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metla.ani
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Join Date: Feb 2009
Posts: 5

Displacer vs. DP LT

06/15/2011 5:51 AM

Displacer and DP LT are both dependent on specific gravity of the fluid in a drum / vessel. Please let me know the selection criteria or when I shall go for Displacer rather than DP measurement?

Thank you all in advance.
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Pathfinder Tags: Displacer DP level transmitter
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PWSlack
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#1

Re: Displacer vs. DP LT

06/15/2011 5:55 AM

A displacer can only operate relative to atmospheric pressure above the liquid level. So if the vessel is sealed and pressurised, a displacer cannot be selected, whereas a differential pressure instrument can be.

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Ace Boeringa
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United States - Member - New Member Engineering Fields - Control Engineering - New Member

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#2
In reply to #1

Re: Displacer vs. DP LT

06/15/2011 11:45 AM

Sorry PW, this is not correct. Displacers are successfully deployed into many pressurised applications. Boiler steam drums are one example and the reason they are preferred to DP cells for this purpose is that the dry leg of a DP level transmitter can gradually fill with condensation which will show a false low level.
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penttijp
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Join Date: Feb 2011
Location: brisbane, australia
Posts: 25
#3
In reply to #2

Re: Displacer vs. DP LT

06/16/2011 3:39 AM

Stream drum level by dP always has 'a wet leg' reference.

penttijp
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Instruments-guy-SAV
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Location: Venezuela
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#4
In reply to #1

Re: Displacer vs. DP LT

06/16/2011 7:56 AM

Friends,

I´m agree totally with Ace Boeringa, In our plants there are a lot of displacer working in pressurized vessels.

Regards

JP

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penttijp
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Join Date: Feb 2011
Location: brisbane, australia
Posts: 25
#5

Re: Displacer vs. DP LT

06/16/2011 8:25 AM

This depends greatly on the type of vessel, turbulence, ease of making outside connections among many other things. Much like what type of car to buy. If you give your application(s), I can help.

penttijp
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erolf
Active Contributor

Join Date: Jun 2010
Posts: 16
#6

Re: Displacer vs. DP LT

06/30/2011 11:26 PM

reference leg of DPT for STM DRUM is always wet. Condensate pot is provided.
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penttijp
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Location: brisbane, australia
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#7
In reply to #6

Re: Displacer vs. DP LT

07/01/2011 6:40 AM

Yes, I said the same before. Sadly some of the people replying do not know much about these systems.

penttijp
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Users who posted comments:

Ace Boeringa (1); erolf (1); Instruments-guy-SAV (1); penttijp (3); PWSlack (1)

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