23 Bars Within Rotary Vane Compressor - Static Pressure or Total Pressure

You need to ask the compressor supplier. 23 bar seems a big pressure rise for a rotary vane. Need to check inlet and outlet pressures, and whether these are gauge or absolute.

The difference between total and static pressure likely to be small, relative to 23 bar. If discharge velocity is 100 m/s (std. conds) and temperature say 800°C, I make velocity pressure < 0.01 bar.

Codey

Hmm...I think I wasn't clear enough (for which I apologise).. I am referring to those a rotary vane compressor normally used for aircons. I am confused about the pressure of the air within the cylinder (after the suction air is being compressed). These aren't inlet or outlet pressures.

my apologies.

OK, so what is the 23 bar? Is it differential or discharge pressure (if latter, gauge or abs?) The pressure inside the compressor will be a tad higher than the discharge pressure, as there will be losses in the compressor internals.

Codey

it is the pressure that the fluid has been compressed to.

I know i should have clarified but...erm...yeap any idea what the 23 bar might mean and does the pressure value most manufacturers give refer to total pressure or static?

They vary. Some state total pressure, so if you've based your pressure requirement on static, perhaps at a much lower velocity than the compressor discharge, you need to install a properly designed transition piece (gentle expansion) to recover as much pressure as poss.

E.g. axial-flow fan suppliers quote total, but fan ΔP usually more like 23mm water than 23 bar!

Others quote static in the outlet pipe. I think you need to ask.

Cheers.....Codey