Glossary - Cont'd - ufc_3_240

Industrial Water Treatment Operation and Maintenance - index
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UFC 3-240-13FN

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.

Micromho -- An electrical unit of conductance (one-millionth of a mho), which is the

reciprocal of electrical resistance.

Microorganism -- A minute plant or animal in water or earth that is visible only through

a microscope.

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.

Normality (N) -- The concentration of a solution in relation 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.

pH -- Logarithmic measure of hydrogen ion concentration indicating degree of acidity or

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.

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