Seals Flashcards
What are the 3 movements found on pumps, compressors, and valves?
Rotating
Reciprocating
Helical
What is a major disadvantage to compression packing?
It must leak
What is the purposes of compression packing to be left leaking?
Sealing
Cooling
Lubrication
What type of movement is reciprocal?
Back and forth
What type of movement is helical?
Combination of rotating and reciprocating
Why would a packing gland be continuously loaded (live loaded)?
To provide constant pressure on the compression packing
When is the effective service life of compression packing reached?
When adjustment to the stuffing box gland fails to give consistent control of the leakage from the compression packing seal
How is compression obtained with compression packing?
With a gland follower
What is a stuffing box?
The assembly housing packing, a gland, and sometimes a lantern ring or bushing
What is a packing gland?
A sealing complement that holds the packing against the stuffing box
What is a lantern ring?
A ring used to supply or extract different media’s to or from the stuffing box
Explain the characteristic of a lantern ring
A ring
Has a number of holes For lubricants
Where is the lantern ring located?
In the bore of the stuffing box housing
What are the 3 main purposes of a lantern ring?
Protection
Cooling
Lubrication
How often does compression packing need to be “set” ?
Continuously
What happens if you over tighten the compression packing?
Increases friction between parts
Acts as a brake
Where is the most amount of wear (70%) on both a cantrifugal and reciprocating pumps and compressors?
On the outmost rings closest to the gland
What rings do the majority of the sealing in compression packing?
The first 5
What are the other rings used for that are not doing the majority of the sealing in compression packing?
Fill space
What rings will have the most wear in compression packing?
Rings closest to the fluid
What are the 4 main types of compression packing styles?
Square braid
Braid over braid
Inter-braid
Twisted
What type of packing is this?
Braid over braid
What type of packing is this?
Inter-braid
What type of packing is pictured?
Square braid
What type of packing is pictured?
Twisted packing
What’s the amount an O ring should be compressed?
10-30%
What is our main indicator whether a dual seal system is a buffering or barrier type system?
System pressure
What is a big concern when using permeated type gasket maker?
It may fall into piping system
When a pump is operating with a suction lift and air is being drawn through the stuffing box, what is the best way to correct this condition?
Tighten the packing as necessary
What is often used in conjunction with a labyrinth seal to provide complete dynamic sealing in turbines?
Carbon seals
What gasket material is commonly used as a gasket on a high pressure steam line?
Wire reinforced graphite impregnated sheet
How much will an O ring change the position of a part?
Not at all
What is the main purpose of a lantern ring if placed in the bottom of a stuffing box?
Flushing
What is the recommended range for a dynamic O ring?
10-30 percent
