One helium light band equals 0.0000116 inches or 0.3 microns. Seal faces are normally lapped to within three helium light bands of flatness. Horse power 33,000 foot pounds per minute. A common method of measuring work. A method of reducing mechanical seal face loading by reducing the seal face closing area.
Hydraulic force Occurs any time pressure acts on a seal face area.
Force times distance divided by time is a measurement of work done. Hydrocarbon A petroleum product consisting of hydrogen and carbon. Hydrodynamic force Generated at the seal faces because, for all practical purposes, liquid is not compressible. Hydrodynamic seal Special geometric features on the seal face that provide lift by taking advantage of the rotation of one seal face upon the other. A premature fatigue of metal caused by the presence of free hydrogen.