×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

air-water ratio dtermination

air-water ratio dtermination

air-water ratio dtermination

(OP)
I have an atmospheric water sump tank with a pump.  I need to pump the water out to a river through several miles of pipe.  I need to add an air/water separator in the line before it reaches the river, so that all the entrained air can come off before water enters the river.  The pipeline goes up several hills and then goes down hill into the river.
How do I determine how much air to water ratio I have to size the separator?

By the way, the line will be pigged at the start up to get all the air out.  The customer does not want air bubbles coming out on continous basis when the system is running. That is why we need an air/water separtor before water gets to the river.

RE: air-water ratio dtermination

After the Pigging Operation is completed, the line will be filled with either the process fluid, water, inert gas etc.
The piping configuration on the Launcher Skid if properly valved will prevent any entry of air.
I do not see how air re-enters the system unless your pump is cavitating - in which case those bubbles are the least of your problem.

RE: air-water ratio dtermination

(OP)
Thanks.   

RE: air-water ratio dtermination

trini,

Water almost always has entrained air that is released in pipelines, hence air valves are used to release it at high points along a pipeline.

cavitation does not produce long lasting air bubbles.  When the water reaches discharge pressure, those bubbles have collapsed due to the higher pressure.

ratash,

You might not need a separator.  Have you considered air release valves?

I have not failed. I've just found 10,000 ways that won't work."-Edison  "If Edison had a needle to find in a haystack, he would proceed at once to examine straw after straw until he found the object of his search.  I was a sorry witness of such doings, knowing that a little theory and calculation would have saved 90% of his work.- Tesla

RE: air-water ratio dtermination

(OP)
You are brilliant, because that makes sense.  To me once the start up is over, there should be no air in the system. I am curious how the air gets in. Regards-

RE: air-water ratio dtermination

BigInch,
Thanks - I learnt something

RE: air-water ratio dtermination

(OP)
BigInch,

Who is the manufacturer of these valves, and what kind of valve is it?  Our route has several high points. Thanks-

RE: air-water ratio dtermination

(OP)
BigInch,

Please disregard my last question, I found the information on those valves.  

If you were to figure out how air can be entrained, how would you arrive at that number?  My pressur eis about 100 psig.

RE: air-water ratio dtermination

(OP)
BigInch,

Please disregard my last question too.  Your mention of air release valves helped a lot.  Regards- RATASH

RE: air-water ratio dtermination

Look for the maximum soluability of air in water at given pressures and temperatures.  If the pressure or temperature of the water changes from what is at the pipeline inlet, it will take in more air, if possible, or reject the air that it has, according to whatever the maximum amount is that it can hold at the pressure and temperature of the pipeline at any point.  However, bubbles released at all points may tend to collect at the high points nearby. Which high point depends on the velocity and pipeline slope and if they can float upstream against the current or must move downstream with the pipeline velocity.

http://www.engineeringtoolbox.com/air-solubility-water-d_639.html

Ya. This website is a good place to learn stuff.

"I'm all in favor of keeping dangerous weapons out of the hands of fools. Let's start with typewriters."
- Frank Lloyd Wright (1868-1959)

RE: air-water ratio dtermination

(OP)
Thanks.  You are the best!

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources