What is the working principle of the muffle furnace

Ashing in the muffle furnace

Incineration in a muffle furnace means the thermal decomposition of hydrocarbon-containing products, leaving the inorganic components behind. Conventional muffle furnaces have been used for a wide variety of incinerations for a long time. A sample is weighed into a crucible, which has been dried or annealed and tared beforehand. The sample is then placed in a convectively heated muffle furnace, where it usually remains for several hours until the weight is constant. The crucible is then removed from the oven and placed in a desiccator to cool for a good hour before reweighing can take place.

This relatively simple process is extremely labor-intensive and time-consuming, which is a major problem, especially in production and quality control, and prevents quick access to ongoing productions. This often results in inferior goods outside of the specified specification and the reduced product quality also reduces the manufacturer's revenues.

In addition to ongoing production, quick determination of the ash content is also of great importance when inspecting incoming raw materials and in research and development. The high-tech muffle furnace systems from CEM provide a remedy here: The Phönix and the Phönix SAS.
The areas of application for these systems are:

  • Dry incineration of plastics, oils, food, animal feed, cereals, etc.
  • Determination of the loss on ignition or the residue on ignition
  • Determination of the structure of filling goods
  • Melts and melts, e.g. B. for elemental analysis
  • Drying, annealing and heat treatments
  • Determination of sulphate ashes according to Pharm. Eu. and DAB

Ashing of automotive plastic components to measure the glass fiber content

The content of fillers, e.g. B. glass fibers or glass spheres, essentially determines the properties, product quality and costs of a plastic compound. The measurement of the ash content and the control of the glass fiber structure are part of every manufacturing process and the incoming inspection. In accordance with certified quality assurance systems according to DIN ISO 9000ff, which are now established by most production companies, the product quality should be checked at short intervals and as Consistently enable rapid intervention and adaptation of the manufacturing process.

This requirement is offset by an incineration time of several hours (up to 8 hours) in the conventional muffle furnace - far too long to be able to intervene effectively in production based on the measurement results or to influence the unloading when the goods are delivered. Also in research and development, e.g. B. of automotive plastic components, a fast, flexible test execution is becoming more and more important.

The high-tech, high-speed muffle furnace PhönixTM from CEM ensures a significant time reduction of up to 97% compared to conventional technology while maintaining the same analytical quality. What used to take hours is now possible in minutes and is therefore an alternative to conventional technology. Automotive components are incinerated in just 15 minutes and the glass fiber content and structure are determined.

Advantages of ashing

The advantages of this technology are a drastic reduction in time and "clean" work. The built-in exhaust air system automatically removes smoke and vapors. What used to take hours with conventional technology can now be achieved in minutes with Phönix technology.

There are essentially 3 time advantages:

  1. The annoying, dirty and time-consuming pre-incineration is completely eliminated. The sample is placed directly in the Phoenix furnace.
  2. The ashing time is reduced from hours to minutes. With the Phoenix, the samples are typically incinerated in 10-20 minutes.
  3. There is no need to cool the porcelain crucible in the desiccator. A special highlight is the fact that the CEM crucibles cool down in seconds. After being removed from the oven, the crucibles cool down in a few seconds and can therefore be immediately weighed back on the scales.

For applications in the pharmaceutical industry, the Phönix has been further developed into the automatic sulfate incinerator Phönix SAS
The determination of sulphated ash according to the German Pharmacopoeia (DAB) is a lengthy process due to the individual work steps (takes about a day) and is also extremely uncomfortable for the user. The sample material (mostly pharmaceutical samples or raw materials) is mixed with sulfuric acid in a porcelain or platinum crucible, heated in a water bath, then pre-incinerated on an open flame and then incinerated in a muffle furnace at approx. 600 ° C. In addition to the complex work steps, handling the fuming sulfuric acid is cumbersome and harmful to health.

CEM as a technology driver

With the Phönix SAS, CEM has developed a sulphate incineration system. In addition to a drastic reduction in time, a suction and neutralization system ensure more comfortable work. The complete incineration including pre-incineration is carried out in the Phönix SAS. A quartz tube leads from the incineration insert to a separation and neutralization device. The flue gases are extracted by means of a vacuum pump. The incineration time is significantly reduced to approx. 90 minutes, and several samples can be incinerated at the same time.

This article appears during the CEM week on chemie-zeitschrift.at

Category: CEM weekTags: CEM, muffle furnace, incineration