# Pressure vessel

1. Jul 28, 2011

### bionic6manuel

I would like to make a pressure vessel with a pressure of about 9 bars/130.5 psi, that contains about 250 grams of water at about 175 degrees Celsius. My question is how big should the pressure vessel be.

2. Jul 28, 2011

### gsal

as big as you want

3. Jul 28, 2011

### xxChrisxx

9 bar really isn't a lot of pressure.

You can work this out yourself, work out the maximum stress (hoop and axial) and compare to the pressure vessels stress strain curve at 175 C.

EDIT: Also depends what you are doing with said pressure vessel, and what the application is. Do you have to work to set codes?

4. Jul 28, 2011

### xts

Despite I usually encourage people for home experiments, this time I would really discourage making it if you have not any experience with mechanical engineering (you haven't - otherwise you would not ask such questions).

Such pressure and volume seems to be not so impressive, but is pretty sufficient to shoot improperly secured valve with energy of handgun bullet, or to cause serious burns over large parts of your body.

5. Jul 28, 2011

### bionic6manuel

xxChrisxx I have no idea about hoop and axial, but this is what i would like to achieve. I would like to make a cube out of epoxy say 16 cubic cm and in the center I would like to put a spherical pressure chamber with a radius of about 5 cm. The pressure would be 9 bars and heat inside the chamber would be 175 degrees Celsius. Say the tensile strength is 4000 PSI of the epoxy would I be able to make pressure chamber with the epoxy

6. Jul 28, 2011

### xxChrisxx

Why do you want to do that? What are you acutally trying to achieve?

You certainly can't make a pressure vessel from epoxy alone.

7. Jul 28, 2011

### bionic6manuel

So what else should i put into the epoxy to make it strong enough. Does the thickness of the walls play a role, say i have a wall with a thickness of 5 cm

What i would like to make is a closed chamber "closed system" with a heating element and a heat sensor when ever the chamber gets to 173 degrees Celsius I shut off the devise till the temperature drops then repeat the process again.

Wikipedia says "theoretically any material can be used to make a pressure vessel". So i thought any material with a thick enough wall will hold pressure.

Last edited: Jul 28, 2011
8. Jul 28, 2011

### SteamKing

Staff Emeritus
If you have no idea about hoop or axial (stress), you probably should not be trying to make your own pressure vessel.

9. Jul 28, 2011

### DaveC426913

No it's all right, he's got wikipedia to guide him.

Seriously, bionic6manuel, you've got an awesome combination for disaster here: steam, pressure and lack of knowledge/experience.

10. Jul 28, 2011

### bionic6manuel

To DaveC426913 you are right about what you said about me. But you did not answer the question i put forward it is easy to say what you did "Seriously, bionic6manuel, you've got an awesome combination for disaster here: steam, pressure and lack of knowledge/experience". Lack of knowledge/experience I have, answer the question everybody has to learn. That is why I am posing on this forum, no matter how dumb my questions are

11. Jul 28, 2011

### xxChrisxx

Theoretically you can make it out of anything, even lime jelly. Not really practical though. As you are a beginner at this you need to remember the following.

Pressure vessels are made from steel.

12. Jul 28, 2011

### nasu

At 175 Celsius the usual epoxy does not work too well. It may become softer, decompose, change properties. Another thing to take into account.

13. Jul 28, 2011

### sophiecentaur

When you think of the level of safety 'hoops' you have to jump through when producing a pressure cooker for kitchen use (1 Bar only), I should say the 9 Bars is a pressure that demands some respect if any significant volume is involved.
If I needed to make something like that I would buy a thick steel tube and weld some flat ends to it, bolted together with strong bolts. Also, I'd include a safety valve before I went anywhere near it. I got to a great age because of this general attitude. I know it may not be cool but both eyes and an unblemished complexion makes one less unattractive to women, for a start.

14. Jul 28, 2011

### Staff: Mentor

Dangerous activities are not discussed here on the PF. Based on your lack of knowledge and experience, working with a pressure vessel constitutes a dangerous activity. Thread closed.