SECTION 4
PREVENTIVE MAINTENANCE
4.6 Severe or Stubborn Contamination
55
Removing Difficult Contamination
Many contaminants can be detected and removed
under microscopic examination. If cleaning fails to
produce an acceptable clean test, examine the ther-
mocouple head under a microscope at 30X to 60X
power.
Gross contamination can usually be removed by
repeated cleaning, although mechanical scrubbing,
as described below, may expedite the process.
NOTE:
Concentrated ammonium hydroxide (from local stores)
can be used to remove stubborn contaminants, but it
may not be effective on oily, greasy, or waxy materials.
For these more difficult situations, try cleaning agents
such as acetone or a laboratory detergent such as
Wescor’s Thermocouple Cleaning Solution with Anionic
Detergent (SS-223) or Alconox.
To remove deposits:
1
Apply cleaning agents using the methods
described in Section 4.3.
2
Cut a wooden swab stick on a sharp angle to
form a fine point.
3
Scrub the surface of the mount with the swab
stick and rinse.
Performed under the microscope, this procedure is
unlikely to damage to the thermocouple itself. With
patience, and repeated use of cleaning agents, even
the most severely contaminated thermocouple can
be cleaned.
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