Section 8
Troubleshooting
12A Water Still 8-1
Thermo Scientific
General
Problem
Causes
Solution
Frozen Teflon Stopcock Plug
Teflon has an expansion much greater than that of
Borosilicate glass. A plug installed too tightly will
freeze in its glass shell.
Use cold water or ice to cause the Teflon to
shrink and loosen. Never use heat.
Leaks
The most common leak is one occurring in the
vinyl drain tubing. Hot water causes softening and
pulling loose at the plastic barbed connectors.
Runs of vinyl tubing should be supported to
reduce the pull on the plastic connectors. Small
clamps may be used to firmly hold the vinyl tub-
ing to the plastic connectors.
Rough boiling
Rough boiling is the result of alkali attack to the
matte finish on the heaters. The most common
cause is using water pretreated with NaCl regener-
ated water softeners.
Remove heater and lightly roughen surface with
150 grit sandpaper.
Scale Build-up
A brownish-white scale in the boiler indicates that
the demineralizer is not being used or the car-
tridges need changing.
Clean boiler per cleaning instructions. Scale
should not be allowed to accumulate as heaters
may be damaged.
Heater Failure
Heater failure due to scale buildup or
alkali attack will not be replaced under
warranty
Short life on Vycor immersion heaters can usually
be attributed to use of water pretreated with NaCl
regenerated water softeners or excessive scale
buildup.
Softened water used as a boiler feed causes a
concentration of sodium ions and alkaline attack
of the Vycor glass. Rough boiling will be the first
indication of alkaline attack. At failure, the heaters
will usually pinhole and water entering will short
out the element.
If softened water must be used, heater life can
be prolonged somewhat by draining boiler every
day.
Scale build-up will occur when boiler feed is not
being deionized.
When using the still without the deionizer,
scale build-up must be removed after every 15-
20 hours of operation (see Section 7). Failure to
do so will cause heaters to build up heat inter-
nally and fail or cause glass envelope failure
near the air/water interface.
