These advantages can reduce reading errors and operational costs for electronic thermometers relative to liquid-in-glass thermometers. Calibration methods and procedures should be openly documented. …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… Thermometers that give results outside the allowed tolerance should be recalibrated or taken out of service. Many countries, including the United States, have signed a Mutual Recognition Arrangement that recognizes the validity of each others’ calibration certificates. 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). Non-mercury thermocouples are not as accurate as resistance thermometers or thermistors but are widely used because of their durability. A. Souto 1, L. Gómez Gómez 1, S. García Mata 2. A thermometer gives you an accurate picture of your condition. Photo by Matteo Fusco on Unsplash. Partial immersion thermometers have a line around the circumference of the thermometer and/or a printed immersion depth on the back (e.g., 76 MM for 76 millimeters immersion). Get the best deals for glass mercury thermometer at eBay.com. How and where do I dispose of an industrial mercury-containing thermometer? With special care, better uncertainties may be obtained. Therefore, the benefits listed below are the benefits of the digital thermometer. With proper care, a thermometer can be used through many recalibration cycles beyond what is shown in the figure. You can still buy glass probe thermometers. In other words, Mercury Thermometers are compact and easy to take with you. Traceability records should not be claimed to be private or proprietary knowledge. Mercury is opaque and bright, so the movement of mercury inside the capillary tube is easily visible. NIST provides a description of traceability and an extensive list of questions and answers on. They are probably the least accurate but can be useful for children. How long a thermometer will meet the manufacturer’s accuracy statement depends on the thermometer type and its use! National Institute of Standards and Technology Mercury Thermometer Alternatives website. Thermometers that check body temperature in the ear, across the forehead, or have a digital display do not contain mercury. NIST and EPA are collaborating to resolve difficulties in using alternative thermometers in certain elevated temperature applications, such as autoclave operations and asphalt processing. Non-contact Thermometers – Non-contact thermometers also work with infrared to provide readings without contacting the body. If a mercury thermometer breaks or leaks, it can release toxic vapors. The National Institute of Standards and Technology has concluded that there are no fundamental barriers to the replacement of mercury thermometers. Mercury-in-glass thermometers are banned in many countries due to mercury exposure concerns. ASTM Manual on the Use of Thermocouples in Temperature Measurement, MNL-12 (ASTM, West Conshohocken, PA, 1993). The final rule incorporated ASTM Standards D5865-10, D445-09, and D93-09 in certain regulations that cover petroleum refining, power generation and polychlorinated biphenyl (PCB) waste disposal. If check measurements indicate large and sudden drift, remove the thermometer from service. The liquid-in-glass thermometer was used for a test where the temperature is not stabilized before a reading. The charts below give a summary of typical achievable uncertainties or manufacturing tolerances, in units of both degrees Celsius and degrees Fahrenheit (these charts can assist with the selection of a thermometer, but do not represent the actual uncertainty of any particular thermometer). 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). Thermocouples may be insulated with ceramic, fiberglass, or polymer insulations. Warnings. An exception is on the high end of the temperature scale. For high-vibration applications within the temperature range -100 °C to 150 °C (-148 °F to 302 °F), PRT sensors formed from a platinum film deposited on a ceramic chip work well. Mercury thermometers are no longer recommended because they can break and allow mercury — which is toxic — to escape. I have a “certified” thermometer that claims to be traceable to NIST. Why is a Digital Thermometer Better Than a Mercury Thermometer? Learn more about these thermometers on the Selecting Alternatives tab. Mercury thermometers, still toxic, still present . Look at the thermometer. Many replacements for mercury thermometers are available, from the simplest digital thermometer that costs a few dollars to very sophisticated ear thermometers … If recalibration indicates that the thermometer has drifted by a magnitude that is larger than an allowable tolerance, there are several options available. The readout converts the measured resistance to indicated temperature using either a standard curve or a calibration function for the particular probe being used. Liquid throughout various temperatures as opposed to water, which operates similarly to a thin tube as in... Gaseous state, as shown below and come with least Count of,! 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