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Industrial Mechanic 2nd Block, Harmonized > Alb Mod Compression Packing > Flashcards

Alb Mod Compression Packing Flashcards

1
Q

Compression packing must ____ so it can either lubricate and/or seal rotating and reciprocating shafts

A

leak

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2
Q

Shaft/sleeve replacement, constant adjustments, downtime, housekeeping, environmental considerations and energy consumption are all ____ associated with packing

A

costs

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3
Q

Compression packing must ____ as opposed to acting as a static seal

A

control leakage

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4
Q

Motion on pumps and compressors can be: (3)

A
  • Rotary
  • Reciprocating
  • Helical
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5
Q

As well as sealing, compression packing can act as a:

A

Bearing

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6
Q

Compression packing must be confined and squeezed. This is accomplished in the confined area of the:

A

Stuffing box of the pump or compressor or valve

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7
Q

Packing is confined in a stuffing box with the aid of a:

A

Gland follower

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8
Q

The throttling of fluid aids in: (3)

A
  • Sealing
  • Cooling
  • Lubrication
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9
Q

Throttling of fluid reduces the chance of the packing running: (2)

A
  • Dry

- Hot

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10
Q

If packing is allowed to run dry and hot, it can:

A

Permanently damage the shaft

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11
Q

In some cases, packing must prevent air from:

A

Entering the pump

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12
Q

______ are special profiled rings with interference fit on the shaft and walls of the stuffing box. In this case, the fluid aids the sealing fit.

A

Automatic packings

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13
Q

Automatic packings seal in ____ direction(s)

A

Only one

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14
Q

The key factor to jam-type packing relies on its impermeability to the fluid it is sealing. When packing is made of fibers and yarns, there are many voids in the packing. To assist in plugging these voids, a ____ is added.

A

saturant

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15
Q

Saturant may be made of: (3)

A
  • Petroleum based
  • Graphite
  • PTFE (Teflon)
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16
Q

As the packing is compressed and the machine runs, saturant in the packing washes out and the packing _____ and needs to be _____

A

shrinks and needs to be adjusted

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17
Q

If overtightened, packing will act as a brake due to friction between moving parts. In the situation that packing is improperly adjusted, the saturant:

A

Acts as a lubricant

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18
Q

Roughly ___% of the wear on shafts is on the outermost rings of packing closes to the gland

A

70%

Note: This is on both centrifugal and reciprocating pumps and compressors

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19
Q

Automatic/moulded packing are made of various materials and are designed to seal automatically and are:

A

Pressure actuated

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20
Q

automatic packing does not require the same amount of manual gland adjustment as compression packing, but in the case of _____ packing, a gland allows you to change the pressure on the packing if the fluid cannot provide sufficient pressure

A

V-packing

Note: In other cases, the stuffing box is large enough to accommodate the use of spring loaded V packing

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21
Q

What two ways can you give packing more abrasion resistance? (2)

A
  • Saturant

- Special yarns

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22
Q

This packing is very flexible and commonly used for reciprocating applications

A

Square braid

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23
Q

This packing is very dense and works well in high pressure applications

A

Braid over braid

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24
Q

This packing is strong and resists being deformed or extruded under high pressure

A

Interlocking braid

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25
Q

This packing is constructed by twisting strands together to form a rope

A

Twisted packing

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26
Q

This packing is made of metal foils and special alloys, and used for close tolerance rods and shafts

A

metal packing

27
Q

This packing is a graphite ribbon that comes in rolls and is radially wrapped around the shaft to form rings of any thickness.

A

Radially wound packing

Note: the ribbons are wrapped around the shaft until they just fit into the stuffing box, and can be die formed outside of the stuffing box

28
Q

Some of the metals used for metal packing are: (3)

A
  • Babbitt
  • Aluminum
  • Copper
29
Q

Spiral wound packing must be installed with the spiral oriented for:

A

Shaft rotation

30
Q

Jam packing requires ____ and therefore is stacked to fill the stuffing box

A

more than one set of rings

31
Q

If shaft speeds are high, the pumping medium is high temperature, corrosive, or abrasive, an additional component is necessary to aid lubricating, sealing, flushing, cooling

A

Lantern ring aka Steel cage

32
Q

When you have a lantern ring, your stuffing box is fitted with a:

A

seal water connection

33
Q

In some cases, with a lantern ring, you use an external water source for cooling. In other cases, you use:

A

The pumping medium

34
Q

The lantern ring does not touch the shaft because its bore is larger than the shaft, and in most cases, is made of:

A

a softer material than the shaft

35
Q

If the liquid entering the lantern ring is above that of the pump or valve, approximately __ psi to __ psi, the elevated pressure keeps the pumping medium inside the pump and away from the packing

