BUCHI DuMaster D-480 - Manual (Page 188)

Operation Manual D-480 ©BÜCH Labortechnik AG
8 - Maintaining the instrument 188
Purpose and frequency of crucible replacement
Why replace the ash crucible?
It is necessary to replace the ash crucible because combustion residue in the ash crucible can distort
readings.
When to replace the ash crucible?
The intervals at which to replace the ash crucible depend very much on what substanmces you are
analyzing. Generally speaking, it has to be replaced after 80 analyzed samples. When analyzing
samples with extremely high mineral compound content a replacement becomes necessary already
after 20 samples.
Types of ash crucibles
The following table lists the various types of ash crucibles and their usage:
Ash crucible type Usage
Ceramic ash crucible Standard application
Steel ash crucible When analyzing liquid samples (mandatory).
Removing the ash crucible
Note
The following section describes the first part of replacing the ash crucible. The topic is continued in
Installing the ash crucible (on page 191).
Process
The section is divided into the following phases:
 Preparing the instrument, Gas pressure
 Removing the ash crucible
Safety instruction
Strictly observe the safety instruction "Replacing the ash crucible/finger" under Warning notes
during operation (on page 24).
Requirements
Before starting work, the following requirements must be met:
 Keep a tube rack ready to hold hot components.
 Keep a tube extractor ready.
Phase 1: Preparing the instrument, cool down the furnace / gas pressure
Safety instruction
Strictly observe the safety instruction "Gas pressure" under Warning notes during operation (on
page 24).
To prepare the instrument for maintenance work follow the instructions in "Preparing the instrument,
Gas pressure" in Preparing and following up maintenance work (on page 171).