Conversion from Cubic inches per hour to Cubic inches per second

Information about the Cubic inch per hour (in³/h)

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.

Information about the Cubic inch per second (in³/s)

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.