RN Scientific & Educational Abbreviation

Residue Number

Radon

Lumber used to support the roof sheeting and roof loads. Generally, 2 X 10's and 2 X 12's are used. The rafters of a flat roof are sometimes called roof joists. A naturally-occurring, heavier than air, radioactive gas common in many parts of the country. Radon gas exposure is associated with lung cancer. Mitigation measures may involve crawl space and basement venting and various forms of vapor barriers.

Revue numismatique

Reflection Nebulosity

Reynolds Number

The ratio of inertial and viscous forces in a fluid defined by the formula Re = rVD/?, where r = Density of fluid, ? = Viscosity in centipoise (CP), V = Velocity, and D = Inside diameter of pipe.