# Finding Quality Using Specific Volume?

• dillonmhudson
In summary, you could use specific volume to find quality if you also knew something about the fluid, such as pressure or temperature.
dillonmhudson
Can you or can you not use specific volume to find quality? I know it can be found using mass but can you use specific volume?

Quality of what?

dillonmhudson said:
Can you or can you not use specific volume to find quality? I know it can be found using mass but can you use specific volume?
You could if you also know something else about the fluid. For example, pressure or temperature. You could also find it if you knew enthalpy, entropy, internal energy or some other https://www.physicsforums.com/showthread.php?t=54198", you need 2.

For example, let's say we have steam with a specific volume of 0.0435 ft3/lbm. If that steam is at atmospheric pressure (saturation temperature 212 F), the quality is roughly 0.1%. But if the pressure is 1000 psig (saturation temperature 547 F), the quality is roughly 44%. You need a second state variable to pin down the physical state of the fluid.

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Q_Goest said:
You could if you also know something else about the fluid. For example, pressure or temperature. You could also find it if you knew enthalpy, entropy, internal energy or some other state variable. What you're trying to do is determine the state of the fluid, which you can't do with just one state variable, you need 2.

For example, let's say we have steam with a specific volume of 0.0435 ft3/lbm. If that steam is at atmospheric pressure (saturation temperature 212 F), the quality is roughly 0.1%. But if the pressure is 1000 psig (saturation temperature 547 F), the quality is roughly 44%. You need a second state variable to pin down the physical state of the fluid.

Q Goest, can you explain how you made these calculations? Are you references some table or using a formula?

Thanks.

NSSER said:
Q Goest, can you explain how you made these calculations? Are you references some table or using a formula?
I use a computerized database, basically steam tables on a computer.

v = x*vG + (1-x)vL

if you know pressure, or temperature, then you can look it up
i think you may need one more variable

check out steam tables, and start fiddling with the numbers (just start writing stuff down, make sure you do good book keeping, and something might pop out)

edit: ignore me, do what Q_goest says

edit again: if you know mass, then specific volume is a function of density. you'd need temperature, or pressure.
is there a specific problem you're trying to solve, or just curious?

## 1. What is specific volume and why is it important in finding quality?

Specific volume is a property of a substance that measures the amount of volume occupied by a unit mass of that substance. It is important in finding quality because it is directly related to the density of a substance, which is a key factor in determining its purity and overall quality.

## 2. How is specific volume calculated?

Specific volume is calculated by dividing the volume of a substance by its mass. This value is usually expressed in units of cubic meters per kilogram (m^3/kg) in the SI system.

## 3. Can specific volume be used to compare the quality of different substances?

Yes, specific volume can be used to compare the quality of different substances. Generally, a lower specific volume indicates a higher density and therefore a higher quality substance.

## 4. How does temperature affect specific volume?

Temperature can significantly affect the specific volume of a substance. As temperature increases, the specific volume of a substance decreases, indicating a higher density. This is due to the effect of thermal expansion, where the molecules of a substance spread out as they gain more energy, resulting in a decrease in density.

## 5. What are some practical applications of using specific volume to find quality?

Specific volume is commonly used in industries such as food and beverage, pharmaceuticals, and chemicals to ensure the quality and purity of products. It is also used in environmental science to monitor the quality of air and water samples. Additionally, specific volume is used in the design and operation of various industrial processes to ensure efficient and high-quality production.

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