Commonly Used Water Terms M - R
Welcome to the Water Guy list of commonly used water terms. Navigate the page
sections below:
MAGNESIUM
One of the elements making up the earth's crust. Magnesium compounds, when
dissolved in water, make the water hard. The presence of magnesium in water is a
factor contributing to the formation of scale and insoluble soap curds.
MANGANESE
An element sometimes found dissolved in ground water, usually with dissolved
iron but in lower concentrations; causes black stains and other problems similar
to iron.
MANGANESE GREENSAND
Greensand which has been processed to incorporate in its pores and on its
surface the higher oxides of manganese. The product has a mild oxidizing power.
and is often used in the oxidation and precipitation of iron.
manganese and/or hydrogen sulfide. and in their removal from water.
MEDIA
The selected materials in a filter that form the barrier to the passage of
certain suspended solids or dissolved molecules.
MEDIUM
Singular form of media.
MG/L
The abbreviation for milligrams per liter.
MICRON
A linear measure equal to one millionth of a meter.
MICRON RATING
The term applied to a filter to indicate the particle size of suspended solids
that will be removed. As used in industry standards. this is an "absolute" not
"nominal" rating.
MILLIGRAM PER LITER (mg/I)
A unit concentration of matter used in reporting the results of water and waste
water analyses. In diluted water solutions. it is practically equal to the part
per million, but varies from the ppm in concentrated solutions such as brine.
As most analyses are performed on measured volumes of water, the mg/l is a more
accurate expression of the concentration. and is the preferred unit of measure.
MILLIMICRON
A unit of length equal to one thousandth of a micron, often used to express the
wavelength of colors of visible light in colorimetric analytical procedures. The
symbol for the millimicron is "mu."
MINERAL
A term applied to inorganic substances (such as rocks and similar matter) found
in the earth strata, as opposed to organic substances such as Plant and animal
matter. Minerals normally have definite chemical composition and crystal
structure. 'The term is also applied to matter derived from minerals. such as
the inorganic ions found in water. The term has been incorrectly applied to ion
exchangers, even though most of the modern materials are organic ion exchange
resins.
MOLE
The molecular weight of a chemical compound expressed in grams.
MOLECULE
The simplest combination of atoms that will form a specific chemical compound;
the smallest particle of a substance which will still retain the essential
composition and properties of that substance, and which can be broken down only
into atoms and simpler substances.
MOST PROBABLE NUMBER (MPN)
The term used to indicate the number of organisms which, according to
statistical theory, would be most likely to produce the results observed in
certain bacteriological tests; usually expressed as a number in 100 ml of water.
NEGATIVE CHARGE
The electrical charge on an electrode or ion in solution due to the presence of
an excess of electrons.
NEUTRAL
In electrical systems. the term used to indicate neither an excess nor a lack of
electrons; a condition of balance between positive and negative charges. In
chemistry. the term used to indicate a balance between acids and bases; the
neutral point on the pH scale is 7.0. indicating the presence of equal numbers
of free hydrogen (acidic) and hydroxide (basic) ions.
NEUTRALIZATION
In general the addition of either an acid or a base to a solution as required to
produce a neutral solution. The use of alkaline or basic materials to neutralize
the acidity of some waters is a common practice in water conditioning.
NONCARBONATE HARDNESS
Water hardness due to the presence of compounds such as calcium and magnesium
chlorides, sulfates or nitrates; the excess of total hardness over total
alkalinity.
OPERATING PRESSURE
The range of pressure, usually expressed in pounds per square inch. over which a
water conditioning device or water system is designed to function.
OSMOSIS
A process of diffusion of a solvent (such as water) through a semi-permeable
membrane which will transmit the solvent but impede most dissolved substances.
The normal flow of solvent is from the dilute solution to the concentrated
solution.
OXIDATION
A chemical process in which electrons are removed from an atom. ion or compound.
The addition of oxygen is a specific form of oxidation. Combustion is an
extremely rapid form of oxidation, while the rusting of iron is a slow form.
PARTICLE SIZE
As used in industry standards, the size of a particle suspended in wat.er as
determined by its smallest dimension. usually expressed in microns.
PARTS PER MILLION (ppm)
A common basis for reporting the results of water and waste water analyses,
indicating the number of parts by weight of a dissolved or suspended
constituent. per million parts by weight of water or other solvent. In dilute
water solutions. one part per million is practically equal to one milligram per
liter. which is the preferred unit.
