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EMCO Orifice Plate Series MEF/2 with Single Pressure Tapping for Insertion between RTJ Flanges


The EMCO Orifice Plate is used as a primary element in flow measurement of liquid, gas and steam applications based on the differential pressure principle. According to this working principle, the orifice plate creates a flow restriction in the pipeline to allow measurement of the resulting pressure drop and flow rate. 

The Orifice Plate Series MEF/2 is constructed with a single pressure tapping for insertion between ring type joint (RTJ) flanges. 




Design and calculation standards
ISO 5167-2 2003, ASME MFC-3M, ANSI B 16.5, Shell Flow Meter Engineering Handbook
DN 50 - 600, 2" - 24"
Pressure rating
600 - 2500 lbs RTJ
Plate thickness
3 - 8 mm
β (d/D)
0,3 < β < 0,75
Vent or drain hole
On request
AISI 316, AISI 304 22Cr Duplex, 16Mo3, 13CrMo4-5, other materials on request.
Mounting style
Between flanges with RTJ according to ANSI B 16.5 or to API
Pressure taps
Threaded: ½" NPT int. (standard) or ½” BSP. Flanged: ½” and ¾”, 600, 1500 and 2500 lbs RTJ.
Tap Location
At least 15° apart, depending on size and pressure rating
Orifice plate shapes
Square edge concentric as standard. See above illustrations for other shapes.
The orifice plate is marked with "+" and"-" and flow direction.

Technical Data

+/- 0,5 % for β < 0,6 and equal to β for β values above 0,6ove 0,6
Pressure loss
Depending on β, for β equal to 0,6 : ca. 60 % of the differential pressure measuredntial pressure measured
Limits for Reynolds No
Re(D) > 5000 for 0,1< β 16000 x β 2 for β > 0,56 according to ISO 5167-2 2003 2000 < Re < 108 according to ASME MFC-3M 108 according to ASME MFC-3M


Before installation, the orifice plate must be kept clean and protected against corrosion and physical damage. It is also important that you pay careful attention to to the sharp edge of the plate. Once ensured that it is clean, install the orifice plate carefully such that the orifice bore aligns with the centre of the pipeline. Tap location varies depending on whether it is used for liquid, gas or steam. It is not supplied with any safety devices and must not be used for higher pressure, than stated on the name plate. The pipe system must therefore be equipped with a safety device. However, this type of primary element requires no special maintenance.

Download the installation guide above for more detailed information. 

Who to contact?

Christoffer Thrane
Sales & Marketing Manager


Learn about the important difference between orifice plates and restriction plates