http://en.wikipedia.org/wiki/Ideal_gas_law

The gas law

PV = nRT

assumes one simple,thing - It is a closed system ie there is no transaction of matter or energy across the system boundaries and it is under steady state.

In your case it is both - there is a mass (the flow of air dows have mass) and the energy (at elast the Kinetic energy) and the matter is not at steady state either.

In case of you it is not the referred equations but the fluidflow equations apply.

Think exactly what is happening in either case.

The starting point for all this is the virial equation which goes something like

PVm/RT = 1 + B/Vm + C/Vm^2 + D/Vm^3 + ...

where vm is the molar volume and B,C,D ... are constants to be derived form experiment. NOTE that the ideal gas equation of state, vander wall, redlich-kwong or any other you may come up with are derived from this form.. This equation is derived directly from statistical mechanics and as you can see, it is a polynomial form and you can include as many coefficients are you please for the order of accuracy that you wish to calculate..

It is important to mention that in general, there are two types of pressure and you seem to be confused. there is static pressure, that is caused by the random motion of the the particles due to thermal energy and there is dynamic pressure where the fluid particles have a motion that is not statically random but induced by a pressure difference..

THE EQUATION OF STATE DOES NOT DEAL WITH DYNAMIC PRESSURE BUT WITH STATIC PRESSURE..

Hi,

A normal pressure gage on say a steam pipe or whatever measures only static pressure, right? By normal I mean one that is located in the wall of the pipe. Is it possible that the static pressure could drop but the dynamic pressure increases therefore the total pressure remains the same - say when a valve is opened or whatever. My reason for asking is that I saw recently a pressure gage on a steam line that dropped in pressure at one take off point but at a different take off point upstream (on the same distribution system) the pressure gage remained unaffected. (Both pressure gages are calibrated and in working condition.)

Fundamentals

PV=nrt (gas law)

This is sufficient to clear your doubts.

"Air is stored in a receiver of 1 m³ volume at 6 bar pressure means the volume of air 1 m³ and pressure exerting on th walls of receiver is 6 bar. If the same 1 m³ amount of air is introduced in the 3 m³ Capacity of receiver then the pressure impacting on the walls of receiver will be less."

In your experiment, continous flow, you filled the 3 m³ receiver/system to the pressure of the 1 m³ receiver, 6 bar. You increased the amount of the air.

The increase in volume refers to the receiver/container, not the amount of gas.

The volume of the receiver or system is inversely proportional to the pressure, as the amount of gas remains constant.

You increased the amount of air to get to 6 bar pressure (1 m³ container at 6 bar to 3 m³ at 6 bar).

If you set the system at the pressure of the closed receiver example (1 m³ at 6 bar to 3 m³ at less than 6 bar) your amount of gas stays the same, volume of receiver increases, and pressure drops.

So Boyle's Law still holds true.

Your answer may lie in the Hagen-Poiseuille equations which is a precise solution to the Navier-Stokes equations in Fluid dynamics.

The basic solution assumes incompressible fluid and laminar flow but has an approximation to compressible fluids, if I remember correctly.

One thing I remember is that solving it for a specific application is a big pain.