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IMERC Fact Sheet


Mercury Use in Gas & Electric Cooking Ranges
& Other Cooking Equipment

Last Update: January 2010

"Mercury Use in Gas and Electric Cooking Ranges and Other Cooking Equipment" summarizes the use of mercury in cooking equipment. This Fact Sheet covers the types of cooking devices that contain mercury; the total amount of mercury in all of the devices that were sold as new in the U.S. in 2001, 2004, and 2007; companies that have phased-out the products' manufacture and sale; recycling and disposal; and non-mercury alternatives.

The information in this Fact Sheet is based on data submitted to the state members of the Interstate Mercury Education and Reduction Clearinghouse (IMERC)1 including Connecticut, Louisiana, Maine, Massachusetts, New Hampshire, New York, Rhode Island, and Vermont. The data is available online through the IMERC Mercury-Added Products Database.2

A number of important caveats must be considered when reviewing the data summarized in this Fact Sheet:

  • This Fact Sheet focuses on mercury use data for flame sensors used in cooking equipment. It does not include total mercury use data for fluorescent lamps used in cooking ranges; these fluorescent lamps are covered in a separate fact sheet entitled, Mercury Use in Lighting.3 It also does not include total mercury information for mercury relays used in cooking equipment; all uses of mercury relays are covered in the fact sheet entitled, Mercury Use in Switches and Relays.4
  • The information may not represent the entire universe of mercury-containing cooking equipment sold in the U.S. The IMERC-member states continuously receive new information from mercury-added product manufacturers, and the data presented in this Fact Sheet may underestimate the total amount of mercury sold in this product category.
  • The information summarizes mercury use in cooking equipment sold nationwide since 2001. It does not include mercury-added gas or electric ranges or other types of mercury-containing cooking equipment sold prior to January 1, 2001 or exported outside of the U.S.
  • Reported data includes only mercury that is used in the product, and does not include mercury emitted during mining, manufacturing, or other points in the products' life cycle.

 

Mercury Components in Cooking Ranges

Mercury-added components are used in a variety of cooking ranges: gas, gas-electric, and electric. Gas ranges typically contain only one mercury-added component - a mercury flame sensor or gas shut-off valve. Gas-electric and electric ranges may contain fluorescent bulbs for backlighting. Gas-electric ranges may also contain a mercury flame switch, which acts similarly to a flame sensor. Commercial electric ranges may contain mercury relays. Each of these components is described below:

Mercury Flame Sensor
Mercury Flame Sensor
Photo Source: Vermont Department of Environmental Conservation
Click for a larger view
Flame sensors, also called automatic gas shut-off valves, are used as safety devices in gas ranges and other appliances. A flame sensor stops the flow of gas if the open flame does not produce heat, such as when the pilot light is out or the product is malfunctioning. Mercury is contained within the bulb of the sensor, and the heat of the pilot light vaporizes and expands the mercury, causing the gas valve to open. Today's household gas-electric ranges do not require a flame sensor because the electrical current controls the pilot light. For more information about mercury use in gas and electric ranges, go to: www.newmoa.org/prevention/mercury/projects/legacy/appliances.cfm#go

Fluorescent bulbs provide backlighting for control panels. Mercury in the bulb vaporizes, producing ultraviolet energy that passes through phosphor coatings to produce visible light. See the Mercury Use in Lighting3 fact sheet for more information about how fluorescent lighting works.

Example of Fluorescent Lighting in Gas Ranges Example of Fluorescent Lighting in Gas Ranges
Examples of Fluorescent Lighting in Gas Ranges
Photo Source: Vermont Department of Environmental Conservation
Click for a larger view

Relays are electrically controlled devices that allow electrical current flowing through one circuit to switch the current on and off in a second circuit. Relays are often used to switch large current loads by supplying relatively small currents to a control circuit. There are two general families of relays: electro-mechanical and semiconductor.

Mercury displacement relays are one type of electro-mechanical relay; they use metallic plunger devices containing magnetic shells or sleeves to displace mercury. When power is off, the mercury level is below the electrode tip of the plunger and no current path exists between the insulated center electrode and the mercury pool. When power is applied, the pull of the magnetic field draws the plunger down into the mercury pool and the plunger centers itself within the current path. When power is shut off, the buoyancy force of the mercury causes the plunger, which is lighter than the mercury, to resume its original position. The mercury level then drops, breaking the current path through the center electrode and mercury pool.

Mercury Gas Safety Valve Mercury Relay for an Oven
Mercury Gas Safety Valve
Photo Source: Blodgett
Click for a larger view
Mercury Relay for an Oven
Photo Source: Garland
Click for a larger view
Other mercury relays (e.g., mercury contactor, gas safety valve) are used in industrial and commercial electric convection ovens and conveyer ovens where high temperatures in the oven make the use of standard mercury flame sensors or thermocouples impractical.

