Reproduced with the permission of the Controller of HMSO
and the Queen's Printer for Scotland.
Identification: Mercury containing pressure gauges, which can be found in many settings, can be identified by the presence of a tube containing silver liquid in an instrument used to measure pressure. Weather barometers are used to determine atmospheric pressure. There are various types of mercury barometers available for home, commerical, and laboratory uses. For example, Barometers may contain a large volume of mercury held in a reservoir. Collectable antiques are often mounted on a decorative wooden plaque or on a highly polished metal mounting. Laboratory and commercial barometer units are less decorative and built for functionality.
Mercury Content: Mercury content generally ranges from 300 to 600 grams. Rare old collectable barometers have been found to contain as much as 6 kilograms (P.Collins, Barometer World Ltd, 2003, personal communication).
Alternatives: Aneroid and digital options are usually available. Electronic programmable and digital barometers are also considered to be accurate as the mercury barometer (Galligan et al., 2002).
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Batteries
Use: Mercury-containing batteries generally consist of the button cell type found in wrist watches, hearing aids, calculators, and various types of applications in labs, hospitals, and military and commercial facilities (NEWMOA, 2003).
Description: Mercury oxide, silver oxide, and button cell batteries are the most common mercury-containing batteries (NEWMOA, 2003). Since the late 1990s North American battery manufacturers have reduced mercury content in batteries by 95%. The use of mercury in alkaline batteries has been eliminated except for button cells (GLBTS, 2003).
Identification: Observing battery packaging is the best method of identifying mercury-containing batteries. Product labels may also be helpful in identifying mercury-containing batteries.
Mercury content: Batteries generally contain between 5 and 25 milligrams of mercury per battery. Specialty batteries for labs, hospitals, and military and commerical applications may have a higher mercury content (NEWMOA, 2003).
Alternatives: Where practical, electrical devices are preferable to battery-operated products. The use of rechargeable batteries is also a good alternative. Alkaline batteries are less durable than mercury batteries. Most batteries have an alternative replacement of the rechargeable type. Not all replacements may be compatible with products. Consult with device manufacturer's directions for replacement criteria. Rechargeable batteries are initially more expensive, but cost recovery can be quick depending on use.
If not properly disposed of, all batteries are an environmental hazard. Rechargeable and disposable batteries are recyclable where programs exist.
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Dental Amalgam
Use: Dental Amalgam is used by dentists to fabricate a hard durable tooth filling.
Description: Dental amalgam is used for restoring teeth and is prepared by mixing approximately equal parts of liquid mercury and alloy powder, which typically consists of silver, tin, copper, and zinc.
Identification: Mercury containing amalgam is a metallic silver colour. Mercury can often be found in dental offices in amalgam capsules and possibly in elemental form.
Mercury Content: Silver coloured dental amalgams generally contain about 50% mercury.
Alternatives: Alternative filling materials include; composites, glass ionomers, gold foil, gold alloy, metal-ceramic crowns, and gallium alloys. These options can be more expensive and may not be as durable as mercury amalgams.
When restoring teeth with dental amalgam, use pre-capsulated amalgam to avoid using liquid (elemental) mercury. Purchase the capsules in a variety of sizes in order to better select the right amount of material for a particular restoration.
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Flame Sensors
Use: Mercury flame sensors were used in older gas-fired appliances (e.g. dryers, stoves, and furnances) to open or shut off gas. Another type of flame sensor is used in fire detection systems that are sued to activate sprinkler systems or alarms.
Description: Some older gas-fired appliances may contain mercury flame sensors. A flame sensor consists of a metal bulb and a thin tube attached to a gas-control valve. There is mercury inside the tube and it expands or contracts to open or shut off the gas valve (G&S Mechanical Services, 2003).
Identification: Gas-shut-off flame sensors can usually be identified by a slender, lengthy piece of copper tubing, with one end fitted with a coupling to screw into an appliance and the other end sealed with a slighter larger piece of tubing that contains the mercury (G&S Mechanical Services, 2003).
Mercury content: Sensors contain about 1 gram of mercury.
Alternatives: Due to high cost, retrofitting an appliance with an electric ignition pilot is not recommended unless the appliance is already wired with electricity. However, most new appliances have been manufactured with non-mercury flame sensors (Purdue University, 2003). Old appliances can be replaced with either an appliance with an electric ignition or an electrical appliance.
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Flowmeters
Use: Flowmeters measure the rate of flow of gas, water, air and streams.
Description: Flowmeters are used in water and sewage treatment plants, power stations, and many other industrial applications. Mercury-containing flowmeters are generally no longer manufactured and have been replaced by electronic or digital units (Galligan et al., 2002).
Identification: Flowmeters can be described as having manometers attached to an assembly for the measurement of the rate of flow of a liquid or gaseous substance.
