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Single point application Single point application using a remote meter Single point application using an automatic switchover standby Multi-point application Multi-point application using an automatic switchover standby Injecting chlorine into a pipe line using supply pressure Injecting chlorine into a pipe line using a centrifugal pump Injecting chlorine into a pipeline using a turbine positive displacement pump![[Section Divider]](wave.gif){kind=small}
Frequently Asked Questions
Q - How is chlorine used to disinfect water?
Q - I heard that chlorine can be an irritant and
may even be toxic in certain situations. What about chlorine safety considerations?
Q - What is a sulfonator?
Q - What happens to an operating chlorinator/sulfonator
if the water source is shut off? What if the vacuum line is damaged or disconnected?
Q - I heard that sulfur dioxide can be an irritant
and may even be toxic in certain situations. What about sulfur dioxide safety
considerations?
Q - Can one chlorinator/sulfonator be used to inject
gas into multiple water lines?
Q - Can a pair of chlorinators/sulfonators configured
as an automatic switchover system supply a single water line? A - Yes.
Q - Can multiple chlorinators/sulfonators draw gas
from a single container or tank?
Q - What is dechlorination?
Q - How is the amount/rate of gas passing through
a chlorinator/sulfonator device controlled and measured?
Q - What is chlorine?
A - Chlorine Chlorine is a chemical element that can be found in liquid, gaseous,
or solid state. It is reactive and most commonly found mixed with other compounds.
It is among the most common of elements. The salt and other compounds in sea water
are a large source of chlorine.
Chlorine gas mixed with water in precisely controlled amounts kills bacteria and
microbiological organisms in water. It is globally used for reliable water disinfection.
Chlorine also has the advantage of insuring clean water up to the end-users tap.
The actions of other types of water disinfectants, such as ozone and ultraviolet
light, are only temporary. Chlorine also helps remove tastes and odors and controls
the growth of slime and algae in mains, pipes, and storage tanks.
Liquid chlorine evaporates at temperatures above minus 30°F at normal atmospheric
pressure . It is normally kept and transported in special containers or tanks
of varying sizes; 100 lbs, 150 lbs, and ton size being the most common. These
containers are designed to allow the equilibrium pressure of the evaporating and
expanding chlorine gas inside to maintain the liquid state of the chlorine. The
gaseous chlorine can then discharged out the top of the container, precisely measured
and controlled through a chlorinator, and injected into the water supply to be
disinfected.
A - It is accomplished through the process known as chlorination.
A - Chlorine Safety Considerations:
During the last century, in the United States and abroad, chlorine gas has been
proven to be a safe and most effective way to disinfect water supplies. The practice
of chlorinating public drinking and waste water has been one of the most profound
positive steps forward in assuring overall public good health. In fact, an article
in Life Magazines' Fall, 1997 Millennium Issue reports "water purification" as
ranking 46th in the top 100 advances of the past 1000 years; ahead of other major
health-related achievements such as the discovery of DNA, X-rays and anesthetics.
Chlorine gas is not considered to be toxic, but it is a respiratory, eye, and
possible skin irritant. It can cause breathing difficulties and even suffocation
in very high concentrations.
Chlorine is not explosive or flammable, but can support combustion.
There is no question that all forms of chlorine must be used and handled with
appropriate knowledge, care, and respect in order to eliminate the potential for
unsafe conditions.
Chlorine gas is easy to visually identify because it is yellowish or green in
color and is considerably denser then air. Therefore, the gas will sink into low-lying
places, allowing one to see it and escape.
Because of the density and expansion factors, chlorine containers should never
be placed in direct sunlight or exposed to other direct or indirect heating sources!
Chlorine should never be put in the proximity of large quantities of ammonia,
since the two can react violently.
It should also be noted that chlorine is corrosive to many common metals and other
substances.
A - Due to the high concentrations of bacteria and other microbiological organisms
in waste water, commensurate high concentrations of chlorine are necessary for
proper disinfection. Treated waste water is discharged to tributaries through
NPDES (National Pollutant Discharge Elimination System) outfalls, and an NPDES
permit restricts the allowable chlorine concentration of the discharged water.
Sulfonators are used to inject measured amounts of sulfur dioxide into chlorinated
waste water for the purpose of dechlorination.
A - The water passing through the ejector device creates the vacuum which draws
the gas through the connected chlorinator/sulfonator device. Therefore, if the
water source is turned off or if the vacuum line is damaged or disconnected, the
necessary vacuum is lost and the flow of gas is stopped.
Neither the chlorinator/sulfonator or ejector devices require electrical power
to operate.
A - Sulfur Dioxide Safety Precautions:
Sulfur dioxide gas is not considered to be toxic, but it is a respiratory, eye,
and possible skin irritant. It can cause breathing difficulties similar to the
symptoms of a chest cold.
All forms of sulfur dioxide gas must be used and handled with appropriate knowledge,
care, and respect in order to eliminate the potential for unsafe conditions.
Sulfur dioxide gas is colorless and therefore is not easy to visually identify.
It has a distinctive pungent odor that will alert the user of a leak in ample
time before irritation can occur. It is somewhat denser then air and will sink
to low-lying spaces.
Because of the density and expansion factors, sulfur dioxide containers should
never be placed in direct sunlight or exposed to other direct or indirect heating
sources!
It should also be noted that sulfur dioxide is corrosive to many common metals
and other substances.
A - Yes.
