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Natural gas meter, antiquated, indoors (C) Daniel FriedmanMercury Hazards in Appliances & in Natural Gas Regulators
Where is mercury found in gas regulators & in household appliances & pump controls

  • POST a QUESTION or COMMENT about inspecting, testing, diagnosing, and repairing gas piping, gas regulators, and gas storage tank defects used with LP or natural gas burning appliances

Mercury hazards in gas regulators, home appliances, switches, and controls.

Here we describe the most-common places that mercury may be found in regulators, switches, controls and appliances found in the home as well as in many other buildings.

Really? Well yes but: People can be exposed to harmful levels of mercury through inhalation or skin contact, but the primary route of exposure for most people today is eating mercury-contaminated fish. - CA EPA (2005)

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Mercury Hazards in Appliances & in Natural Gas Regulators

Mercury bulb thermostat in old Honeywell T87A (C) Daniel Friedman at InspectApedia.comMercury was widely used as a reliable position control switch, most-often as a small quanity of mercury inside of a glass tube that rolled on or off of electrical contacts as the position of the tube was tippped.

Probably the most-widel-installed mercury switch was in Honeywell's traditional T87 wall thermostat used to control heating and air conditioning equipment and manufactured as early as 1953.

How to check your thermostat for mercury:

Simply pull the cover off of your thermostat and look for the glass bulb containing a drop of mercury - upper left in our photo.

Modern Honeywell and other room thermostats don't contain mercury and have not for some time. Instead these newer temperature sensing devices may use a thermistor.

Watch out: Mercury is a neurotoxin and even short-term exposure to high levels of metallic mercury vapors may cause effects including lung damage, nausea, vomiting, diarrhea, increases in blood pressure or heart rate, skin rashes, and eye irritation.

Long term exposure can cause damage to the brain, kidneys, liver and heart.

When a mercury-containing product breaks and the mercury is spilled, the exposed mercury can evaporate and become an invisible, odorless toxic vapor. Some of these products such as mercury-containing thermometers can break easily and spill mercury.

To prevent mercury releases, these products should be used and stored safely by maintenance personnel and service technicians. - U.S. HUD (2008) and Main DEP (2004)

Where was Mercury Commonly Used in Home Devices?

Mercury switches were used in a range of electrical appliances such as chest freezers, sump pumps (and bilge pumps), washing machines and water heaters. sile

Mercury may also appear in electrical switches such as silent wall toggle switches, garage door openers, electric irons, clothes dryer lids, washing machine lids and sensors, and other sources listed herein.

Thermocouples, in particular steel or stainless-steel (not copper) used on older gas appliances may also contain mercury, and finally (well semi-finally), mercury was also used as a component in some natural gas regulators.

Mercury may also be in your car, in a hood light switch or trunk light switch sensor.

Details about where mercury was used in these controls and switches and how to remove or dispose of mercury switches, regulators and other controls safely are given in this article.

Mercury Hazards in Home Appliances, Thermostats, Controls, Reglators & Other Sources

Mercury bulb switch in an old Honeywell T87 thermostat (C) Daniel Friedman at Inspectapedia.comOur photo shows what a mercury bulb looks like in a traditional room thermostat, viewed from above with the thermostat cover removed.

Photo below: a large drop of mercury is shown in the end of a glass bulb the mercury bulb switch used in older Honeywell T87 room thermostats.

In this position the metallic droplet of mercury makes an electrical connection between two metal probes forming the actual position-sensitive switch.

Really? mercury inside of the glass bulb is not a direct health or environmental hazard. Don't panic about an old mercury-bulb thermostat or control, but do handle its disposal properly.

The mercury hazard would arise if the (rather tough) glass bulb is shattered, releasing mercury.

That can happen during scrap metal operations when an older appliance containing a mercury switch is re-cycled.

Most communities have regulations about the disposal of mercury switches and controls and provide disposal advice. You'll find examples in our citations below.

Research on the question of whether or not mercury was also used in gas appliances, where it appears and how to handle mercury-containing switches and controls is given below.

Household & Building Small Mercury Hazard Sources, Research, Cleanup Instructions

Mercury switch in an older Honeywell T87 wall thermostat (C) Daniel Friedman at Inspectapedia.comAll appliances manufactured after March 1, 2000 should be labeled if they incorporate a mercury-containing device.

Question: do old gas appliance pressure regulators contain mercury?

Photograph of a gas regulator showing details2019/02/16 Michael Soules said:

Do older gas pressure regulators leading to an individual gas appliance (gas fireplace, range, etc.) ever contain mercury?

I know that older gas regulators leading into a home sometimes contain mercury, and would like to know if the pressure regulators for a single appliance can as well. (The specific situation I'm interested in involves a gas fireplace connected to a very old-looking pressure regulator.)

Here are the articles I've seen that discuss mercury pressure regulators:

This mercury hazard Q&A were posted originally at GAS LP & NATURAL GAS SAFETY HAZARDS

Reply: yes, some: reports of in-home mercury spill hazards during removal of old gas regulators

What a great question, Michael. Thank you. Mercury in gas appliance regulators isn't something I'd considered.

Hryhorczuk (2006) certainly makes the point, in the NCBI citation you offered, but specifically that paper focuses on gas regulators at the building point of supply, not appliance regulators.

Many older homes are equipped with mercury-containing gas regulators that reduce the pressure of natural gas in the mains to the low pressure used in home gas piping.

Removal of these regulators can result in elemental mercury spills inside the home. In the summer of 2000, mercury spills were discovered in the basements of several Chicago-area homes after removal of gas regulators by gas company contractors.

Subsequent inspections of approximately 361,000 homes by two northern Illinois gas companies showed that 1,363 homes had residential mercury contamination.

Urine mercury screening was offered to concerned residents, and results of urine bioassays and indoor mercury air measurements were available for 171 homes. Six of these 171 homes (3.5%) had a cumulative total of nine residents with a urine mercury ≥ 10 μg/L.

The highest urine mercury concentration observed in a resident was 26 μg/L.

Positive bioassays were most strongly associated with mercury air concentrations > 10 μg/m3 on the first floor [odds ratio (OR) = 21.4; 95% confidence interval (CI), 3.6–125.9] rather than in the basement (OR = 3.0; 95% CI, 0.3–26), and first-floor air samples were more predictive of positive bioassays than were basement samples.

Overall, the risk of residential mercury contamination after gas regulator removal ranged from 0.9/1,000 to 4.3/1,000 homes, depending on the gas company, although the risk was considerably higher (20 of 120 homes, 16.7%) for one of the contractors performing removal work for one of the gas companies.

Gas companies, their contractors, and residents should be aware of these risks and should take appropriate actions to prevent these spills from occurring and remediate them if they occur.

Your EPA citation (thanks again) states

Issue: Some homes that were built prior to 1968 have a mercurycontaining gas pressure regulator adjacent to the gas meter.

Most of these devices were manufactured and installed in the 1940s and 1950s, but a few were manufactured and installed in some areas as late as 1967. These devices contain approximately two teaspoons of mercury.

Mercury spills have sometimes occurred during improper removal of these devices, causing a potentially significant health risk and resulting in costly cleanups.

Recommended Management: Mercury-containing gas pressure regulators should be removed only by qualified gas company personnel.

Frankly I was surprised that anybody was seriously worried about a mercury spill from removing an old gas service regulator as normally those devices would be removed intact. I suppose if one were internally damaged a mercury spill might still ensue.

Again neither of those articles points to gas appliance regulators.

Watch out: another common source of mercury in heating equipments are older mercury-bulb type room thermostats like the old Honeywell T87 thermostat scited earlier.


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