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Date Submitted: 03/23/2012 11:58 PM
APPENDIX A. LIST OF DEFINITIONS
A.1 List of Definitions
accuracy. How closely an instrument measures the true or actual value of the process
variable being measured or sensed.
acidic. The condition of water or soil which contains a sufficient amount of acid
substances to lower the pH below 7.0.
activated carbon. Adsorptive particles or granules of carbon usually obtained by heating
carbon (such as wood). These particles or granules have a high capacity to selectively
remove certain trace and soluble organic materials from water.
air binding. A situation where air enters the filter media. Air is harmful to both the
filtration and backwash processes. Air can prevent the passage of water during the
filtration process and can cause the loss of filter media during the backwash process.
alarm contact. A switch that operates when some pre-set low, high or abnormal
condition exists.
algae. Microscopic plants which contain chlorophyll and live floating or suspended in
water. They also may be attached to structures, rocks or other submerged surfaces. They
are food for fish and small aquatic animals. Excess algal growths can impart tastes and
odors to potable water. Algae produce oxygen during sunlight hours and use oxygen
during the night hours. Their biological activities appreciably affect the pH and dissolved
oxygen of the water.
alkaline. The condition of water or soil which contains a sufficient amount of alkali
substances to raise the pH above 7.0.
alkalinity. The capacity of water to neutralize acids. This capacity is caused by the
water's content of carbonate, bicarbonate, hydroxide and occasionally borate, silicate, and
phosphate. Alkalinity is expressed in milligrams per liter of equivalent calcium carbonate.
Alkalinity is not the same as pH because water does not have to be strongly basic (high
pH) to have a high alkalinity. Alkalinity is a measure of how much acid can be added to a
liquid without causing a great change in pH.
analog....