Hi,

can we use Pressure transmitter as flow transmitter?
how it could be possible?

how many types of orifice plates?

I am newbie with instrumentation, please give me link to study well.

Regards,
Linda

 

The basic relation for pressure and flow is derived from Bernoulli's Equation - a statement of conservation of energy. In a reduced (simplified) format, Bernoulli's eqn relating flow and pressure is,<pre>
Q = k * sqrt ( 2 * (P2 - P1) / rho)</pre>
Where,

Q = volumetric flow

k (in this simple case), is a combined variable representing discharge coefficient and area of the flow element, or other more complicating dynamics such as compressibility factor.

P2,P1 = upstream and downstream pressures

rho = fluid density

One thing to note is the there is a sqrt() relation between flow and pressure. Google search a Pressure drop vs. Flow curve, and you'll see that flow is difficult to measure when the available pressure drop (P2-P1) is small. This leads to topics of "rangeability" or "turndown," and an instrument's accuracy.

Here's a link obtained from google to a short intro to flow measurement (including physical principles other than pressure):
https://www.idc-online.com/technica...ntation/Industrial_Instrumentation - Flow.pdf

Good Luck