Thanks for the replies
kiwi chick - eeesh, nice reading! Still trying to find the pictures they are referring too - I could maybe make sense of it then.
Andy - That wasn't entirely what I meant though. I was more concerned with the physics of what happens inside the pitot tube. Does the 90 degree bend help the measurement of flow by scaling down the rate of flow, or does it have a negligible affect on the flow parameters?
barit1 - *nodnod* But, what do you mean by water trap?