Transcript Feed-Forward Instantaneous Water Heater

Legionella.
What is it and how do we treat it?
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©2006 Armstrong International, Inc.
Legionella – What is it?
• Type of bacteria found in bodies of water
• At least 39 species have been identified
• More than 60 serogroups have been identified
• Some serogroups have several subtypes
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Legionella Pneumophila
• Most common species of all
• 15 serogroups
• Serogroup 1 has at least 50 subtypes
• Causes 85 to 90 percent of all cases
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What is Legionaires’ Disease?
• A multisystem illness with a deadly type of
pneumonia
• Named by the press to identify the unknown
bacterium
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Legionaires’ Disease
• First identified – Bellevue-Stratford Hotel –
Philadelphia, July of 1976
• Illness struck 221 people
• 72 who did not attend the convention
• 34 died
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Did you know?
• 2.4 million cases of pneumonia each year in the
U.S.
• 10,000 to 100,000 are cases of Legionaires’
disease
• Only 1,000 to 3,000 are reported to CDC
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Legionaires’ Disease
• Cases go undetected due to lack of testing
• Other cases missed because test procedures
are not sensitive enough
• Deaths from undetected cases classified as
pneumonia with an unknown cause
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Legionaires’ Disease
• Most cases occur one or two cases at a time and
not an outbreak
• Sporadic cases generally not reported to the
public
• Overall opinion is that the problem is not that
great
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Legionaires’ Disease
• Considered an environmental disease – water to
people. Not communicable.
• Transmission occurs when airborne water
droplets containing Legionella are inhaled
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The Risk of Infection is Based on Two
Key Factors
1. The number of bacteria reaching the body
2. The resistance of the individual
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Legionella – Where does it come from?
• Poorly treated water
• Poorly designed plumbing systems
• Poorly treated plumbing systems
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Primary Sources of Legionellae Bacteria
• Domestic Hot Water Systems
• Cooling Towers
• Evaporative Condensers
• Respiratory Care Equipment
• Showers
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Primary Sources of Legionellae Bacteria
• Faucets
• Whirlpool Baths
• Humidifiers
• Fountains
• Grocery Store Produce Mister
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Legionella – Where does it live?
• Bacterial amplifiers
• Biofilm within plumbing systems
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Storage Tank Feed-Back System
Temperature signal
is “fed back” through
capillary tube
Temperature
Reg Valve
Thermometer
Heated Water
Safety
Relief
Valve
Liquid or Gas
Filled Bulb
P
Storage Tank
Steam
Supply
V.B.
F&T
Trap
Condensate
Return
Recirculatin Pump
Recirculated Water
Make Up Water
Legionellae and Temperature
• Below 68°F legionellae can survive but are dormant
• Legionellae growth range (68°F – 122°F)
• Ideal growth range (95°F – 115°F)
• Above 122°F legionellae can survive but do not multiply
• At 131°F legionellae die within 5 to 6 hours
• At 140°F legionellae die within 32 minutes
• At 151°F legionellae die within 2 minutes
• Disinfection range (158°F - 176°F)
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Preventive Measures
• Maintain mechanical and plumbing systems for
the control of Legionella
• If you are high risk for Legionella consider more
costly measures to fix your systems and reduce
the risks
• Document all preventive measures to show you
took responsible action
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Environmental Samplings
• CDC does not recommend regular water
sampling
• Negative results may create a false sense of
security and positive results a false alarm
• Sampling results, though sometime inconclusive,
provide lifesaving information
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Samplings – Yes or No?
• Weigh value of information provided against the
cost
• Weigh the risk of misleading sampling against
the risk of not sampling
• Consider risk management
• DO NOT use as a substitute for preventive
measures
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Methods of System Treatment
• Superheat and Flush (thermal)
• Feed-Forward Instantaneous Water Heaters
(thermal)
• Hyperchlorination (biocide)
• Ultra Violet Rays (biocide)
• Ozone (biocide)
• Chlorine Dioxide (biocide)
• Copper/Silver Ionization (biocide)
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Superheat & Flush Positives
• Inexpensive
• Proven effective irrespective of water quality
• Non aggressive to pipe work and fittings
• Non toxic/consumable
• No professionally qualified personnel required to
administer treatment
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21
Superheat & Flush Negatives
• Potential scald risk
• Non-effective unless sterilization temperature is
achieved (biofilm)
• Dead-legs may not permit adequate flushing
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Temperature/Time Burn Chart
Temperature in F°
Time for 1st degree burn
111.2
5 hours
116.6
35 minutes
118.4
10 minutes
122.0
1 minute
131.0
5 seconds
140.0
2 seconds
149.0
1 second
158.0
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What types of Water Heaters are on the
market today?
