Feed-Forward Instantaneous Water Heater

Download Report

Transcript Feed-Forward Instantaneous Water Heater

Legionella.
What is it and how do we treat it?
www.armstronginternational.com
©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
“Expect many enjoyable experiences!”
David M. Armstrong
2
Legionella Pneumophila
• Most common species of all
• 15 serogroups
• Serogroup 1 has at least 50 subtypes
• Causes 85 to 90 percent of all cases
“Expect many enjoyable experiences!”
David M. Armstrong
3
What is Legionaires’ Disease?
• A multisystem illness with a deadly type of
pneumonia
• Named by the press to identify the unknown
bacterium
“Expect many enjoyable experiences!”
David M. Armstrong
4
Legionaires’ Disease
• First identified – Bellevue-Stratford Hotel –
Philadelphia, July of 1976
• Illness struck 221 people
• 72 who did not attend the convention
• 34 died
“Expect many enjoyable experiences!”
David M. Armstrong
5
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
“Expect many enjoyable experiences!”
David M. Armstrong
6
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
“Expect many enjoyable experiences!”
David M. Armstrong
7
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
“Expect many enjoyable experiences!”
David M. Armstrong
8
Legionaires’ Disease
• Considered an environmental disease – water to
people. Not communicable.
• Transmission occurs when airborne water
droplets containing Legionella are inhaled
“Expect many enjoyable experiences!”
David M. Armstrong
9
The Risk of Infection is Based on Two
Key Factors
1. The number of bacteria reaching the body
2. The resistance of the individual
“Expect many enjoyable experiences!”
David M. Armstrong
10
Legionella – Where does it come from?
• Poorly treated water
• Poorly designed plumbing systems
• Poorly treated plumbing systems
“Expect many enjoyable experiences!”
David M. Armstrong
11
Primary Sources of Legionellae Bacteria
• Domestic Hot Water Systems
• Cooling Towers
• Evaporative Condensers
• Respiratory Care Equipment
• Showers
“Expect many enjoyable experiences!”
David M. Armstrong
12
Primary Sources of Legionellae Bacteria
• Faucets
• Whirlpool Baths
• Humidifiers
• Fountains
• Grocery Store Produce Mister
“Expect many enjoyable experiences!”
David M. Armstrong
13
Legionella – Where does it live?
• Bacterial amplifiers
• Biofilm within plumbing systems
“Expect many enjoyable experiences!”
David M. Armstrong
14
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)
“Expect many enjoyable experiences!”
David M. Armstrong
16
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
“Expect many enjoyable experiences!”
David M. Armstrong
17
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
“Expect many enjoyable experiences!”
David M. Armstrong
18
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
“Expect many enjoyable experiences!”
David M. Armstrong
19
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)
“Expect many enjoyable experiences!”
David M. Armstrong
20
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
“Expect many enjoyable experiences!”
David M. Armstrong
21
Superheat & Flush Negatives
• Potential scald risk
• Non-effective unless sterilization temperature is
achieved (biofilm)
• Dead-legs may not permit adequate flushing
“Expect many enjoyable experiences!”
David M. Armstrong
22
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
-----“Expect many enjoyable experiences!”
David M. Armstrong
23
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
“Expect many enjoyable experiences!”
David M. Armstrong
24
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
“Expect many enjoyable experiences!”
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
“Expect many enjoyable experiences!”
David M. Armstrong
30
Hyperchlorination Positives
• Inexpensive
• Effectively kills bacteria in the water
“Expect many enjoyable experiences!”
David M. Armstrong
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
“Expect many enjoyable experiences!”
David M. Armstrong
32
Ultra Violet Positives
• Harmless and non-toxic
• Effectively kills bacteria in the water
“Expect many enjoyable experiences!”
David M. Armstrong
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
“Expect many enjoyable experiences!”
David M. Armstrong
34
Ozone Positives
• Effectively kills bacteria in the water
“Expect many enjoyable experiences!”
David M. Armstrong
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
“Expect many enjoyable experiences!”
David M. Armstrong
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
“Expect many enjoyable experiences!”
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
“Expect many enjoyable experiences!”
David M. Armstrong
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
“Expect many enjoyable experiences!”
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
“Expect many enjoyable experiences!”
David M. Armstrong
40
Questions?
“Expect many enjoyable experiences!”
David M. Armstrong
41