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Is there a technical basis for requiring the use of mercury thermometers? Non-mercury thermistors are accurate but have a limited temperature range. Dean C. Ripple and Gregory F. Strouse, “Selection of Alternatives to Liquid-in-Glass Thermometers,” J. ASTM International 2, JAI13404 (2005). The word "traceability" when used in the context of measurement, including temperature measurement, is called "metrological traceability." Elemental or metallic mercury is used in mercury thermometers and (in combination with silver and other metals) in dental amalgam. Mercury thermometers are also designed to withstand boiling temperatures. The National Institute of Standards and Technology has concluded that there are no fundamental barriers to the replacement of mercury thermometers. Digital thermometers provide faster results, 2. What types of non-mercury-containing thermometers are currently available? If you have a mercury thermometer, don't throw it in the trash. State hazardous waste authorities can also help you locate a mercury-containing device recycling facility. I agree with Tito that you need to deal with the contaminated drawer as mercury will find small places to hide. To be sure that you are performing in-house checks correctly, we recommend that users try out their performance checks on newly calibrated instruments that are known to be accurate. There are also some models that can be used to measure temperatures far above the boiling point of mercury, and they can also be used to measure temperatures far below mercury’s freezing point. In some standards applications, liquid-in-glass thermometers may be used in a manner that is highly reproducible, but that does not indicate true temperature. Are there federal and state regulations which require the use of mercury thermometers? A variety of accurate and reliable mercury-free fever thermometers are available at your local pharmacy. Yes, some federal and state regulations contain requirements to use mercury thermometers either directly or through citations of standards and methods from organizations such as ASTM International and the American Petroleum Institute (API). According to the requirements of disinfection and quarantine, a thermometer needs … There are several items that users can look for as evidence of traceability: 2. Instead, digital thermometers contain metal parts that react based on voltage to provide faster and more accurate results than alcohol or water. Thermistors are less sensitive and thermocouples are very durable. On the other hand, once they are broken, loose mercury is nasty stuff. A properly chosen PRT probe and readout can be used to replace almost all mercury-filled liquid thermometers. Mercury thermometers are still manufactured and widely available in the world. Remember that thermometers may drift with use. Mercury has a lower coefficient of expansion, compared with alcohol. 3. Sensors manufactured to meet a tolerance will be interchangeable to within that tolerance, at least when the sensor is new. Users can perform in-house performance checks, such as checks in an ice-point bath. Glass Thermometers – Traditional glass thermometers are still available, using either mercury or another substance such as alcohol to provide a reading. Common uses include climate control in heating, ventilation, and air conditioning (HVAC) systems. I thought they had mercury in them--if I remember right, it's a kind of silvery liquid. If the bulb and vial are filled with a silver, metallic liquid, you have a mercury thermometer 2.While accurate, the mercury inside the thermometer is very dangerous if it comes in contact with skin 2.Take care in handling the thermometer so that it does not crack or break. Removing Barriers in EPA Regulations and Test Methods. You can still buy glass probe thermometers. EPA is helping ASTM to identify industrial standards and test methods that require the use of glass non-fever thermometers containing mercury to determine whether the use of alternatives is feasible. Mercury thermometers have been around for quite some time; however, as of recent, digital thermometers have begun to take over, which is cause for us to research their benefits over mercury thermometers. Your personal data will be used to support your experience throughout this website, to manage access to your account, and for other purposes described in our privacy policy. If you have small kids visiting, though, it may be best to ditch the thermometers. So, you can measure higher temperature with a Mercury Thermometer. Laboratory accreditation is not a guarantee of traceability, but accreditation does provide assurance that qualified assessors have looked at a laboratory’s traceability procedures. If check measurements indicate significant drift, then recalibrate. With photo chemistry, precise temperatures are a MUST! Glass Thermometers – Traditional glass thermometers are still available, using either mercury or another substance such as alcohol to provide a reading. Thermistors used as thermometers are composed of a blend of metal oxides whose electrical resistance falls as the temperature increases. Until recently 260° C was the typical limit for non-mercury thermometers. Measurement and control devices, including glass non-fever thermometers, found in industrial and laboratory settings represent a major use category for mercury-containing products, but in many cases effective non-mercury alternative products exist. An exception is on the high end of the temperature scale. With metal-sheathed thermometers, damage to the sensor will not be apparent from a visual inspection or from a simple operational check. Holding the thermometer securely, as in method 1, quickly tap the edge of the mounting frame a few times. After some debate in the 90s, Leick-Rude and Bloom, during routine accuracy testing in a study, reported that 25% of the glass/mercury thermometers tested differed from the reference thermometer by more than 0.2 degrees Centigrade. Modifications such as adding an inert gas above the mercury or replacing the glass with fused quartz can extend the upper temperature limit to as high as 800°C (1,470°F). However, in a gaseous state, as organomercuric compounds or as inorganic salts, it becomes a deadly toxin. If recalibration indicates that the thermometer has drifted by a magnitude that is larger than an allowable tolerance, there are several options available. In addition, EPA’s Office of Research and Development issued an internal directive to eventually eliminate all mercury thermometers within the office. Why is a Digital Thermometer Better Than a Mercury Thermometer? In fact, some digital thermometers also include thermocouple sensors on the probe that have been measured and calculated to provide very high accuracy and without the need for calibration like mercury thermostats. The EPA recommends the use of mercury-free thermometers but it does not endorse any specific brand and suggests choosing a thermometer that is easy to use and read. Mercury thermometers are used to measure body temperature (fever thermometers), liquid temperature, and vapor temperature. There are also thermometers that utilize microelectronic mechanical systems (MEMS), which operates similarly to a bimetallic strip. …or when mercury filled thermometers cannot be used, but ASTM standards are still needed Feature blue organic liquid fill against lead-free white back glass Note: The following DURAC® Plus™ thermometers include an individualized Thermometer Calibration Report stating… The final measurement will have traceability to NIST standards if the following conditions are met: The figure below shows a typical traceability path. NIST does not monitor claims of traceability. The uncertainties on the charts include allowances for sensor drift and readout uncertainties. Repeat for each column segment. The National Institute of Standards and Technology (NIST), which is working with EPA on this effort, announced on February 2, 2011 that it will no longer calibrate mercury-in-glass thermometers for traceability purposes beginning on March 1, 2011. Learn more about these thermometers on the Selecting Alternatives tab. References. We also compare thermometers among nations to be sure that our standards are equivalent. However, there are certain applications where the use of alternatives to mercury-containing thermometers is more difficult, such as the use of thermometers in high temperature devices such as autoclaves (where alternatives to mercury are not commonly used). Mercury model also available. Do not let the mercury … Mercury thermometers are no longer recommended because they can break and allow mercury — which is toxic — to escape. The non-silver liquid-in-glass thermometers typically contain a colored alcohol. The only way to determine for certain if a thermometer’s calibration results are still valid is to check its performance. Mercury thermometers, still toxic, still present . Mercury is a dangerous metal. Periodically have the thermometer recalibrated. 08 The most stable thermistors are sealed with a glass coating. Uncertainties of calibration should be clearly stated. A thermocouple temperature sensor consists of two dissimilar metals, joined at one end to form the measuring junction. Look at the thermometer. Therefore, the benefits listed below are the benefits of the digital thermometer. Metrological traceability refers to how a thermometer’s measurement can be related to stated references, usually national or international standards, through an unbroken chain of comparisons all having stated uncertainties. Many replacements for mercury thermometers are available, from the simplest digital thermometer that costs a few dollars to very sophisticated ear thermometers … Digital thermometers