Mercury content: Flowmeters can contain up to 5000 grams of mercury (Purdue University, 2003).
Alternatives: Digital and electronic instrumentation may replace most manometers used in flowmeters. The price range varies depending on the application.
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Hydrometers
Use: Hydrometers measure the specific gravity and density of a liquid.
Description: Hydrometers are most commonly used in laboratories, the petroleum and dairy industries and in the production of alcohol.
Identification: Hydrometers have a long stem of mercury in a glass tube, similar to a laboratory thermometer, except that the bulb at the bottom of the hydrometer is wider and weighted to keep the hydrometer upright when placed in a liquid.
Mercury content: Content can range from 0.002 grams to 1 gram depending on the application and size of instrument.
Alternatives: Alternatives to mercury-containing hydrometers are alcohol-filled, digital, and aneroid hydrometers (NEWMOA, 2003). Alcohol-filled and mercury-filled hydrometers are equally reliable in measuring specific gravity.
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Hygrometers/Psychrometers
Use: Hygrometers measure the moisture content in air. A psychrometer is the most common type of hygrometer.
Description: Psychrometers are best described as dual thermometers, one with a wet base and the other with a dry base. Moisture from the wet base evaporates and absorbs heat causing the thermometer reading to drop. Relative humidity is calculated from he difference between the wet-and dry-base thermometers using a conversion table (Galligan et al., 2002). Although not common in most workplaces, hygrometers/psychrometers are found in workplaces where ambient moisture measurements are used for predicting weather and atmospheric conditions.
© Copyright Commonwealth of Australia 2005,
Bureau of Meteorology (ABN 92 637 533 532),
Hydrometer/Psychrometer, 2005, Government of Australia
Identification: Hygrometers look like industrial thermometers with the distinct attachment of a cotton bulb. Sling psychrometers are designed to be twirled in the air to measure ambient moisture.
Mercury content: Content generally ranges from 3 to 7 grams.
Alternatives: Alternatives include alcohol-filled and digital instruments. Both alternatives are equally reliable to mercury-containing prodcuts. In fact, the digital hygrometers can be more accurate if properly calibrated because human error is eliminated (Galligan et al., 2002).
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Lamps
Introduction
Fluorescent lamps contain small quantities of mercury, an essential component, but are far more energy efficient than incandescent lights. Coal-fired electricity generation is one of the largest sources of mercury emissions in Canada, and the use of fluorescent lamps in place of incandescent bulbs can reduce energy consumption and may, as a result, decrease overall mercury emissions during the lifecycle of the bulb.
All fluorescent lamps contain mercury as it is currently an essential component of the lamps. Currently there are no alternative lighting devices that are as energy efficient as fluorescent lamps. The best option remains selecting low mercury, long-life lamps and disposing end-of-life lamps properly.
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Mercury Containing Lamps Links
Are mercury-containing fluorescent lamps better for the environment than incandescent bulbs?
Mercury is found in fluorescent bulbs for cooking applications, such as mercury use in gas & electric cooking ranges & other cooking equipment. Please see the NEWMOA mercury-added product fact sheet site for more information.
Fluorescent Lamps - Questions and Answers
Below is a list of the various types of lamps containing mercury:
Compact Fluorescent Lamps
Use: Compact fluorescent lamps are frequently used in place of traditional incandescent lights in the hospitality industry, offices, and home lighting systems.
Description: Compact fluorescent lamps have all the same characteristics as linear fluorescent tubes, except they have been designed to replace incandescent bulbs, which are common in residential, commercial, industrial, and accent lighting applications.
Identification: Compact fluorescent lamps are similar in size to the incandescent bulb; however, the bulb has been replaced with a coiled, compact fluorescent tube.
Mercury content: Mercury content is generally between 1 and 25 milligrams.
Alternatives: The compact fluorescent lamp is currently the most energy efficient lamp for its application. Purchase high-efficiency, low-mercury lamps whenever possible.
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Fluorescent U-Tubes
Use: Fluorescent U-Tubes are used in appliances, ceiling fixtures, and display cases. They are usefulwhen fluorescent light is desired, but the available space is too small for traditional linear fluorescent lamps.
Description: Fluorescent U-Tubes have all the same characteristics as linear fluorescent tubes, except they take up half the space of a comparable linear fluorescent.
Identification: Fluorescent U-Tubes can be identified by the distinct U-shaped fluorescent tube.
Mercury content: Mercury content is approximately 3 to 12 milligrams.
Alternatives: Purchase high-efficiency, low mercury lamps whenever possible. Pricing of U-tube lamps is comparable to regular fluorescent lamps. A ballast replacement may be needed to meet optimum operating requirements.
