Mercury Switch Analysis
GROUP MEMBERS:
Darrell Biggs
Melissa Bauer
Frank Bain
Fred DeSanti
Project Focus
Research the dangers of mercury
switches
Analyze their usefulness
Discuss alternatives to mercury tip/
tilt switches
Compare costs of the different
alternatives
Mechanics of a Tilt/Tip Switch
Consists of a glass or metal encasement
Two electrode contacts on one side
Free floating ball of mercury or another
conductor enclosed in the encasement
This ball allows current to flow between
the electrodes
Switching Device in “Off”
Position
Tube
Electrodes
Ball Bearing or Mercury Ball
Figure 1.1
Switching Device in “On”
Position
Tube
Ball Bearing or Mercury Ball
Electrodes
Figure 1.2
Design of Mercury Switch
Figure 1.3a
Design of Ball Switch
Figure 1.3b
Actual Mercury Switch and Ball
Switch
Ball switch
Mercury switch
Figure 1.4
Why Mercury is Used
Liquid at room temperature
Sensitive to small movements
Surrounds the electrode which allows it
to pass larger amounts of current
Conducts electricity
Products Which Contain
Mercury Switches
Thermostats that contain 2 to 6
switches each
Space heaters where it is used as a
safety device
Steam irons (safety device)
Flotation devices to control the amount
of fluid in a tank
Mobile homes used as a leveling device
Car trunk and hood lamps
Hazards of Mercury Use
HIGHLY TOXIC
Can remain in the atmosphere for up to a
year
Does not degrade in the environment
Primary source of exposure is through water
supply
Causes severe damage to body through
inhalation and ingestion of contaminated fish
What Alternatives Are There to
Mercury Switches?
Switches which use ball bearings
instead of mercury
Experimental material with mercury-like
properties in a vacuum but unstable in
air
(high cost)
Life Cycle Cost Comparison
Research &
Development
Machining &
Operating
Disposal
Mercury
Switch
$20,000
$35,000
$1,400
Ball
Switch
$50,000
$35,000
Minimal
Table 1.1
Multi-Attribute Economic
Analysis
Factors
Weight
MS
BS
Life cycle cost .35
60
50
Environmental .10
Effects
Safety
.25
30
100
40
90
Ease of Use
.30
80
80
Sum =
1.0
58.0
74.0
Customer Point of View
Table 2.1
Multi-Attribute Economic
Analysis
Factors
Weight
MS
BS
Life cycle cost .30
60
50
Environmental .15
Effects
Safety
.35
50
100
30
90
Ease of Use
.20
70
70
Sum =
1.0
50.0
75.5
Company Point of View
Table 2.2
Solutions
Discontinue use
of mercury in
household products
Pass legislation to
control the use
and recycling of
mercury in industry
Arrange collection
facilities for used
mercury
Acknowledgements
Mr. Robert Romano,
President Comus Intl.,
Nutley, NJ
Dr. James Luxhoj,
Rutgers University
Dr. Priscilla Hayes,
Cook College
Mercury Switch Analysis
?? QUESTIONS ??