Custody FlowMeter

[sgms]

Does anyone can help me how to create rquisition for custody flowmeter (mass flow)?

 

[JLSeagull]

Start with the contract requirements. Usually the requirements for custody transfer meter a.k.a. the cash register are stated in a contract for that custody transfer. Perhaps API, ASME, ISO or other standards apply. This affect the technologies available.

What is the fluid and properties such as density, the line size and range of flow rates (perhaps multiple meters), pressure, temperatue, etc. Perhaps Coriolis is a good mass flow meter. However one may not be able to measure the required rate.

 

[dcasto]

API MPMS sections are the most commonly contractual standards that apply, you can purchase here:

http://engineers.ihs.com/collections/api/596.jsp

For Europe and other places ISO sets the standards see here to purchase those.

http://www.iso.ch/iso/en/CatalogueListPage.CatalogueList?COMMID=1218&scopelist=

The GPA has some standrds that cover some operational and other standards that are jointly with ASTM. Go here for those

http://www.gasprocessors.com/

The Coriolis is a good mass meter as is the orifice meter or turbine. Operational and calibration proceedures and NOT the design and type become the driving force for most meter installations. What infastructure exists or will be require to calibrate, inspect or prove the meter to meet the standards?

 

[khan101]

Depending on the line size and measured fluid,

1) <6" Coriolis

2) >6" Turbine + Density

3) >6" Mag + Density

4) Orifice + Density

You can also use a multipass ultrasonic.

If the line size is really big e.g. >12" and your customer approves, you can use SonarTrac by CiDRA which is relatively new and non-invasive.

Thanks,

 

[sgms]

Thanks for reply,

Recently we met the supplier that able to supply 10" coriolis mass flowmeter. The pipe run is not suitable for DP or turbine meter installation, also the flow have to be measure by mass (ton/hr). The fluid is methanol 99.95% grade.
Approval and certification required for this meter.

 

[quark]

Liquids don't have significant density change with respect to temperature (unless process decides the extremes). You can use averaging pitot tubes (aka annubars). If the liquid temperature is constant, getting the reading in tons/hr is as easy as X x Y = Z. With variable temperatures, the density table can be fed into the processor and you can get the mass flowrate accordingly.

A 10" coriolis meter is a wonder to weak guys like me.

 

[dcasto]

A DP is used in custody transfer all the time. The equation for flow is easily handled. With very pure methanol, an equation of stste will generate the density at flowing conditions extremly accurate. The same goes for a turbine meter.

The difference between the coriolis, DP (orifice), and turbine meter is in calibration. Just how do you do it?

With all three you can install or use a prover; ballistic or ball type. You'll also have to calibrate the temperature and pressure transmitters feeding the EOS. HOWEVER witha DP, you only need an DP test set to prove it.

 

[sgms]

we have bad experience with volumetric measurement, then we decide to have mass flowmeter, also the piping for meter run is not suitable for DP or other type, even with utilizing the straightener.
what the testing shall be done and what certificate that required for this purpouse?

 

[dcasto]

A DP meter is a mass meter. the mass flow generates the DP. But if you have physical lenght constraints for an orifice meter or turbine meter, the Coriolis meter is your best option.

Normally, the meter will ship from the factory with whatever certificates you may want including ISO 9000 documentation on its quality control. It will have certificates that it has been calibrated with water.

After installation you will need to calibrate or prove the meter at least monthly. While the meter is in operation, you must divert the flow through the custody meter and into a volumetric prover device and document the meter has read read the same volume that the volumetric prover has read (there will be an prover factor of something close to 1.0 generated to make the custody meter match the prover system). You will next have to sample the fluid and measure its density compared to desity prover (picnomiter?. Again a factor will be applied to make the custody meter match the proving device. The density and volumetric provers are certified annually back to an international standards board. In the API MPMS Chapter 14.1 and GPA 2174 this proceedure is documented.

 

[Ashereng]

sgms,

When my client prove meters, they usually contract that out to various outfits that will come to your site and certify your meters. They are licensed by the appropriate governing bodies (in my case, Measurement Canada). I am not sure of the frequency, but that is also dictated by either Measurement Canada and/or the existing contract with the buyer).

"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

 

[sgms]

Thanks everyone

 

[quark]

A DP meter is a mass meter. the mass flow generates the DP.

That requires explanation. Only thermal and coriolis types are true mass flow meters. DP meters will not give mass readings unless the actual readings are multiplied by actual density.

 

[randi]

For accurate custody transfer measurements refer to "Invensys" - they are the experts in this area

 

[dcasto]

For metering expertise, go to the sourse, not a vendor. Go to RW miller.

It takes mass to get force. It takes velocity times area to get volume.

 

[Ashereng]

There are many vendor that sell custody meters. It is up to you to determine what you need for your application.

"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?