Materials (110101j) and material allowances Flashcards
what is a ferrous metal? ex
metal that contains iron contents
mild steel
what is a non ferrous metal? ex
metal that does not have iron in it
Aluminum
what are some examples of pure metals?
Gold, silver, copper, aluminum these metals are pure and can be found on the table of contents
What is a alloy?
Alloy metals are combination metals that have two or more metals.
what is expanded metal?
metal that is formed from slitting and expanding diamond shapes.
what is another name for hardware cloth and what is it?
Birdscrean, it is wire mesh that is used for fresh air intakes
what is perforated metal?
sheets that have been punched by a machine that creates holes and or different shapes for design ( commonly used for acoustic purposes in commercial)
what sizes are common for Hardware cloth/Birdscrean?
1/4” x 1/4”
1/2” x 1/2”
1” x 1”
when a metal is brittle how is it described?
something that measure the ability to withstand distortion of a metal
(how fragile it is)
when a metal is conductive how is it described?
a metal that can transfer electricity through it, or heat and letting atoms flow through it easily
when a metal is ductile how is it described?
it can be bent twisted and stretched without losing and properties and without permanent deformation
when a metal is elastic how is it described?
the ability to take it to its yield point and for it to return without permanent deformation
when a metal is hardened how is it described?
the metal is very strong but very brittle it can withstand a lot of pressure but will become more brittle as this increases
when a metal is malleable how is it described?
it can be easily drawn out by hammering or when forces are applied (soft)
what is oxidization?
all metals have and oxide layer this is due to the metal coming into contact with oxygen
what is galvanic action?
This is a corrosive prosses that results when dissimilar metal come into contact with some kind of electrolyte such as moisture
what are some ways that we can prevent galvanic action?
by using some kind of bushing for example a layer of vapor barrier or pain or rubber coatings
how is ferrous metal gauged?
by using the U.S standard gauge
How are non ferrous metals gauged?
American standard wire gauge, AKA the brown and sharp gauge
is galvanized metal gauged the same as mild steel?
Galvanized metal is coated after being made to size therefore it gauges out slightly thicker
what is a ration known for cast iron?
Cast iron is > 3% carbon
What two ways does black iron come?
Hot rolled and cold rolled
what is more accurate for size hot rolled or cold rolled and why?
cold rolled is more accurate as its procedure of forming is more forgiving and distortion is taken into account and is prevented as best as possible.
When is a metal sheet considered to be a plate?
after 1/8” thickness
can zink-coated metal be used in food aspects?
no, they are poisonous
what are some different ways that galvanized coatings are added?
electro galvanizing or hot dip or cold galvanizing
what does electro galvanizing make, trade name?
Satin coat, paint lock, wipe coat
what is galvalume good for?
great for venting solutions as it is corrosion resistant
what are common types of stainless grades?
304 ( dull not polished) - 316 ( finished )
what is the bend radius for aluminum to avoid fracturing?
3x material thickness
how is copper gauged?
by the weight in ounces per square foot
what are the alloys of brass?
copper and zinc
what is thermosetting plastic described as?
plastic that hardens underheat
what is thermosetting plastic described as ?
softens when heated and hardens when cooled
what are the advantages of fiberglass ductwork?
they have great insulating properties and they are light weight
why is flex duct with insulation good?
because it allows for the run to be insulated so it does not lose and thermal properties
mild steel is AKA what?
low carbon steel
why is flex duct not good?
high amount for friction loss
what is the formula for an id measurement?
add 20% of the material thickness to their side of the bend line
(in add 20)
what is the formula for an OD measurement?
subtract 80% of the metal thickness on all sides of the bend
(out sub 80)
what is mean diameter?
the measurement of the middle of the circumference (actual diameter
what is relevant to the mean diameter for ID and OD measurements?
that you adda metal thickness to OD and subtract one for ID