A

10 to 15

36
Q

The pressure inside a stuffing box is often below atmospheric, so instead of the medium leaking out, air leaks into the stuffing box from outside. This happens ______ and can affect pump performance

A

during startup

37
Q

If the lantern ring is used for sealing and cooling, it is aligned under the seal water connection and must be considered when packing the pump. If the lantern ring is used to keep harmful abrasives and chemicals away from the packing, it is:

A

located at the bottom of the stuffing box

38
Q

The approximate leakage rate of compression packing is:

A

40 to 60 drips per minute

39
Q

Many times, compression packing requires lubrication while running. The lubrication can come from: (2)

A
  • The pumping medium

- external supply

40
Q

There are situations where lubrication is not necessary, like when a self lubricating packing is used, such as:

A

teflon (PTFE)

41
Q

____ is a compression packing material. It is used on rotating and reciprocating shafts and valves where high temperature must be considered. Can be used with chemicals, but not strong oxidizers.

Limited to 315°C, 2500 feet per minute, and 500 PSI

A

Carbon yarn

42
Q

____ is a compression packing material. Has a low coefficient of friction, excellent heat conductivity and chemical resistance. Less leakage than other packing, and can be used with strong acids, caustics, chemicals

Limited to 1925°C (non oxidizing environments) 2500PSI (valve) 500PSI (pump) 2500-4000 feet per minute

A

Graphite yarn

43
Q

____ is a compression packing material. It is usually found in the most severe applications, highly corrosive and oxidizing environments as well as the food industry.

Limited to 250°C 1000-1800 feet per minute and 300 PSI

A

PTFE Fibre

44
Q

___ is a compression packing material. It is normally found in reciprocating applications and is usually formed to a special profile, such as a V.

limited to oils, phosphate esters, solvents and water up to 148°C with maximum pressure dependent on the profile of the packing

A

Duck and rubber

45
Q

Plastic is a compression packing material made of synthetic yarns and binders braided to form compression packing. What are the three most common materials? (3)

A
  • Phenolic fibre
  • Acrylic yarns
  • kevlar filament
46
Q

metal is a compression packing material that is in the form of foils or ribbons. These are rolled, twisted or crimped and often used in conjunction with other materials to form a square cross section. Often also lubricated with a saturant of both oil and graphite. What are the three most common materials? (3)

A
  • Uncoated annealed soft copper
  • Lead babbit
  • Aluminum packing
47
Q

____ is a compression packing material that has the same basic construction as other packing and is used in both rotating a reciprocating applications. Can be saturated with PTFE, oils, waxes or graphite. Generally used hydraulic or marine applications pumping cold water, brine, or cold oil.

Limited to 93°C, 300PSI, and 1500 feet per minute

A

Vegetable fibre

48
Q

____ is a compression packing material that is usually impregnated and saturated with PTFE and has an interlock braiding construction. It is a tough, economical packing used in pumps and valves

Limited to 260°C, 500 PSI and 1500 feet per minute.

A

Commercial grade asbestos

49
Q

Packing has to be replaced periodically due to: (2)

A
  • Deterioration

- Loss of saturant

50
Q

The frequency of repacking depends on: (3)

A
  • Operating conditions
  • Type/quality of packing
  • If it has been installed/adjusted properly
51
Q

You remove old packing using a:

A

packing hook/puller

52
Q

If excessive wear is discovered on the shaft when changing packing, what can you do to repair it? (2)

A

replace the sleeve

refurbish the shaft

53
Q

If old packing is unevenly worn, it indicates the pump shaft is gyrating, indicating the shaft is bent. Runout should not exceed ____”

A

0.003”

54
Q

If old packing shows signs of extrusion, this indicates:

A

too much clearance between the shaft and the throat

55
Q

What are four reasons that packing may prematurely fail? (4)

A
  • Wrong type
  • Wrong size
  • Improper installation
  • excessive heat
56
Q

The best way to cut packing is using a:

A

Mandrel the same diameter as the shaft

57
Q

If you encounter difficulty installing the packing due to the fullness, do not:

A

strike it with a hammer

Note: instead, roll it out

58
Q

When packing a pump, seat the rings firmly, except PTFE filaments and graphite yarns, which should be:

A

tightened gently and firmly once the pump is running

59
Q

Stagger joints in packing at least __° apart

A

90

60
Q

When packing a pump, seat each individual ring using either: (2)

A
  • tamping tool

- split bushing

61
Q

Allow packing to ___ when starting a newly packed pump

A

leak freely

62
Q

Leaking during the first hour of operation:

A

enhances the life of the pump

63
Q

When a valve has been repacked and on-line for a day or so, retighten the follower even if there:

A

is no leakage

Industrial Mechanic 2nd Block, Harmonized (28 decks)

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