• Feed-Back Units: Operate on a differential of
water TEMPERATURE
• Feed-Forward Units: Operate on a differential of
water PRESSURE
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Storage Tank Feed-Back System
Temperature signal
is “fed back” through
capillary tube
Temperature
Reg Valve
Thermometer
Heated Water
Safety
Relief
Valve
Liquid or Gas
Filled Bulb
P
Storage Tank
Steam
Supply
V.B.
F&T
Trap
Condensate
Return
Recirculatin Pump
Recirculated Water
Make Up Water
Feed-Forward Instantaneous Water Heater
Control Valve Schematic
Blended Water Out @ P2
Mixing
Chamber
“Over-heated”
Water from
tube bundle
Valve #3
P1
P2
Valve #2
Supply Water In @ P1
Valve #1
Tube
Bundle
Feed-Forward Instantaneous Water
Heater Positives
• Sterilizes water in the heat exchanger as a
function of making hot water
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David M. Armstrong
27
Feed-Forward Instantaneous Water Heater
Control Valve Schematic
Blended Water Out @ P2
Mixing
Chamber
“Over-heated”
Water from
tube bundle
Valve #3
P1
P2
Valve #2
Supply Water In @ P1
Valve #1
Tube
Bundle
Feed-Forward Instantaneous Water
Heater Positives
• Sterilizes water in the heat exchanger as a
function of making hot water
• Non aggressive to pipe work and fittings
• Non toxic/consumable
• No scald risk
“Expect many enjoyable experiences!”
David M. Armstrong
29
Feed-Forward Instantaneous Water
Heater Negatives
• Water which bypasses the heat exchanger is not
sanitized
• Does not kill bacteria in the system biofilm
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David M. Armstrong
30
Hyperchlorination Positives
• Inexpensive
• Effectively kills bacteria in the water
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31
Hyperchlorination Negatives
• Hazardous material which requires trained
operators in order to handle
• The chemical is a carcinogen
• Aggressive to pipe work and fittings
• Does not kill bacteria in the biofilm
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32
Ultra Violet Positives
• Harmless and non-toxic
• Effectively kills bacteria in the water
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33
Ultra Violet Negatives
• Expensive
• Only effective at point of treatment
• High maintenance cost – lamps wear out and
are fragile and need replacement
• Micro organisms can become resistant and
repair UV damage
• Does not kill the bacteria in the biofilm
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34
Ozone Positives
• Effectively kills bacteria in the water
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35
Ozone Negatives
• Difficult to maintain effective levels of ozone in
the system – decomposes into water
• High ozone levels may damage pipe
• Not tested in facilities – its use would be
pioneering
• Does not kill the bacteria in the biofilm
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36
Chlorine Dioxide Positives
• Effectively kills bacteria in the water
• Early indications show potential of killing
bacteria in the biofilm as well as removal of
biofilm
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David M. Armstrong
37
Chlorine Dioxide Negatives
• Expensive
• Concentration levels required often exceed
health standards – health & safety issues
• Aggressive to copper piping
• Needs special storage – hazardous material
• Chemical (Potassium, Chlorate and Hydrochloric
Acid) is unstable – may explode
• Professionally qualified personnel required
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38
Copper/Silver Ionization Positives
• Use of sacrificial anodes produce ions that kill
Legionellae bacterial in the water
• Ions also kill bacteria in the biofilm
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David M. Armstrong
39
Copper/Silver Ionization Negatives
• Expensive
• Constant monitoring of ion levels
• Sacrificial anodes need regular replacement
• Ion levels can become toxic if they accumulate
• Professionally qualified personnel required
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David M. Armstrong
40
Questions?
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David M. Armstrong
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