25 May 2005
Microbiocide -- A material added to cooling tower water and chilled water to control
the growth of microorganisms such as algae, bacteria, and fungi.
-- An electrical unit
of conductance (one-millionth
of a mho), which
Microorganism -- A minute plant or animal in water or earth that is visible only through
Milligrams Per Liter (mg/l) -- A unit of the concentration of water or wastewater
constituent. It is 0.001 gram of the constituent in 1000 milliliters (ml) of water.
Neutralizing Amines -- Chemicals used to neutralize carbon dioxide in steam
condensate to prevent corrosion.
-- The concentration
of a solution
to a normal solution.
Normality is a measure of the "strength" of a given solution. The normal solution
contains a specific weight of a substance per liter based on the characteristics of the
substance. Thus, a half-normal solution would be expressed as 0.5 N or N/2.
Oxygen Scavenger -- A chemical used to remove final traces (trace amounts) of
oxygen from boiler feedwater.
-- Logarithmic measure
of hydrogen ion concentration indicating degree
alkalinity of a solution. The pH range varies from 1 to 14. Values below 7.0 indicate
acidity and above 7.0 indicate alkalinity (basicity).
pHeq -- The pH of equilibrium. The adjusted pH value of a water based on the empirical
relationship between total alkalinity and pH developed from studies of hundreds of
cooling systems. Development of an empirical relationship was necessary because pH
in cooling waters is often buffered, a factor which affects the relationship between pH
and bicarbonate alkalinity.
pHs -- The pH of saturation. It is the pH value below which a material will go into
solution (dissolve) and above which it will precipitate. It is applied to calcium carbonate
in the Langelier, Ryznar, and Practical Scaling Indices. It is a function of the calcium
hardness, the total alkalinity, the total dissolved solids (TDS) and the temperature. It is
determined with graphs, tables, or special slide rules. This equation is useful:
pHs = 12.27 - 0.00915T - log CaH - log TA + (log TDS)/10.
Phosphates -- Chemicals used for corrosion control in cooling towers and deposit
control in boilers. Commonly, these occur as orthophosphates or polyphosphates. The
level of the active phosphate chemical is reported either as percent P2O5 (phosphorus
pentoxide) or as PO4 (phosphate), with these two oxides of phosphate being related by
factor as follows: PO4 = 1.34 x P2O5.