Description: height of the centre of the exhaust pressure gauge; Name: height of exhaust pressure gauge 
Description: Height of the zero or centre position of the outlet manometer, or other point as defined by the manometer calibration ; Name: Height of the outlet manometer
Description: PN (nominal pressure) is an alphanumeric variable for reference purposes, relating to a combination of mechanical and measurement properties of a pipe component. It comprises the letters PN followed by a dimensionless number (according to EN 1333/96.08); Name: Nominal pressure of the muffs, A1