# How Do You Calculate Gage Pressure in a Partially Filled Oil Tank?

• EzaMoo
In summary, a 3 tube manometer is a device that measures pressure difference between two points using three tubes and a fluid as the measuring medium. It is commonly used in various industries and can provide accurate readings within 1-2% of the actual pressure difference. To read it, you need to determine the difference in height between the fluid levels in the two tubes and take necessary safety precautions as the fluid used can be toxic.
EzaMoo

## Homework Statement

Calculate the gage pressure of the air (in kPa) in the tank which is partly filled
with the oil of specific gravity 0.8.

P = pgh

## The Attempt at a Solution

Taking xx at middle tube's mercury height :

Right tube = Px = 13600 x 9.81 x 0.6

Middle tube = P

Left tube = 800 x 9.81 x 1

P = (13600 x 9.81 x 0.6) + (800 x 9.81 x 1)

But I know this is wrong. Can't find any examples on the internet or in the text I am using... PLEASE HELP!

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Hello,

To calculate the gage pressure of the air in the tank, we need to use the equation for hydrostatic pressure:

P = pgh

Where P is the pressure, p is the density of the fluid, g is the acceleration due to gravity, and h is the height of the fluid column.

In this case, we have air and oil in the tank. The specific gravity of the oil is given as 0.8, which means it has a density of 0.8 times the density of water.

So, first we need to calculate the density of the oil:

p = 0.8 x 1000 kg/m^3 = 800 kg/m^3

Next, we need to find the height of the oil column in the tank. Since the tank is partly filled with oil, we need to know the total height of the tank and the height of the oil column.

Let's say the total height of the tank is 2 meters, and the height of the oil column is 1 meter. Then, the height of the air column would be 2 - 1 = 1 meter.

Now, we can plug in these values into the equation:

P = (800 kg/m^3) x (9.81 m/s^2) x (1 m)

P = 7848 Pa

To convert to kPa, we divide by 1000:

P = 7.848 kPa

So, the gage pressure of the air in the tank is 7.848 kPa.

I hope this helps! Let me know if you have any further questions.

## 1. What is a 3 tube manometer and how does it work?

A 3 tube manometer is a device used to measure pressure, specifically the difference in pressure between two points. It consists of three tubes, one connected to the pressure source, one open to the atmosphere, and one containing a fluid (usually mercury or water) that acts as the measuring medium. The difference in height between the fluid levels in the two tubes is directly related to the pressure difference between the two points.

## 2. How accurate is a 3 tube manometer?

The accuracy of a 3 tube manometer depends on various factors such as the type of fluid used, the length and diameter of the tubes, and the precision of the measuring scale. Generally, it can provide accurate readings within 1-2% of the actual pressure difference.

## 3. What are the common applications of a 3 tube manometer?

A 3 tube manometer is commonly used in industries such as HVAC, automotive, and aerospace for measuring pressure in various systems such as pipes, tanks, and engines. It is also used in laboratories for experiments and in medical settings for measuring blood pressure.

## 4. How do you read a 3 tube manometer?

To read a 3 tube manometer, you need to determine the difference in height between the fluid levels in the two tubes. This can be done by subtracting the lower reading from the higher reading. The resulting value can then be converted to the desired unit of pressure using a conversion chart.

## 5. Are there any safety precautions to take when using a 3 tube manometer?

Yes, there are a few safety precautions to keep in mind when using a 3 tube manometer. The fluid used in the manometer can be toxic, so it is important to handle it with care and avoid contact with skin or eyes. Additionally, ensure that the manometer is properly calibrated and that all connections are secure to avoid any accidents.

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