7 replies to this topic

[chemtan]

Hello all,

I have an application where flow measurement downstream of a gasoline pump has to be done. Due to space constrains, I'm a bit confused on which type of flow measurement device should I use... Some data of my system is below:

Pumps:
Configuration: 2 X 100% ( 1 op. 1 standby)
Location of flow meter: Each one on individual pump discharge line
Pump flow rate: 8020 USGPM
Normal Discharge Pressure: 250PSIG
Max. Disch. Pressure: 300PSIG
Discharge Line: 20 inch

Meter:
Accuracy required: +/- 1%
Type: To be decided based on straight run requirement due to space constrain.
Available piping space: Total of 4.7m

My exact query is:

1. How much straight run reduction is possible when using straightening vanes with orifice meter in this system.
2. If I use flow nozzle with straightening vanes, how much straight runs will i require upstream and downstream of this system.
3. Any other meter that can fit into mine this system and meet accuracy requirements.

Edited by chemtan, 21 November 2010 - 10:11 PM.

[breizh]

Hi Chemtan,

Why not considering a geared OVAL meter :

http://www.icenta.co...ear-Flow-Meters

Hope this helps

Breizh

[sheiko]

Chemtan,
The upstream side of a meter is usually more critical than the downstream side. It's hard to give a definitive answer as the min. straight runs depends on the type of meter and the type of turbulence device (elbow, valve, pump, tee, ...) relative to the meter. Some guidelines recommend a min. of at least 3 to 10 pipe diameters upstream and at least a min. of 2 pipe diameters downstream.
Other guidelines?

Edited by sheiko, 24 November 2010 - 03:23 PM.

[Zauberberg]

See attached guidelines, and see if you can fit in between the recommended figures given for orifices and venturi nozzles/tubes.

Accuracy will also depend on the required turndown, and each flow element has its own preferred range.

Attached Files

•  Installation Guidelines.pdf   347.93KB   75 downloads

[sheiko]

Excellent Zauber!

[Novice Instrum]

Hi

If you are looking for standard, ISO 5167 Table3 gives upstream/downstream straight run requirement for orifice plates.

Regards

[chemtan]

See attached guidelines, and see if you can fit in between the recommended figures given for orifices and venturi nozzles/tubes.

Accuracy will also depend on the required turndown, and each flow element has its own preferred range.

Zauber,

Thanks for sharing the file. i could not find any direction about the values in paranthesis in this table, can you please explain?

further more, I'm looking for reduction in these straight length requirements if straightening vanes are used, how much reduction in these straight length requirements is possible.

[Zauberberg]

I wouldn't rely on the flow straighteners, particularly in your application since you need 1% accuracy of the flow element. In any case, I would discuss the subject with vendors and see what we can come up with.

As for the parentheses, it means how much you can reduce the straight line length and get away with additional 0.5% measurement uncertainty (as per my understanding). In other words, if there is e.g. a fully open globe valve upstream of the orifice with Beta ratio = 0.35, you can reduce the straight line length from 18 to 9 diameters, and get additional 0.5 measurement error.

The ISO 5167 table (referring to the previous post) is attached below, and you can see essentially the same philosophy being applied.

Attached Files

•  ISO Table.pdf   145.28KB   49 downloads