# Unit (cm) any alternative to the obvious?

• frodft
In summary, the conversation discussed a problem in a spray drying process where a liquid is sprayed into a chamber with air containing water. One outlet stream has wet air and the other has dry solids. The air inlet stream has a temperature of 167 degrees Celsius and a measurement of -40cm H2O, which may refer to a unit of pressure used in the medical field in the 1980s. The speaker questions the meaning of "cm" and suggests that it could potentially be a measurement of pressure using the formula ro*g*h.
frodft
The problem involves a spray drying process in which a liquid containing dissolved or suspended solids is sprayed into a chamber that has air flowing into it which contains water.

One outlet stream has the wet air, and the other has dry solids.

The Air inlet stream is described as having a temp of 167 celsius and -40cm H2O

My question is, what do they mean my cm? If they meant centimeters then this problem can't be solved because I need more than a one-dimensional measurement of the amount of water in that stream. There is no information about the dimensions of the pipe, and there is no more information about that stream than I have stated. So the obvious roadblock is if there is another unit for cm or they meant something else.

pressure?

Cubic Metre ?

apparently it is a unit of pressure that was used in the '80's in medicine. I don't know what it was doing in my chemical engineering textbook 30 years later but there you go.

In this case isn't "-40cm H2O" just a suction = ro*g*h where ro is the density of water, g is the gravitational constant, and h the 40 centimeters. That's not particularly medical.

## 1. What is the purpose of using units in scientific measurements?

Units provide a standardized way of measuring and communicating quantities in the scientific community. They allow for accurate and precise comparisons between different experiments and observations.

## 2. Why is the use of "cm" as a unit of measurement so common?

"Cm" stands for centimeters, which is a unit of length in the metric system. The metric system is widely used in scientific research because it is based on multiples of 10, making calculations and conversions easier.

## 3. Are there any alternative units to "cm" that can be used in scientific measurements?

Yes, there are many alternative units that can be used in scientific measurements depending on the quantity being measured. For length, some alternatives to "cm" include meters (m), millimeters (mm), and kilometers (km).

## 4. Can units other than "cm" be used in scientific publications?

Yes, scientific publications often use a variety of units depending on the field of study and the specific measurements being reported. However, it is important to clearly specify the units used to avoid confusion.

## 5. How do scientists convert between different units of measurement?

Scientists can use conversion factors and equations to convert between different units of measurement. These conversion factors are based on the relationships between the units and can be found in conversion tables or calculated using dimensional analysis.

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