This article guides you through using and calibrating a mercury thermometer. It covers safe disposal, regulatory details, and environmental concerns. It also highlights the shift towards safer alternatives.
Key Takeaways from Using a Mercury Thermometer
- Mercury thermometers offer precision due to mercury’s unique properties, require regular maintenance for accuracy, and have alternatives like digital and bimetal thermometers for a range of temperatures.
- Mercury has severe environmental and health risks, including neurological damage and developmental deficits; broken thermometers must be handled with extreme care to avoid mercury exposure.
- Due to the dangers of mercury, proper disposal of mercury thermometers is crucial, and there are regulatory efforts to reduce their use in favor of non-mercury alternatives.
Basics
Mercury thermometers have a rich history, tracing back to the early 18th century, with significant contributions from Fahrenheit, leading to their widespread adoption over devices sensitive to atmospheric pressure variations. These thermometers are constructed of a tubular glass, with a mercury-filled reservoir at the tube’s base and a capillary bore through the stem, making them efficient instruments to measure temperature. If the thermometer is broken, there is a potential release of mercury vapor, which can be hazardous.
The accuracy and ease of reading mercury thermometers are due to the following factors:
- Quick response of mercury to temperature changes
- High level of conductivity
- Uniform thermal expansion
- Non-adherence to glass
- Visibility
These thermometers have an operational temperature range typically from 35 to 673 degrees Fahrenheit, which can be extended to higher temperatures with inert gas and specialized materials. The principle is simple: mercury moves through the bore as it expands or contracts in accordance with temperature changes.
However, like all tools, mercury thermometers are not immune to wear and tear. Their accuracy can degrade over time due to factors such as:
- Calibration
- Handling
- Environmental conditions
- Natural wear on the capillary and mercury column
Regular maintenance and calibration can help in mitigating these challenges and ensuring accurate battery readings.
Measuring Body Temperature
Mercury thermometers are often used as clinical thermometers for measuring body temperature. They are not just limited to meteorological or laboratory use; they have been a reliable tool for measuring body temperature. This can be done orally, rectally, or axillary (armpit). Each method has its own procedure and results in varying temperature readings.
An oral temperature reading involves placing the mercury thermometer under the tongue, closing the mouth, and waiting for about five minutes. For measuring armpit temperature, the thermometer is placed in the deepest crease of the armpit and held in place for approximately five minutes with the arm closed. For newborns, the most accurate measurement is the rectal temperature, which involves lubricating the thermometer’s tip, gently inserting it rectally, and waiting for about five minutes.
Once the body temperature is measured, it’s imperative to thoroughly read the mercury column on the thermometer. Make sure to consider that temperature readings can differ based on the location of measurement:
- Oral temperatures typically average 98.6 degrees Fahrenheit
- Rectal temperatures are about 0.5 to 1.0 degrees higher
- Armpit temperatures usually turn out to be 0.5 to 1.0 degrees lower.
Precautions
Mercury thermometers measure body temperature efficiently. However, you must take precautions for accuracy and safety. Do not use them for children under age 4 who cannot keep their mouths closed. Also, wait 20 to 30 minutes after eating or drinking before taking an oral temperature.
When taking a rectal temperature with a mercury thermometer, follow these steps:
- Insert the thermometer only about a half inch, and do not force it if resistance is felt.
- Cleaning or disinfecting the thermometer before and after use is vital to prevent the spread of germs.
- Above all, handle the thermometer with care. Avoid shaking or dropping it, as mishandling can lead to inaccuracies in temperature readings.
Additionally, breaking the thermometer can cause mercury poisoning. This happens if someone ingests or inhales the mercury.
Mercury-Free Alternatives
Digital thermometers are a popular alternative to mercury thermometers. While mercury thermometers have been a staple for centuries, advancements in technology have brought forward mercury-free alternatives. Digital thermometers, such as those utilizing sensors like platinum resistance (PRT), thermistors, and thermocouples, offer an alternative to mercury containing thermometers. Bi metal thermometers, another mercury-free option, are capable of measuring temperatures ranging from -200 °C to above 500 °C, depending on the sensor type.
Another practical alternative is the glass thermometer, specifically non-mercury liquid-in-glass thermometers. These provide accurate measurements with nominal uncertainties as low as 0.02 °C, catering to temperature ranges from -196 °C to 300 °C. The selection of electronic thermometers, such as digital thermometer sensors, is dependent on the desired level of measurement accuracy, application environment, and potential exposure to mechanical shock. These thermometers can also offer advanced features, such as minimum and maximum temperature display, alarms, and options for connectivity, such as wireless or USB. However, certain conditions or damage may render a thermometer unusable, making it crucial to choose the right type for your specific needs.
Globally, there’s a growing trend of transitioning towards mercury-free thermometers in medicine. Countries like the Philippines and Argentina have mandated the phase-out of mercury-in-glass thermometers from hospitals, opting for non-mercury digital thermometers.
Environmental and Health Concerns
Mercury exposure poses severe health risks, including neurological issues and developmental deficits in children. Technological advancements and concerns over mercury’s environmental and health impacts drive the shift to mercury-free alternatives. Consuming contaminated seafood often exposes people to methylmercury, a potent neurotoxin. This exposure can damage vision, coordination, speech, and muscle strength. Pregnant women ingesting methylmercury risk their children’s development, impacting cognitive thinking, memory, attention, language, motor skills, and visual spatial abilities.
Inhaling mercury vapor from broken products can lead to tremors, emotional instability, and insomnia. It also causes neuromuscular changes, headaches, sensory disorders, and changes in nerve responses. Excessive mercury exposure leads to mood swings, memory loss, kidney and gastrointestinal damage. At high levels, it can cause respiratory failure and death. Brief exposure to high mercury concentrations can cause loss of appetite, fatigue, insomnia, and changes in behavior or personality.