Table 1 presents the amount of mercury in each of the three components that are used in gas, gas-electric, and electric ranges, as reported to the IMERC-member states. The Table covers the amount of mercury in flame sensors, fluorescent lamps, and relays that are used in cooking ranges and not for other uses.

Table 1: Amount of Mercury in Cooking Ranges
Mercury Component Amount of Mercury in Individual Component
Flame sensor > 100 - 1,000 mg
> 1,000 mg
Relay > 1,000 mg
Fluorescent lamp > 5 - 10 mg
> 10 - 50 mg

 

Mercury Use in Flame Sensors

Table 2 presents the total amount of mercury in flame sensors sold in the U.S. during calendar years 2001, 2004, and 2007.5

Table 2: Total Mercury Sold in Flame Sensors in the US (pounds)
2001 Total Mercury 2004 Total Mercury 2007 Total Mercury
4,963 (2.5 tons) 2,363 (1.2 tons) 1,970 (1.0 tons)6
[Note: 453.6 grams = 1 pound; All numbers are rounded to the nearest whole number.]

Table 2 shows that 2.5 tons of mercury was used in flame sensors in 2001 and 1.2 tons in 2004, which reflects a dramatic decline of more than 50 percent. In 2007, mercury use in flame sensors further decreased to slightly less than 1 ton, or an additional 17 percent from 2004. Overall, mercury use in flame sensors has declined approximately 60 percent since 2001.

Many states have passed legislation restricting the sale of mercury-added switches and relays, including flame sensors, individually or as a component in a larger product (i.e., gas ranges). As more of these state laws go into effect, mercury use in this product category will likely continue to decline.

 

Phase-Outs & Product Bans on the Sale of Mercury Components Found in Cooking Equipment

The following IMERC-member states currently have restrictions on the sale and/or distribution of mercury-added switches/relays, including flame sensors, individually or as a component in another product: California, Connecticut, Illinois, Louisiana, Maine, Massachusetts (phase-out effective May 1, 2009), Minnesota, New Hampshire, New York, Rhode Island, and Vermont.7 In response to these mercury product bans and phase-outs, many companies have ceased manufacturing mercury flame sensors and/or stopped selling products that contain these devices in these states.

In addition to the flame sensors commonly used in gas and gas-electric cooking ranges, other types of cooking equipment may contain a mercury component, such as a mercury switch or relay. Some examples of mercury-containing cooking equipment that have been reported to the IMERC-member states include barbeque grills, fryers, hot plates, griddles, and rotisseries. A number of gas-electric and electric ranges containing a fluorescent lamp for backlighting have also been reported to the IMERC-member states. Additional background information on these products can be found in the NEWMOA report, Trends in Mercury Use in Products: Summary of the IMERC Mercury-added Products Database, June 2008 at: http://www.newmoa.org/prevention/mercury/imerc/factsheets/mercuryinproducts.pdf.

Some manufacturers of cooking equipment continue to sell products containing mercury-added components (including switches and relays) into other states in the U.S. Some of these manufactures have applied for and been granted a phase-out exemption from one or more of the IMERC-member states, thereby allowing them to continue to sell products containing a mercury switch or relay (e.g., flame sensor) for a specified period of time after the effective phase-out date. The exception is California, which strictly prohibits the sale of mercury-containing flame sensors (also known as diostats) and does not allow manufacturers to apply for an exemption for this product.

The following is a list of companies and mercury-added cooking equipment products that have reportedly been eliminated by the manufacturers from the U.S. market since 2001:

Maytag reported to the IMERC-member states that they phased-out the manufacture of appliances with mercury-containing fluorescent bulbs in 2002. They also reported that they phased-out the manufacture of mercury flame sensors used in gas cooking appliances in 2006.

Burner Systems International, Inc. (formally Harper-Wyman and Appliance Controls) reported to the IMERC-member states that they no longer manufacture mercury shut-off valves for gas- electric ovens as of 2004.

Pitco Frialator, Inc. reported to the IMERC-member states that they phased-out the manufacture and sale of their commercial frialators with mercury-added relays in 2004.

Whirlpool reported to the IMERC-member states that they phased-out the manufacture of the particular models of gas ranges containing a mercury safety switch in 2005. New models are no longer manufactured with mercury. The company also reported that they phased-out the use of fluorescent bulbs in their ranges in 2007.

Electrolux Home Products, Inc. reported to the IMERC-member states that they phased-out the manufacture of cooking ranges with a mercury safety valve as of January 1, 2007.