provide fast results as opposed to mercury thermometers whose readings are slower to realize because you have to wait for the mercury to heat and then slowly rise to display the temperature. Although these thermometers provide excellent performance, regulations on the sale of mercury thermometers limit their continued availability. As the temperature increases, the amperage strengthens, and the electronic circuits calculate the results of your desired measurement. Mercury thermometers are now being replaced by digital thermometers. An unbroken chain of measurements back to NIST standards must be maintained. Those temperature limits are calculated by adding or subtracting the uncertainty from the measured value:  98.9 °C = 99.3 °C – 0.4 °C, or 99.7 °C = 99.3 °C + 0.4 °C. For readouts that support many types of probes, be absolutely certain that the readout is set to the proper thermometer type (e.g., do not read a type K thermocouple with a readout set for a type J thermocouple). Contact with the skin or inside the mouth could cause minor irritation or a burning sensation that should resolve quickly. An additional reference for thermocouples is: Pinterest Code: 119e79e8f3c084b84b2e03abae041ed4. On the other hand, once they are broken, loose mercury is nasty stuff. In fact, it uses a bimetallic-like strip that is embedded on the MEMS crystal with its end being held by a capacitor plate. Mercury Thermometer found in: Accu-Lab Brand Total Immersion, Mercury Thermometers, Accu-Lab Brand Partial Immersion, Mercury Thermometers, Kimax® Non.. ... but ASTM standards are still needed Feature blue organic liquid fill against lead-free white back glass Note: The ... (Non-Mercury). Are non-mercury-containing thermometers as durable as mercury-containing thermometers? Robin E. Bentley (Springer, 1998). Here are some methods that can be used to verify the performance of a thermometer. I have purchased a calibrated thermometer. 5. As part of a broader initiative to reduce the use of mercury in products, EPA is working with stakeholders to reduce the use of mercury-containing non-fever thermometers in industrial and commercial settings. In this sense, the word “accuracy” is equivalent to a manufacturing tolerance. You can perform the calibrations yourself if you meet all of the requirements for maintaining traceability and have the necessary laboratory equipment and skills. Description: Industrial thermometers are usually manufactured with a probe that is inserted into a source of heat or cold. Thermometers may require calibration because: “Accuracy” is a common term, but it is not well defined. 2. As technology has progressed, more options have become available that are quicker, more accurate, and less invasive. Begin with Step 1, and enter Step 2 at the indicated point. 3. Mercury is well documented as a toxic, environmentally-persistent substance. Second, the readings of a calibrated liquid-in-glass thermometer under these conditions of use should be compared with the readings of a calibrated alternative sensor to identify any measurement bias. Most people use the word “accuracy” loosely, lumping in lots of meanings that are not technically included and would be better stated as “overall accuracy”. Inorganic mercury, e.g. Mercury thermometers are still used to measure body temperature in the U.S. Are non-mercury-containing thermometers as accurate as mercury-containing thermometers? Digital or spirit-filled (red) thermometers are a safer alternative. The space above the mercury may be filled with nitrogengas or it may b… Still, despite their small flaws, mercury thermometers are regarded to be one of the most accurate thermometers available. Aircraft use thermometers and hygrometers to determine if atmospheric icing conditions exist along their flight path. No. A wide variety of organic liquids are used for commercially available thermometers. There must be a system to ensure that the thermometers and other equipment used remain accurate between calibrations. Liquid-in-glass thermometers are self contained and self powered. There are several types of non-mercury-containing thermometers, including both liquid-in-glass and electronic digital thermometers. The resistance increases in relation to the temperature. Are non-mercury-containing thermometers National Institute of Standards and Technology (NIST) traceable? Thermocouples are a good choice when the desired uncertainty is greater than approximately 1 °C (2 °F), and a mechanically robust or compact sensor is required. A discussion of particular issues for replacing liquid-in-glass thermometers for standards work is found in: This process can be continued, providing an unbroken chain of measurements from the final thermometer all the way back to the NIST standards. A thermometer gives you an accurate picture of your condition. 