Pressure Drop & Flow Rate for Oxygen Delivery Tube

In summary: If Poiseuille flow holds for your system (and it most likely does if the flow is laminar and steady), the relevant formulas are:\Delta P = \frac{8LQ\mu}{\pi R^{4}}, where\Delta P is the pressure drop between inlet and outlet, L the length of tube, Q the volumetric flow rate (liters/min, for example), R the tube radius, and \mu the viscosity (in Poise, or equivalent)So, you have mixed units- convert everything into MKS. Air at room temperature has a viscosity of about 17 *10^-6 Pa*s.
  • #1
wjt
1
0
I am on home oxygen and receive the gas through a 50feet long tube about .1" inside diameter.If the Machine delivers a flow rate of two liters per second, what is the pressure drop through the tubing; What is the flow rate at my end of the tubing?
 
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  • #2
If Poiseuille flow holds for your system (and it most likely does if the flow is laminar and steady), the relevant formulas are:

[tex]\Delta P = \frac{8LQ\mu}{\pi R^{4}}[/tex], where

[tex]\Delta P[/tex] is the pressure drop between inlet and outlet, L the length of tube, Q the volumetric flow rate (liters/min, for example), R the tube radius, and [tex]\mu[/tex] the viscosity (in Poise, or equivalent)

So, you have mixed units- convert everything into MKS. Air at room temperature has a viscosity of about 17 *10^-6 Pa*s. Now you can calculate the pressure drop.

The flow rate at the outlet is the same as the inlet- conservation of mass.

If there are viscous losses (entirely possible given the aspect ratio of tubing and flow rate), then YMMV.
 
  • #3
You can use the Bernoulli losses formula to calculate it.

([tex]\frac{P1}{\gamma}[/tex] +Z1) -( [tex]\frac{P2}{\gamma}[/tex] +Z2) = [tex]\frac{8fLQ^2}{\ g(Pi)^2D^5}[/tex]

Q is the flow rate.
P is the pressure at point X.
f is the friction factor of the pipe.
L is the length of the tube.
gamma is ro*g.
Z is the elevation at point X.
 
Last edited:
  • #4
wjt said:
I am on home oxygen and receive the gas through a 50feet long tube about .1" inside diameter.If the Machine delivers a flow rate of two liters per second, what is the pressure drop through the tubing; What is the flow rate at my end of the tubing?

Hi wjt, could you please re-check that data as it seems a bit unreasonable. Fluid at 2L/second through 0.1 inch diameter would give a required mean flow velocity of 395m/s which is supersonic.

In SI units :

Flow Rate, Q = 2E-3 m^3/s
Radius, r = .1 * 2.54E-2 / 2 = 1.27E-3 m
Cross section : A=pi r^2 = 5.07E-6 m^2

Therefore the mean velocity is, Q/A = 395 m/s

Are you sure it's not 2L/min instead of 2L/s ?
 

1. What is pressure drop in an oxygen delivery tube?

Pressure drop in an oxygen delivery tube refers to the decrease in pressure as the oxygen flows through the tube. This decrease in pressure is a result of friction and resistance within the tube, which can affect the flow rate of oxygen.

2. Why is pressure drop important in oxygen delivery tubes?

Pressure drop is important in oxygen delivery tubes because it directly affects the flow rate of oxygen. If the pressure drop is too high, the flow rate of oxygen will decrease, resulting in inadequate oxygen delivery to the patient.

3. How is pressure drop calculated in an oxygen delivery tube?

Pressure drop is calculated by measuring the pressure at two points in the oxygen delivery tube and calculating the difference between the two pressures. This can be done using a pressure gauge or by using the Bernoulli's equation.

4. What factors can affect pressure drop in an oxygen delivery tube?

There are several factors that can affect pressure drop in an oxygen delivery tube, including the length and diameter of the tube, the material of the tube, and any obstructions or bends in the tube. These factors can increase the friction and resistance within the tube, resulting in a higher pressure drop.

5. How can pressure drop and flow rate be optimized in an oxygen delivery tube?

Pressure drop and flow rate can be optimized in an oxygen delivery tube by using a tube with a larger diameter, shorter length, and smoother material. Additionally, minimizing any obstructions or bends in the tube can also help reduce pressure drop and improve flow rate. Regular maintenance and cleaning of the tubes can also help optimize their performance.

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