Material Selection & Properties Flashcards

Which property makes copper tubing in refrigerators particularly valuable during recycling?

Answer: High corrosion resistance and conductivity

Copper's excellent electrical conductivity and corrosion resistance make it highly sought after in secondary metals markets.

What is the primary concern when recycling appliances containing polyurethane foam insulation?

Answer: Foam may contain ozone-depleting blowing agents that must be recovered

Older polyurethane foam was blown with CFCs or HCFCs, requiring controlled recovery to prevent atmospheric release.

Which appliance component is most likely to contain mercury and requires special handling?

Answer: Thermostat switches and relays

Mercury tilt switches and relay contacts were commonly used in older appliance thermostats and must be removed before shredding.

Galvanized steel in appliances is coated with which material to prevent corrosion?

Answer: Zinc

Galvanization applies a zinc coating to steel, providing sacrificial cathodic protection against rust.

What distinguishes Type 304 stainless steel commonly found in dishwashers from carbon steel?

Answer: It contains 18% chromium and 8% nickel alloy additions

Type 304 (18-8) stainless steel's chromium and nickel content creates a passive oxide layer that resists corrosion.

Which plastic resin code is commonly found on polypropylene washing machine tubs?

Answer: #5 (PP)

Polypropylene (PP, resin code #5) is used for washer tubs due to its chemical resistance, durability, and heat tolerance.

During appliance shredding, eddy current separators are used to recover which material?

Answer: Non-ferrous metals like aluminum

Eddy current separators induce opposing magnetic fields in non-ferrous conductors like aluminum, physically ejecting them from the conveyor stream.