light water

By reference to atomic weight and atomic mass; more at light hydrogen.

light water (uncountable)

2. (inorganic chemistry) Any water molecules (H₂O) containing two protium (¹H, hydrogen-1) atoms.

   Alternative forms: lightwater, light-water

   Synonym: diprotium monoxide

   Hypernyms: water, H₂O < substance

   Coordinate terms: heavy water (²H₂O), semi-heavy water (¹H-²H-O), super-heavy water (³H₂O)

   2. Water in its usual form (as occurs in nature without human intervention), which is mostly of such form.
   4. Water which has had even the usual small amount of deuterium removed (by human intervention): deuterium-depleted water.
4. Foam formed by water and any of various additives, used in firefighting because it floats on flammable liquids lighter than water. (The additives were originally fluorocarbon surfactants but today are increasingly fluorine-free.)

   Hypernyms: firefighting foam < foam

   • 2001, Roger C. Mardon, An Illustrated History of Fire Engines, →ISBN, page 112:

     The light water (AFFF) of the TACR was to be backed up by fluorinated protein foam instead of standard protein foam.

   • 2014, John R. Ridley, Safety at Work, →ISBN, page 504:

     These fires can be extinguished with water spray, alcohol-resistant foam, light water, vaporising liquids ("Halons"), carbon dioxide and dry powder.

   • 2015, Phil Hughes, Ed Ferrett, Introduction to Health and Safety at Work, →ISBN:

     They can be extinguished by carbon dioxide, dry powder, water spray, light water and vaporising liquid

• (protium water): light water reactor

• (protium water): light hydrogen

• leatwright