Hi Pierre, As I said, I am not a hydraulic engineer. However, you stated that there are many different types of "head". Can you add these types of head up (either as scalars or as vectors)? If so, they must all be in the same units - pascals. If not, then there has been some messy overloading of names.
Regards Martin -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Pierre Abbat Sent: 25 September 2008 04:22 To: U.S. Metric Association Subject: [USMA:41752] Re: hydraulics in metric On Wednesday 24 September 2008 14:54:06 Martin Vlietstra wrote: > Pierre, > > From my limited knowledge of hydraulics, but with a degree in physics, I > would suggest that the head should ideally be measured in pascals - after > all what you are measuring is a pressure. In the case of a static head, > you would use the equation > P = density x height x gravity. Head isn't pressure. It's energy divided by a quantity of fluid. If the fluid were measured by volume, head would indeed have units of pressure, but there are other kinds of head, such as velocity head (kinetic energy divided by amount of fluid). Pierre