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Fluomeric Lamps
Use: Fluomeric lamps are used as replacement lamps for incandescent systems for a variety of applications. High-wattage fluomeric lamps have long-burning life (up to 20,000 hours) and are ideal for high-bay lighting applications such as industrial lighting, repair shops, street lighting, building facades, security lighting, billboards, and sports arenas. Smaller lower wattage models are suitable for schools, stores, and display lighting.
Description: These lamps are self-ballast and produce brighter light than incandescent lamps. No ballast, wiring, or special fixtures are required to retrofit existing incandescent fixtures (Duro-test lighting, 2003).
Identification: Fluomeric lamps are not very distinguishable from regular incandescent lamps. They can be clear, white (frosted colour), and reflector flood (aluminum reflector with a frosted face). Prodcut labeling and packaging should be examined to determine whether the lamp is fluomeric.
Mercury content: Content is approximately 2 milligrams per lamp.
Alternatives: Alternatives to regular fluomeric lamps include other forms of mercury-reduced lamps. Regular fluomeric lamps can be replaced with more energy efficient mercury reduced units at a comparable price. The initial cost of a fluomeric lamp is considerably more than an incandescent bulb, but the lamp may be used for a longer period of time.
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Linear Fluorescent Lamps
Use: Fluorescent lamps are commonly used to illuminate offices, stores, warehouses, street corners, and homes.
Description: Fluorescent lamps are sealed glass tubes that contain small amounts of mercury (an essential component), inert gas, and phosphor powder coated along the inside of the tubes. Fluorescent lamps are highly efficient, using electric discharge through low-pressure mercury vapour to produce ultraviolet (UV) energy.
Identification: Fluorescent lamps generally range in diameter from 2.54 to 3.81 centimetres (1 to 1.5 inches); and in length rom 0.61 to 2.44 meters (2 feet to 8 feet). Mercury-reduced fluorescent lamps can have a green band or writing at the ends.
Mercury content: Content ranges from 3 to 12 milligrams (mercury-reduced lamps) to 10 to 50 milligrams (non-mercury reduced lamps).
Alternatives: Purchase high-efficiency, low-mercury lamps whenever possible.
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Mercury Vapour Lamps
Use: Mercury vapour lamps are frequently found in several high intensity discharge (HID) lamp applications. They are used as farmyard lights, for street lighting and general floodlighting, and in parking lots.
Description: The lamp consists of a glass envelope with a pinched quartz glass tube and various metal electrodes within. An electronic current is passed through to form an arc to display light.
Identification: Light emission is identifiable by a bluish glow. The quality of colour rendition is not as good as metal halide or high-pressure sodium vapour lamps.
Mercury content: Content varies with wattage from 25 milligrams in a 75-watt lamp to 225 milligrams in a 1500-watt lamp (Purdue University, 2003).
Alternatives: Purchasing high-efficiency, low-mercury lamps whenever possible requires minimal cost. Retrofitting existing systems with non-mercury alternatives (e.g. solid-state lighting) can be costly with a lengthy payback period.
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Metal Halide Lamps
Use: Metal halide lamps are used to light sport stadium fields and other areas where a very bright light is required.
Description: Metal halide lamps are the brightest light available and are frequently found in several HID applications. They offer better lighting than mercury or sodium vapour lamps. Metal halide lamps can take up to 5 minutes to light up after being switched on; or 20 minutes if turned off and on again (ignition and restrike). This light emits a bright white light close in quality to incandescent lamps. Lights must be matched up with ballasts. These lamps are not interchangeable with other high intensity discharge (HID) (Florida Power and Light, 2003).
Identification: Consists of glass envelope with a pinched quartz glass tube and various metal electrodes within. An electronic current is passed through to form an arc and then a light display.
Mercury content: Content varies with wattage from 25 milligrams in a 75-watt lamp to 225 milligrams in a 1500-watt lamp (Purdue University, 2003).
Alternatives: Purchasing high-efficiency, low-mercury lamps whenever possible requires minimal cost. Retrofitting existing systems with non-mercury alternatives can be costly with a lengthy payback period (e.g. solid-state lighting).
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Sodium Vapour Lamps
Use: Sodium Vapour lamps are economical high intensity discharge (HID) lamps used for street lighting and general floodlighting and in parking lots.
Description: Sodium vapour lamps consist of a glass envelope with a pinched quartz glass tube and various metal electrodes within. An electronic current is passed through to form an arc and then a light display. There are two general models of sodium vapour lamps: high-pressure sodium (70-1000 watts) and low-pressure sodium (35-180 watts) (Lamptech, 2003).
Identification: Light emission is identifiable by a yellowish glow.
Mercury content: Mercury mass varies with wattage from 20 milligrams (35-watt lamp) to 145 milligrams (1000-watt lamp) (Purdue University, 2003).
