I'm trying to determine the force or pressure applied to a surface based on mass air flow. I have a 4" pipe, that could also be 3" or 3.5", but for this example we'll stick with 4" OD. .065 wall thickness This pipe has air traveling through it at various speeds, pressures and temperatures. The information I have is only mass air flow. Min Flow: = .06 lbs/min or .79 SCFM Max Flow: =200 lbs/min or 2625 SCFM Pressure ranges from 25 in Hg (vacuum) to 35psi. Temp ranges from -20F to 250F. What I'm trying to determine is the range of force or pressure that would be exerted on some type of force/pressure sensor that I install inside this tube. I need to know this range before I can choose an appropriate sensor. I believe that the figures quoted above for mass air flow can be converted to velocities. Then those velocities, along with the area of the tube can be used to calculate the range of force exerted on a sensor. I don't yet have the dimensions of the sensor because I haven't selected one yet. I know this will have some bearing on the equation because you will probably need to know the surface area of the sensor that the air will be hitting. I am looking at one type of sensor right now that is actually a cable, 3.5mm in diameter. If I choose this form, I will probably lay several of these cables across the cross-section of the tube in a grid fashion, then take a measurement from the sensor that has the highest reading. I have to do this because there may be bends in this tube before or after the sensor, so the majority of the air flow may not necessarily be in the center. Let me know if you need more info. This area isn't my strong point, sorry, I'm just a redneck that knows how to do some metal fabrication, so put it in as much of laymans terms as possible. I believe that a formula is whats needed, so just give an example of the values/variables used. All help and input will be greatly apprecaited.