OnlineConversion Forums Welcome to OnlineConversion.com Forums

Go Back   OnlineConversion Forums > Main Forums > Convert and Calculate

Convert and Calculate Post any conversion related questions and discussions here. If you're having trouble converting something, this is where you should post.
* Guest Posting is allowed.

Reply
 
Thread Tools Display Modes
  #1  
Old 02-19-2008, 11:39 AM
Unregistered
Guest
 
Posts: n/a
Default Converting % Dissolved oxygen to mg/L

Does anyone know how to convert % dissolved oxygen to milligrams per liter?
Reply With Quote
  #2  
Old 02-20-2008, 05:01 AM
JohnS JohnS is offline
Moderator
Long Time Member The Golden Calculator Award Over 5000 Posts
 
Join Date: Dec 2007
Location: SE Michigan, USA
Posts: 9,536
Rep Power: 19
JohnS will become famous soon enough
Default Re: Converting % Dissolved oxygen to mg/L

There are tables or formulas that express the maximum (saturated) O2 as a function of temperature, pressure, and salinity in mg/L. Detrmine saturated value, then multiply by the given percentage.

This Wikipedia article is a place to start (skip over the blood section), The formula for water considers salinity and temperature, but not pressure. Follow the link to the USGS site for a pdf document with tables. They include pressure. http://en.wikipedia.org/wiki/Oxygen_saturation

Much like water vapor in air for humidity calculations, it is not a trivial conversion
Reply With Quote
  #3  
Old 02-21-2008, 04:45 AM
JohnS JohnS is offline
Moderator
Long Time Member The Golden Calculator Award Over 5000 Posts
 
Join Date: Dec 2007
Location: SE Michigan, USA
Posts: 9,536
Rep Power: 19
JohnS will become famous soon enough
Default Re: Converting % Dissolved oxygen to mg/L

Here is an "official" (web copy) of the USGS memo on calculating this. http://water.usgs.gov/admin/memo/QW/qw81.11.html
It is the only method accepted for USGS work. It contains typos probably related to conversion to the web. (missing minus signs, superscripts, etc)

This document is a "readme" for an Excel spreadsheet that implements the method. The author mentions the typos above and formula corrections he made (see Table 1) to get results in agreement with USGS tables. http://science.nature.nps.gov/im/uni...tor_Readme.doc

I think between the two, you can duplicate the math.
Reply With Quote
  #4  
Old 11-02-2010, 06:50 AM
Unregistered
Guest
 
Posts: n/a
Default Re: Converting % Dissolved oxygen to mg/L

Perhaps it's just me as I'm not seeing it. Although the links that you've provided are great, but the equation(s) are for calculating DO saturation, using atmospheric pressure, temp, and salinity, and didn't show anything on how to convert DO mg/L to DO saturation.

I know this is an old questions, so hopefully you'll come across it and provide some additional insight.

Thanks :-)
Reply With Quote
  #5  
Old 11-02-2010, 11:04 AM
JohnS JohnS is offline
Moderator
Long Time Member The Golden Calculator Award Over 5000 Posts
 
Join Date: Dec 2007
Location: SE Michigan, USA
Posts: 9,536
Rep Power: 19
JohnS will become famous soon enough
Default Re: Converting % Dissolved oxygen to mg/L

Quote:
Originally Posted by Unregistered View Post
Perhaps it's just me as I'm not seeing it. Although the links that you've provided are great, but the equation(s) are for calculating DO saturation, using atmospheric pressure, temp, and salinity, and didn't show anything on how to convert DO mg/L to DO saturation.

I know this is an old questions, so hopefully you'll come across it and provide some additional insight.

Thanks :-)
You have to calculate the saturated value for the conditions, then

Percent_Saturation = actual_DO/saturated_DO * 100%

or actual_DO = (Percent_Saturation/100) * saturated_DO

Saturation percentage is somewhat like relative humidity; it is a fraction of what the medium is capable of holding. The saturation value must be calculated.
Reply With Quote
  #6  
Old 02-23-2011, 06:05 AM
Unregistered
Guest
 
Posts: n/a
Default Re: Converting % Dissolved oxygen to mg/L

Quote:
Originally Posted by Unregistered View Post
Does anyone know how to convert % dissolved oxygen to milligrams per liter?
0.115686275 mg/L per 1%
Reply With Quote
  #7  
Old 07-10-2012, 08:36 AM
Unregistered
Guest
 
Posts: n/a
Default Re: Converting % Dissolved oxygen to mg/L

P1V1=P2V2

hope this formula helps.
Reply With Quote
  #8  
Old 07-30-2012, 01:42 AM
Unregistered
Guest
 
Posts: n/a
Default Re: Converting % Dissolved oxygen to mg/L

Quote:
Originally Posted by Unregistered View Post
0.115686275 mg/L per 1%
how reliable is this conversion?
Reply With Quote
  #9  
Old 07-30-2012, 06:44 AM
JohnS JohnS is offline
Moderator
Long Time Member The Golden Calculator Award Over 5000 Posts
 
Join Date: Dec 2007
Location: SE Michigan, USA
Posts: 9,536
Rep Power: 19
JohnS will become famous soon enough
Default Re: Converting % Dissolved oxygen to mg/L

Quote:
Originally Posted by Unregistered View Post
how reliable is this conversion?
It is perfect when saturated_DO is exactly 11.5686275 mg/L (about 9 C, 760 mm) and wrong the rest of the time. Saturated DO is a complex function of temperature, pressure and salinity. See the tables referred to in the above links to see how much it varies with these parameters. There is no shortcut.
Reply With Quote
  #10  
Old 08-15-2012, 10:36 AM
Unregistered
Guest
 
Posts: n/a
Default Re: Converting % Dissolved oxygen to mg/L

I need to convert a DO reading in mg/L to a percentage.
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -8. The time now is 10:52 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright 1997-2005, 2007, OnlineConversion.com