CHAPTER 17 PLASTICS TEST
1. There are five different pieces of equipment in the dryer/classifier system, which
one is not.
a. scalping box
b. dryer and helix
c. classifier
d. melt divert valve
e. dryer vent fan
f. pellet divert valve.
2. The __________ separates trash from the pellet slurry.
a. helix
b. scalping box
c. dryer
d. homogenizer
3. The dryer dries pellets using ____________.
a. heat
b. centrifugal force
c. high speed air
d. b & c
4. Various additives such as _____________ help narrow molecular weight
distribution and swell.
a. monoflurophosphate
b. stearate
c. white oil
d. peroxide
5. An __________ is a device designed to prevent damage to equipment and
personnel. This is accomplished by stopping or preventing the start of certain
equipment functions unless a preset condition has been met.
a. interlock
b. permissive
c. hold-out
d. lock-out
6. A ____________ is a special type of interlock that controls a set of conditions that
must be satisfied before a piece of equipment can be started.
a. passive interlock
b. permissive
c. DCS
d. hardwire circuit
7. A _____________ is a polymer filtering device. It comes in a variety of designs
and shapes which range from circular, flat multi-layered screens to a group of 27
horizontal mesh filtering screens held in a large steel cylinder is the next area the
melt passes through. The _________ traps any particles or foreign objects in the
polymer stream.
a. die filter
b. screen pack
c. melt diverter
d. cylinder filter
8. It is the function of the _____________ to thoroughly mix the streams of granules,
peroxide and additive(s). The ___________ achieves this by stirring its contents
with a large spiral auger as the material is moved along by the auger in a trough.
a. homogenizer
b. ribbon blender
c. feed tank
d. extruder
9. The discharge side of homogenizer is equipped with a _____ to hold a constant
level for better mixing.
a. weir
b. ribbon blender
c. feeder
d. pelletizer
10. ___________ deal with start up items whereas hardwire interlocks deal with shut
down items.
a. passive interlock
b. permissive
c. DCS
d. hardwire circuit
11. Melting the granules:
a. breaks molecular bonds and reduces swell
b. encapsulates the additives in the polypropylene
c. allows the polymer to be cut up into pellets
d. b & c
12. There are two types of interlocks:
a. softwire and hardwire
b. permit and interlock
c. cold and hot
d. open and closed
13. A solids feeder connected to an air system that is used to transfer plastic. When
the slide valve is opened under a feed tank, granules drop into a ___________.
Granules move through the system without altering pressures on either side of the
star feeder with the aid of a vent.
a. air system
b. homogenizer
c. star feeder
d. variable feeder
14. The ____________ rotating knives cut the strands of polymer as they leave the die
holes in the Extruder, producing pellets, the product of the Extruder post. The
newly formed pellets are carried away and kept from sticking together by a flow of
water which is a part of the pellet water system.
a. water tanks
b. homogenizers
c. classifiers
d. pelletizers
15. The ___________ separates good pellets from over-sized or misshapen pellets.
a. star feeder
b. classifier
c. pelletizer
d. homogenizer
16. Industrial manufacturers use synthetic resins to make paints, lubricants, adhesives,
hard and soft plastic, plastic fibers and fabric, resistant, decorative and transparent
plastic. Various methods are used in this process. Which one has been left off?
a. _______- solid resins are melted and pushed by a screw or screws through
a heated chamber and specially shaped die. (using a hot glue gun)
b. molding- melted resins are squeezed into a mold. (making waffles)
c. laminating- sheets of paper or metal foil pass between rollers and are
coated with melted resins. The sheets are pressed together to form things
like electronic circuits. (like making a sandwich)
d. casting- melted resin is poured into a mold. (like making jello)
e. calendering- melted resins is spread over sheets of paper or cloth to form a
protective coating over things like playing cards. ( like spreading syrup on
a pancake)
17. The __________, the first part of the dryer, is a dewatering device that separates
the bulk of the water off by gravity.
a. pelletizer
b. scalping box
c. spirex
d. helix
Match the following components with their descriptions
18. ______Homogenizer-
19. ______Extruder Feed Tank
20. ______Main Granule Feeder-
21. ______Pellet Water Chamber & Pelletizer
22. ______Twin Screw Extruder-
23. ______Pellet Dryer & Classifier-
24. ______Granule & Additive Ribbon Blender & Pure Additive Feeders
25. ______Granule Blenders-
26. ______Air System & On-test & Off test Bins
27. ______Bulk Product Loading
A#______Granules are received from the polymerization section and stored in the
granule blenders. Lab tests verify product quality.
B#______Granules are transferred via an air system to the extruder feed tank.
Nitrogen and air are the primary gases used to transfer the porous granules
or powder. Lab tests verify product quality.
C#______ a pre-determined amount of granules are dumped into the ribbon
blender from the feed tank and blended with an additive. This is metered
into the homogenizer. Pure additive feeders are composed of a hopper and
a feeder that discharges into the homogenizer. These steps are optional
depending on customer specifications.
D#______ granules or powder is fed through a two stage feeder into the
homogenizer. The granule feeder discharges granules at 25 to 35,000
pounds per hour.
E#______ Additives and the granule stream are metered through weigh feeders
into a continuous blender (Homogenizer ). Peroxide is also metered in at
the Blender to control melt flow rate.
F#______ The blended stream is fed to an extruder where it is melted. The melted
stream is devolatized and pumped through a filtering screen (screen pack)
in the extruder.
G#______ After going through the screen pack, the Polymer is split into many
smaller streams and forced through a multi-holed die plate. These smaller
streams enter a water filled chamber and are cut by blades mounted on a
pelletizer shaft flush against the die. The molten pellets are immediately
quenched in the under water pelletizer chamber.
H#______ Pellet H20 slurry is separated into two streams as it enters the dryer.
H20 is returned to the pellet H20 tank. The pellet stream is spun dry inside
the dryer and dropped onto a classifier. The classifier is a large sieve
shaker that allows properly shaped pellets to pass through but removes
irregular pellets and clusters of pellets to a scrap box.
I#______ The good pellets are transferred via an air system to a receiving bin.
Laboratory testing verifies product quality. On-test bins hold about 40,000
pounds. If the laboratory results are good the product is transferred to the
large 400,000 pound pellet blenders for railroad or hopper truck loadout.
J#______ The pellets are then loaded into a hopper car, hopper truck or moved to
warehouse bins for packaging in a box, bag or super sac (bulk bag) for
distribution to the customer. Final samples are verified by the lab and
retained for future reference. The run data and sample results are typically
sent to the customer.
28. Please sketch a simple flow diagram of a modern plastics finishing facility. Label
key equipment.
29. The dryer ___________ removes moisture and heat from the pellets.
a. scalping box
b. inertia
c. vent fan
d. helix
30. The purpose of the extruder is to:
a. melt the granule, flake, pellet mixture
b. pump molten rope through the dryer
c. dry out and mix polymer
d. a & b
31. In its granular and flake form polypropylene has:
a. broad molecular weight distribution and swell
b. inconsistent additive content
c. high melt flow
d. a & b
32. The _________________ system removes pellet water from the pellets and
classifies them according to size.
a. dryer / classifier
b. pelletizer / pellet chamber
c. scalping box / helix
d. classifier / homogenizer
33. A complex device composed of a heated jacket, a set of screws or screw, a heated
die, large motor, gear box and a pelletizer.
a. rotary gear pump
b. extruder
c. dryer
d. pelletizer
34. Customers will not accept raw granules because of:
a. swell
b. color
c. the danger of dust explosions
d. ppg’s
Answer Key Chapter Seventeen Extruders