Alternatives: Purchasing high-efficiency, low-mercury lamps whenever possible requires minimal cost. Retrofitting existing systems with non-mercury alternatives (e.g. solid-state lighting) can be costly with a lengthy payback period.
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Manometers
Use: Manometers are used to measure air, water and gas pressure. Those containing mercury are almost exclusively used to measure gas pressures. They are used also as primary pressure standards in laboratories, meteorology and industry, and to calibrate secondary pressure measuing instruments like electronic and aneroid gauges.
Description: A mercury manometer consists of a vertical tube (usually made of glass) containing liquid mercury. Gas pressure is pushed up the column of mercury in the tube and the height of the mercury column indicates the pressure relative to the reference.
Identification: Laboratory manometers range from bench-and wall-mounted units to larger self-supporting encased apparatuses. Dairy manometers are commonly found in dairy barns hooked to automated milking equipment.
Mercury content: Milking system manometers contain approximately 340 grams of mercury (State of Ohio EPA, 2001). Other manometers may contain from 100 to 500 grams or more (Purdue University, 2003).
Alternatives: Alternatives to manometers include devices that use a non-mercury liquid, needle bourdon gauges, aneroid manometers, and digital manometers. Digital manometers can be more accurate than mercury manometers if properly calibrated.
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Medical Devices
Introduction
Medical devices are commonly used in the medical field. Some of these medical devices include esophageal dilators, gastrointestinal tubes and sphygmomanometers, which are fully described below. Exposure to mercury is the result of surgery practices, mercury spills when measuring high blood pressure and from extractions of intestinal obstructions. It is important to ensure that mercury-containing medical devices are used safely, effectively and are properly labelled. Of course, the best method of practice is to ensure staff and patients are aware of the hazards of using these medical devices and to avoid using high mercury-containing medical devices as much as possible.
Many medical devices that were commonly used years ago are slowly being phased out due to their potential harm to patients and potential for liabilities. Alternatives for practicioners are becoming standard in the medical field, are dropping in price and many devices are easier to use.
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Esophageal Dilators
Use: Esophageal dilators are used only in the medical field: they are used to dilate the esophagus of a patient during thoracic surgery, otolaryngology, and other medical procedures (University of Michigan, 2003). Mercury-filled dilators are becoming rare.
Description: Mercurial devices take advantage of the weight characteristics of mercury. The device is slipped down a patient's throat into the esophagus past the narrowed section.
United States. California Department of Health Services, Environmental Management Branch. A Guide to Mercury Assessment and Elimination in Healthcare Facilities. December 2002. pp. 10.
Identification: The dilator is two tubes in one. The space between the outer and inner tubes houses the medium, typically mercury.
Mercury content: Esophageal dilators may contain more than 1000 grams of mercury (Sustainable Hospitals Project, 2003).
Alternatives: Mercury-containing dilators should be replaced immediately, because they have been known to rupture during handling causing undue harm to human health and the environment (Galligan et al., 2002). Water- and tungsten-filled dilators are common alternatives to mercury-containing esophageal dilators. The tungsten-filled dilator requires no retraining for medical practitioners (University of Michigan, 2003). Dilators have an expiration date, because the outer rubber casing degrades with time.
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Gastrointestinal Tubes
Use: Gastrointestinal, Blakemore, and cantor tubes are used in the extraction of intestinal obstructions. Gastrointestinal tubes are only found in the medical field. Research suggests that these devices are no longer widely used (Galligan et al., 2002).
Description: Mercurial devices use mercury as a weight to guide the tube into place by gravity.
United States. California Department of Health Services, Environmental Management Branch. Hospital Pollution Prevention (P-2) Strategies. December 2002. p. 9-16.
Identification: The gastrointestinal tube consists of an internal tube to allow the passage of air; and a larger outer tube into which mercury or an alternate substance is poured for weight.
Mercury content: These devices may contain approximately 1000 grams when filled to capacity.
Alternatives: An alternative for mercury gastrointestinal tubes is tungsten-weighted tubes.
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Sphygmomanometers
Use: Sphygmomanometers are manometers used to measure human blood pressure. Mercurial sphygmomanometers have been the standard in the medical field for many years but are being phased out and replaced with aneroid and digital products due to liability associated with mercury spills.
Description: A mercury sphygmomanometer is a mercury manometer connected to a bladder cuff that wraps around a patient's arm. A vertical glass tube containing mercury indicates the cuff pressure while the person taking the pressure listens for arterial sounds in the patient's arm with a stethoscope.
United States. California Department of Health Services, Environmental Management Branch. Hospital Pollution Prevention (P-2) Strategies. December 2002. p. 9-16.
Identification: The device typically uses a bladder cuff that wraps around a patient?s arm. Two hoses come off the cuff: one to a bulb/pump for pumping air pressure, and the other to the mercurial device that measures the actual pressure.