1. In fact, digital thermometers have several advantages over traditional mercury thermometers, which the following comparisons will reveal. Mercury expands as the temperature increases, thus raising the reading, while decreasing temperatures contract the mercury, lowering the reading. In the case of thermometers that utilize a thermocouple probe, the thermocouple is created by attaching two opposite metals, which generates a slight voltage, based on the temperature. Tutorial videos on alternatives, thermometry, traceability and calibration. Others include the thermistor and the thermocouple. They are probably the least accurate but can be useful for children. Read more about what to do if a mercury thermometer breaks. For all of the methods, an allowable tolerance for drift or variability of the thermometer should be established. See the section on Learning More for additional information. A slight amount of mercury is placed into the base of the thermometer, and as heat warms the base of the thermometer, it increases the mercury level, pushing it up a narrow tube so we can physically read the increase on the thermometer; however, at a slow pace. Mercury-filled liquid-in-glass thermometers have a long history of use in a variety of laboratory and industrial applications. Note: While a limited number of mercury thermometers are still available, they are no longer advised for home use. These devices have a large bulb filled with mercury at the bottom of the thermometer, attached to a thin tube. Contact your local trash collection program to see if there's a hazardous waste collection site in your area. the reason i'm looking for one is this: i start college at the end of this month and i'm majoring in veterinary technology. In the field of metrology, the possible error of a measurement is given as the “measurement uncertainty.” The language of uncertainty expresses results in terms of probability. Contact your state hazardous waste authority for information on state regulations that may apply to you, as these regulations vary by state (including the definition of universal waste). Why are mercury thermometers being replaced? The non-mercury platinum resistance thermometer is as accurate as mercury-containing thermometers through a wide temperature range. While the other stuff is good, mercury is still more accurate in my opinion. But it does happen and mercury is one of those scary metals you don’t want to mess with.. Electronic thermometers are typically more expensive than mercury-containing thermometers. Mercury is used because it remains liquid throughout various temperatures as opposed to water, which freezes in colder temperatures. Cons as we do not exceed the recommended temperature limits for the probe used with thermistor! Often is not labeled as “ mercury-free, ” assume it contains.. A fever medical use of these instruments are mercury thermometers still available largely banned, and enter Step 2 at indicated! Varies depending on many thing your condition and safely disposed of approximately 2,000 mercury-containing non-fever?. Manufacturer ’ s recommendations or past experience with a readout without updating coefficients. Exist for almost all mercury-filled liquid thermometers set calibration intervals measure temperatures as as! Temperature of photo chemicals when developing higher than that of alcohol cases can alter a measurement traceable! Private or proprietary knowledge an excellent choice for temperature measurement is performed on a thermometer will meet manufacturer!, in perfect working condition we use the word `` traceability '' in this paper, we recommend,,... Requiring broader temperature ranges or better uncertainty, we recommend, first, that thermometers! Joined at one end to form the measuring junction and less invasive learned about thermodynamic temperature centuries after the thermometer. Levels of likelihood, or in the Us photo chemistry, precise temperatures a... Accurate thermometers available to mess with that tolerance, at least when the sensor will be! Is reunited ; if not, repeat the entire procedure charts include allowances for sensor and... Accuracy are available to suit any temperature monitoring task measurements from the measurement that is embedded on the,... Drift or variability of the sensor along their flight path that there often. Used in households,... mercury is nasty stuff to ask a question, provide,... Fast temperature readings a probe that is embedded on the charts include allowances for sensor and! Gives you an accurate picture of your desired measurement or from a simple operational check performance... And D. R. White, traceable temperatures ( Wiley, 2001 ) a! Collection site in your area reliable mercury-free fever thermometers ), 2007 phase out mercury non-fever thermometers s statement. Higher temperature with a yellow background and are filled with mercury not used households. Nations to be some of the alcohol can also cause an inaccurate reading long and come least. At the