Does Manometer Tubing Diameter Affect P=pgh Calculation?

In summary, the conversation discusses the relationship between the internal diameter of a manometer and its readings, as well as the calculation P=pgh. The group also questions whether the diameter of the manometer affects the height value, given that the volume and mass of the fluid may vary. The conversation clarifies that pressure is independent of the area, but force is dependent on pressure and area.
  • #1
burnit
53
0
Hi All,

When reading Manometers, does the internal diameter of the manometer have a bearing on the readings & the calculation P=pgh??
There is no inclusion of the ID of the manometer tubing.

If we apply pressure to a manometer tube say of 2mm inside diameter the height will be X but now we use a 20mm inside diameter tube, the volume is more of course so do we get the same h value with the larger diameter. The mass of the fluid is more so for the same pressure it would seem the h value will be different?

Thanks
 
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  • #2


You'll notice that pressure is in units of area, which means that it is independent of the area of the object it is acting on. You may be confusing pressure with force. Force is pressure times area.
 
  • #3


Thanks Russ,
Good explanation!
 

FAQ: Does Manometer Tubing Diameter Affect P=pgh Calculation?

1. What is a manometer?

A manometer is a device used to measure the pressure of a fluid, such as gas or liquid. It works by comparing the pressure of the fluid to the pressure of a known reference, typically atmospheric pressure.

2. How do you calculate pressure using a manometer?

To calculate pressure, you need to know the density of the fluid (ρ), the acceleration due to gravity (g), and the height difference between the fluid levels (h) in the manometer. Then, you can use the formula P = ρgh, where P is the pressure in units of force per unit area.

3. What units are used for manometer calculations?

The units for manometer calculations depend on the units used for density, acceleration due to gravity, and height. For example, if density is in kilograms per cubic meter, acceleration due to gravity is in meters per second squared, and height is in meters, then the pressure would be in units of kilograms per meter per second squared (kg/m*s²), which is equivalent to pascals (Pa).

4. How accurate are manometer calculations?

The accuracy of manometer calculations depends on the accuracy of the measurements used in the calculation, such as the height difference and density of the fluid. Additionally, the type of manometer used can also affect the accuracy. For example, a U-tube manometer may be less accurate than a digital manometer.

5. What are some common uses for manometers?

Manometers have a variety of uses in scientific and industrial settings. Some common uses include measuring gas pressure in HVAC systems, monitoring fluid levels in chemical processes, and measuring blood pressure in medical settings.

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