ABB TotalFlows

cyoung120

Member
Join Date
Jul 2013
Location
OH
Posts
92
Hi Guys,

I was just wondering if there is an advantage of using a ABB TotalFlow G4 board to totalize a 4-20 signal instead of just reading the totalizer right from the flow meter via Modbus.
 
I have no idea what a TotalFlow G4 board is, but reading directly from the flowmeter digitally is certainly more accurate and is always my preferred method.
 
Is this a liquid or gas meter run? Is it custody transfer or allocation? What is the meter type?
 
I think you will be better served by using Modbus or pulse input. Totalizing using a analog signal is not the most accurate way to handle flow measurement.
 
I think you will be better served by using Modbus or pulse input. Totalizing using a analog signal is not the most accurate way to handle flow measurement.

I agree completely. But what if it was a custody transfer application? Would that make a difference? I see these all over the area used by oil and gas. When I ask the question "Why not just use the one from the transmitter" I get the response that the Total Flow has some magical algorithm that just makes it right. I guess I am just wondering if the total is that awesome or if this is just a case of "this is the way we have done it for the last 20 years why change now"
 
I agree completely. But what if it was a custody transfer application? Would that make a difference? I see these all over the area used by oil and gas. When I ask the question "Why not just use the one from the transmitter" I get the response that the Total Flow has some magical algorithm that just makes it right. I guess I am just wondering if the total is that awesome or if this is just a case of "this is the way we have done it for the last 20 years why change now"




are you sure they are using 4-20? I have been doing oil and gas for 20 years and have never seen a 4-20 signal being totalized on a totalflow. I am not even sure that it has that capability.
 
are you sure they are using 4-20? I have been doing oil and gas for 20 years and have never seen a 4-20 signal being totalized on a totalflow. I am not even sure that it has that capability.


Yes I am positive. I just hooked one up this week. I landed the flowmeters analog signal to J23 Terminal 1 and 2. This was on a XRC_G4_Board.
 
Like diat150 I have been in the Oil Measurement Business for a long time (30 years) and haven't seen a flow computer give the option of totalizing off of a 4-20mA signal. I am not as familiar with the Total Flow units as I am with other Flow Computers so they may do things differently.

But what if it was a custody transfer application? Would that make a difference?
To answer your question: In a true Liquid Petroleum Custody Transfer application you will need to use a volume pulse input to the Flow Computer. The reason is that the meter will need to be Calibrated or Proved as it is called in the industry. To do this you will need to use what we call a Prover. This device is highly accurate and has a known volume. The electronics in the Prover will accept the volume pulses and compare them to the known volume of the Prover. It is pretty much all a software function now. In the old days we had to do it manually. A Meter Factor is then generated to be put into the Flow Computer. The Flow Computer will use this factor to correct the volume so that it shows the true volume based on the Proving. Since Volume Pulses were used to calibrate the meter it must be used to totalize the total volume. That way things are Apples to Apples.

I get the response that the Total Flow has some magical algorithm that just makes it right.
Of course the meter is only one part of a Custody Transfer system. You will also need to run the Temperature, Pressure, and Density into the Flow Computer where it will take these measurements and create a true Net Volume. So yes while not magical, the Total Flow, like all Flow Computers, have algorithm's that make all the calculations in order to present the totals in a way that conforms with the API recommendations or Contract requirements.

There are a lot of things I skipped over here to keep things basic but I will say this: I have been designing, building, automating and repairing Petroleum Measurement equipment for a long time and just about every day I learn something new. The field is very vast and complicated, it is full of "this is how we have always done it" and sometimes when I think that there is no way that something is going to work it ends up working and I come away with a new learning experience.

Good luck in your journey.
 
Yes I am positive. I just hooked one up this week. I landed the flowmeters analog signal to J23 Terminal 1 and 2. This was on a XRC_G4_Board.


I have never seen anyone use it, but I know the XRC has isagraf and some other programming language. Maybe they used that. I have never seen an option to totalize a 4-20 in the configuration menu when setting up a liquid run, but I have also never looked too hard either.


I would either bring it in as a pulse if they dont want to monitor the device on it own or communicate to the device directly.
 

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