Hi AOC,
1. The Differential pressure across the orifice is the pressure drop across the orifice that you require. This is the deciding parameter to size the orifice.
2.Even though there is a differential pressure, there is some amount of pressure energy that is lost in the entrance, exit of the orifice as heat, sound energy. This is what is called the pressure loss. It can be found in Crane Fluid Flow Technical Paper TP-410.
3. The Static Pressure at a point is nothing but the pressure measured at that point using devices like the pitot tube.
There are two components to pressure.
-- One is by the bulk fluid at rest, called the static pressure.
-- The other is by virtue of the force exerted by the same fluid if it is in motion, called dynamic pressure
The sum of the these pressures is called the Stagnation pressure.
4. So, the static pressure in your case would be the pressures measured at the tappings of the orifice in question.
Regards,
Shantanu
Edited by shantanuk100, 27 April 2016 - 12:19 AM.