Intermediate Heads Differential pressure

[TanEng]

In a reactor having 2 chambers, uper chamber having a design pressure of 10 kg/cm2 & lower chamber having a design pressure of 12 kg/cm2. The differential pressure is 1.5 kg/cm2.
Can we calculate intermediate Head thickness using differential pressure as a design pressure?

 

[TGS4]

Two comments:

First, units of mass/area does not equal units of pressure - which are force/area. kg/cm^2 does not conform to ANY system of units.

Second - will there be any situation (foreseeable or not foreseeable) when only one chamber could be pressurized while the other one is not? I include hydrotest in the list of situations. You'll need to ask your process engineer about that.

 

[JStephen]

I would think you'd want to design so either chamber could be pressurized separately.

Here in the US, we go through school learning inch-pound system and SI system- but never use the kg/cm^2- but I notice it's not at all uncommon on non-US items such as mill test reports. It's exactly the same reasoning as our lbf and lbm units.

 

[deanc]

See UG-19 and UG-21,also UG-99(e) if SecVIII.

http://www.coade.com/support_downloads.asp?varflag=0&varreturn=dl

Unit Conversion Program---unconvert.zip

This is a great freebie from a good bunch of folks.

With due regards to TGS4,this program will convert those units for you.

 

[TGS4]

Thanks deanc - I know how to convert it - I just shouldn't have to. Pressure is force/area. I shouldn't have to multiply mass/area by acceleration (gravity) to get to force/area. (BTW - I was itching for a firestorm when I wrote my first post, so I expected as much...)

 

[jte]

Next time I issue an RFQ for a vessel I think I'll specify the design pressure as tons per square fathom!

jt

 

[deanc]

TGS4-Figured as much-all in good fun,no?

jte: Only if the WPS restricts welding during the full moon.

 

[TGS4]

Yes deanc - all in good fun. I thought that the forums were getting a little stuffy...

jte - and only if inspected by a left-handed, blue-eyed inspector.

You know, it's almost St. Patrick's day - the day where we're all a little irish - and can enjoy the guinness. Is it Friday yet???

Actually - I was reminded of the units issue upon reading of the successful insertion-into-orbit of the latest NASA Mars satellite. Remember the one a few years ago that smeared itself on the surface of the red planet b/c of a units snafu?

 

[waross]

There was an incident stemming from a units snafu when a passenger airliner made a dead stick landing in Canada.
The Canadian metric police decreed that on a particular day, aircraft fuel loads must be reported in kg instead of lbs. As you know many accidents are the result of more than one simultaneous problem.
There were a series of "issues" concerning the fuel load. The fuel load was 20,400 lbs. It should have been 20,400 kg.
Somewhere over western Ontario the aircraft ran out of fuel.
Two factors saved the flight. One of the pilots had glider experience and the other had flown out of a military airport (Gimli) near Winipeg years ago. They could not make the Winipeg airport which is west of the city but they could make it to the former military strip which is north-east of Winipeg.
It was later reported that Beoing set up the problem in a flight simulator and their test pilots "Crashed" the first three atempts to re-enact the flight.
There was a movie made of the story. It comes around occasionally on late night television.

http://en.wikipedia.org/wiki/Gimli_Glider

yours

 

[waross]

GIMLI GLIDER

 

[deanc]

TGS4-Your point is well taken. Time and money continues to be wasted.

Soft and Hard metric is the most recent catch-all.

Fortunately the Code Committees are beginning to give us some guidance. Hear the meetings are quite interesting.

 

[JStephen]

jte- don't forget that the cube root of a gallon is a perfectly good unit of lenth. And you can measure volume in units of acres^1.5.

 

[arto]

how about velocity in furlongs per fortnight?

 

[waross]

"And you can measure volume in units of acres^1.5." Those were the days, even though the corrections for atmospheric pressure and the phase of the moon were somewhat onerous.

I understand that one of the reasons the cube root of a gallon fell out of favor as a unit was the confusion resulting from the American insistance on a gallon of Coors, while the British preferred a gallon of Guiness.
yours

 

[jaimeleiva]

Hello, to anyone, what do they mean when they say mill test pressure, and to what is equivalent (e.g., design pressure,etc..)
Thank you