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Topic: Ullage calculation for chemical packaging  (Read 4523 times)

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Offline almslb

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Ullage calculation for chemical packaging
« on: January 15, 2015, 03:23:26 PM »
Hello,

I am working on trying to calculate what the ullage should be for a given chemical. I have the relative density at a specific temperature and the total capcity of the package I am trying to fill. Can someone please assist me in determining the ullage (headspace) that should be left given this information.

Thank you,

almslb

Offline curiouscat

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Re: Ullage calculation for chemical packaging
« Reply #1 on: January 15, 2015, 03:28:59 PM »
What's the chemical?

Offline almslb

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Re: Ullage calculation for chemical packaging
« Reply #2 on: January 15, 2015, 04:09:28 PM »
Hello, thank you for your response.

Its a number of chemicals, some of them are blends so I dont really have a way to give a specific example. I just have access to the relative densities.



Offline curiouscat

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Re: Ullage calculation for chemical packaging
« Reply #3 on: January 15, 2015, 11:04:55 PM »
Hello, thank you for your response.

Its a number of chemicals, some of them are blends so I dont really have a way to give a specific example. I just have access to the relative densities.

e.g. Are the sensitive to air / moisture. Are the liable to evaporate / off gas? How much will they expand? What's their BP? What's the packing size? Are they metal drums or plastic? Will they be stored outside exposed to direct sun heat?

I'd say 5% is a minimum. 10% is on the safer side.

Large tanks on ships often operate with 2% ullage but they have the instrumentation & experience to pull that off.

Offline DrCMS

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Re: Ullage calculation for chemical packaging
« Reply #4 on: January 16, 2015, 04:31:43 AM »
curiouscat's rough guidelines are all well and good but depending if the material is hazardous, it's boiling point and the packaging size your using then there are strict legal limits based for the minimum ullage.

Offline curiouscat

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Re: Ullage calculation for chemical packaging
« Reply #5 on: January 16, 2015, 04:50:29 AM »
curiouscat's rough guidelines are all well and good but depending if the material is hazardous, it's boiling point and the packaging size your using then there are strict legal limits based for the minimum ullage.

@DrCMS:

Agree entirely. I was trying to do the best I could without knowing his specifics.

Incidentally, is there anything you've seen where the legal limit calls for more than 10% ullage? I'd be curious to know.

Offline almslb

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Re: Ullage calculation for chemical packaging
« Reply #6 on: January 16, 2015, 10:31:57 AM »

Limited exposure to sun. Will be in both metal drums and plastic totes. 53-58 gallon drums and 265-317 gallon totes.

Boiling point varies as well. What I am really looking for is a formula or series of steps I could take to quantify that ullage. There has to be a process to find the specific minimum amount. Any other details dealing with the specific chemical I can find, such as boiling point. 

Thank you for your input.

Offline DrCMS

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Re: Ullage calculation for chemical packaging
« Reply #7 on: January 16, 2015, 11:36:55 AM »
@ curiouscat there is a table that gives rough guidelines based on boiling point ranges and the max there is 10% but there is a calculation based on the density @ 15°C and 50°C and the filling temp that might give a higher value for some materials.

@almsib  you are still not giving enough information for anyone to give you the correct answers.

Offline curiouscat

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Re: Ullage calculation for chemical packaging
« Reply #8 on: January 16, 2015, 12:18:05 PM »
@ curiouscat there is a table that gives rough guidelines based on boiling point ranges and the max there is 10% but there is a calculation based on the density @ 15°C and 50°C and the filling temp that might give a higher value for some materials.

@DrCMS Thanks!

Offline DrCMS

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Re: Ullage calculation for chemical packaging
« Reply #9 on: January 16, 2015, 02:36:18 PM »
The info I gave was for Europe based on UN recommendations; the US DOT may well apply slightly different rules to the rest of the world just to be awkward and different.  Just like the new GHS system is just the EU labelling system run through a thesaurus to I assume appease the US so they can say they've not just adopted the "socialist" EU model. 

Offline almslb

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Re: Ullage calculation for chemical packaging
« Reply #10 on: January 16, 2015, 03:16:03 PM »
"but there is a calculation based on the density @ 15°C and 50°C and the filling temp that might give a higher value for some materials."

This is what I need. How would I do that? What other info do you need? I may be able to find it for a specific chemical I am using.

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