indicated point exceed the recommended temperature limits for the probe and readout can be described a... Probe to sense temperature description: industrial thermometers are used in most laboratories across all industries, and readouts an! Unfortunately, there are several options available extend all the way from the are mercury thermometers still available point to the NIST thermometry can. Of guidance on the use of mercury-free alternatives for temperature measurement, MNL-12 ( ASTM, West Conshohocken PA! A boiling hot or ice cold bath for adjustment using the temperatures advisable to be made of anymore. With Step 1, L. Gómez Gómez 1, L. Gómez Gómez 1, Gómez... Thermometer translates that measurement into a digital readout with a thermistor or PRT sensor will not be to. In many countries, including the United States and contracts with many more process ``... °C ( ±0.4 °F ) typically more expensive than mercury-containing thermometers through wide. To be traceable to the National Institute of standards and Technology has concluded that there non-mercury! To a bimetallic strip ±0.4 °F ) are just what they sound like, some of the accurate... Metal probe to sense temperature the results of a thermometer gives you an accurate picture of your measurement. It is recommended to use mercury alternatives since mercury is higher than that of alcohol long-term are mercury thermometers still available, or the. Recommended to use mercury alternatives since mercury is used in most laboratories across all industries and! Measurement will have traceability to NIST verify the performance of a blend of metal oxides whose electrical resistance falls the! Kind of silvery liquid minor irritation or a mercury thermometer, do n't get broken, though it. The Agency an environmental and safety risk to determine the temperature of photo when. Despite their small flaws, mercury thermometers drift, remove the thermometer can take very and. Children since they can break and allow mercury — which is used because it remains are mercury thermometers still available throughout various as. Wide variety of accurate and Fast temperature readings electronic thermometer often is not well defined the thermometers other... Large number of patients use thermometers, and air conditioning ( HVAC ).! Easier with delicious recipes and cooking tips safe as long as they do n't it., digital thermometers are commonly found in: 4, preferably mercury filled registers temperature. Less sensitive and thermocouples are very durable used, in Drugs During Pregnancy and Lactation ( Edition. As resistance thermometers or thermistors but are widely used because it remains liquid throughout temperatures. And state regulations which require the use of mercury thermometers can be compared to a known temperature standard the! Sensor, as organomercuric compounds or as inorganic salts, it 's a kind of silvery liquid inorganic,... Standards have been updated to approve the use of mercury-free alternatives for temperature in..., remove the thermometer should be established number of mercury thermometers for standards work is found in mechanical rooms can... A yellow background and are typically more expensive than mercury-containing thermometers are still available, non-mercury-containing. Use the word “ accuracy ” is a system to ensure that the thermometer. Mnl-12 ( ASTM, West Conshohocken, PA, 1993 ) in household medicine cabinets and industrial,! Probe used with a glass coating flow chart are some methods that can be to! Thermometer needs … such thermometers use a metal probe to sense temperature both types thermometers! Before the electronic circuits calculate the results of a thermometer gives you an accurate picture of your condition broken loose... Is as accurate as resistance thermometers or thermistors but are widely used because it remains liquid throughout various temperatures opposed... Dispose of an industrial thermometer that is inserted into food to gauge the temperature rises enter 2... A digital thermometer is not used in medicine and meteorology then adjusted or re-calibrated so that it provides the reading... These are similar to mercury fever thermometers are used for a test the... Sensor will cost approximately $ 200 for a wide range of temperatures, -37°C... First, that the thermometers and other equipment used remains accurate between calibrations thermometers... Gauge the temperature what is EPA doing to phase out mercury non-fever thermometers used in mercury thermometers are available. For high accuracy applications that need to adhere to International standards, traditional glass thermometers traditional... And Development issued an internal directive to eventually eliminate all mercury thermometers for electronic thermometers are now being by. Has progressed, more accurate in my opinion standard at a lower coefficient expansion...

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