Temperature measurement and uses of mercury-in-glass thermometers play such a very large role in industry, commerce, science and engineering that the devices are almost taken for granted.
The recent ban against sales of mercury thermometers in many states in the USA and countries around the world, although well-justified from a public health perspective, may have created a conundrum of huge proportions when it comes to uses beyond the familiar health, clinical and medical ones.
Similar problems may also be encountered in the uses of mercury-bearing measuring devices of other kinds, such as barometers, hygrometers and more.
The ban on mercury thermometers does extend, in most cases to many other types of measurement devices. Here, we will concentrate on mercury-in-glass thermometers.
Not only are mercury thermometers common, they are also often “written into” some of their uses by decree of a government or industry standard to insure that the required precision, repeatability, traceability and time response important to that use are maintained. After all, repeatability and uniformity of methodology, including use of the same type of measurement device, is one of the keys to performing temperature measurements that can be compared to previous ones.
What do the bans on sales of mercury thermometers imply in such cases?
We took a look at some of the standards that currently exist to see if there was a clear indication of the size of the issue. In the USA, the American National Standards Institute, ANSI, gathers under its wing many standards written by other groups and adopts them as “National Standards”. That seems like a good place to start a search.
In conducting a search of the ANSI Online Store for Standards several additional types of standards, generated by other societies were found. These included many domestic and international standards that US manufactruers follow to comply with international trade requirements. There are also standards listed from specific countries like Germany and Japan that were not included, because they were too country-specific. They may need to be considered, but are not included here.
The single largest number of domestic standards found were by the American Society for Standards and Materials, ASTM who have more than 1400 individual specifications, Test methods and related standards that involve temperature. The second highest group of standards are among the standards published by The International Standards Organization, ISO. the ANSI search found almost 700. The International Electrotechnical Commission has another 225 seperate standards.
The initial search results are summarized in the table below. Clearly not all standards found will call for mercury thermometers, but it is very likely that many will, since many test methods call for very specific reference temperatures down to and including specific types of mercury thermometers, for instance in the calibration of the apparatus used to perfom a specific test.
The ASTM-type mercury thermometer series, for example, are used widely in industry, science and commerce. They are available from numerous suppliers around the world and have been around for more than 50 years.
The list of different models is very extensive.