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specific gravity

Posted: Thu Jul 23, 2015 5:33 am
by fishflipper
any way we can have RA read salinity in specific gravity? i wouldn't think it would be too difficult to have the app to a conversion.

Re: specific gravity

Posted: Thu Jul 23, 2015 4:26 pm
by lnevo
It's a math formula so it should be doable, but just for display purpose. Where are you looking to read that? In your phone app? Portal? Or screen...

You could easily do a custom screen code to show the sg instead. Doing the rest is gonna take a lot of back end changed

Re: specific gravity

Posted: Thu Jul 23, 2015 7:49 pm
by rimai
You can also do the math and display it in a custom variable.

Re: specific gravity

Posted: Fri Jul 24, 2015 4:44 am
by lnevo
How would you present 1.025 in a custom variable...

Re: specific gravity

Posted: Fri Jul 24, 2015 6:14 am
by fishflipper
i would like to see it in the app on my phone. how can i have it do the math for me?

Re: specific gravity

Posted: Fri Jul 24, 2015 9:31 am
by rimai
lnevo wrote:How would you present 1.025 in a custom variable...
You got a point.
Maybe just show the last 2 digits?

Re: specific gravity

Posted: Fri Jul 24, 2015 5:42 pm
by lnevo
I would just go by ppt at that point lol

Re: specific gravity

Posted: Fri Jul 24, 2015 5:43 pm
by lnevo
Roberto, maybe you can just have it as a preference in the portal and display in the preferred format we could easily do the same elsewhere.

Re: specific gravity

Posted: Fri Aug 14, 2015 4:40 am
by fishflipper
so...do we think this will be possible?

Re: specific gravity

Posted: Sun Aug 16, 2015 1:07 pm
by lnevo
I could not find the formula only a lookup table. Unless you can find the math its not going to be simple or accurate.

Re: specific gravity

Posted: Sun Aug 16, 2015 1:45 pm
by fishflipper
If I can find the formula would it be possible?

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Re: specific gravity

Posted: Sun Aug 16, 2015 2:03 pm
by lnevo
Yeah

Re: specific gravity

Posted: Mon Aug 17, 2015 11:13 am
by cypho
Here is the current standard for the calculation: http://www.teos-10.org/software.htm

But that is probably 100x more complicated needed. I would just use a lookup table or a simple linear plot between two data points in the table near your target range.

Re: specific gravity

Posted: Tue Aug 18, 2015 10:21 am
by lnevo
I cannot find a function in that to convert conductivity to SG. Can you be more specific what I'm looking for?

Re: specific gravity

Posted: Tue Aug 18, 2015 3:05 pm
by cypho
You are looking for Specific Volume. SV is the inverse of SG: SG = 1/SV

gsw_specvol_CT_exact or gsw_specvol
http://www.teos-10.org/pubs/gsw/html/gs ... exact.html
http://www.teos-10.org/pubs/gsw/html/gsw_specvol.html

Other interesting/useful functions:

gsw_SP_from_C
http://www.teos-10.org/pubs/gsw/html/gsw_SP_from_C.html

gsw_SA_from_SP
http://www.teos-10.org/pubs/gsw/html/gs ... om_SP.html

Re: specific gravity

Posted: Wed Aug 19, 2015 6:08 am
by lnevo
Great let me look through that and see what I can gather.

Re: specific gravity

Posted: Tue Sep 01, 2015 8:46 am
by fishflipper
Any movement on this?

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Re: specific gravity

Posted: Tue Sep 01, 2015 9:02 am
by lnevo
Have not had enough time. Honestly would not get hopes up for it.

Re: specific gravity

Posted: Tue Sep 01, 2015 10:08 am
by fishflipper
Ok, I appreciate the effort.

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