41 Cistern Program

[Gerson W. Barbosa]

(08-19-2016 10:05 PM)aurelio Wrote:  strange that in solving the problem is always considered as a parameter the cross section of the head, but not the section, which is assumed always circular
Vessels often have elliptical section

Ciao, Aurelio!

This online calculator includes the formula. I'd posted previously another link but the formula therein was wrong, so I deleted it. Sorry!
Are there heads of types other than flat for such elliptical cross section tanks? Hopefully not – the calculations woud be far more complicated.

https://en.wikipedia.org/wiki/Head_(vessel)

Gerson.

[aurelio]

(08-19-2016 11:29 PM)Csaba Tizedes Wrote:  

(08-19-2016 10:05 PM)aurelio Wrote:  Vessels often have elliptical section

The end of the vessels are spherical in the center and the connected part is a toroid. This is connecting to the short cylindrical part - in the DIN standard. I guess in the ANSI this is same.

Csaba

maybe I completely misunderstood the meaning of "vessel" , but how are called those kind of tank ?

they are out of standards? the picture shows a old truck but actually mostly truck load this kind of vessel on the road .)

[aurelio]

(08-20-2016 05:34 AM)Gerson W. Barbosa Wrote:  This online calculator includes the formula.
Gerson.

thank-you Gerson, grazie for the link!!

[Csaba Tizedes]

(08-20-2016 07:51 AM)aurelio Wrote:  meaning of "vessel"?

Our company designs "pressure vessels" for pneumatic conveying, therefore I use "vessel" often. But in English these equipments "tanks". I guess both of them are correct if you do not want to talk about it on academic level

Here it is a picture about it:



Just for clarification, our "pressure vessel" looks like this vessel or tank:



Csaba

[Gerson W. Barbosa]

(08-20-2016 05:34 AM)Gerson W. Barbosa Wrote:  Are there heads of types other than flat for such elliptical cross section tanks? Hopefully not – the calculations woud be far more complicated.

Answering my own question, yes, there are. The one in the first picture here is clearely not flat by the curved reflection of the ladder on the surface of the head. "Flat or slightly rounded ends", the specifications state. If the cross sections of both the head and the tank are elliptical, then simple exact formulas for parcial volumes are not possible, I think.

[Csaba Tizedes]

(08-20-2016 03:40 PM)Gerson W. Barbosa Wrote:  ... yes, there are ... simple exact formulas for parcial volumes are not possible, I think.

I guess you're know that the shape of the vessels' end (head) is depends on the application. Your example clearly shows that nearly flat bottoms are applicable for low pressure and for the higher pressure the standard bottom is suitable.

For vessel volume calculations the standards are includes the volume of each bottoms.
For partially filled tanks the standard or owner company also gives a tabulated volume depends on level inside the vessel (eg. horizontal fuel tanks under the ground) - because it has cost impact.

The real application is very simple: do not calculate anything if it has cost impact or if it has not, that is not real application You know it: Money makes the world go round.

Csaba

[Gerson W. Barbosa]

(08-20-2016 06:57 PM)Csaba Tizedes Wrote:  

(08-20-2016 03:40 PM)Gerson W. Barbosa Wrote:  ... yes, there are ... simple exact formulas for parcial volumes are not possible, I think.

I guess you're know that the shape of the vessels' end (head) is depends on the application. Your example clearly shows that nearly flat bottoms are applicable for low pressure and for the higher pressure the standard bottom is suitable.

For vessel volume calculations the standards are includes the volume of each bottoms.
For partially filled tanks the standard or owner company also gives a tabulated volume depends on level inside the vessel (eg. horizontal fuel tanks under the ground) - because it has cost impact.

The real application is very simple: do not calculate anything if it has cost impact or if it has not, that is not real application You know it: Money makes the world go round.

Csaba

Yes, I've realized that vessels with rounded ends are mandatory for high pressure applications, like compressed air containers. But then again what is the point of calculating partial volumes in such cases?

"Money makes the world go round". Quite true! We have a similar phrase here (o dinheiro move o mundo).

I've found calculator and formulas for volume and base area of ellipsoidal caps at

http://keisan.casio.com/has10/SpecExec.c...1311572253

It appears their surface areas is the problem there is no simple solution to:

https://en.wikipedia.org/wiki/Ellipsoid

Gerson.