Gas ovens containing mercury-added flame sensors were once commonly used in recreational vehicles (RVs), trailers, and campers. In 2004 and 2005, these manufacturers reported to the IMERC-member states that they no longer sell products with mercury-containing cooking equipment. A full list of RV manufacturers that have reportedly phased-out the use of mercury- added flame sensors in cooking equipment in recreational vehicles, trailers, and campers is included in Appendix A in the IMERC fact sheet entitled, Mercury Use in Switches and Relays.4

 

Disposal and Recycling of Mercury-Containing Cooking Ranges

Although new gas and electric ranges, and other cooking equipment, are transitioning to mercury-free, there may be many that are still being used and/or stored in homes or businesses. Used gas and electric ranges that contain mercury components are subject to waste disposal restrictions.

Large appliances, including gas ovens, are considered "white goods" and require special handling and disposal. Because white goods have market value as scrap metal, they can be recycled and reused as long as the hazardous components are removed. Persons should contact their state and/or local environmental departments to verify solid waste disposal regulations, especially those pertaining to mercury-containing components and devices. They can also check with their local municipality to find out about the specific recycling and disposal options for white goods.

Local appliance recyclers and scrap metal yards may collect white goods for scrap metal recycling purposes. A qualified service technician can safely remove the mercury flame sensor from the gas range before shredding the larger unit. The mercury device can then be sent to a recycler for reclamation. Fluorescent lamps and other mercury components (e.g., relays) must also be removed from gas and electric ranges and other cooking equipment prior to disposal and/or recycling.

For more information about the proper removal of mercury components from gas or electric cooking ranges, including dismantling instructions, photographs, and/or diagrams, see:

 

Non-Mercury Alternatives

An example of a non-mercury alternative for replacing the mercury flame sensor in gas ranges is the electronic ignition system. Using an electronic ignition system in gas appliances eliminates the need for a standing pilot light. In most cases, the electronic ignition system is a cost effective and functional replacement for the mercury flame sensor. However, because electricity must be present in order to light the appliance and ensure the safe and controlled flow of gas to the appliance, this alternative would not be suitable for remote areas where electricity is intermittent or unavailable.

The piezoelectric spark ignition system is another example of a non-mercury alternative that eliminates the need for a standing pilot light and hence, the mercury flame sensor. Piezoelectric spark ignition systems are used in camp stoves, gas grills, and lighters. This system does not rely on an electrical grid but works by using a spring-loaded hammer that, when activated by a push-button or knob, strikes a crystal of piezoelectric material (e.g., quartz). When the crystal is struck, it produces an electrical discharge and ignites the gas.

Non-mercury thermocouples are another viable alternative for many applications. The thermocouple consists of two dissimilar metals joined together at one end, which create an electrical voltage when heated. In appliances with pilot lights, the thermocouple sits in the pilot flame and uses the heat of the pilot light to generate electricity. The electricity runs to an electromagnetic valve and holds it open, allowing gas to flow as long as the pilot remains lit - if the flame goes out, the thermocouple cools and the electrical current stops, closing the valve and shutting off the supply of gas. This type of thermocouple is now used in place of the mercury flame sensors for gas ovens found in most recreational vehicles or other stand-alone applications.

 

 

 


1 IMERC: http://www.newmoa.org/prevention/mercury/imerc/about.cfm
2 Mercury-Added Products Database: http://www.newmoa.org/prevention/mercury/imerc/notification/index.cfm
3 Mercury Use in Lighting Fact Sheet: http://www.newmoa.org/prevention/mercury/imerc/factSheets/lighting.cfm
4 Mercury Use in Switches & Relays Fact Sheet: http://www.newmoa.org/prevention/mercury/imerc/factSheets/switches.cfm
5 The data cited in this report is from a NEWMOA Power Point Presentation entitled, Trends in Mercury Use in Products: Analysis of the IMERC Mercury-added Products Database, presented at the ?2009 Mercury Science & Policy Conference with a Special Focus on the Great Lakes & Northeast Regions,? on November 17, 2009: http://www.newmoa.org/prevention/mercury/conferences/sciandpolicy/presentations/Wienert_Session3B.pdf
6 Several companies that manufacture mercury flame sensors have not yet reported their total mercury use for 2007 and are non-compliant with the IMERC triennial notification requirements. When estimating 2007 totals for these companies, NEWMOA used the same amount reported in their 2004 notifications
7 State Mercury-Added Product Ban Guidance: http://www.newmoa.org/prevention/mercury/imerc/productban.cfm

 

 

Last Modified 02/17/2011

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