| Fluid ounces per second (fl oz/s) | Milliliters per minute (mL/min) |
|---|---|
| 1 Fluid ounce per second | 1704.78375 mL/min |
| 2 Fluid ounces per second | 3409.5675 mL/min |
| 3 Fluid ounces per second | 5114.35125 mL/min |
| 4 Fluid ounces per second | 6819.135 mL/min |
| 5 Fluid ounces per second | 8523.91875 mL/min |
| 10 Fluid ounces per second | 17047.8375 mL/min |
| 20 Fluid ounces per second | 34095.675 mL/min |
| 25 Fluid ounces per second | 42619.59375 mL/min |
| 50 Fluid ounces per second | 85239.1875 mL/min |
| 100 Fluid ounces per second | 170478.375 mL/min |
| Reference | Fluid ounces per second (fl oz/s) | Milliliters per minute (mL/min) |
|---|---|---|
| A domestic shower | 5.27926 fl oz/s | 9000 mL/min |
| A kitchen tap | 5.86585 fl oz/s | 10000 mL/min |
| A garden hose | 8.79877 fl oz/s | 15000 mL/min |
| The Amazon river | 7.35577 × 109 fl oz/s | 1.254 × 1013 mL/min |
The fluid ounce per second is a unit of volumetric flow rate equal to one imperial fluid ounce passing a point every second. Its symbol is fl oz/s. The imperial fluid ounce is 28.413 millilitres, defined as one twentieth of an imperial pint, so this unit describes the flow of a steady pour rather than a plumbing system.
Its natural home is the bar and the kitchen. A pint glass filled in twelve seconds is being poured at about 1.7 fluid ounces per second, and a bartender free-pouring spirits counts seconds against a known rate to measure a shot without a jigger. Automatic dispensing guns on a bar are calibrated in exactly these terms so that a portion is repeatable across a busy evening.
Beverage plants use it for filling heads. A bottling line filling half-litre bottles at 200 bottles a minute must deliver about 59 fluid ounces per second in total, divided among however many heads the filler carries. Each head's individual rate determines the fill time, and the fill time determines how fast the carousel can turn.
The unit persists in British and Commonwealth food and drink specifications, where recipes, dispense rates and portion controls have been written in fluid ounces for generations. A soft-drink dispenser is set so that the syrup and the carbonated water arrive in a fixed ratio, and both rates are naturally quoted in fluid ounces per second.
A warning belongs here: the American fluid ounce is 29.574 millilitres, about four per cent larger than the imperial one, and the American pint holds sixteen of them against the imperial twenty. A flow rate quoted in fluid ounces per second therefore differs by four per cent between the two systems, and by twenty per cent when the same number of ounces is called a pint.
For a sense of scale, 35 fluid ounces per second is about a litre per second, and one fluid ounce per second fills a pint in twenty seconds and a gallon in a little under three minutes. It is the rate of a fast tap or a generous jug.
One fluid ounce per second equals about 28.41 millilitres per second, about 0.02841 litres per second, or about 1.734 cubic inches per second.
The millilitre per minute is a unit of volumetric flow rate equal to one millilitre passing a point every minute. Its symbol is mL/min. It is the working unit of clinical medicine and of analytical chemistry, two fields in which the quantity delivered matters far more than the speed of delivery.
Intravenous infusion is the clearest case. A drip is set in millilitres per hour for slow fluids and in millilitres per minute for fast ones, and an infusion pump is programmed with a rate and a volume. A litre of saline given over four hours runs at about four millilitres per minute; the same litre given rapidly in an emergency may run at a hundred.
Liquid chromatography works in the same range. A conventional analytical column is run at one millilitre per minute, a figure so standard that it appears as a default in almost every published method. Narrower columns run proportionally slower, and the flow must be held steady to within a fraction of a per cent, because the time at which a compound emerges depends on it.
Anaesthetic and oxygen delivery use the unit too, though there the fluid is a gas. Oxygen therapy is prescribed in litres per minute, and the small adjustments within that are made in hundreds of millilitres per minute. In each case the rate is a prescription, and the equipment exists to hold it constant.
Sixty millilitres per minute is one millilitre per second, so the conversion between the two is the same factor as between minutes and seconds. That relationship makes it easy to move between the fast and slow ends of the same equipment: a pump specified in millilitres per minute can be reasoned about in millilitres per second by dividing by sixty.
For everyday scale, a millilitre per minute would fill a teaspoon in five minutes and a cup in four hours. It is a rate slow enough that watching it is uninformative, which is why the instruments that use it display a totalised volume as well as a rate.
One millilitre per minute equals about 0.01667 millilitres per second, 60 millilitres per hour, or 0.001 litres per minute.