Mercury content: Content can vary from 20 to 60 grams of mercury.
Alternatives: Alternatives to mercurial sphygmomanometers are aneroid and digital products. Both are reliable, accepted as standard, and comparable to mercurial sphygmomanometers. Digital products continue to drop in price and are easiest to use.
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Mercury Compounds
Use: Mercury-containing chemicals and compounds may be used for various tasks in laboratory and industrial settings and may be used throughout facilities in a variety of applications.
United States. California Department of Health Services, Environmental Management Branch. Hospital Pollution Prevention (P-2) Strategies. December 2002. p. 9-16.
Description: Mercury can be found in a range of chemicals, mixtures of chemicals and waste. Chemical examples include:
Arsenic-calcium reagent
CPK reagent
Elemental mercury, CAS No.7439-97-6
Mercuric Sulfate, CAS No.7783-35-9
Mercurous Chloride, CAS No.7546-30-7
Merthiolate (Thiomersal), CAS No.54-64-8
For a complete list of chemicals, mixtures of chemials and wastes please refer to Mercury-containing product stewardship manual (pdf & html versions).This list can be found in Appendix A.
Identification: Mercury chemicals are found in several settings. Chemicals and mixtures may be identified through:
Iventories of hazardous materials
Product labels
Material safety data sheets
Transportation of dangerous goods manifests, if transported
Waste manifest, if chemicals and mixtures have been identified as hazardous waste
Mercury content: Content will vary depending on the amount and mercury concentration of the chemical, mixture or waste.
Alternatives: Non-mercury alternatives should be considered whenever practical. Ensure due care is taken to en sure proper product substitutions are allowable. This includes ensuring manufacturer specifications, job specifications, and procurement requirements are met.
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Pyrometers
Use: Pyrometers are used to measure extremely hot materials in foundry applications and exhaust temperatures for large engines (Galligan et al., 2002).
Description: Mercury is the medium used in the stem of mercurial pyrometers.
Identification: The typical mercurial pyrometer is equipped with a dial gauge and temperature-sensing stem. It is difficult to tell the difference between mercury and non-mercury alternatives. Mercurial pyrometers are becoming obsolete as nitrogen probes or digital instruments are replacing them.
Mercury content: Content ranges from 5 to 10 grams. Verify with manufacturer specifications for actual content.
Alternatives: Alternatives available to mercurial pyrometers include nitrogen containing stem and digital instruments. Costs of alternative products depend on model, stem length, attachments and certificate of calibration.
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Relays
Introduction
A relay is a device that is capable of opening a normally-closed circuit or closing a normally-open circuit. When the relay is not energized, the normally-closed circuit is complete and the normally-open circuit is open. When the relay is energized, it switches roles, opening the normally-closed circuit and closing the normally-open circuit. This dual nature of a relay allows for two types of applications: a device may be attached to the normally-closed circuit so that the device is always on until the relay energizes to turn it off, or a device may be attached to the normally-open circuit so that the device is always off until the relay energizes to turn it on (Keri Systems, Inc., 2004).
Commonly used relays include displacement and contactor relays and wetted reed relays. Relays are used frequently in commercial and industrial activities due to their low maintenance, reduced noise, minimum weight and size. Also, relays are those needed devices that are capable of withstanding adverse environments and thus, are found in computers, business machines and laboratory equipment. However, as a result of their beneficial qualities and thus, frequent use they have higher risks associated with them related to mercury pollution. A full description of displacement and contractor relays as well as wetted reed relays is found below.
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Displacement and Contractor Relays
Use: Mercury displacement and contactor relays are ideal for adverse environments, such as corrosive, dirty, or moist ambient environments where high current rushes are encountered (Magnecraft & Struthers-Dunn, 2003). These devices are generally used to control electrical circuits.
Description: "Mercury displacement" and "contactor" relays are two terms that are frequently used interchangeably. The device has a self-renewing contact that maximizes contact life and minimizes contact resistance. There are limited components within the device, eliminating the need for hinges, pivots, pins, or mechanical linkages to wear out or break. Life expectancy of this device exceeds other types of comparable products handling the same loads and duty cycle (MDI, 2003). These relays are ideal for commercial and industrial applications due to their low maintenance, reduced noise, minimum weight, and size.
Identification: The device is sealed and found mainly in molding machines, large battery chargers, and industrial electric heaters. Other applications include mining and refineries. The only way to truly identify the device is to verify the manufacturer label.
Mercury content: Mercury content can vary, but can be in the range of 150 grams (Mercury Displacement Industries Incorporated Engineering Department, 2004, personal communication).
Alternatives: This device is very specific for its application and alternatives have generally not provided equal performance or reliability (MDI, 2002). Procurement of alternatives may not be recommended.
