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Associate

Join Date: Sep 2009
Posts: 34

Any DP Flow Transmitter model for Bi-Directional Flow

10/24/2009 11:00 AM

Gents,

Is there any specific new DP Flow Transmitter model for Bi-Directional Flow ??? especially from Rosemount ?? or any other ???

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Guru
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#1

Re: Any DP Flow Transmitter model for Bi-Directional Flow

10/24/2009 11:28 AM

Emerson Process deal with the distribution of Rosemount instruments. Contact them directly, perhaps?

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#2
In reply to #1

Re: Any DP Flow Transmitter model for Bi-Directional Flow

10/24/2009 11:37 AM

ur correct, but i wanted some experience input as well, regarding the real experienced someone had with the model (that is if such model does exist)

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

Join Date: Jan 2007
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#3
In reply to #2

Re: Any DP Flow Transmitter model for Bi-Directional Flow

10/24/2009 12:31 PM

In principle, if a differential pressure instrument (why anyone uses these blessed things for flow these days when so many more attractive options are available, mumble, grumble....) can be ranged into the negative differential pressure region, then yes. Set the milliamp range to go from minus a pressure to plus a pressure, and set an intermediate reading (12mA is mid-range between 4mA and 20mA, for example) on the receiving instrument to read zero. The receiving instrument may never read exactly zero when there is no flow, though, which is a feature that may need to be overcome by other means. The other thing that needs to be overcome is what to do when the reading drops below 4mA under fault conditions, for example, which may cause the receiving instrument to read an abnormally high reverse flow unless other precautions are taken.

Sales Engineers from instrument distribution companies are in the best position to advise. It really is a matter of contacting them directly.

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#4

Re: Any DP Flow Transmitter model for Bi-Directional Flow

10/24/2009 10:53 PM

What are you using as a primary element. You are reading differential pressure across something. The two most-used elements I've seen used are orifice plates and venturi tubes. You cannot run a venturi backwards and orifice plates typically have a bevel on the downstream side. It will not read accurately if the flow runs in reverse.

Be careful if you are using this technology on a fluid that can be better served by an alternate method if your only goal is to reduce costs by using DP.

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#5

Re: Any DP Flow Transmitter model for Bi-Directional Flow

10/26/2009 10:21 PM

Dear Rathore,

If you are using DP generating flow elements, which are strictly unidirectional then bidirectional transmitter will not produce correct measurement.

If it is a Liquid application suitable for Magflows, then Magflowmeter can be configured for bidirectional flow.

Regards,

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Participant

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#6

Re: Any DP Flow Transmitter model for Bi-Directional Flow

10/26/2009 10:47 PM

You can use an orifice plate, the plate does not have the downstream bevel as one of the experts commented on. IF you are measuring gas, you could use a Rosemount 3095 and it should be able to give you the full range in either direction. I have a customer using two Cameron DP Cone meter close coupled together with Multivariable flow transmitters then we use a Cameron 1131 flow computer to calculate the flow and keep track of the Natural gas going in and out of the Storage wells.

Associate

Join Date: Sep 2009
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#7
In reply to #6

Re: Any DP Flow Transmitter model for Bi-Directional Flow

10/26/2009 11:04 PM

The service in my case is STEAM, hmmm .... the downstream bevel should not be there .... any reference to specific vendor models for these types of orifices ??

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#8
In reply to #7

Re: Any DP Flow Transmitter model for Bi-Directional Flow

10/26/2009 11:27 PM

Depending you where you are located any company that makes orifice plates can make the bidirectional orifice. I am sure Emerson's Daniel division is one vendor to look at.

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andrew_ward (1), preynold (2), PWSlack (2), srzambre (1), Usman Nazar Rathore (2)

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