Mercury Switch Analysis

GROUP MEMBERS:Darrell BiggsMelissa Bauer

Frank BainFred 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 encasementTwo 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

Electrodes

Tube

Ball Bearing or Mercury Ball

Figure 1.1

Switching Device in “On” Position

Tube

Electrodes

Ball Bearing or Mercury Ball

Figure 1.2

Design of Mercury Switch

Figure 1.3a

Design of Ball Switch

Figure 1.3b

Actual Mercury Switch and Ball Switch

Mercury switch Ball switch

Figure 1.4

Why Mercury is Used

Liquid at room temperatureSensitive to small movementsSurrounds 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 eachSpace heaters where it is used as a safety deviceSteam irons (safety device) Flotation devices to control the amount of fluid in a tankMobile homes used as a leveling device

Car trunk and hood lamps

Hazards of Mercury Use

HIGHLY TOXICCan remain in the atmosphere for up to a yearDoes not degrade in the environmentPrimary 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

$20,000 $35,000 $1,400

$50,000 $35,000 Minimal

Research & Development

DisposalMachining & Operating

MercurySwitch

BallSwitch

Table 1.1

Multi-Attribute Economic Analysis

Life cycle cost .35 60 50

Environmental Effects

.10 30 100

Safety .25 40 90

Ease of Use .30 80 80

Sum = 1.0 58.0 74.0

Customer Point of View

Factors Weight MS BS

Table 2.1

Multi-Attribute Economic Analysis

Life cycle cost .30 60 50

Environmental Effects

.15 50 100

Safety .35 30 90

Ease of Use .20 70 70

Sum = 1.0 50.0 75.5

Company Point of View

Factors Weight MS BS

Table 2.2

Solutions

Discontinue use of mercury in household productsPass legislation to control the use and recycling of mercury in industryArrange collection facilities for used mercury

Acknowledgements

Mr. Robert Romano, President Comus Intl.,

Nutley, NJDr. James Luxhoj,

Rutgers UniversityDr. Priscilla Hayes,

Cook College

Mercury Switch Analysis

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