Paul is a chemical engineer working in a coating division of a large semiconductor fabrication facility.
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Paul is a chemical engineer working in a coating division of a large semiconductor fabrication facility. He is

tasked to order a large set of O-rings for vacuum valves in chemical vapor deposition, sputtering, and metal evaporation systems. A large selection of O-rings from different elastomers is available. These O-rings vary in price and have different operation temperatures, as shown in the table below:

Elastomer

Price (per 10)

Operation Temperature (F)

Buna-N

$120

-35 to 250

Kalrez

$180

-15 to 620

Polyurethane

$100

-30 to 180

Silicone

$140

-65 to 300

Viton

$160

-15 to 437

Normally, the systems operate at room temperature and Paul wants to select the least expensive first. Then, he remembers that systems undergo a special "bake-out" process—they are heated to high temperature prior to operation. Operation temperature of elastomers should be at least 20 K (degrees Kelvin) above "bake-out" temperature.

"Bake-out" temperatures are provided in the table below:

System

Bake-out Temperature (C)

Chemical Vapor Deposition

70

Sputtering

100

Metal Evaporation

130

What type of O-rings should Paul select for each system to save money for the company? How can he explain decision in the report he will submit to his manager?

Note that temperatures are given in American, metric, and SI units. Paul needs to convert them into one system to find correct answer.

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