# Units for pressure in a cylinder

• Pranshu
In summary, when calculating pressure on a spherical cylinder in a wind tunnel, the hydrostatic formula can be used to determine the pressure difference (P2-P1) by using the density (ρ) and gravity (g). The units for ρ can be in kg/m^3 and g in m/s^2, and the units for the difference in height (h2-h1) can be in either meters or millimeters. However, using h in mm will result in a unit of N mm/m^3 instead of the standard unit of N/m^2.
Pranshu
I am calculating pressure on a spherical cylinder of 10 mm diameter by wind tunnel. when measuring values in manometer filled with water which density is 1000 kg/m^3 so by hydro-static formula the pressure difference is [P2-P1=ρg(h2-h1)]

so by this formula the ρ unit is in kg/m3 and gravity(g) we know 9.81 m/s^2 so the unit of (h2-h1) must be meter? or mm will be fine as well?
I am confused by this small problem..

<<Mentor note: Removed comments unrelated to question>>

Last edited by a moderator:
The formula does not presuppose anything about the units. You will get the same units out as you put in.

Orodruin said:
The formula does not presuppose anything about the units. You will get the same units out as you put in.
Thank you...

But the unit which i put in must be same...for instance if i have ρ in meter and g in meter as well...so can i use h means the height in mm?
or it should be meter too?

that's my real question.

You can use h in mm, but it will make your result have units of N mm/m^3 instead of N/m^2. (The first is equivalent to units of mPa.)

Pranshu

## 1. How is pressure measured in a cylinder?

Pressure in a cylinder is typically measured using a pressure gauge, which displays the pressure in units such as psi (pounds per square inch), kPa (kilopascals), or bar. The gauge is connected to the cylinder through a valve, and the pressure reading is taken when the valve is open and the gas inside the cylinder is allowed to flow.

## 2. What is the standard unit for pressure in a cylinder?

The most commonly used unit for pressure in a cylinder is psi (pounds per square inch). However, other units such as kPa (kilopascals) and bar are also commonly used in different industries and regions.

## 3. How does temperature affect pressure in a cylinder?

In a closed cylinder, temperature and pressure are directly proportional. This means that as the temperature of the gas inside the cylinder increases, the pressure also increases. Conversely, as the temperature decreases, so does the pressure.

## 4. What is the maximum pressure that a cylinder can hold?

The maximum pressure that a cylinder can hold depends on its size, material, and intended use. Cylinders used for storing compressed gases typically have a maximum pressure of 200-300 bar, while cylinders used for hydraulic systems can have a maximum pressure of up to 700 bar.

## 5. How do I convert pressure units in a cylinder?

To convert pressure units in a cylinder, you can use conversion factors or online conversion calculators. For example, to convert psi to bar, you can multiply the psi value by 0.06895. It is important to make sure you are using the correct conversion factor for the specific units you are converting.

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