Convert from Mass Flow Rate to Volum Flow Rate? 8

[MonicaLee]

It is possible to convert from Mass Flow Rate to Volume Flow Rate? Can we convert
3165 kg/hr to scft/min?

If you can convert, please show me how. I got a result for 1.9433 scft/min.

Thank you very much for your help

 

[TGS4]

You convert mass flow rate to volumetric flow rate by dividing by the density of the fluid. You can confirm this by ensuring that you carry your units in your calculations.

 

[mbeychok]

Monica Lee:

Yes, you can easily convert kg/hr to scf/min as explained in the response you got from TGS4, but you must provide us with the following information:

(1) Is the fluid a gas or a liquid?
(2) What is the fluid? Give us the name or chemical formula.
(3) There are many different reference conditions for the term "standard cubic feet (SCF)". What are the reference temperature and pressure of your SCF?


Milton Beychok
(Contact me at www.air-dispersion.com)

 

[MonicaLee]

I never convert from mass to volumetric, I thought we just convert from kg to oz to cft. I guess I got the wrong result, could someone explains why is that concept wrong. Is that because we have different density for different fluid properties?

The fluid in this application is HC Gas at rel. Temp. 52C and 110-132 pressure.

Thank you in advance.

 

[MonicaLee]

Pressure BarG = 110/132 (Oper./Set)
Cp/Cv = 1.01
Operating Viscosity = CP = 1.61E-02
Barometric Press BarG 1.01
Calc. Area mm2 = 30
Sel. Area mm2 = VTA
Orifice Designation = VTA

Can we convert
3165 kg/hr to scft/min?

 

[katmar]

Monica Lee,

This will sound harsh, but it is the fact of the matter. You should not be working on this problem. It seems that you are dealing with a very high pressure relief valve on a flammable system. If you do not know the difference between gage and absolute pressure, any formula someone gives you here will mean that you are applying a recipe that you do not understand. Rather pass this problem on to an engineer in your organization, or employ a registered contractor.

I am sorry to be so negative, but you are opening yourself (and your employer) up to all sorts of liability issues if you work on this problem.

regards
Katmar

 

[MonicaLee]

All I asked for is a conversion from 3156 kg/hr to scft/min.?

I am surprised if noone can't convert with the data given. Please provide some help. Thank you.

 

[TGS4]

I've got to agree with katmar on this one. You need to secure the services of a professional engineer experienced in this field.

Remember that the old adage "You get what you pay for" also applies to anything you get in this forum. The value of the advice is worth exactly what you pay for it - NOTHING.

 

[MonicaLee]

I appreciate your TGS4 for your opinion. In this case, I do not seek for an opinion but someone who has direct experience dealing with conversion factor from mass to volumetric flow. Can someone else provide some assistance?

 

[Alph]

Monica,

Use can use the following steps :

1) Kg/hr ===> lb/hr = x 2.2046
2) lb/hr ===> lb/min = / 60
3) lb/min ===> lbmol/min = / MW
4) lbmol/min ===> scf/min = x 379.5

Where
x = multiply
/ = divide
MW = Mol Wt
SCF @ 60° & 14.7 psia

 

[pmover]

good job Alph!

while i do not know where the posting is (this forum or otherwise), but Art Montemayor wrote a fundamental response to a similar posting that engr's should take heed in.

Monica, Alph's response provide you a technique for determining flow of the fluid (HC gas) at 60°F and 14.7 psia. i trust you can obtain the MW of HC gas. . . yes, the pressures involved in the application are not to be taken lightly. . .

good luck!
-pmover

 

[mbeychok]

Monica:

The conversion method that Alph gave you is quite correct. However, considering your poor presentation of the data required to make the conversion even after you were told more data was needed, I agree with Katmar and TGS4 that it seems you don't know what you are doing and you should obtain the services of an experienced engineer.


Milton Beychok
(Contact me at www.air-dispersion.com)

 

[Tremolo]

Leave it to a bunch of engineers to take a simple question and make it complicated.

If you look at Alph's answer, you’ll notice that no additional information was required beyond Monica's initial question.

TREMOLO

 

[mbeychok]

Tremolo:

If you look at Monica's original post and at Alph's answer, you will see that:

(1) She did not tell us if the fluid in question was a gas or a liquid.

(2) She did not tell us what the fluid was nor did she characterize it by giving us its MW or chemical name.

(3) She did not specify what her reference temperature and pressure were for her SCF.

After being asked for that information:

(1) She still did not characterize her fluid beyond telling us that it was a hydrocarbon gas.

(2) She gave us the barometric pressure as 1.01 bar gauge rather than bar absolute. (Which by the way has nothing to do with the data needed for the conversion).

