Previous in Forum: Bruel & Kjaer Type 7001   Next in Forum: Need Help Identifying a Connector Manufacturer
Close

Comments Format:






Change Mode
Close

Subscribe to Discussion:

CR4 allows you to "subscribe" to a discussion
so that you can be notified of new comments to
the discussion via email.

Close

Rating Vote:







Add Vote
7 comments
Rate Comments: Nested
HiTekRedNek
Guru

Join Date: Oct 2006
Location: 44.56024"N 15.307971E
Posts: 8277
Good Answers: 270

Eductor Sizing

04/09/2013 4:25 PM

I want to design an eductor that will pull a high vaccum(as close to 1 Atmos.as possilble) from a tube that is 2.5 inch diameter and a current flow rate of 1200 CFM.In other words,I want to be able to evacuate a quantity of air greater than the incoming volume of air from the 2.5 inch inlet.How much volume and velocity of incoming air will I need?I realize pulling 1 atmosphere is a high goal, so I will compromise for a reasonable value that is feasible.The fluid will be air in both cases.I have been unable to find a calculator on line that will accept these parameters, so it might not be possible.

Any help will be appreciated.

__________________
 "A man never stands so tall as when he stoops to help a child." "Never argue with a stupid person.They will drag you down to their level and beat you with experience" "To create an apple pie from scratch, first you must create a universe"
Register to Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.
lyn
Guru

Join Date: Oct 2008
Posts: 42355
Good Answers: 1693
#1

Re: Eductor Sizing

04/09/2013 5:04 PM

Look for ejectors, not eductors.

Jet Air Ejectors - Engineered Systems - NASH

Atmospheric Air Ejectors Brochure - Transvac
Register to Reply
Codemaster
Guru

Join Date: Jul 2005
Location: Stoke-on-Trent, UK
Posts: 4496
Good Answers: 137
#6
In reply to #1

Re: Eductor Sizing

04/10/2013 7:43 AM

Good to know Transvac are still going. Used them years ago. Needed to do air/water backwsh on sand filters on sea water for well injection (secondary recovery) on a North Sea oil platform. Seawater available at 5 barg, and to avoid using an air blower wanted an eductor to suck in air at about 3 x the water flow and mix with the water. We thought the Germans are good at this sort of thing, so we approached Haskell and Koerting who both said it couldn't be done. Then we heard about Transvac who said no problem. We installed theirs and it worked a treat, so did the sand filters!

__________________
 Give masochists a fair crack of the whip
Register to Reply Off Topic (Score 5)
Just an Engineer
Guru
Australia - Member - New Member

Join Date: Feb 2008
Location: Australia
Posts: 2181
Good Answers: 255
#2

Re: Eductor Sizing

04/09/2013 5:36 PM

I suspect that the calculators that you have found on line have difficulty because of your desire to get that ultimate goal of 1 Atmos.

The algorithms probably have a denominator that includes a factor of "1-target" and when you enter 1 as your target they get a divide by zero fault.

Use those calculators again, but start at 0.5 and then creep up by halving the difference until you get to your limits of ability to supply the required air flow.

__________________
 Just an Engineer from the land down under.
Register to Reply
tcmtech
Guru

Join Date: Jun 2009
Location: South of Minot North Dakota
Posts: 8376
Good Answers: 775
#3

Re: Eductor Sizing

04/09/2013 6:55 PM

I don't recall the exact specs for high volume high vacuum production butI do recall working in the oil fields a few summers ago running a super vac truck.

I think they could maintain around 20 inches a vacuum through a 2.5" hose but the pumps were something like 100+ HP positive displacement rotary screw types.

Just guessing but to get the next 9ish inches of vacuum you may be needing to double that power level!

If you get that far don't stick your tongue on it unless you want taking a deep breath in from your backside to be the last thing you do!
Register to Reply
IdeaSmith
Guru

Join Date: Mar 2012
Location: Out of your mind! Not in sight!
Posts: 4424
Good Answers: 108
#5
In reply to #3

Re: Eductor Sizing

04/09/2013 11:55 PM

You put a bitter taste to this!

__________________
 Common Sense Dictates
Register to Reply Off Topic (Score 4)
IdeaSmith
Guru

Join Date: Mar 2012
Location: Out of your mind! Not in sight!
Posts: 4424
Good Answers: 108
#4

Re: Eductor Sizing

04/09/2013 11:53 PM

you sure its not exhaust gas or CO?

:-)

__________________
 Common Sense Dictates
Register to Reply Off Topic (Score 5)
ozzb
Guru
Hobbies - Fishing - Old Salt Hobbies - CNC - New Member United States - US - Statue of Liberty - New Member

Join Date: Mar 2007
Location: Rosedale, Maryland USA
Posts: 5197
Good Answers: 266
#7

Re: Eductor Sizing

04/10/2013 1:26 PM

An eductor is just one device that makes use of the Venturi effect. You may find the info need in that.

http://www.ce.utexas.edu/prof/kinnas/319lab/applets/venturi/venturi.html

__________________
 Life is not a journey to the grave with the intention of arriving in a pretty, pristine body but rather to come sliding in sideways, all used up and exclaiming, "Wow, what a ride!"
Register to Reply
Register to Reply
Have a Different Question?
7 comments
Copy to Clipboard

Users who posted comments:

Codemaster (1); IdeaSmith (2); Just an Engineer (1); lyn (1); ozzb (1); tcmtech (1)

Previous in Forum: Bruel & Kjaer Type 7001   Next in Forum: Need Help Identifying a Connector Manufacturer

Advertisement

Got Something to Say?
Ask a Question
Start a Discussion

Search this Forum
General Discussion:
Go

CR4 Sections
Aerospace
BioMech & BioMed
Chemical & Material Science
Civil Engineering
Communications & Electronics
Education and Engineering Careers
Electrical Engineering
General Discussion
Instrumentation
Manufacturing
Mechanical Engineering
New Technologies & Research
Software & Programming
Sustainable Engineering
Transportation

Site Directories
Forum Directory
Blog Directory
User Group Directory
RSS Feeds

CR4 Rules of Conduct
CR4 FAQ
Site Glossary

Who's Online (91 right now)
Show Members
Advertisement