Jump to content







Photo - - - - -

Comparison Of Turbine With Positive Displacement Meters For Custody Transfer




Comparison Of Turbine With Positive Displacement Meters For Custody Transfer Positive displacement (PDM) and turbine (TMs) are the two types of flowmeters acceptable as primary measurement instruments for custody transfer of liquid petroleum products.

TMs use a bladed rotor contained in a flow tube that is axially suspended in the direction of flow. As fluid passes through the tube, the rotor spins at a rate proportional to the fluid velocity. Blade rotation is generally detected by a sensor whose output is used to infer a volumetric flowrate.

A PDM divides the flowstream into discrete volumetric segments. A known volume of fluid is mechanically isolated in the meter and passed from inlet to outlet by the alternate filling and emptying of compartments. This process is usually translated into a rotary motion that operates a counter. Most PDMs are direct reading and do not require an external power source. Each segment of fluid volume passing through the meter is counted to yield a measure of total volume. Terms used to describe the type of PDM include rotating disk, oscillating piston, sliding vane, bi–rotor and oval gear designs.

Attached Image

TMs infer a volumetric flowrate from a velocity measurement whereas PDMs do not measure flowrate but measure totalized volume directly.

Relative comparison of TMs and PDMs based on several parameters are described in the attached table.

Enjoy reading and looking forward to have comments from members of "Cheresources".

Regards,
Ankur.





Ankur,

I like your selection of topic very much. Really it is very good information.

What is your opinion about the corrolis flow meter? As we had used this type for gas line transfering to GAIL header.

Regards,
Jatin
Jatin,

PD & Turbine meters are not used for gas measurement. Coriolis meters or ultrasonic meters are the choice for gas measurement. My blog entry makes it clear that PD & Turbine meter are meant for liquid product custody transfer measurement.

Regards,
Ankur

Dear Ankur,

 

For LPG loading(LPG flow rate 70 m3/hour), could you pls. advise whether we should use Turbine meter or PD meter.

 

Regards,

Pradeep

Dear Ankur,

 

For LPG loading(LPG flow rate 70 m3/hour), could you pls. advise whether we should use Turbine meter or PD meter.

 

Regards,

Pradeep

Pradeep,

 

LPG viscosities are low. I would without hesitation use a turbine meter for LPG application.

 

Regards,

Ankur.

Dear Ankur,<br />Excellent topic. Thank you indeed.<br />May we conclude that if rangeability and product viscosity are within TM’s range then for same accuracy we can go for TM over PDM to optimize cost?<br />Regards<br />Zatish<br />

Zatish,

 

Yes, that is correct. Low viscosity products are ideally suited for TMs. However, for PDMs, low viscosities can cause slippage and give more measurement error.

 

Regards,

Ankur.

Dear Ankur,

Hello andGood Day. I often visit here and get updated. I am looking for some guidelies. Infact I am planning to deliver a lecture to my office colleagues on           " Chemical Engineering for Non Chemical Engineers". Our company is into Engineering and Projects implementation of Large scale chemical/ petrochemical / steal and fertilizers. Can I have some guideline on the content of such course. The audience will be Project and other discipline engineers who are dealing with EPC companies in reviewing their packages, and engineering documents and also involved into operations of the plants.

Please advise and I also seek support from other members on this issue.

Regards,

Imran

imranahmed_67@yahoo.com

Dear ankur,

my company is preparing a standard  for the governement on the maximum allowable uncertainties for metering systems of differents hydrocarbon products oil, gas(fuel and flared) , LPG and condensates. So would you please tell me about some companies standards in this matter if any? THANK YOU IN ADVANCE

benabed,

 

Have a look at the following link:

 

http://www.npd.no/Gl...forskriften.pdf

 

Regards,

Ankur.

Latest Visitors

  • Photo
    panoskagiou
    Today, 02:59 PM
  • Photo
    tausif
    Today, 09:03 AM
  • Photo
    mike10
    Today, 03:52 AM
  • Photo
    Mach21
    Today, 03:26 AM
  • Photo
    magnoguzman
    Yesterday, 09:17 PM
  • Photo
    mosa
    Yesterday, 08:59 AM
  • Photo
    Philipo Nzaghi
    Yesterday, 08:39 AM
  • Photo
    breizh
    Yesterday, 05:52 AM
  • Photo
    Marsh Whesly
    Yesterday, 05:47 AM