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Participant

Join Date: Nov 2016
Posts: 4

Level Sensor Fisher 49B with DLC3010

11/12/2016 5:54 AM

Dear All,

Fisher 249B with DLC 3010 is installed to measure level of liquid / condensate hydrocarbon of SG 0.51 at process pressure of 700 psi and temperature that varies from 80 degree f to 100 Degree f. Problem is the PV drift in night from zero to 30 percent while actual level in glass gauge is zero. What we have done is, PV trimed zero and calibrated sensor (min / max and two point) with water and it performs well with water. checked transducer card and electronic card of dlc 3010 and found o.k. (even we replaced dlc 3010 but no change, we dont have new displacer and driver rod) checked plc input channels and cable and found them o.k. as well. But problem still persists. Any help shall be appreciated please.

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Pathfinder Tags: Fisher Level 49B Displacer
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Guru
United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

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#1

Re: Level sensor fisher 49B with DLC3010

11/12/2016 7:31 AM

Please advise what the equipment manufacturer has said in response to the telephone calls so the forum can eliminate this/these from the options.

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Guru

Join Date: Sep 2016
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#2

Re: Level sensor fisher 49B with DLC3010

11/12/2016 9:32 AM

Are you a mechanical engineer in profession? You should consult one or if you are one, then study Thermodynamics, especially properties of pure substance.

This is a float type assembly transducer. Which do you think is more accurate your sight or the float? A float will submerge to a gas but most unlikely to liquids.

Gas can condensate to lower temperatures at the same pressure during night time. Do you have the property-phase plot for that hydrocarbon? Given at 700 psi and 80deg F or actual lowest temp. during night time. If you are just an instrument guy, ask the mechanical engineer. If you are an engineer, you should cope up, too little knowledge at an oil and gas plant is near catastrophe.

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Participant

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#3
In reply to #2

Re: Level sensor fisher 49B with DLC3010

11/12/2016 9:47 AM

thanks alot for your reply. Its not float it is displacer based level measuring tranmitter. Yes I am waiting for oil and gas experienced instrument engineer to suggest valuable solution.

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Guru

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#4
In reply to #3

Re: Level sensor fisher 49B with DLC3010

11/12/2016 9:54 AM

So the displacer is not a float? I suggest you learn google search. Fisher 249B.

Well, good luck with that!

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Participant

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Posts: 4
#5
In reply to #4

Re: Level sensor fisher 49B with DLC3010

11/12/2016 1:12 PM

Float and displacer do look like same but work on different principles. 249b is diplacer with fixed weight. any how thanks for helping in problem resolution and valuable suggestion. i am not here to argue. I am still waiting for any solution else i will buy new displacer and replace as all other parts are fine including torque tube, driver tube and transducer module.

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Guru

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#7
In reply to #5

Re: Level sensor fisher 49B with DLC3010

11/12/2016 4:57 PM

O I strongly agree you and Lyn should see an instrument engineer. Or study may be. And, good luck of wasting the owner's money, I hope he didn't find out what you're doing.

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Guru

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#6
In reply to #4

Re: Level sensor fisher 49B with DLC3010

11/12/2016 4:08 PM

A float does just that, it floats on top of a liquid following the surface up and down.

A displacer is usually heavier than the fluid so it doesn't float but as the fluid level rises the weight on it's supporting linkage changes due to the amount of fluid the displacer is displacing.

This force would be used in a strain gauge or some form of force balance system.

The Shamsuddin is correct!

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Guru

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#8
In reply to #6

Re: Level sensor fisher 49B with DLC3010

11/12/2016 5:02 PM

A what? See the calibration of this guy obviously, calibration at 0% weight was heavier than 100%. Basic transducer concept is based on bouyant force-> It simply a float transducer.

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Participant

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#9
In reply to #8

Re: Level sensor fisher 49B with DLC3010

11/13/2016 12:55 AM

Thank you for sharing video. Point is that we have already calibrated sensor with water (min/max and two point method) and it reads water levels as per expectations. Problem is what? when we put sensor in service to measure condensate hydrocarbon level of SG 0.51 its reading is drifting in night time. Every thing itself seems o.k.

And owner has full confidence in me and he knows what I am doing, you need not to be worried in this regard.

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Guru
Safety - Hazmat - New Member United States - US - Statue of Liberty - New Member Engineering Fields - Chemical Engineering - Old Hand

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#11
In reply to #9

Re: Level sensor fisher 49B with DLC3010

11/14/2016 1:57 PM

Do you agree that your S.G. fluid of 0.51 gravity when having been calibrated with water, cannot be correct for the lighter fluid, as it will indicate less displacement?

Example: the probe might be displacing 1 Liter volume, thus is displacing 1 Kg water. When the same probe is immersed in 0.51 S.G. hydrocarbon, it still displaces 1 liter, but now only displaces 0.51 Kg. Does that help you?

The probe should be calibrated in the same fluid, or somehow compensated in software.

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Guru
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, and now disconnecting as Little England and Wales (not too sure about Wales bit, either). Kettle's on.
Posts: 26689
Good Answers: 700
#10

Re: Level Sensor Fisher 49B with DLC3010

11/13/2016 12:01 PM

So, what did the equipment manufacturer actually say during the telephone calls? The forum needs to know. Otherwise the thread is a gross waste of everyone's time.

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gutmonarch (4); James Stewart (1); lyn (1); PWSlack (2); Shamsuddin (3)

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