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Wetted Reed Relays
Use: Mercury wetted reed relays are used for a variety of switching applications and are found in computers, business machines, machine tool control systems, and laboratory equipment (Magnecraft & Struthers-Dunn, 2003).
Description: A mercury wetted reed relay has the characteristics of an electro-mechanical relay that employs a hermetically sealed reed switch. The mercury wetted reed relay comprises a glass ampoule with the base reed immersed in a pool of mercury and the other end capable of moving between two sets of contacts. The device is particularly useful in very low voltage applications (Galligan et al., 2002) and is inexpensive, versatile, and commonly used in industry.
Identification: Mercury wetted contacts comprise a glass-encapsulated reed with its base immersed in a pool of mercury and the other end capable of moving between one or two stationary contacts.
Mercury content: Content is approximately 1 gram (NEWMOA, 2003).
Alternatives: Mercury wetted relays can be replaced by dry reed magnetic relays for most applications. Exceptions to this include the requirement of no-contact bounce, long operational life, or low contact resistance (Galligan et al., 2002). Manufacturers of wetted reed relays generally also produce dry reed relays.
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Switches
Introduction
Switches are devices that regulate the flow of electricity; when open they allow current to flow and when closed they prevent current from flowing. Switches that contain mercury can be used to regulate electricity flow based on changes in pressure, temperature, or position.
Some temperature or pressure sensitive and mechanical switches may contain mercury. Typical examples may be found in the hood and trunk light switches in some cars made before 2000, silent wall switches, garage door openers, clothes dryer lids, microwave ovens, proximity or position sensors found in irons and space heaters, sump pumps and bilge pumps.
The average mercury-containing switch may have as much as three grams of mercury; however, large switches can contain up to 70 grams.
In many cases, non-mercury, electronic alternatives are available.
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Listed below are common types of switches:
Float Switches
Use: Float switches monitor liquid levels. Float switches are most frequently used in sump pumps. They are also found in bilge pumps, boilers, sewage treatment plants, and pumping stations.
Description: Two basic types in use are buoyant floating switching products, activated by rising and falling liquid, and stationary devices, actuated by the lack of or the presence of a liquid (Galligan et al., 2002).
Identification: The mercury will be contained in a cylindrical or global outer casing within the interior in a sealed ampoule. When the device is manually moved, a sloshing sound/movement will be heard or felt. A rolling sound or feel will be a good indication that the device is not mercury but a metal ball.
Mercury content: Mercury content can vary significantly depending on the size of switch. Normally, the content is below 1 gram per switch; however, float switches can have as much as 15 grams per switch.
Alternatives: Mechanical switches may be used to replace mercury switches for most applications. If in doubt, contact the manufacturer regarding mercury alternative availability and practicality. The prices of mechanical float switches are normally similar to mercury-containing float switches.
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Pressure Switches
Use: There are several different designs of pressure switches, each having a unique application. Pressure switches are used in a variety of applications because of their reliability and long operational life as a result of having few moving components and not being subject to arcing. The switch can handle high inductive loads and has a quiet operation with no bounce on contact. The switch is hermetically sealed making it ideal for dust, moisture, and explosive atmospheres (Galligan et al., 2002).
The switch is becoming less popular with the food and beverage industry due to its mercury content. Some pressure switch designs are diaphragm, piston, bellows, and flex circuit. Switches have been used in HVAC systems, medical devices, automotive industry (ABS Breaks), appliances, and a host of miscellaneous applications (e.g. fire pumps, scrubbers, machine tools) (Galligan et al., 2002; NEWMOA, 2003; (GLBTS, 2003).
Description: Mercurial pressure switches convert a pressure change into an electrical switching function. The switch measures pressure changes as pressure, vacuum or differential between two pressure inputs.
Identification: Pressure switches comprise a diaphragm, piston, or other pressure-responsive sensor, coupled to actuate a mechanical switch, mercury switch, or transistor.
Mercury content: Content ranges from 1 to 20 grams depending on the application and design (Galligan et al., 2002).
Alternatives: Alternatives include mechanical pressure switches and solid-state pressure switches (Galligan et al., 2002).
Alternatives are widely available and vary in price depending on use and design. Not all alternatives may be suitable for any one application without retrofit. Electrical requirements laid out by manufacturers of equipment must be strictly adhered to.
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Temperature Switches
Use: Temperature switches are used in food warming trays, hot water boilers, ovens, sterilizers, molding machines, heat exchangers, labeling machines, water baths, heat sealers, refrigerating equipment ventilation equipment, alarm systems, bearings, popcorn machines, hot stamping, watering fountains, vending machines, deep fat cookers, and textiles. Due to their mercury content, these switches are becoming less popular with the food and beverage industry.
