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engineerlicht
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Join Date: Oct 2007
Location: Olympia Fields, IL
Posts: 2

Metering Dirty Air Flow in an Air Pollution System

10/02/2007 11:14 AM

I need suggestions as to be best way to accurately meter "dirty" air flow at temps 150 - 300 F. System has a 48 inch diameter main duct. 10ga steel. sytem pressure 10-15 inches WC Chuck
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PWSlack
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United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

Join Date: Jan 2007
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#1

Re: Metering Dirty Air Flow in an Air Pollution System

10/02/2007 11:45 AM
  1. Pitot-tube-and-manometer; do a traverse across the duct?
  2. Ultrasonic flowmeter looking at the velocity echoes coming from the moving dirt particles?
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engineerlicht
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Join Date: Oct 2007
Location: Olympia Fields, IL
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#2
In reply to #1

Re: Metering Dirty Air Flow in an Air Pollution System

10/02/2007 5:09 PM

Thanks for the prompt response.

Pitot tubes tend to get dirty and thus give false readings. Where can I find a source for the ultrasonic flowmeter?
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Howetwo
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Join Date: Jun 2005
Posts: 394
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#3
In reply to #2

Re: Metering Dirty Air Flow in an Air Pollution System

10/03/2007 9:08 AM

A thought. What if you bleed control air to the pitot tube -- using an adjustable restrictor -- actually you might need two, for Tp and Sp. Enough so that the orifices on the tubes were kept clear. Calibrate the resultant signal against a standard pitot tube for the range of velocities you are interested in.

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Ried
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Join Date: Dec 2005
Posts: 1602
Good Answers: 19
#4
In reply to #3

Re: Metering Dirty Air Flow in an Air Pollution System

10/03/2007 9:31 AM

A second thought, install solenoid valves and periodically sequence them to isolate the P transmitters and blow out the pitot statics with compressed air. The shut off the "blow off" air and reopen to the P transmitters. Depending on dirt in system, one or two 15 second blasts should keep the system clean.

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PWSlack
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United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

Join Date: Jan 2007
Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on.
Posts: 32175
Good Answers: 839
#5
In reply to #2

Re: Metering Dirty Air Flow in an Air Pollution System

10/04/2007 5:46 AM

http://www.google.co.uk/search?hl=en&sa=X&oi=spell&resnum=0&ct=result&cd=1&q=Ultrasonic+flow+meter&spell=1

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