Pressure, force & flow

Kilopascals against pounds per square foot for bearing and floor loads; kips, kilonewtons and pounds-force for point loads; pounds per square inch against feet of head for pumps; cubic feet per minute against litres per second and cubic metres per hour for air; gallons and litres per minute for water; velocities in feet per minute and metres per second; and torque in foot-pounds and newton-metres.

Whether the figure is spread over an area or concentrated at a point, because the units look alike and the consequences do not. A kilonewton is a load and a kilopascal is that load divided by the area it sits on, and reading a bearing capacity as a column load — or the reverse — is out by whatever the footing measures. Where a page converts one, it will not convert the other for you.

Sizing the pump, the duct, the pad or the bolt. These restate a figure; choosing it is a design.