Orifice Plate Permanent Pipe Losses

[jnb14495]

I am designing an orifice plate to reduce the pressure in a system. I know how to use orifice plates to measure flow via differential pressure, but I do not know how to calculate the losses in head pressure in a system due to this constriction. Anybody know of some resources?

Here are my givens.

Fluid- Water
Pressure- High side 2800 psi
Pipe diameter- 3.438 in
Desired pressure downstream- 950 psi
Find Orifice diameter

Thanks for your help

jnb

 

[davefitz]

Well, the system in question has a 1900 psid press drop- a bit more than an agricultural dist. system, wouldn't you admit?

Reinventing the wheel is OK- we've all seen it before.

One can use a series of orifices, but you still need to confirm the pressure at the vena contracta of tehlast orifice is higher than saturation pressure for teh case of the highest flow and highest fluid inlet temperature in order to avoid cavitation.

The problem outlined is a common problem with power plants- either boiler feed pump recirc or older supercritical boiler startup systems - the cadilac fix that preserves plant avaiability is to use capilary tubes or an anticav valve. In the case of a $1billion USD power plant , one can pay the extra money to ensure availability. If its an agircultural ditch worth $50 K, maybe not.