LimsPulse
Thermal analysis & ovens

Muffle Furnace

An electrically heated, insulated chamber that reaches several hundred to over 1000 °C. In QC it is used to ignite samples for sulphated ash (residue on ignition) and to bring crucibles to constant mass.

  • Pharmaceutical
  • Food
  • Cement and ceramics
  • Mining
  • Environmental
Photo of a Muffle Furnace
Photo: Karelj, Public domain (cropped), via Wikimedia Commons
Follow your site SOP
This is a typical operating sequence for learning. Your instrument model and approved SOP take precedence.
STAGE 1

Before you start

  1. 1Check the calibration status label.
  2. 2Check the chamber is clean and empty.
  3. 3Make sure the furnace is under or near an extraction hood if fumes are expected.
  • Keep flammable materials well away from the furnace.
STAGE 2

Heating

  1. 1Set the required temperature and switch on.
  2. 2Wait until the display is stable at the set point (allow time for the chamber to soak).
STAGE 3

Loading and ignition

  1. 1Wear heat-resistant gloves and a face shield. Use long crucible tongs.
  2. 2Place pre-charred crucibles in the centre of the chamber, away from the door and walls.
  3. 3Close the door quickly and start the timer once the set point is recovered.
  • Never put an uncharred organic sample directly into a hot furnace; it may ignite.
  • Do not open the door more than necessary; the temperature falls fast.
STAGE 4

Removing and cooling

  1. 1Remove the crucibles with tongs onto a heat-resistant tile for a short time.
  2. 2Transfer them to a desiccator and let them cool to room temperature (a fixed time, as per SOP).
  3. 3Weigh each crucible promptly.
  • Do not put a red-hot crucible straight onto a cold bench or into a plastic desiccator.
In LimsPulse · Calibration Management

Keep every Muffle furnace in control: usage logs, calibration and maintenance schedules, and automatic blocking of overdue instruments.

See how