PATHOGEN
An organism which may cause disease.
PERMANENT HARDNESS
Water hardness due to the presence of the chlorides and sulfates of calcium and
magnesium, which will not be precipitated by boiling. This term is largely
replaced by IInoncarbonate hardness. 01 pH: The reciprocal of the logarithm of
the hydrogen ion concentration. The pH scale is from zero to 14. and 7.0 is the
neutral point. indicating the presence of equal concentrations of free hydrogen
and hydroxide ions. pH values below 7.0 indicate increasing acidity. and pH
values above 7.0 indicate increasing base concentrations.
PH
The reciprocal of the logarithm of the hydrogen ion concentration. The pH scale
is from zero to 13, and 7.0 is the neutral point, indicating the presence of
equal concentrations of free hydrogen and hydroxide ions, pH values below 7.0
indicate increasing acidity, and pH values above 7.0 indicate increasing base
concentrations.
PORTABLE EXCHANGE
A term applied to water softeners and filters which are designed for connection
to a water system with special fittings, and disconnection and transport to a
central station or plant for regeneration or servicing.
POSITIVE CHARGE
The electrical charge on an electrode or ion in solution due to the removal of
electrons.
PPM
The abbreviation for part per million.
PRECIPITATE
To cause a dissolved substance to form a solid particle which can be removed by
settling or filtering, such as in the removal of dissolved iron by oxidation,
precipitation, and filtration. The term is also used to refer to the solid
formed. and to the condensation of water in the atmosphere to form rain or snow.
PRESSURE DIFFERENTIAL
The difference in pressure between two points in a system due to differences in
elevation and/or pressure drop due to flow.
PRESSURE DROP
A decrease in water pressure during flow due to internal friction between
molecules of water, and external friction due to irregularities or roughness in
surfaces past which the water flows.
RATED CAPACITY
The basis for calculating the number of gallons delivered by a water softener
between regenerations. or amount of time between servicing of a filter. as
determined under specific test conditions.
RATED PRESSURE DROP
The pressure drop of a freshly regenerated and/ or backwashed water softener or
filter at the rated service flow. with clean water at a temperature of 60 F. as
determined under standard test conditions.
RATED SERVICE FLOW
The manufacturer's specified maximum flow rate at which a water softener will
deliver soft water. or a filter will deliver quality water (as specified for its
type) as determined under standard test conditions. A manufacturer may also
specify a minimum flow rate or a range of service flows.
RATED SOFTENER CAPACITY
A water softener capacity rating based on grains of hardness removed while
producing soft water between successive regenerations. and related to the pounds
of salt required for each regeneration as determined under standard test
conditions.
RAW WATER
Untreated water or any water before it reaches a specific water treatment device
or process.
REDUCTION
A chemical process in which electrons are added to an at<gn. ion or compound.
RED WATER
Water which has a reddish or brownish appearance due to the presence of
precipitated iron and/or iron bacteria.
REGENERANT
A solution of chemical compound used to restore the capacity of an ion exchange
system. Sodium chloride brine is used as a regenerant for ion exchange water
softeners; acids and bases are used as regenerants for the cation and anion
resins used in demineralization.
REGENERATION
In general, includes the backwash, brine, and fresh water rinse steps necessary
to prepare a water softener exchange bed for service after exhaustion.
Specifically, the term may be applied to the "brine" step in which the sodium
chloride solution is passed through the exchanger bed. The term may also be used
for similar operations relating to demineralizers and certain filters.
REGENERATION LEVEL
The quantity of regenerant used in regeneration of an ion exchange unit or
system, usually expressed in pounds per regeneration and/ or pounds per
regeneration per cubic foot of ion exchange.
RESIDUAL
The amount of a specific material remaining in the water following a water
treatment process. May refer to material remaining as a result of incomplete
removal (see Leakage) or to material meant to remain in the treated water (see
Residual Chlorine).
RESIDUAL CHLORINE
The amount of chlorine found in the water after treatment.
RESIN
Synthetic organic ion exchange material, such as the high capacity cation
exchange resin widely used in water softeners.
REVERSE DEIONIZATION
The use of the anion exchange resin ahead of the cation exchange resin (the
reverse of the usual order) in a deionization system.
REVERSE OSMOSIS
A process for the removal of dissolved ions from water. in which pressure is
used to force the water through a semi-permeable membrane. which will transmit
the water but reject most other dissolved materials.
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