WHY IS A PYREX INSULATOR
"STRONG AS STEEL"?
The "short-time" (regular M and E) strength of PYREX
10" suspension units averages 30,000 lbs., compared
to 20,000 to 25,000 lbs. for standard competitive
insulators. In this test the hardware fails in the
PYREX unit 95 per cent of the time; in competitive
units the dielectric fails. The glass insulator is
as strong and reliable as its steel hardware.
IS A PYREX INSULATOR EVER THE WEAKEST LINK
IN A TRANSMISSION LINE?
No! The conductor will fail before the insulator
breaks! Strings of PYREX 10" units have withstood
20,000 lb. time-loads for months; have withstood
15,000 lb. loads for years; and will withstand
12,000 lb. loads indefinitely. At 12,000 lbs. the
compression stresses are barely neutralized -- the
glass hasn't even begun to work! Very few standard
competitive insulators are able to meet 12,000
lb. time-load tests.
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WHAT ABOUT REPEATED LOADING?
PYREX 10" suspension insulators will withstand the
rapid application and removal of a 20,000 lb. load
500 times without failure. They can be vibrated,
under 12,000 lb. load, night and day for 5 months
without failure. They will support 12,000 lbs.
continuously through ten cycles, boiling water
to ice water, and will not fail. When subsequently
tested to destruction every unit will exceed its
conservative rating of 18,000 lbs. Competitive
units often fail in these tests.
WHY ARE MOST IMPACT TESTS MISLEADING?
Because they do not simulate service conditions.
PYREX suspension insulators are rated at 100
inch pounds (higher than other insulators) but
we contend that this is not a satisfactory test.
The vagaries of stone throwing and rife shooting
cannot be imitated by a swinging pendulum striking
one arbitrary chosen plane on an insulator shell.
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