ORIFICE PLATE & RESTRICTION ORIFICE:
Orifice plate is a device
used for measuring volumetric flow rate in a pipe. Orifice plate works based on
Bernoulli's principle. Bernoulli's equation states that pressure drop across
the orifice plate is directly proportional to the volumetric flow rate passing
through the orifice plate.
A
restriction orifice also works on the same principle, but serves a different
purpose. The main difference between orifice plate and restriction orifice is
their usage. Restriction orifice is used for killing pressure in a pipe by
increasing fluid velocity. Restriction orifice and orifice plates are similar
in structure and both are based on Bernoulli's equation.
Orifice plate is a thin
plate with an orifice in the middle. It is placed in a pipe where the
volumetric flow measurement needs to be done.
When the
fluid flows through the orifice in the orifice plate, fluid velocity changes
and according to Bernoulli's equation pressure also changes. By measuring the
difference between pressure values immediately before and after the orifice
plate, volumetric flow calculation can be done.
In case
of restriction orifice, the size of the orifice is chosen in order to have
desired pressure drop across the restriction orifice. This effect is known as
choked flow across the orifice.
As the name suggests, function of a restriction orifice is to
restrict the flow and kill pressure downstream of the orifice.
