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EMCO Orifice Plate Series ISB/1 for RF Flanges


The EMCO Orifice Plate is used as a primary element in flow measurement of liquid, gas and steam applications according to 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. Our orifice plates have been tested and tried for over 50 years and measure up to the highest industry and compliance standards. 

The Orifice Plate Series ISB/1 is a single bore plate for mounting between raised face flanges.  




Design and calculation standards
ISO 5167-2, ASME MFC-3M, ISA RP 3.2, Shell Flow Meter Engineering Handbook, L. K. Spink, AGA no. 3
2" - 24" according to ANSI b 16.36, 50 mm < D < 1000 mm according to ISO 5167-2 and 50 mm < D < 900 mm according to ASME MFC-3M
Pressure rating
300 - 600 lbs RF
Plate thickness
3 - 16 mm depending on plate size
Bore (d)
d > 12,5 mm
β (d/D)
0,2 < β < 0,75 for highest accuracy.
Vent or drain hole
On request
AISI 316, Duplex, Monel, 6Mo, Titanium, others on request
Mounting style
Between raised face flanges according To ANSI B16.36 or DIN 19214, other standards on request
Orifice plate shapes
Square edge concentric as standard. See above illustrations for alternative shapes.
With name plate in AISI 316 with the following inscription : TAG no., serial no., pressure rating, inner pipe diameter., bore, material.

Technical Data

+/- 0,6 % for β < 0,6 and equal to β for values above 0,6
Pressure loss
Depending on β, for β equal to 0,6 : ca. 60 % of the differential pressure measured
Limits for Reynolds No
Re > 1260 x β^2 D according to ISO 5167 2000 < Re < 10^8 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. 

Installation of orifice plate

Who to contact?

Christoffer Thrane
Sales & Marketing Manager


Learn how we calibrate our flow meters

Calibration of a flow meter