Millwright 2Nd Year - Mechanical Seals

Front 1

The purpose of a mechanical seal is to prevent leakage around a __________ shaft

Back 1

Rotating

Front 2

Referring to figure 45, identify the following parts by name

Back 2

Item 1 stationary seal

Item 2 stationary seal square packing/gasket (secondary seal)

Item 3 rotating seal

Item 4 rotating seal PTFE wedge packing (secondary seal)

Item 5 compression ring, rotating

Item 6 Seal retainer

Item 7 multiple spewing

Item 8 locking collar set screw

Front 3

What prevents leaking along the shaft?

Back 3

Rotating seal ring secondary seal packing

Front 4

Name four of the secondary seal designs discussed in the module

Back 4

o-ring

U-cup

PTFE wedge

V-ring

Square/gasket

Delta

Front 5

What type of stationary seal ring packing is found in the illustration

Back 5

Square/gasket

Front 6

What type of closing mechanism is found in the illustration

Back 6

Multiple spring

Front 7

Name four sealing points on mechanical seals

Back 7

Primary seal between the seal faces

Secondary seal point on the stationary seal

Secondary seal point on the rotating seal

Point of contact between the gland and the pump

Point of contact between the shaft and the sleeve

Front 8

Primary seal faces must be ___________and___________.

Back 8

Smooth and flat

Front 9

It is common practice to have the sealing faces made of the same material

Back 9

False; similar materials will cause galling/adhesion

Front 10

What should be taken into consideration in choosing a seal face material

Back 10

Corrosive properties of the liquid, temperature of the pumped liquid and lubricity of the materials

Front 11

What are the two types of closing mechanisms found on pusher seals?

Back 11

Single springs

Multiple springs

Front 12

The nearer you position the retainer to the stationary seal ring, the ____________the closing force exerted on the sealing faces.

Back 12

Greater

Front 13

Too much closing force causes_________________.

Back 13

Higher seal face loading

Loss of lubrication

High heat

Premature wear

And premature seal failure

Front 14

A non-pusher type seal is also referred to as a ____________

Back 14

Bellows

Front 15

What three types of material are used for construction of the bellows

Back 15

Elastomer

PTFE

Metal

Front 16

Name the two means of providing a drive for the rotating ring.

Back 16

Mechanical

Friction

Front 17

What are three reasons for providing flushing fluid

Back 17

Lubrication

Cooling

Heating

Cleansing

Front 18

On a centrifugal pump that develops discharge pressure exceeding 500 psi, you would expect to find a (an) _____________mechanical seal

Back 18

Balanced

Front 19

If you have to inspect the rotating assembly often, an inside mechanical seal is preferred?

Back 19

False; inside mechanical seals would require pump disassembly to inspect the rotating assembly

Front 20

What is the main difference between single mechanical seals and double mechanical seals?

Back 20

Single seals have one set of primary seals; double seals have two sets

Front 21

When seals come from the manufacturer, they are lapped to within four light bands

Back 21

False; they are lapped to within one to three light bands from the manufacturer

Front 22

The wear pattern on a seal should be within 0.005” in depth before the lapping process takes place

Back 22

True

Front 23

Name three of the four factors to be considered when measuring for flatness

Back 23

Straightness of the lines

Parallelism of the lines

Degree to which the lines are evenly spaced