Gaskets are materials used to seal one compartment of a device ...
Gaskets are materials used to seal one compartment of a device ...
Gaskets are materials used to seal one compartment of a device ...
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about twenty times more expensive than asbes<strong>to</strong>s, by weight, but because they<br />
<strong>are</strong> less dense and stronger, less is needed for reinforcement purposes. At<br />
higher temperatures, the fibers physically degrade and thus <strong>are</strong> not good<br />
replacements for asbes<strong>to</strong>s products for high temperature applications.<br />
Aramid packings <strong>are</strong> usually 20 percent aramid fiber, by weight, and 60 <strong>to</strong><br />
65 percent filler, while the remaining 20 <strong>to</strong> 25 percent is binder <strong>to</strong> keep the<br />
fibers in a matrix. Typical applications for valves and pumps require a very<br />
strong packing material that will withstand moderate<br />
temperatures and<br />
pressures without deteriorating.<br />
Raymark Corporation, in Stratford, CT, was the only asbes<strong>to</strong>s packing<br />
manufacturer <strong>to</strong> cite aramid packings as a substitute for asbes<strong>to</strong>s products.<br />
They can be <strong>used</strong> for general service in most plants (A.W. Chester<strong>to</strong>n 1983).<br />
Aramid-based products <strong>are</strong> likely <strong>to</strong> be 1.5 <strong>to</strong> 3 times as expensive as the<br />
asbes<strong>to</strong>s products they replace, therefore aramid packings cost between $45.30<br />
and $90.60 per pound. The price increase is due <strong>to</strong> production and material<br />
cost increases<br />
(ICF l986a).<br />
There <strong>are</strong> no performance disadvantages due <strong>to</strong> the dilution <strong>of</strong> the aramid<br />
fiber with mineral<br />
fillers and this helps <strong>to</strong> reduce the price <strong>of</strong> packings.<br />
The service life is estimated <strong>to</strong> be the same as the life <strong>of</strong> the asbes<strong>to</strong>s<br />
product. Industry estimates indicate that aramid products will capture 20<br />
percent <strong>of</strong> the <strong>to</strong>tal packings market. The average price for an aramid-based<br />
packing is estimated <strong>to</strong> be $67.95 per pound (ICF l986a, Palmet<strong>to</strong> Packing<br />
1986).<br />
2. Fibrous Glass Mixtures<br />
Fibrous glass is generally coated with a binder such as neoprene, TFE,<br />
or graphite in the manufacturing process <strong>to</strong> make packings. Glass fibers <strong>are</strong><br />
relatively easy <strong>to</strong> process in<strong>to</strong> packing <strong>materials</strong> and <strong>are</strong> <strong>used</strong> extensively in<br />
packing <strong>materials</strong>.<br />
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