Upstream Pressure of Orifice

https://en.wikipedia.org/wiki/Orifice_plate

The pressure is higher upstream, varies with the pressure, varies with the diameter of the aperture, varies with the viscosity of the material in the fluid state, and to some degree with the temperature. Not suitable for non newtonian materials(except in special cases), nor thixotropes below critical shear.

Apertures are calibrated to a fluid by measurement over a range and used with a measuring method, such as a manometer or pressure gauge.

From the above, derive the equation of volume flow....

I thought this was already covered in chapter 4 of your textbook.

Student daze...

dharam veer darama episode 9 April 2008 Mp3 Mp4 3GP ...

I don't know, but I bet your textbook does. Why don't you just look it up, Mildred?

Maybe it is a trick question, with the answer "none", since flow depends on differential pressure rather than upstream pressure alone.

Oh dear, I can think of some really funny answers to this.

Thanks for answer Suppose an orifice is designed at 8 bar upstream pressure but now upstream pressure is 4 bar , so what is effect on flow.

https://en.wikipedia.org/wiki/Orifice_plate

It seams to me that you do not understand the difference between differential and absolute pressure. Also since 1 bar is so close to nominal atmospheric pressure, one should not dismiss the effect of atmospheric pressure. You've have been given links to orifice flow metering already. This implies to me a reading comprehension deficiency.

Good Luck in your future schooling efforts, either formal or self taught.

It will be less, but the given information is insufficient to tell how much less.

The basic principle of the relationship of DP to flow rate is explained in this thread:

http://cr4.globalspec.com/thread/72991/Flow-Transmitter-Range

The numbers are different, (flow is approximately doubled, not DP), but the concept is there, along with a link to a tutorial.