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II NON-POROUS |
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This is an important characteristic having a direct
bearing on the life of an insulator. In Pyrex power
insulators there can be no deterioration due to
porosity. High pressure dye tests are not necessary
to prove the correct manufacture of these insulators.
The quality of the glass as it comes from the tank can
be readily determined by visual inspection.
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III NO GLAZE |
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Pyrex insulators are the same all the way through.
he surface of the accepted product is perfectly
smooth and no finishing operations are required after
the insulator bodies are removed from the moulds.
Glaze is not needed to provide a cleaning surface
not to lend strength to the insulator. Chipping
or fracturing the skirt of a Pyrex insulator does
not in any way affect the life of the unit.
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There can be no deterioration--because the under
body when exposed is exactly the same in all of its
resistant properties as the original surface.
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IV TRANSPARENCY |
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An outstanding characteristic of Pyrex insulators
is their transparency. This feature enables not only
manufacturing control of the quality of the product by
constant visual inspection, but--of equal importance--the
purchaser can see what he is buying. There is no
question of under-fired or over-fired ware. Every
individual handling a Pyrex power insulator is in effect
an inspector.
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V FREEDOM FROM STRAIN |
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During the working of vitreous materials, strains may be
imposed in the bodies. In the case of Pyrex insulators,
these strains are removed in a carefully controlled
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