They are widely used in other applications due to their reliability and long operational life as a result of having few moving components and not being subject to arcing. The switch can handle high inductive loads and has a quiet operation with no bounce on contact. It is also hermetically sealed making it ideal for use in dust, moisture and explosive atmospheres (Galligan et al., 2002).
Description: A mercurial temperature switch converts a temperature change into an electrical switching function. The switch uses a temperature responsive sensor that is coupled to a mechanical actuating switch usually housing a mercury ampoule (Galligan et al., 2002).
Identification: A mercury temperature switch is similar to a mercury tilt switch, in that some sort of ampoule is required to complete the circuitry and is usually attached to some type of mechanical switching device such as a bi-metal strip that expands and contracts (Galligan et al., 2002).
Mercury content: Ampoules contain 1 to 10 grams of mercury.
Alternatives: Alternatives to a mercury temperature switch include mechanical pressure switches and solidstate pressure switches (Galligan et al., 2002). Alternatives are widely available and vary in price depending on use and design. Not all alternatives may be suitable for any one application without retrofit. Electrical requirements laid out by manufacturers of equipment must be strictly adhered to (Galligan et al., 2002).
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Tilt Switches
Use: Tilt switches are widely used in a variety of applications because of their reliability and long operational life as a result of having few moving components and not being subject to arcing. The switch can handle high inductive loads and has a quiet operation with no bounce on contact. The switch is hermetically sealed making it ideal for use in dust, moisture, and
explosive atmospheres (Galligan et al., 2002). The switch is becoming less popular with the food and beverage industry due to its mercury content.
Tilt switches are ideal for monitoring and control devices and applications. The device by itself can be purchased as a single component for later incorporation into a specific application such as mining operations, test and laboratory equipment, heavy equipment, industrial, marine, medical equipment, robotics, agriculture, and others, including alarms, lights, logic controllers, cell phones, anti tamper devices, kitchen appliances, and automotive applications (lighting). Tilt switches can also be built into the later examples as an integral part of the unit (Galligan et al., 2002; (NEWMOA, 2003; GLBTS, 2003; NYSDEC, 2003; MA DEP,2003).
Description: A tilt switch is actuated based upon the changes it senses in either position or rotation. There are a number of parameters by which a switch may be constructed, including, but not limited to tilt or rotation angle, number of axes, switch points, accuracy, output rating, life expectancy, regulatory requirements, environmental conditions, intrinsic safety, and space occupied (Galligan et al., 2002).
Identification: Mercury tilt switches are typically small tubes with electrical contacts at one end of the tube. The mercury is situated internally where it can make contact with internal electrodes when tilted (Galligan et al., 2002).
Mercury content: The mercury content of the tilt switch varies from 0.4 to 71 grams depending on application and design.
Alternatives: Alternatives to a mercury tilt switches include, metallic ball switches, electrolytic tilt switches, potentiometers, mechanical switches, solid-state switches, and capacitive switches (Galligan et al., 2002). Not all alternatives may suitable for any one application (Galligan et al., 2002).
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Thermometers
Introduction
The term thermometer applies to instruments that measure temperature. Various types, for a multitude of purposes, exist on the market and can be found in households, laboratories, medical facilities, industries, and schools. Mercury has traditionally been used in thermometers since it expands and contracts consistently with temperature. Held within a bulb at the base of the instrument, mercury is free to move up and down a capillary tube where its position can be associated with a specific temperature.
Mercury may be found in fever, basal, scientific, industrial and cooking thermometers. Thermometers containing mercury can be easily identified by the colour of the material in the bulb.
Digital or spirit-filled (red) thermometers are a safer alternative. Infrared (ear) thermometers may be used as an alternative to mercury fever thermometers. Recently, thermometers containing gallium, indium, and tin, have become available as a mercury-free alternative.
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Below you will find descriptions of thermometers, such as fever thermometers, industrial thermometers and laboratory thermometers:
Fever Thermometers
Use: Fever thermometers measure human body temperature including oral, rectal, or auxiliary (armpit). Fever thermometers are commonplace in homes and medical institutions; however, sales of mercury-containing fever thermometers have been decreasing as alternatives increase in popularity.
Description: The term ?thermometer? applies to instruments that measure temperature. Various types, for a multitude of purposes, exist on the market and can be found in households, laboratories, industries, and schools. The mercury is held within a bulb and is free to move up and down a capillary tube. Because mercury expands and contracts consistently with temperature, its
position in the capillary tube can be associated with a specific temperature.
Identification: Mercury may be in fever, basal, and cooking thermometers. Thermometers containing mercury can be easily identified by the colour of the material in the bulb. If the bulb is silver, the thermometer most likely contains mercury. New fever thermometers containing gallium, indium, and tin are an exception to this as they will also appear silver in color. These thermometers are marketed as ?mercury-free? thermometers and will probably be clearly marked as such. If the bulb is any other colour, e.g. red or blue, it is most likely spirit-filled.
