What is a pyrometer? A pyrometer is a device that measures high temperatures for applications beyond the range of a mercury thermometer (673° F or 356° C). Pyrometers, also referred to as pyrometric devices, are used to monitor temperature for a wide variety of applications. From kilns, furnaces, heat treat ovens, and industrial processes, to measuring the surface temperatures of distant planets!
Contact vs Non-Contact Pyrometers
Pyrometers can be contact or non-contact. Contact pyrometers, such as pyrometers for kilns, use thermocouples that are in thermal contact with the object or atmosphere. Non-contact pyrometers, on the other hand, use optical systems to measure the radiation of a surface without the need for thermal contact.
Both types of pyrometers have their pros and cons. Contact pyrometers, also known as resistance pyrometers or thermocouple pyrometers, are subject to degradation from heat exposure and are limited by the range of the thermocouple. However, they are highly accurate and usually less expensive.
Non-contact pyrometers, also referred to as optical pyrometers, radiation pyrometers, or infrared pyrometers, have far greater range – both in terms of physical distance as well as maximum temperature. Non-contact pyrometers can measure temperatures exceeding 7232° F or 4000°C – nearly three times higher than most contact pyrometers. Non-contact pyrometers can also measure temperatures of moving objects or objects that cannot be touched. However, they are significantly more expensive and less accurate.
Pyrometers for Kilns
As you can probably imagine from the comparison above, contact pyrometers are generally more suitable for kiln temperature monitoring. Affordability and accuracy, as well as the temperature range of most kiln firing schedules, makes using a thermocouple pyrometer with your kiln a pretty obvious choice!
A Brief History of Pyrometers for Kilns
While the earliest known pyrometer dates back to the “Hindley Pyrometer” in 1732, the first pyrometer for kilns was invented by English potter Josiah Wedgwood in the 1780s. Josiah Wedgwood is an interesting figure in the history of pottery. He was a wildly successful potter, industrialist, and entrepreneur – a savvy marketeer, technological innovator, prominent abolitionist, and fashion tastemaker in 18th century England, possibly the closest thing pottery has had to a ‘rockstar.’
(An interesting aside, the fortune Wedgewood amassed selling his line of pottery to the aristocracy of England and the rest of Europe, including Queen Charlotte of England and Queen Catherine of Russia, helped fund the research of his grandson, Charles Darwin. Yes, that Charles Darwin. Wedgwood was quoted as saying, “Fashion is infinitely superior to merit,” although his pottery was widely considered to possess both due to his dedication to utilizing the latest advancements in technology).
Wedgwood’s pyrometer was an optical pyrometer that was used to visibly compare the color of the clay in the kiln to the color of clay fired at known temperatures (similar in principle to this firing chart!). Later he replaced this early pyrometric technology with using of shrinking clay rings or expanding metal bars to measure the temperature of his kilns.
In 1885, Dr. Herrmann Seger developed the pyrometric cone, another pyrometric device based around a similar principle, which remained the standard in pyrometry for at home kilns all the way up until the invention of digital kiln controllers and digital pyrometers in the 1980s. For industrial kilns and furnaces, the Siemens brothers developed a platinum thermometer that could measure temperatures up to 1832° F or 1000° C in the 1860s through the 1870s.
Alternatively, for higher temperatures, the disappearing filament pyrometer was invented by L. Holborn and F. Kurlbaum in 1901. This was another optical pyrometric device that worked by adjusting current through a filament until it matched the color (and thus temperature) of an incandescent object. Evolutions in disappearing filament and brightness pyrometers continued throughout the 20th century.
Modern Digital Pyrometers for Kilns
In the 1980s, the world became digital, and the modern thermocouple pyrometer was born. Digital pyrometers for kilns use thermocouples that attach to a temperature sensor to precisely monitor kiln temperature.
While digital kiln controllers can be used to monitor kiln temperature, a dedicated digital pyrometer adds additional capabilities. For instance, you can use a digital pyrometer to add digital temperature monitoring to a manual kiln or use it in addition to a programmable digital kiln controller to act as a safety redundancy device to provide automatic safety shutoff in case of relay failure.
The TAP Monitor Digital Pyrometer Limit Controller
The latest evolution in digital pyrometers for kilns is the TAP Monitor, which is now available for preorder! The TAP Monitor is an advanced, user-friendly limit controller and digital pyrometer that gives kiln operators the ability to precisely monitor kiln temperature – remotely! – regardless of their existing kiln control method.
Available as a plug-and-play standalone pyrometer limit controller or as a set of configurable components for DIY installs and oven builds, TAP Monitor gives ceramicists, potters, glass artists, and bladesmiths the ability to:
- Precisely monitor the temperature of their kiln, oven, or forge via the TAP Kiln Control Mobile App.
- View digital pyrometric readouts from any manually controlled kiln, including remote readouts via TAP Kiln Control Mobile when TAP Monitor is connected to a local network with internet access.
- Easily add precise, real-time digital temperature readings to their manual kiln or oven.
- Pair TAP Monitor with their existing automatically controlled kiln for remote monitoring.
- For added safety, use TAP Monitor as a standalone and safety relay controller.
Explore Kiln Control Solutions by SDS Industries
In addition to the TAP Monitor Digital Pyrometer, the TAP Ecosystem includes a variety of programmable kiln controllers that give artists complete control of their kilns – without complicated controls or clumsy user interfaces. The TAP and TAP II Controllers by SDS Industries provide users the most advanced, precise, and easy-to-use programmable digital kiln controllers on the market today. With responsive touchscreen controls, an intuitive graphical UI, and integration with the TAP Kiln Control Mobile App, TAP Kiln Controllers can pair with any relay-controlled kiln or oven.
We invite you to explore our selection of programmable kiln controllers, pyrometers, standalones, and conversion kits on our online store. You can also purchase TAP Digital Controllers or TAP Controlled Kilns and Heat Treat Ovens through one of the following distributors:
- Hot Shot Oven & Kiln
- Mobile Glassblowing Studios, LLC
- Jen-Ken Kilns
- Kiln Frog
- Sheffield Pottery
- Delphi Glass