403 - Test 3 Material

Question 0

Cavitation sounds like…

Answer 0

Screeching gravel tumbling

Question 1

NPSHa

Answer 1

Resultant positive pressure on the suction side of the pump.
Must be greater than NPSHr.
= Hsp +- Hs - Hf - Hvp

Question 2

Signs of cavitation

Answer 2

Lower flow rate

Lower head

Question 3

Causes of cavitation:

Answer 3

Low NPSH

Question 4

Things to look for because of failure:

Answer 4

Improper installation
Bearings and seals
Clearance after installation
O-rings and/or bearing break
Excessive radial and arial loads

Question 5

Entrained Air

Answer 5

2% gas by volume will cause 10% reducing in capacity.
Additional efficiency problems
Noise and vibration

Question 6

Causes of entrained air

Answer 6

Leaky suction lines
Air pockets
Free falling discharge into tank
Vortexing

Question 7

Waterfall effect

Answer 7

Fluid free falling directly over or on the foot valve could carry air into the suction line.
Baffles can help separate air.

Question 8

Vortexing

Answer 8

Normally caused by excessive suction velocity or low fluid levels relevant to the suction inlet.

Question 9

Excessive throttling

Answer 9

Centrifugal pumps should never be operated continuously near zero capacity or shut off.
Throttling is the use of a valve to limit the discharge flow near the pump or down the line.

Question 10

Throttling with abrasive liquids

Answer 10

Abrasive solids in liquids cause faster erosion of the pump impeller

Question 11

Most injuries come from fluids by

Answer 11

Burn and injection

Question 12

Pinhole leak can be at speeds up to

Answer 12

600+ ft/sec

Question 13

How much psi to puncture skin?

Answer 13

100 psi

Question 14

<2000 psi

Answer 14

40% amputation

Question 15

> 2000 psi

Answer 15

50% amputation

Question 16

<7000 psi

Answer 16

Non prognostic

Question 17

> 7000 psi

Answer 17

100% amputation

Question 18

Amputation rates between

Answer 18

16-48%

Question 19

First degree burn

Answer 19

First layer of skin

Question 20

Second degree burn

Answer 20

First and second layer of skin

Question 21

Third degree burn

Answer 21

All 7 layers of skin burned