounces per hour (fl oz/h) | Cubic inches per second (in³/s) |
|---|---|
| 1 Fluid ounce per hour | 0.000481630959708 in³/s |
| 2 Fluid ounces per hour | 0.000963261919415 in³/s |
| 3 Fluid ounces per hour | 0.00144489287912 in³/s |
| 4 Fluid ounces per hour | 0.00192652383883 in³/s |
| 5 Fluid ounces per hour | 0.00240815479854 in³/s |
| 10 Fluid ounces per hour | 0.00481630959708 in³/s |
| 20 Fluid ounces per hour | 0.00963261919415 in³/s |
| 25 Fluid ounces per hour | 0.0120407739927 in³/s |
| 50 Fluid ounces per hour | 0.0240815479854 in³/s |
| 100 Fluid ounces per hour | 0.0481630959708 in³/s |
| Reference | Fluid ounces per hour (fl oz/h) | Cubic inches per second (in³/s) |
|---|---|---|
| A domestic shower | 19005.3 fl oz/h | 9.15356 in³/s |
| A kitchen tap | 21117 fl oz/h | 10.1706 in³/s |
| A garden hose | 31675.6 fl oz/h | 15.2559 in³/s |
| The Amazon river | 2.64808 × 1013 fl oz/h | 1.2754 × 1010 in³/s |
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.
The cubic inch per second is a unit of volumetric flow rate equal to one cubic inch passing a point every second. Its symbol is in³/s. A cubic inch is 16.387 cubic centimetres, a little over a tablespoon, so this unit describes the modest but visible flows of imperial engineering practice.
Hydraulics is where it survives most strongly. American hydraulic pumps and cylinders are still catalogued in inches, and a cylinder's speed follows directly from the flow divided by the piston area: a 2-inch bore cylinder has an area of 3.14 square inches, so 31.4 cubic inches per second extends it at 10 inches per second. Working in inches throughout avoids converting the bore, the stroke and the flow separately.
Machining uses the same idea for material removal. A milling cutter taking a 0.1-inch depth at 0.5 inch width and 20 inches per minute of feed removes one cubic inch per minute, and a modern machining centre roughing aluminium can exceed twenty. Tool manufacturers publish removal rates in these units because their customers' machines are dimensioned that way.
Small engines and pumps carry the unit too. An engine's displacement in cubic inches, multiplied by its speed, gives the air it swallows: a 350 cubic inch V8 at 3,000 revolutions per minute ingests 525,000 cubic inches a minute, or about 8,750 per second, ideal efficiency assumed. The old American habit of naming engines by cubic inches is the same measurement standing still rather than flowing.
Metering and dispensing in imperial industries follow. Adhesive dispensers, lubricators and grease systems on American plant are specified in cubic inches per second or per minute, and a shot of grease from an automatic lubricator is quoted in cubic inches per cycle, which the cycle time converts into a rate.
For a sense of scale, 61 cubic inches per second is about a litre per second, and one cubic inch per second fills a US gallon in a little under four minutes. That is roughly the rate of a garden tap opened a quarter turn, which makes the unit easy to picture despite its unfamiliarity outside the imperial trades.
One cubic inch per second equals about 16.39 cubic centimetres per second, 0.01639 litres per second, or about 0.2597 US gallons per minute.