Definition: A cubic inch per hour (in3/h) is a unit of volumetric flow rate that measures the volume of a substance passing through a surface per unit of time. It represents the amount of volume, measured in cubic inches, that flows every hour.

History/origin: Similar to cubic inches per minute, this unit is derived from the inch, a unit of length in the imperial and United States customary systems of measurement. The 'per hour' component indicates the rate at which the volume is changing over time. Its origin is tied to the establishment of the imperial system.

Current use: Cubic inches per hour is used in contexts where measuring very small flow rates is necessary. It is utilized in applications where flow rates are expected to be very low, such as certain chemical processes or small-scale machinery.