ALTANA BYK-Gardner Permeability Cup - Manual (Page 3)

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Description
This cup was developed by Dr. W.R.R. Park and
will perform the same function as the Payne
Permeability Cup. That is, the vapor permeability
of any fi lm material such as paint, plastic, varnish,
cloth or coated papers can be conveniently
determined using this device. This improved cup
consists of three main parts:
• shallow fl anged cup
• a fl at retaining ring mounted on eccentric
pins on the threaded fl ange of the cup
• a threaded ring cover.
Both the threaded cup and threaded cover are
knurled to prevent slipping when clamping and
unclamping the test sample. The fi lm under test
is clamped tightly between the rubber gasket
and the fl at retaining ring, covered with the
polyethylene gasket, and held in a gas-tight seal
when the ring cover is screwed down tight.
The water vapor permeability is obtained in one of
two ways:
1. A desiccant such as silica gel, calcium
chloride or phosphorous pentoxide is placed
in the cup before the fi lm is clamped in place.
The cups is mounted above an aqueous salt
solution contained in a sealed desiccator. The
vapor pressure of this salt solution can be
varied by changing the salt concentration. A
salt solution must be used since it is important
that the vapor pressure of the liquid be less
than that of pure water at the test temperature,
or else condensation will occur on the
desiccator walls on the permeability cup itself.
Any condensation would interfere with accurate
weighing. At intervals, the cup is weighed to
determine how much through the exposed
Description