Flow

Question 1

Regarding the flow of gases A carrier gas with lower density is likely to increase flow

Answer 1

True. The lower the density of a fluid, the greater the flow in turbulent conditions.

Question 2

Regarding the flow of gases In laminar flow, flow depends on viscosity

Answer 2

True

Question 3

Regarding the flow of gases In laminar flow, gas flow is proportional to the fourth power of the radius

Answer 3

True

Question 4

Regarding the flow of gases In turbulent flow, flow is inversely proportional to the square root of pressure

Answer 4

False. In turbulent flow, flow is directly proportional to the square root of pressure and inversely proportional to the square root of density (ρ).

Question 5

Regarding the flow of gases Resistance is inversely proportional to the length of a tube

Answer 5

False. Resistance is directly proportional to the length of the tube.

Question 6

Regarding the flow of gases Endotracheal tube adaptors (e.g. Magill) are specifically designed to avoid turbulent flow

Answer 6

False. Magill adaptors are not specifically designed to avoid turbulent flow and may add to resistance in the circuit.

Question 7

Regarding the flow of gases Helium increases the density of inspired gases and therefore the likelihood of turbulent flow within the respiratory system

Answer 7

False. When helium is used as part of heliox, it lowers the density compared to the same proportional volume of nitrogen in air. Therefore, it improves gas flow within the upper airways where flow is turbulent.

Question 8

Regarding the flow of gases If Reynold’s number exceeds 1000, turbulent flow is likely to be present

Answer 8

False. A Reynold’s number greater than 2000 indicates increased likelihood of turbulent flow.

Question 9

Regarding the flow of gases The critical velocity at which laminar flow changes to turbulent flow varies only with the gas involved

Answer 9

False. The critical velocity occurs at a Reynold’s number of 2000, so the likelihood of turbulence depends on fluid density, viscosity, velocity and tube diameter.

Question 10

Regarding the flow of gases Turbulent flow can only be measured using vane meters

Answer 10

False. Turbulent flow can be measured using multiple techniques.

Question 11

A pneumotachograph May consist of a large number of smaller tubes

Answer 11

True

Question 12

A pneumotachograph May contain a differential pressure transducer

Answer 12

True

Question 13

A pneumotachograph Is not affected by the gas viscosity

Answer 13

False. Output is affected by viscosity.

Question 14

A pneumotachograph May give an erroneous reading in the presence of condensed water vapour

Answer 14

True

Question 15

A pneumotachograph Works on the principle of Poiseuille’s law

Answer 15

True

Question 16

Regarding gas or liquid flow:

In laminar flow, flow is determined by the pressure gradient divided by resistance

Answer 16

True

Question 17

Regarding gas or liquid flow:

In a laminar flow, resistance is constant and independent of flow

Answer 17

True

Question 18

Regarding gas or liquid flow:

Resistance increases with flow in turbulent flow

Answer 18

True

Question 19

Regarding gas or liquid flow:

Hagen-Poiseuille’s law does not apply in turbulent flow

Answer 19

True

Question 20

Regarding gas or liquid flow: Flow through an orifice is always laminar

Answer 20

False. Flow through an orifice is always turbulent.

Question 21

Flow is laminar in tubes that are very long compared with their diameter

Answer 21

True. In the rotameter, at low flows, the bobbin is at the narrower end of the tube, so the gas flows across an obstruction of greater length than diameter, i.e. the gas behaves as if flowing through a tube and flow is laminar.

Question 22

Flow is turbulent when Reynold’s number is <2000

Answer 22

False. Flow is turbulent when Reynold’s number is >2000.

Question 23

Flow through an orifice is influenced by the density of a fluid or gas

Answer 23

True

Question 24

Velocity is higher and pressure is lower at the point of constriction in a tube

Answer 24

True

Question 25

At low haematocrit, blood flow is better in blood vessels

Answer 25

True

Question 26

Flow Is doubled by doubling the length of a tube

Answer 26

False. If the length of a tube is doubled, then the flow is halved.

Question 27

Flow Is doubled by quadrupling the radius

Answer 27

False. Flow increases 16 times by doubling the radius according to the Hagen-Poiseuille equation (remember r to the fourth power).

Question 28

Flow May be reduced by using an agent with a higher density

Answer 28

True

Question 29

Flow Is raised if the viscosity is raised

Answer 29

False. If viscosity increases, flow is decreased, according to the Hagen-Poiseuille equation.

Question 30

Flow Is determined by the Hagan-Pousseille equation

Answer 30

True

Question 31

The Venturi effect Is related to kinetic energy and potential energy

Answer 31

True

Question 32

The Venturi effect Is related to potential energy and gravitational energy

Answer 32

False. The Venturi effect is based on the Bernoulli principle, so is related to potential and kinetic energy not gravitational energy.

Question 33

The Venturi effectIs used in nebulizers

Answer 33

True

Question 34

The Venturi effect Uses a fall in kinetic energy

Answer 34

False. The Venturi effect, is based on the Bernoulli principle, where a drop in pressure (analogous to potential energy) is accompanied by a rise in flow (analogous to kinetic energy). Venturi masks use this principle to increase flow by entraining a second fluid into the flow path of the driving fluid.

Question 35

The Venturi Effect Uses a fall in potential energy

Answer 35

True

Question 36

Flow may be measured by a pressure drop across an orifice

Answer 36

True

Question 37

Flow may be measured by using ultrasound

Answer 37

True

Question 38

Flow may be measured by high frequency sound wave reflection

Answer 38

True

Question 39

Flow may be measured using a bell spirometer

Answer 39

True

Question 40

Flow may be measured using a pneumotachograph

Answer 40

True