(3) She still did not define her SCF ... indicating that she really didn't understand the need to do so.

(4) She gave us some extraneous data indicating that she was dealing with a high pressure relief valve ... which really requires an experienced engineer rather than someone needing help with a very simple conversion.

As one who works in the nuclear field, you should be especially sensitive to the problems that can be caused by inexperienced people.

Milton Beychok
(Contact me at www.air-dispersion.com)

 

[MonicaLee]

Thank you everyone's concern and special thanks to Alph. I agree with Tremolo, why makes life more complicated than it already is. I might be inexperience but doesn't mean I can't ask question, right? That is the only way I can learn, why do I have to hire a PE when things can be taught in minutes or a matter of a reference book? Just be patient and kind-hearted then everyone will live in peace, bureacratic partisan will meet its match someday. Again, thank you for everyone's contributions.

By the way, how do you make fund contributions to this forum? Thank you again.

 

[quark]

The simplest answer is as elementary as the definition of the density that, density = mass/volume or mass = volume x density(at the fluid temperature and pressure)

There are two confusing comments from the OP.

1. It is possible to convert from Mass Flow Rate to Volume Flow Rate?

2. I never convert from mass to volumetric, I thought we just convert from kg to oz to cft.

Confusion resulting from first question is due to the fact that the question is very basic and second due to the fact that it is not clear. What you convert from kg to oz?

Katmar and Mbeychok are very valuable members of these forums and they are extra generous by providing invaluable and free information through their websites. Katmar even wrote a free computer program of unit conversion which includes conversion of mass flow to volumetric flow. They have been continuously and patiently replying questions related to mass flow and volume flow and a little search would have given the OP more knowledge than what they required.

My intention is not to prove that the OP is wrong but Katmar and Mbeychok are also not wrong either.

It is not wrong to ask basic questions and also not wrong to get some hard words in return. Atleast we will never forget the basics then after.

MonicaLee,

Go to Support Eng-Tips! menu below Hi MonicaLee main menu on the top left corner of the page.

Regards,

 

[25362]

MonicaLee, you say you guess you got the wrong result in your mass-to-volume flow rate conversion exercise.

Let us see how did you proceed with your estimation. I feel it would trhen make it easier to give you some advice that you would understand.

 

[katmar]

Monica,

I admire your willingness to ask questions and I hope that you do not let my previous post discourage you from continuing to do so. I have always encouraged young engineers to ask questions, even if the question seems stupid. It is better to ask the question and appear stupid, than to stay silent and remain ignorant - but it takes real courage to do this.

If you are to continue working in this field I would strongly encourage you to take some formal classes in chemistry, physics and thermodynamics as a starting point. Here in South Africa the concepts of mass, volume, density and the ideal gas law are taught at approximately Grade 10 level at school. As you obviously do not have this background I believe you will struggle to progress further unless you have a solid foundation to build on.

Please take my earlier remarks (as well as those from TGS4, MBeychok and Quark) seriously. You did not explain why you wanted to perform this conversion. Now you have the answer from Alph, but we do not know what you want to do with it. A typical application of that information would be to size the downstream piping from the relief valve. If you are going to use this converted value for further calculations then I must repeat my earlier comment - please get professional help because the risks of getting this sort of calculation wrong are significant. We are talking of "go to jail" stuff here, and I would never wish that on a fellow engineer.

regards
Katmar

 

[MonicaLee]

Hello everyone again,

I thought we stopped at the previous post when Alph goes to the point and gave me what I needed. Mr. Katmar, I think you go to far on your concern. You are right, I can't disguise as a professional engineer based on the question I asked but like everyone else, I can't be Ms. Know-It-All, there would be area I might need some learning curves to be trained. I, however, will put more progress into this area. My question might be unclear but it's very directed to what I needed. You are right, I am asking to learn about relief valve in a piping application for a valve manufacturer.
I know it seems to be irritant when you see a posting like mine. I appreciate your patience and I assume you might be in a management position by the way you described yourself. You might have many concern about other people that is why you come here to help. Sometime you might be a great Teacher/Educator but as far as being an Engineer, we go to the field, diagnose the problem and quickly grap a solution pertaining to that problem. There is not much time allowed for a good theory. In any oil & gas applications, there are tons of applications, equipment, and processes. We have very short time/little money to handle all problems. If we are seeking for "professional" help for everyone of the problems, then we or I will be "out of luck" very shortly. Please understand my position and have some sympathy for the young engineer for her learning curve.
Again, when I posted something here, I listen empathically to everyone's comments and in return, I reply. I would like to thank everyone for their time and devotion for this forum to assist people who are struggling for daily technical challenges.

 

[25362]

You still haven't replied my post.