Flow Flashcards
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.
Regarding the flow of gases In laminar flow, flow depends on viscosity
True
Regarding the flow of gases In laminar flow, gas flow is proportional to the fourth power of the radius
True
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).
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.
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.
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.
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.
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.
Regarding the flow of gases Turbulent flow can only be measured using vane meters
False. Turbulent flow can be measured using multiple techniques.
A pneumotachograph May consist of a large number of smaller tubes
True
A pneumotachograph May contain a differential pressure transducer
True
A pneumotachograph Is not affected by the gas viscosity
False. Output is affected by viscosity.
A pneumotachograph May give an erroneous reading in the presence of condensed water vapour
True
A pneumotachograph Works on the principle of Poiseuille’s law
True
Regarding gas or liquid flow:
In laminar flow, flow is determined by the pressure gradient divided by resistance
True