Nylon to Alum pitot line

[RVG8tor]

I am using the SafeAir pitot/aoa line kit on my plane. I want to run a section of aluminum line under a console to keep things from interfering, this entails some fitting to join the nylon and aluminum line. I can use either 3/16" or 1/4" aluminum tubing. The 1/4" has a inside diameter closer to what the nylon tubing is but the 3/16" line would take up less room, which is at a premium under the left console.

My limited memory of physics tells me since these lines are measuring pressure that a section of smaller diameter tubing should not effect the pressure of the line. Do I have this correct, a change is line size should not effect the measurement of line pressure?

The Dynon AOA system uses two lines and I believe it measures the difference between the pitot pressure and the pressure of a secondary hole in the pitot tube that is at a slight angle to the main pitot hole.

Thanks

[Veetail88]

Mike,

If you were moving any volume of air through the tubing, then the diameter would indeed have a large effect as you would incur friction loss of pressure.

Since you are measuring a static pressure, you should not see any affect.

Now if you were to use a really small diameter tube or put in a really small oriface or restriction, you would then see a delay in the pressure equalizing from one end of the tubing run to the other as you are indeed moving a very small volume of air.