Description: Period of time from the commissioning of a plant, part of a plant, a component or a line system; Name: service life
Description: passed time period after comissioning of a system, sub-system, component or piping; Name: Operating time 
Description: determined through a surface, product of the sound pressure, p, and the component of the particle velocity, un, at a point on the surface in the direction normal to the surface, integrated over that surface; Name: sound power