In fluid mechanics, head represents the mechanical energy of a fluid per unit weight, typically measured in meters or feet of water. It dictates the pressure available to drive flow through a system or the lift a pump must overcome. In engine design, the head is the heavy casting bolted to the top of the cylinder block that houses the valves and combustion chambers.
Heard on the job
We're losing too much head across this pipe run, so we need to upsize to a three-inch line.
Also heard as
- cylinder head
- pressure head
Do not mix it up with
- Boss: A boss is a protruding mounting point on a casting, while a head is a major structural cover or a fluid pressure metric.
Related terms
Cylinder
The tubular chamber in which a piston travels to compress a fluid or convert fluid pressure into mechanical work.
Fluid mechanics
The study of how liquids and gases behave at rest and in motion under various forces.
Pump valve
A mechanical barrier that directs or restricts fluid flow within a pumping system.