Interface Level Measurement

Hey... Can anyone tell me the difference between the Capacitance type and displacer type

> It is methanol and water.

Another way to do this is to install a tube density meter (Emerson, it is 1 meter long) vertical in a side pipe such that the interface will be somewhere within the height of the density meter.
If the density meter is full of water then the density reported is that of water, if it is full of methanol then the density reported is that of methanol.

If the tube is part filled with methanol and water, the density will be proportionate to the relative amounts of ethanol and water.
This will be true whether the methanol and water are fully mixed or if they are one above the other in the tube.

The density reported is then proportional to the height of the interface whether it is a clean interface or diffuse.

This is an approach adopted for a similar separation in a pharmaceutical plant - they cooled the tank to help separate the methanol and water, and use the signal to regulate the outflow from the bottom of the tank so as to maintain a constant interface level even though this was a continuous separation process.

Dear JMW
Salaam

Seems that very few people read replies to their posts in this forum.
As I have stated before controlling interface level between liquids with different densities DOES NOT need any electronic or even mechanical instrument.No moving parts, no electronics and the interface level(clean or diffuse) will stay where you want it.
Show me you are interested and I can elaborate, or, Drop me a line at [email protected] for details.

According to me, interface level measurement is for the tank containing two different media, having two different densities. eg. drum level with steam and water, crude/bitumen etc...

G.Vivegan
Coimbatore,TN
INDIA.

first you can do simple equation that will give you the required calibration the equation is as follows say for instance oil which is 0.8 and water is 1. and other liquid is as you say 1.5
and you are using water as calibration the maths is simple
1.5 DIVIDED BY 0.8 DIVIDED BY 1.00 X WHATEVER RANGE YOU REQUIRE I.E IF IT WAS 50% IT WOULD BE 0.8 DIVIDED BY 1.5 DIVIDED BY 1.00 X 50 =0.26.
this would be 50% of your level if calibrating with water so for 100% output if calibrating waith water the level it the torque tube should be 0.52% or 50% of the measurement between tapping points i hope this helps you.

regards tom holland

> What is the best procedure of commissioning the LT chamber?

please try to allow and open lower tapping of LT and check the observe the LT reading and reading shall be 100%and after that open the LT top tapping v/v and observe the LT reading shall be 0%and after that commissioned it the settling time around 3 minutes.

Will GWR work in a continuously density changing environment where there is no clear interface?

Define "work"! If you mean, will it read something, sure. If you mean, will it accurately detect an interface level even though there is a very large rag layer, no.

The fact is that if there is not a defined interface, there is no way to detect an accurate interface level. Sounds simple, right?

What a lot of measurements are trying to do is to create an inferred measurement from the best signal they can get from their level device. For example, a vortexing fluid doesn't really HAVE a level, but we need to measure a custom engineering unit called "what the level would be if the mixer was turned off and there was one."

There are three ways I can think of to attempt to get a reasonable (and I am defining reasonable loosely here) measurement in your situation. One is to use a gamma level gauge configured as a densitometer to give you continuous density compensation for your GWR probe. That's tricky and expensive.

The other is to talk to J. M. Canty Co (www.jmcanty.com) about their camera-based interface detection and control systems. These are also tricky and expensive.

You could use a dual GWR system. One GWR transmitter would measure top level and the other would be calibrated to track the highest interface point it can see. This is tricky, less expensive, and likely not to work very well.

This is a very difficult measurement because, like the example of a vortexing level, you want to measure an engineering unit called "what the interface would be if the darn density wasn't changing all the time." That is a difficult measurement.

Walt

Walt Boyes, FInstMC, Chartered Measurement and Control Technologist
Life Fellow, International Society of Automation
Editor in Chief, Control and ControlGlobal.com
[email protected]

Dear Soovo Sen
Salaam.

As I have mentioned in my previous posts, effective interface level control based on density does not (repeat NOT) need any electronic instruments. Your case,the way you have stated, is a special one, having "no interface!!" Still,let me have the specifics of your system and what you want to do,off the list if this would be a long post, and I will send you my 40 years old simple solution that is still working perfectly.

Abdollah Sadjadian [email protected]

> Hey... Can anyone tell me the difference between the Capacitance type
> and displacer type

Capacitance meter has fixed area electrodes and the capacitance varies according to the dielectric constant of your process fluid so varying level or interface will vary the capacitance measured in proportion to your level. The displacer works on the principle of Archimedes where the displacers apparent weight changes according to the process fluid level or interface level.

Good morning.

I just joined very recently this forum, so I had not read about this issue before.

I am looking for a good level transmitter for a sump tank in a Wellhead platform (interface level). The sump tank contains crude, water and others. Need transmitters for level indication and Process shutdown.

I am thinking of selecting a GWR transmitter. Is that the best one. If so which manufacturer will you suggest.

Will you be able to advise.

rammohan

I need to measure the interface level of glycol and gasoline. The vessel is under 300 psi. I would be interested in your idea.

Thank you

Hello Rammohan,

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14)ISO Series Analog signal comparison isolated transmitter

Please keep me posted for more details.

Regards,
Nancy
Shenzhen Sunyuan Technology Co.,Ltd.
www.sunyuansz.com
[email protected]

Hi Sam,

I have some questions with regards to using a DP transmitter for Interface level control. I read through some of the feeds and it seems you are the right guy to ask. Would you mind contacting me on my email address ([email protected]) so that I can ask you a few things?

I would really appreciate it.

Thanks,
Brett

> If you can tell us what the interface is, and some information about each fluid, we might be able to help you.

Interface level measurement:

water conductiv ity: 71 micro siemens/cm
15 to 20% wt by wt.
Density: 995 kg/m3
viscosity: 1 cP.
Di electric constant:
Op. pressure atmospheric
Op. temp. 34

Furferal conductiv ity: 41 micro siemens/cm
80 to 85% wt by wt.
Density: 1045 kg/m3
viscosity: 0.79 cP.
Di electric constant:
Op. pressure atmospheric
Op. temp. 34

Tank height 1200 mm.

> Interface level measurement is the hardest level measurement application I know of. Help us out and tell us more.

Dear Gangesh

Salaam

Please read my previous posts on interface level control in this forum and drop me a line at [email protected]. I need some more details of your system and then I will give you an interface level control system, guaranteed for the life of your plant.

Abdollah Sadjadian
email: [email protected]