Question
From Shelly

To Professor Flow

Hi Professor,

I am a student studying process in food manufacturing and I have a question for you. I need to find flow measurement devices that will not contaminate the liquids in the plant. Any bacteria that enters the batch will become a very serious problem for the company.

Answer
Dear Shelly,

Please do a search and try to find manufacturers of SANITARY flowmeters. Also ask for their certificate to prove they really are "sanitary" Alternatively you can go for clamp on ultrasonic flowmeters but this may be too expensive for every application.

Hope this helps

Professor

Question
From David
To Professor Flow

Dear Professor,

I need a good computer simulation program to help me solve a difficult flow problem in a fixed bed catalytic reactor . Have you ever played with any of these programs and can you recommend any that can help me. I don't want to spend money on software and find out it does not help

Answer
David,

I am not a software expert but I just asked one of my guys who works with simulation. He recommended using Fluent software for this. There may be others but I am not aware of them. If someone has experience with others, please email me and I will post a link to the software.

Hope this helps

Professor Flow

Question
To Professor Flow
From Martin (young technican)
I have a problem and have to fix a drifting flow meter, It is a standard liquid-flow transmitter with an orifice and differential pressure transmitter mounted in a pipeline. Over time, a characteristic drifting-flow pattern can be seen. During the night, the flowmeter holds a fairly steady zero-flow rate. In the daytime though the flow starts to increase when I know that nothing is actually happening. We have to regularly change the transmitter and now it is becoming a weekly affair. Please help!

Answer
Martin,
Can you check your field wiring and process taps and connections. Check for leaks. Check your signals from the transmitter to the controller or control system. Check if pressure somehow could be trapped in the impulse lines especially the high pressure tap. You did not tell me the fluid in the pipe. Please investigate what happens to it at different temperatures. You need to start an intelligent investigation as to why this is happening and eliminate possible causes one by one.

Professor Flow

Question
Professor,

Could you please explain briefly what is meant by pressure and temperature compensation

Jack

Answer
This one is quite an interesting topic. Since you asked to keep it brief, I'll certainly try.

The purpose of pressure and temperature compensation is to correct the fluid at flowing conditions to a standard or contractual base temperature and pressure.

The Professor

Question
Dear Mr. Professor
I am interesting with LPG metering. Curently, we use PD or turbine meter for the LPG liquid line and no metering for the vapour return. Since the LPG price is increasing, they are asking to have more accurate LPG metering. This for rack loading application of 30 tonne/hr (3" line) as well as higher capacity pipeline LPG metering of 300 tonne/hr (10" line) I believe coriolis offer better accuracy and having higher capacity for LPG liquid as claimed by most of the coriolis vendor. But how about for the LPG vapor measurement? All the technical paper on the vendor website do not mention LPG vapor metering with coriolis. Please advise If not good or not suitable to measure the vapor, please advise the best one at least for the higher capacity LPG metering. Some people told me that not practical to measure the LPG vapor for rack loading application due to the vapor amount relatively very small. Is it true? If not, how to offset? Thanks a lot for your answers

Regards
Wanto

Answer
My recommendation is to use Coriolis Meters in this instance. These meters are very accurate and have a history of being stable, unless you operate them outside of the expected ranges. In your application, I would recommend the following:

For the 30 tonne/hr I would recommend a 3 inch Coriolis meter.

For the 300 tonne/hr application, I would install 2 four (4) inch Coriolis meters in parallel. The reason for selecting 2 meters in parallel is that you may want to run at only half capacity and if you had a larger meter, your accuracy would be compromised. You could control the meters with DOWNSTREAM flow control valves or run-switching valves. API MPMS Chapter 5.6 Measurement of Liquid Hydrocarbons by Coriolis Meters is the applicable standard for the liquid systems.

The flash gas you can measure with a Coriolis meter as well. The new API MPMS Chapter 14.9 (AGA Report # 11) can be used as a guideline for sizing and application of the gas phase.

