Flashcards in Flow Deck (40)

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1

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

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

2

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

### True

3

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

### True

4

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

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

5

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

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

6

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

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

7

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

### 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.

8

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

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

9

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

### 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.

10

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

### False. Turbulent flow can be measured using multiple techniques.

11

## A pneumotachograph May consist of a large number of smaller tubes

### True

12

## A pneumotachograph May contain a differential pressure transducer

### True

13

## A pneumotachograph Is not affected by the gas viscosity

### False. Output is affected by viscosity.

14

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

### True

15

## A pneumotachograph Works on the principle of Poiseuille's law

### True

16

##
Regarding gas or liquid flow:

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

### True

17

##
Regarding gas or liquid flow:

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

### True

18

##
Regarding gas or liquid flow:

Resistance increases with flow in turbulent flow

### True

19

##
Regarding gas or liquid flow:

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

### True

20

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

### False. Flow through an orifice is always turbulent.

21

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

### 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.

22

## Flow is turbulent when Reynold's number is <2000

### False. Flow is turbulent when Reynold's number is >2000.

23

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

### True

24

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

### True

25

## At low haematocrit, blood flow is better in blood vessels

### True

26

## Flow Is doubled by doubling the length of a tube

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

27

## Flow Is doubled by quadrupling the radius

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

28

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

### True

29

## Flow Is raised if the viscosity is raised

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

30

## Flow Is determined by the Hagan-Pousseille equation

### True

31

## The Venturi effect Is related to kinetic energy and potential energy

### True

32

## The Venturi effect Is related to potential energy and gravitational energy

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

33

## The Venturi effectIs used in nebulizers

### True

34

## The Venturi effect Uses a fall in kinetic energy

### 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.

35

## The Venturi Effect Uses a fall in potential energy

### True

36

## Flow may be measured by a pressure drop across an orifice

### True

37

## Flow may be measured by using ultrasound

### True

38

## Flow may be measured by high frequency sound wave reflection

### True

39

## Flow may be measured using a bell spirometer

### True

40