A - Yes. Multiple chlorinators or sulfonators can draw gas from a single source
and feed correspondingly multiple water or waste water disinfection systems. This
is done through the use of a manifold device which mounts on the container and
allows multiple chlorinators or sulfonators to be attached.
The reader is asked to keep in mind that the capacity of the container must be
sufficient to allow for the sum total of the simultaneous gas draws from all the
devices mounted on the manifold.
A - The practice of removing all or a controlled part of a total combined chlorine
residual in water or wastewater. Dechlorination is normally accomplished through
the measured injection of sulfur dioxide, utilizing a sulfonator device.
Sulfur dioxide reacts with chlorine to form hydrochloric acid, thereby removing
chlorine. The amount of hydrochloric acid formed is minimal, and has very little
effect on the pH of the discharged wastewater.
A - All chlorinators and sulfonators are designed so that the outgoing gas must
pass through a flow meter which controls and measures the gas up to the maximum
allowed for the device.
The Practical Advantages of Chlorine Gas Disinfection
Chlorination of water supplies can be achieved using three different chemical mediums; chlorine gas, calcium hypochlorite (available as a solid in granular form), or sodium hypochlorite (the equivalent to liquid bleach).
The practical advantages and disadvantages of each are summarized in the following
table (White, 1996):
| Gas | Calcium Hypochlorite | Sodium Hypochlorite | |
| % Concentration by Weight of Available Chlorine | 100% | 65% | 3% to 12.5% |
| Quantity of Media Required | Low | Moderate | High |
| Required Storage Space | Minimal | Moderate | High |
| Transportation Costs | Minimal | Minimal | High |
| Safety Concerns (Chlorine gas is a skin and mucous membrane irritant. Chlorine gassings can be the result of a leak from a gas chlorine system or off gassing from sodium hypochlorite liquid or the predisinfection solution prepared by mixing water with calcium hypochlorite). |
|
|
|
| Chemical Addition | None | Calcium | Sodium |
| Decomposition (Degradation of potency with time, as dependent on conditions, while releasing chlorine gas) |
None | Moderate | High |
| Personnel Oversight | Minimal | High | Moderate |
| Additional Comments | "Clean" application | "Messy" application and residue problems are common | "Messy" application |
To summarize, the advantages of GAS chlorination are obvious.
The only theoretical disadvantage is the potential for a gas leak in poorly designed systems. For this reason, all chlorinators are designed to mount directly onto the chlorine cylinder, thereby eliminating ANY pressure lines. Gas chlorination systems are vacuum operated, therefore if a break in the system occurs it automatically shuts down, eliminating the potential for a leak. Hypochlorite systems inject the treatment solutions (at 10 to 15% concentration) directly into the water stream under pressure. If a leak in a hypochlorite treatment system occurs, copious volumes of treatment solution can be released and chlorine gas is immediately vaporized from the concentrated solutions into the surrounding atmosphere. For this reason, hypochlorite systems are no safer than chlorine gas systems.
Besides these practical advantages there are also considerable economic
advantages for the usage of chlorine gas disinfection.
The Economic Advantages of Chlorine Gas Disinfection
The following table clarifies the economic advantages of gas chlorination
disinfection by comparing the necessary capital investment, chemical costs,
and personnel requirements to treat one million gallons per day (1 MGD) of drinking
water to a concentration of one PPM (part of chlorine per million parts of water,
which is equivalent to one mg/L).
| Chlorine Gas (100%) |
Calcium Hypochlorite (65%) |
Sodium Hypochlorite (12.5%) |
|
| Required Equipment | (1)Model 500 chlorinator (1)Booster pump (1)150lb. chlorine cylinder |
(1)Metering Pump (1)50 gal. tank with lid (1)Agitator (1)Level switch |
(1)Metering Pump (1)50 gal. tank with lid (1)Level switch |
| Initial Capital Investment |
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|
|
| Media Quantity Required per Year | 3,030 pounds | 4,661 pounds | 2,920 gallons (app. 24,344 pounds) |
| Chemical Cost per Media Unit * | $0.93/pound | $1.74/pound | $1.75/gallon |
| Chemical Cost per Year | $2,817.90 | $8,110.14 | $5,110.00 |
| # Days Between Media Refill | 18 | app. 7 | app. 6 |
| * Costs vary with geographic location. | |||
Admittedly the initial capital investment for a chlorine gas system is slightly higher than for hypochlorite treatment, however the savings in chemical cost far outweighs the equipment costs, just in the first year. In addition, the personnel oversight required for a hypochlorite system is greater and could be a cause of problems over weekends or holidays.
Besides these economic advantages there are also considerable practical
advantages for the usage of chlorine gas disinfection.
fewest parts
cylinder mounted
modular, not unitary design
mix and match flexibility
all components
are machined, not molded
elastomer
coated yoke
fits any size cylinder
machined from ABS
stable in outdoor installations
resists UV light
simplest
design
all components have closer tolerances than molded
complete 360o gap throat
highest vacuum at lowest flow
three piece check valve
large Teflon
diaphragm
PVDF
alloy seat
Hastelloy "C" spring assembly
operator friendly
inspections without downtime
compatible with all regulators
interchangeability
in any vacuum system
inert to chlorine
simplest design and fewest parts
all components are protected from stress fatigue failure
all components are guaranteed for two full years
panel for
wall mounting
all
components impervious to gas
controls in one place
no fail switching mechanism
no cylinder heel
safest design
no toggles to corrode
has manual override
insures
standby cylinder is open
no pressure means no incidents
safest possible operation
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