Mercury content: Content ranges from 0.5 to 3 grams.
Alternatives: Mercury-free alternatives include digital, alcohol, and glass gallium-indium-tin thermometers. Other alternatives include ear canal thermometers and flexible forehead thermometers. These alternatives can be as accurate as mercury thermometers, and in many cases are easier to read. If mercury-containing thermometers are essential, buy Teflon-coated ones to minimize the release of mercury in case of an accidental breakage.
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Industrial Thermometers
Use: Industrial thermometers are commonly found in mechanical rooms. Common uses include climate control in heating, ventilation, and air conditioning (HVAC) systems.
Description: Industrial thermometers are usually manufactured with a probe that is inserted into a source of heat or cold. The probe is directly connected to a sensing medium, such as mercury, that in turn displays a reading on a calibrated scale.
Identification: Industrial mercury-containing thermometers are generally distinguishable by a silver-coloured column. Mercury-containing thermometers are sometimes misidentified as alcohol-filled thermometers because an optical illusion causes some mercury-filled thermometers to appear to have a red column. Care should be taken to look closely at the column and column size. Mercury-containing thermometers are generally thinner than alcohol-filled thermometers. These devices are often found attached to piping systems, boilers and commercial hot water heaters.
Mercury content: The average mass of mercury used in an industrial thermometer is 5 grams.
Alternatives: Alternatives include alcohol-filled, organic-based replacement-fluid-filled, and digital thermometers.
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Laboratory Thermometers
Use: Laboratory thermometers are used in laboratories to measure temperature. They are most accurate when semi-immersed or totally immersed in the medium being measured. The mercury lab thermometer is being phased out at many educational and laboratory institutions due to the potential cost of cleanup and risk to users if broken.
Description: Laboratory thermometers are long-stemmed with a silver bulb at the end. Mercury located in the bulb expands with increasing temperature and contracts with decreasing temperature. The temperature is measured by reading the level of mercury on a calibrated scale.
Identification: Lab thermometers are distinguished by the long stem and elongated bulb at the end. A silvercoloured liquid generally denotes mercury. Other coloured liquids are not mercury.
Mercury content: The average mass of mercury in a laboratory thermometer is around 5 grams.
Alternatives: Mercury-containing laboratory thermometers are easily replaced with alcohol-filled or organicbased replacement fluid-filled thermometers. Digital laboratory thermometers are equally desirable and in many cases are easier to read.
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Thermostats
Use: Mercury-containing thermostats may be used in heating and cooling systems in residential, medical, commercial and industrial settings.
Description: Thermostats comprise a tilt switch with a mercury ampoule used to activate or deactivate the heating or cooling device.
Identification: Thermostats are typically mounted on walls, usually at chest height. Most non-digital thermostats contain mercury. Thermostats that contain mercury can usually be identified by carefully removing the front plate of the device and visually inspecting the uncovered components. If there are glass ampoules inside that contain a silver liquid, it is most probably mercury.
Mercury content: Ampoules generally contain 3 grams of mercury. There may be one to six ampoules depending on the model and application of the thermostat (Sustainable Hospitals Project, 2003).
Alternatives: Alternatives include programmable mercury-free electronic thermostats. A programmable thermostat automatically sets back temperature in a room or building according to a predetermined schedule, whereas non-programmable thermostats maintain constant room temperature 24 hours per day. Mercury containing thermostats can normally be replaced by electronic alternatives. One advantage of electronic devices is that they can result in energy savings.
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Thermostat Probes
Description: Thermostat probes or flame sensors found in gas appliances consist of a bulb attached to a gas-control valve by a tube containing mercury. They are generally used to prevent gas from flowing when the pilot light of the appliance is off.
Identification: Gas-fired appliances with pilot lights like stoves, clothes dryers, space heaters, water heaters and furnaces may have mercury-containing thermostat probes.
Pictures reproduced, with permission, from the Household Appliance Mercury Switch Removal Manual, Vermont Dept. of Environmental Conservation
Mercury Content: Thermostat probes contain approximately 1 gram of mercury.
Alternatives: Electric flame sensors can be used instead of mercury-containing probes.
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Other
Mercury is no longer deliberately used in the manufacture of most dry-cell batteries. The only batteries still containing mercury are button-cell batteries. These may be found in watches, calculators and items like toys, cards or shoes that light up or make noise.
In some cases, old paints may contain mercury. Certain lighted athletic shoes purchased before 1994 may also contain mercury. Hydrometers, devices used to determine the specific gravity and density of liquids, look similar to thermometers and may contain mercury. They have been used by the petroleum industry, dairy farms, and amateur wine/beer makers. Mercury may also be found in hygrometers/psychrometers, silent wall switches, old pesticides, as well as various medical devices and preservatives.
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