Dynamic Compressors And fans

Question 1

Sectional casings of a dynamic compressor are used for what pressures?

Answer 1

Low pressures

Question 2

Horizontally split casings of a dynamic compressor are used for what pressures?

Answer 2

Under 1000 psi

Question 3

Vertically split casings of a dynamic compressor are used for what pressures?

Answer 3

High pressure applications

Question 4

Which centrifugal fan impeller is the most efficient?

Answer 4

The air foil blade

Question 5

Which centrifugal fan wheel discharges air at the highest velocity

Answer 5

Forward curved blade

Question 6

Describe a perfect vacuum in PSIA

Answer 6

0 psia

Question 7

Describe a perfect vacuum in psig

Answer 7

-14.7 psig

Question 8

Describe a perfect vacuum in Inches HG

Answer 8

29.92 in/hg

Question 9

Using a manometer how would you measure static pressure?

Answer 9

One end would be at a right angle to the duct wall and the other end would be open to atmospheric pressure

Question 10

Using a manometer how would you measure velocity pressure?

Answer 10

One end would be at a right angle to the duct wall and the other end would be open facing the airflow within the duct.

Question 11

How would you measure total pressure using a manometer?

Answer 11

One end would be open facing the airflow within the duct and the other end would be open to atmospheric pressure.

Total pressure= Velocity pressure+Static pressure.

Question 12

Large single suction fans are usually mounted on what kind of bearings?

Answer 12

Double row spherical roller bearings

Question 13

What kind of fan has blades shaped like aircraft or boat propellers?

Answer 13

Axial flow fans

Question 14

Where would you mount a fan for induced draft?

Answer 14

Between the boiler and the chimney

Question 15

How is natural draft accomplished?

Answer 15

By a differential pressure between the top and bottom of the cooling tower.

Question 16

What kind of fan blade would be used if there where high speeds that require a stronger wheel structure?

Answer 16

Radial blade fan

Question 17

What is the purpose of a fan casing?

Answer 17

It is to collect the air leaving the impeller wheel and change the velocity pressure into static pressure

Question 18

What kind of axial fan requires fixed guide vanes?

Answer 18

Vane axial fans (tube axial fan)

Question 19

What are the 2 types of mechanical draft?

Answer 19

Forced draft

Induced draft

Question 20

What are static arrests on a fan duct system?

Answer 20

They ground the static electricity generated while the fan is running

Question 21

What is the name of the circular collection chamber mounted around the fan wheel of a centrifugal fan?

Answer 21

It is called a scroll

Question 22

How can control of air through fans be accomplished?

Answer 22

Inlet louvre, outlet dampers, varying the fan speed.

Question 23

Surge point of a dynamic compressor happens when?

Answer 23

There is high pressure and low flow

Question 24

Stone wall point or choke happens in a dynamic compressor when?

Answer 24

There is low pressure and maximum flow

Question 25

In an axial flow compressor what blade part is mounted directly to the housing and does not spin?

Answer 25

The stators

Question 26

What part of an axial compressor increases gas pressure? And what part increases velocity?

Answer 26

The rotor blades (rotating part) increase the gas velocity, which then converts into pressure as it enters the stator section and slows down.