Orifice Plate-Water 1

[cebain]

Hi all.
I need a white paper showing some calculations for sizing an orifice plate with flange taps. Round bore, through hole (no taper). My application is as follows: 10" ID pipe, 200 inH20 pressure drop. 80 psia line pressure. 300 gpm flow rate. Flange taps (1" up and down stream).

Thanks,
-Chris

 

[m777182]

Look at EN ISO 5167-1....hmm, my version is printed on yellow paper.
M777182

 

[hacksaw]

put some white paper in your printer and print this

Pressure 65.000 psig(79.696 psia )
Temperature 80.0 Deg F
Ambient Pressure 14.696 psia
Liquid Gravity (Gf) 0.998
Viscosity 0.878 cP

normal | maximum
Flow 300.0 | 400.0 Gpm (flowing)
Pipe Reynolds No. (Rd) 107740 | 143653
Mean Fluid Vel. (Pipe) 1.2 | 1.6 ft/Sec
Line Loss 0.02 | 0.04 (psi)/100 ft
Friction Factor (f) 0.0187| 0.0187
Meter Loss(Installed) 3.59 | 6.38 psi


Meter Bore (d) 2.8810 @ 20 Deg C
Pipe i.d. (D) 10.0000 Inches
Beta Ratio (d/D) 0.2881 Inches/Inch
Metal Expansion (Fa) 1.0002 (316 Stainless)
Expansion Factor (Y1) 1.0000
Reynolds Factor (Fc) 0.9960
Drain/Vent Corr. (Fh) 1.0000
Discharge Coef. (Cd) 0.59850
Spinks Factor (S) 0.05005

normal | maximum
Meter Differential (h) 112.5 | 200.0 in w.c.
Flow Rate 300.0 | 400.0 Gpm (flowing)

Q (Gpm) = 5.667*S*D^2*Fa*Fc*Fh*sqrt( h / Gf )

 

[cebain]

Thanks to both of you. I'm going to download a copy of ISO-5167. What is the difference between ISO 5167-1 and ISO 5167-2? Both seem to refer to orifice plates.

 

[btrueblood]

5167-1 has only the background information for various types of orifice flow meters.

5167-2 has specific correlation equations for the discharge coefficient (Cd) of orifice-plate meters.

You'll probably want to get both. Mine are also on white paper, because that's what my printer has loaded in it...

BTW, 5167-3 shows correlations for nozzles and truncated nozzles.

 

[hacksaw]

regardless of the correlations, a water test is usually in order for traceability

good luck,

 

[jsummerfield]

Avoid 200 in-H20 pressure drop with only 80 psia line pressure. A general rule of thumb is 10-inch water per psi.

Review the API Manual of Petroleum Measurement Stnadards Chapter 14, Natural Gas Flow Measurement, Section 3 for Concentric Square Edged Orifice Meters.

Also look at ASME MFC-3M-1989 section 4.2 Method of Sizing the Bore of the Selected Primary Element.

Perhaps you can find an old book called something like Flow Meter Engineering by Spink that provides an easy method for calculatin an orifice plate. The technology has advanced lots since the book was published. However, if you need something easy to use for a PE exam, consider using Spink. It is close enough for multiple choice.




John

 

[dcasto]

The 10" per psi rule is only applicable to compressible fluids, go ahead with the 200"

 

[cebain]

Thanks all. I ran through the calculations in ISO 5167-2. Pretty involved stuff, but I found that if I set the flow rate to design condition of 300 gpm and solved for the Reynolds number (this would give me the design conditions Reynolds number), and then plug the Reynolds number into the equations for C and flow rate, I can then solve through iterating bore size (and hence beta) until the calculated flow rate matches the desired flow rate.

Have I over-simplified or over-complicated this? My numbers are very close to that calculated above, within a 1%.

 

[dcasto]

The reynolds number correction is very small once your in turbulent flow. When I set up custody transfer flow computers I only iterate once for reynolds number.

 

[hacksaw]

to get below the 1% level you need to specific what sort of flow rate units are used, like "flowing" or actual gpms, versus standard gpms, actual temperature, use of weep holes etc.

your reynolds no. correction is at the 0.4% level