Overview
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:
O-Ring Price Table
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. In the process, in order to get the units right he has to convert the degrees F first to degrees Celsius. 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 Celsius.
"Bake-out" temperatures are provided in the table below:
"Bake-out" Temperatures
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.