Dear All,
I wish I had come into this debate sooner. However, I have read most of the replies and have to dissagree to a number of points raised:
1. The main reason Henry Pitot put a 90 degree bend was to help mount the Pitot Head in the direction of flow when the support leg was perpendicular to the duct or pipe wall.
2. Depending on the accracy of k factor required will determine the actual length of Pitot Static pressure tube in front of any blockage to the media velocity being measured.
3. A hole in the back of a Pitot Static pressure tube will and a negative element to the Pitot Static pressure and CAN be calculated out once calibrated.
4. The Total Pressure (Dynamic + Static pressure) is Not known as Pitot Pressure. Pitot Pressure IS the Dynamic pressure, aslo known as Velocity Pressure or Pitot Differential Pressure.
I hope this helps.
Regards, TalkyTaz (Air Measurement Specialist)
PS! If you require a more difinitive method of using the Ellipsoidal Nose Pitot, Please refer to BS1042 : Section 2.1 : 1983.