Orifice plates are the most common flow device you will find in any process plant. Although not very high in accuracy but they are rugged, have low maintenance cost and have been applied successfully in process instrumentation to measure flow.
Listed in the table below are recommended practices when it comes to industrial application of Orifice plates:
|
|
Recommended Practice
in the Use of Orifice Plates |
|
1 |
Orifice plates,
with flange taps, square edge and concentric orifice are normally used on pipe sizes from 2” and above. |
|
2 |
Eccentric or Segmental orifice plates
are typically specified on fluids with suspended solids, sediments
and on biphasic streams. |
|
3 |
Quarter Circle
orifice plates are typically
specified for high viscosity fluids with a Reynolds number between 2500 and
10000. |
|
4 |
The full-scale value for measurements is
normally selected equal to the maximum flow
rounded off at 1-5 % above or adjusted to 1.2 times the normal operating flow
if the maximum flow is unknown. |
|
5 |
Standard calibrated
ranges of differential pressure are typically used for the calculation with a preference for
250 mbar. |
|
6 |
The recommended values of Beta ratio
will be selected within 0.2 - 0.75, preferably between 0.4 – 0.75. |
|
7 |
Orifice bore will
be rounded off to the nearest 0.1 mm. |
|
8 |
Bleed and vent holes are usually specified for orifice plates in horizontal pipe
and with a bore diameter of at least 20 mm. |
|
9 |
Orifice plates for
pipe sizes of ½”, ¾”, 1” and 1”1/2 are usually installed between flanges in meter runs
prefabricated. |
|
10 |
Meter sections will be preferably
flanged. Meter runs and relevant orifice bores are usually sized using the Manufacturer proprietary
algorithms. |
