Contact and Non-Contact Heating Products

Thursday December 20 2018

Heat treatment of samples is one of the underlying procedures in biochemical, medical and pharmaceutical, commercial, environmental, and myriad other analytical laboratories worldwide. It comprises a broad range of techniques that are only unified by the transference of heat from an electrical energy source or an open flame into the sample. It is, however, possible to broadly categorize heating products as either contact or non-contact heating systems.

Contacting heating products rarely contact a sample directly. They touch the surface of glassware or the vessel containing the sample of interest and diffuse heat through the intermediate material. Non-contact heating products, by comparison, introduce heat into a sample remotely. A heating lamp, for example, directs high-intensity near-infrared (NIR) light onto a sample which can generate temperatures upwards of 50°C (122°F) at a distance.

Each of these methods is preferential for distinct applications. In this blog post, Glas-Col explores some of the different types of heating products and why some may be preferential to others.

Heating Products: Lamps and Bunsen Burners

The Bunsen burner is perhaps the eponymous laboratory heating product. It burns a controlled flow of gas beneath a test tube suspended by a clamp or a beaker on gauze and tripod. The uppermost point of the flame touches the surface and diffuses heat into the sample – a method that has been in use since the mid-19th Century. Using open flames in laboratories has gradually fallen out of favor, particularly for chemically-sensitive samples or volatile species.

Heating lamps are similar in principle to Bunsen burners in that they project heat onto the surface area of a sample from a distance. They convert an electrical supply into infrared or NIR light using a bulb of substantial wattage housed in a metallic socket. This focuses light into an intense ‘hotspot’ that is directed onto a sample, rapidly heating them via the transferral of electromagnetic radiation.

Glas-Col’s HOTSPOT Heat Lamp can generate temperatures of up to 60°C (140°F) at up to a foot away, ideal for sensitive samples and low-heat applications.

Heating Mantles, Tapes, and Cords

Contacting heating products are more suitable for higher throughput and more specialized laboratory heating applications. Tapes and cords exceed the temperature capabilities of heat lamps by a factor of up to ten times, generating temperatures of up to 600°C (1112°F). These are usually wrapped around tubes and beakers, which improves thermal uniformity during processing. Wrap-around heating is extremely convenient with good flexibility and enhanced safety due to their electrical grounding.

Heating mantles perform in a similar fashion to tapes, cords, and other wrap-around heating products with the added facet that they are engineered as permanent housings. They eschew the flexibility of alternative products in favor of specialized structures that are uniquely suited to distinct samples types and containers. These heating products convert electricity into heat using internal heating elements, which is subsequently diffused inwards to the encapsulated vessel.

The primary difference between these two groups of heating products is the contact, or lack thereof, between the heater and the vessel. Reducing the path length between a heater and a sample reduces the amount of heat lost before it propagates through the sample material. Contact heaters such as cords or mantles are subsequently preferential from the perspective of energy conservation. Yet direct contact is not always the solution, and heating lamps remain one of the main heating products of choice for sample warming and environment control.

Heating Products from Glas-Col

Glas-Col is one of the world’s leading suppliers of heating products for laboratory applications, with a broad range of products suitable for numerous heating applications. If you would like any more information, please do not hesitate to contact us directly.