Calibration of Thermometers Avoiding the Use of Mercury

避免使用汞的温度计校准

• 批准号: 10061179
• 金额: $ 0.79万
• 依托单位: ISOTHERMAL TECHNOLOGY LIMITED
• 依托单位国家: 英国
• 项目类别: Collaborative R&D
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=10061179
• 关键词: Calibration; Thermometers; Avoiding; Use; Mercury

**Calibration of Thermometers Avoiding the Use of Mercury**High-accuracy laboratory thermometers need to be calibrated by using 'fixed point cells'; cells are used to calibrate thermometers to the highest accuracy, and cells rely on the phase change of a pure substance. At higher temperatures, pure metal ingots are encased in an assembly into which a thermometer can be placed. As the metal ingot melts or freezes the temperature remains constant. These fixed points are specified in the International Temperature Scale of 1990 (ITS-90), the internationally agreed approximation to the SI unit of temperature, the kelvin.The most used low-temperature fixed point cell uses pure mercury, which provides a reference of -38.8344°C. Using mercury is a very convenient and time-honoured (and only) way of calibrating the standard platinum resistance thermometers (SPRTs) used for realising and disseminating the ITS-90\.However, mercury is a hazardous substance, and its use is now prohibited in electronic equipment. The scientific community has great concern that mercury could soon be banned for calibration purposes; it is already very difficult and problematic to ship mercury as cells need to be both supplied for new installation, and moved for re-calibration.Scientists are researching alternatives, including carbon dioxide (CO2, -56.6 °C) and sulfur hexafluoride (SF6, -49.6 °C).Isotech has developed a carbon dioxide (CO2) fixed point cell, it operates at approximately -56.6 °C. We are unable to realise the triple point or to measure the temperature with a sufficiently low uncertainty, not for lack of equipment or commercial service, but for the need of novel realisation and measurement techniques for this new calibration point, both for the thermal performance and for determining the purity of the CO2\.We believe that by leveraging the experience and expertise of the NMI community (i.e. NPL) we can commercialise the CO2 cell, which would solve or reduce the need to use hazardous mercury, reassuring the measurement community and eliminating the environmental concerns over mercury, and giving Isotech a significant commercial advantage in the international marketplace.

**避免使用汞的温度计校准**高精度实验室温度计需要使用“定点电池”进行校准；电池用于将温度计校准到最高精度，电池依赖于纯物质的相变。在较高温度下，纯金属锭被封装在可以放置温度计的组件中。当金属锭熔化或冻结时，温度保持恒定。这些固定点在 1990 年国际温标 (ITS-90) 中指定，这是国际公认的温度 SI 单位开尔文的近似值。最常用的低温固定点电池使用纯汞，它提供 -38.8344°C 的参考值。使用汞是一种非常方便且历史悠久（也是唯一）的校准用于实现和传播 ITS-90 的标准铂电阻温度计 (SPRT) 的方法。但是，汞是一种危险物质，目前禁止在电子设备中使用。科学界非常担心汞可能很快会被禁止用于校准目的；运输汞已经非常困难且存在问题，因为需要为新安装提供电池并进行重新校准。科学家们正在研究替代品，包括二氧化碳（CO2，-56.6 °C）和六氟化硫（SF6，-49.6 °C）。Isotech 开发了一种二氧化碳（CO2）定点电池，其工作温度约为 -56.6℃。我们无法实现三相点或以足够低的不确定性测量温度，不是因为缺乏设备或商业服务，而是因为这个新校准点需要新颖的实现和测量技术，无论是热性能还是确定 CO2 的纯度\。我们相信，通过利用 NMI 社区（即 NPL）的经验和专业知识，我们可以将 CO2 电池商业化，这将解决或减少需求 使用危险的汞，让测量界放心，消除对汞的环境问题，并为 Isotech 在国际市场上带来显着的商业优势。