Orifice Plate Sizing, 1

[instcalg]

I'm sizing this orifice plate for Emulsion service and I noticed that when I incorporate the density at standrad condition, the bore size will be different. I was told that to accurately size an orifice plate, I need to feed both density at operating and at standard conditions into my sizing program. I searched for orifice plate sizing calculations and all I see in the calculations is the density at operating conditions. Does anybody know how density at standard conditions affect the orifice plate's bore size?

Thanks,

 

[zdas04]

Standard conditions are imaginary. The flow never sees standard conditions. To convert volume flow rate at actual conditions to volume flow rate at standard conditions you multiply actual flow rate times the ratio of actual density over standard density. That is where standard density comes into the picture. Often equations will use the components of density in the ratio and cancel the terms that are the same (specific gravity or MW, R(air) or R(universal)) so you see it as Pressure(actual) / Pressure (std), Temp(std)/Temp(actual), Z(std)/Z(actual), but it is still density.

All of the RTU's that I work with will calculate both densities, and many will display both.

If you are doing a sizing calculation that requires density to be input, I would expect the input density to be actual since standard is imaginary.

David

 

[hacksaw]

the correction for density at standard conditions is rather straight forward, it does not change you bore size, only the scale factor for the display converted to some standard measure