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Anonymous Poster

using flow transmitter

08/13/2008 8:17 AM

We are using anubar as a primary element in flow measurements in my plant...

Maximum Flow : 170000 NM3/Hr.

Media Temp.: 260 Deg.

Design DP : 676 mmWc

Media Temperature:

Media: Hot n clean air

Secondary Instrumentation: DP Transmitter

Problem:

Not getting proper flow.

Analysis:

Maximum Flow at Maximum (676pa) DP: 170000 NM3/Hr

Transmitter scale: 0 - 1000Pa

PLC scale: 0 - 1000pa

We are unable to justify the doubts by operation departments. Will u any one can please send your openion.

Thanks & Regards,

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Guru
Philippines - Member - New Member Engineering Fields - Instrumentation Engineering - New Member Engineering Fields - Control Engineering - Who am I?

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#1

Re: using flow transmitter

08/14/2008 8:41 AM

Your info has a discrepancy.

Maximum Flow : 170000 NM3/Hr.

Media Temp.: 260 Deg.

Design DP : 676 mmWc

------------------------

Maximum Flow at Maximum (676pa) DP: 170000 NM3/Hr

mmWC (millimeters water column) is not equal to Pa (Pascals). Also remember that mmWC is referenced to 4°C, not 260°C.

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Active Contributor

Join Date: Aug 2008
Posts: 11
#5
In reply to #1

Re: using flow transmitter

08/27/2008 12:02 PM

Pls check if any leakage is there in the drain valve.

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Anonymous Poster
#2

Re: using flow transmitter

08/14/2008 11:37 AM

flowrate = square root (DP) *6538

SO: 676^.5 * 6538= 170000

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Guru
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#3
In reply to #2

Re: using flow transmitter

08/14/2008 11:09 PM

What unit are you using? mmWC or Pa?

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Power-User

Join Date: Mar 2008
Location: Mumbai
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#4

Re: using flow transmitter

08/16/2008 1:41 AM

Dear Guest

Ref to attcahed file , Kindly Check Your DP range Since the mentioned formula as such is very basic and is not used for annubar sizing, you can convert Your flow into standard condition and size for Dp Based on the selected model "K" and the flowing Pressure and Temp ,( or Select K =0.6),and then recalibrate Xr

Also verify upstream conditions are met, manufactuer will be able to provide the up/down stream requiremnets.

For more Info Visit Dietrich Emerson

Regards

Jose

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Guru
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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.
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#6

Re: using flow transmitter

01/05/2025 5:19 AM

Discuss with the equipment vendor directly. Telephone?

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Guru
Philippines - Member - New Member Engineering Fields - Instrumentation Engineering - New Member Engineering Fields - Control Engineering - Who am I?

Join Date: Oct 2006
Location: Northern Mindanao, Philippines
Posts: 2127
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#7
In reply to #6

Re: using flow transmitter

01/13/2025 11:50 PM

This question is 17 years old and he never answered my question about the units.

He mentioned his instrument is set for 676 mmWC (or 676 mmH2O). Then, he mentions that his maximum flow is set at 676 Pa. Then, his transmitter and his PLC are both scaled for 0 - 1000 Pa.
According to my conversion app, 676 mmH2O is 6629 Pa. So, no wonder his instrument is not giving correct outputs.

I hope he's solved his problems (even after 17 years) (",)

regards,

Vulcan

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