I hope this has helped.

The Professor

Question
Dear Professor,
I am looking for a gas flowmeter. I see that here are lots of types e.g thermal, magnetic,turbine, ultrasonic and coriolis etc. I am looking for a tiny flow meter because I only want to measure a very little amount of gas approximately 0.001-0.004 ml/min, of gas passing through a membrane. Right now we are using a stopwatch and a capillary tube. Can you recommend me something more reliable than this?
from
Dr. Henry Chan

Answer
Henry

I would contact suppliers of gas chromatographs and see what they have to offer. If you want to "regulate" the flow, you can buy a special needle valve with a very low CV range and know (with some confidence) what the flow rate is by the number of turns on the valve. The analyser people should know these things.
Hope this helps

The Professor

Question
Dear Sir

I was asked to develop a new cold potable water meter; but, I have only very little knowledge on the design principles of volumetric (positive displacement) and velocity (turbine) water meter.

Appreciate your recommendation for reference books that could help me for the assigned task.

Thank you.

Answer
Dear LH.

I would recommend you buy Flow Measurement second Edition . We have some links to it from here

http://www.flowmeterdirectory.com/flowmeter_books.html

Also buy others like Flow Measurement Engineering Handbook by Richard W. Miller Published by McGraw-Hill

All of these guys explain it in a different way. If you only read one author, you may end up with a biased opinion of a particular technology. I would also recommend you go to trade shows and look for small new companies that are doing things differently and try to find our what is giving them hope. Some of these big old companies are still using dinasour technology but this does not change quickly because they already have a captive audience and plenty of money to push their products onto innocent clients. Expect to see major changes and new books written over the next three years.

The Professor

Question
Dear professor flow

I need to buy a flowmeter, but i don't know what kind the flowmeter i have to buy. for your information, i am a technical support for medical equiptment like anesthesia machine, ventilator, etc. i have to calibrate and do maintenace for the hospital , almost all of equiptment use max. 15 L/min gas flow.

what kind of the flowmeter i have suppose to buy ? if you don't mind, please provide me information about the flowmeter you suggest to me and where i can find it in indonesia.

thanks & best regards

Rondi

Answer
Dear Rondi

I would contact companies who make low cost flowmeters for low pressure air/gas. You may have to send them meters back to them for calibration or just buy new and calibrated ones.There are alot of variable area or rotameters used in hospitals. Contact them and ask them.Follow this link and ask one of the companies on the page.. If they don't have what you want, they should be able to point to out to someone who does.

The Professor

Question
Dear Professor Flow,

We have installed 3 electromagnetic meters on our 10 inch diesel lines at 40 deg celcius . The flange rating for the meters is 300 ANSI. We don't understand why the flow readings are going all over the place. Can you please recommend us what we could be doing wrong?

Answer
Dear Simon,

Electromagnetic flowmeters are not designed for use with diesel. You will have to completely change out the meters for a completely different technology depending on your accuracy requirements and process conditions.

The Professor

Question
Dear Professor Flow,

I am working in an offshore production company. We have some wells collectively producing large amounts of liquid crude, water , natural gas and sand in different quantities depending on several factors. I would like to know what type of technology is available for the measurement of all four and what type of typical accuracies we would be looking at and lastly what is the cheapest way it can be done properly?

Thanks and regards

Thomas

Answer
Dear Thomas,

There are many ways to go about this. A popular way is to use a mini separator and split the liquid and gas and analyse the water/oil or oil/water ratios and sand. You can contact companies like Agar who specialise in this. There is also a company from Norway called Roxar Flow Measurement that can do all four simulataneously using a method which involves a Venturi, Gamma Ray Densitometer,Capacitance probe , inductance probe and and ultrasonic sand measurement device. This company claims to be able to measure all the void fractions directly and report flow rates immediately for all phases. I guess in both cases you will be looking at accuracies between 2 and 10 percent depending on the conditions. If you want to do it properly it won't be cheap .

The Professor