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23 Cards in this Set
- Front
- Back
The purpose of a mechanical seal is to prevent leakage around a __________ shaft |
Rotating |
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Referring to figure 45, identify the following parts by name |
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 |
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What prevents leaking along the shaft? |
Rotating seal ring secondary seal packing |
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Name four of the secondary seal designs discussed in the module |
o-ring U-cup PTFE wedge V-ring Square/gasket Delta |
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What type of stationary seal ring packing is found in the illustration |
Square/gasket |
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What type of closing mechanism is found in the illustration |
Multiple spring |
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Name four sealing points on mechanical seals |
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 |
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Primary seal faces must be ___________and___________. |
Smooth and flat |
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It is common practice to have the sealing faces made of the same material |
False; similar materials will cause galling/adhesion |
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What should be taken into consideration in choosing a seal face material |
Corrosive properties of the liquid, temperature of the pumped liquid and lubricity of the materials |
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What are the two types of closing mechanisms found on pusher seals? |
Single springs Multiple springs |
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The nearer you position the retainer to the stationary seal ring, the ____________the closing force exerted on the sealing faces. |
Greater |
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Too much closing force causes_________________. |
Higher seal face loading Loss of lubrication High heat Premature wear And premature seal failure |
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A non-pusher type seal is also referred to as a ____________ |
Bellows |
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What three types of material are used for construction of the bellows |
Elastomer PTFE Metal |
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Name the two means of providing a drive for the rotating ring. |
Mechanical Friction |
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What are three reasons for providing flushing fluid |
Lubrication Cooling Heating Cleansing |
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On a centrifugal pump that develops discharge pressure exceeding 500 psi, you would expect to find a (an) _____________mechanical seal |
Balanced |
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If you have to inspect the rotating assembly often, an inside mechanical seal is preferred? |
False; inside mechanical seals would require pump disassembly to inspect the rotating assembly |
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What is the main difference between single mechanical seals and double mechanical seals? |
Single seals have one set of primary seals; double seals have two sets |
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When seals come from the manufacturer, they are lapped to within four light bands |
False; they are lapped to within one to three light bands from the manufacturer |
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The wear pattern on a seal should be within 0.005” in depth before the lapping process takes place |
True |
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Name three of the four factors to be considered when measuring for flatness |
Straightness of the lines Parallelism of the lines Degree to which the lines are evenly spaced |