Mercury also poses significant environmental risks. Broken thermometers release mercury, leading to the production of methylmercury in seafood, which poses serious health risks. As mercury solidifies, cleanup becomes more challenging, worsening the problem.
Handling Broken Thermometers with Mercury
A mercury spill from a broken thermometer requires careful cleanup. Due to the health and environmental risks posed by mercury, handling broken mercury thermometers demands utmost care. If you break a mercury thermometer, follow these steps:
- Immediately try to contain the spill.
- Keep children and pets away.
- Avoid using a vacuum cleaner or broom to prevent vaporization and the spread of mercury.
When handling broken glass, always wear gloves. Avoid wearing contaminated clothing to stop mercury from spreading. Use gloves, eye droppers, plastic bags, cardboard, squeegees, and adhesive tape to collect mercury beads for a safe cleanup. Optionally, apply powdered sulfur to detect and absorb mercury. A flashlight can help you find small beads.
After cleanup, ventilate the area for at least 24 hours to let mercury vapors dissipate. If you need mercury vapor monitoring or face a large spill, hire a contractor with the proper equipment. Dispose of the cleanup materials through a licensed and certified hazardous waste contractor.
Proper Disposal of Mercury Thermometer
Dispose of mercury thermometers as hazardous waste. Proper disposal prevents environmental contamination. Improper disposal introduces mercury vapor to the air and liquid mercury to landfills. It’s crucial to follow local regulations for mercury waste disposal. States and local jurisdictions may have unique regulations, and residents can access collection and exchange programs through local officials.
Store mercury thermometers awaiting disposal in an airtight, leak-proof container labeled as containing mercury. Secure them in a cardboard box for transport to a hazardous waste facility. Do not pour mercury down drains to avoid environmental contamination. Label containers with mercury thermometers ‘DO NOT OPEN’ and keep them away from children and pets.
Regulations and Restrictions for Mercury Thermometer
Regulators have implemented rules to cut down on mercury thermometer use due to its health and environmental hazards. Many organizations are working to reduce mercury thermometer use and promote mercury-free options. For instance, the EPA has worked with stakeholders to reduce the use of mercury-containing non-feiver thermometers in US industrial and commercial sectors.
In January 2012, the EPA’s rule revision facilitated alternative options to mercury thermometers in regulations concerning petroleum refining, electricity production and distribution, and polychlorinated biphenyl (PCB) waste management. Through partnerships with ASTM International and the American Petroleum Institute (API), the EPA has fostered the inclusion of non-mercury alternatives within industry standards, ensuring regulatory flexibility.
On a similar note, the National Institute of Standards and Technology (NIST) ceased the calibration service for mercury-in-glass thermometers on March 1, 2011, to promote traceability, supporting the move away from mercury thermometer utilization. Despite these regulatory updates, some U.S. federal and state regulations still necessitate the use of mercury thermometers or reference specifications for their use through standards by ASTM International and API.
Calibration and Maintenance of Mercury Thermometer
Temperature calibration is essential for maintaining the accuracy of mercury thermometers. To ensure optimal performance of mercury thermometers, both accurate calibration and consistent maintenance are crucial. Calibration involves bringing the thermometer to thermal equilibrium with fixed points such as ice water, where it should read 0 degrees Celsius, and boiling water, where it should read 100 degrees Celsius at sea level. Keep in mind that atmospheric conditions and altitude may alter the boiling point of water, necessitating local adjustments to calibrate the calibration process.
Some mercury thermometers have a calibration nut that allows for fine adjustments while immersed in the reference temperature. When calibrated accurately, mercury thermometers typically achieve a reading accuracy within ±0.1 to ±0.2 degrees Celsius. Regular accuracy checks at known temperature points are crucial, even when recalibration is not possible.
In some cases, you can raise the upper temperature limit of mercury in glass thermometer. Adding an inert gas above the mercury or using fused quartz instead of glass does this. However, handle these measures with extreme caution due to mercury’s hazardous nature, especially at lower meteorological temperatures.
Summary of Mercury Thermometer
Understanding mercury thermometers is a crucial aspect of safe and effective use. From their construction to calibration, these devices require careful handling and maintenance to ensure accurate temperature readings. While mercury thermometers have been widely used for centuries, the health and environmental concerns associated with mercury have led to the development, testing and adoption of mercury-free alternatives.
Remember, safety comes first with mercury thermometers. Handle breaks and dispose of them carefully to avoid health risks and environmental harm. As we develop safer alternatives, let’s be mindful and responsible for our environment.
Frequently Asked Questions about Mercury Thermometer
Do they still make thermometers with mercury?
These thermometers are mostly being phased out due to laws and regulations, and are being replaced by digital or non-mercury options. However, they are still commonly used in certain industries.
Are thermometers with mercury still accurate?
These thermometers are accurate, but they come with drawbacks such as toxicity, fragility, and a high freezing point. There is no significant difference in accuracy compared to electronic thermometers, but electronic thermometers have a greater fluctuation of readings.
What does a mercury thermometer measure?
Traditional thermometers measured outdoor and body temperatures. However, mercury’s extreme toxicity and the risk of organ and nerve damage from broken glass make them unsafe for use.
Why did they ban mercury thermometers?
Authorities banned these thermometers because they release mercury, a health and environmental hazard, when broken. Many countries have prohibited their use in medicine due to mercury’s toxicity. Broken thermometers pose a risk of releasing dangerous mercury vapor into indoor air.
How do thermometers with mercury work?
These thermometers work by utilizing the thermal expansion and contraction of liquid mercury, which moves through a capillary bore to indicate the temperature based on the expansion of flow or contraction of the mercury.
