BS EN 61518 is an International Standard that is applicable to differential pressure (type) measuring instruments (instrument) with a shut-off device (manifold) directly bolted onto them. BS EN 61518 specifies mating dimensions and tolerances, threads, bolts, and gaskets for a maximum allowable working pressure of 41,3 MPa (413 bar) at 38 °C.
BS EN 61518 does not apply to assemblies that provide additional sealing elements (adapters) between the instrument and the manifold. Where the possibility exists, shut-off devices shall be mounted on either side of the instrument, and all connections shall then meet BS EN 61518. Elements, such as flanged coupling joints, may apply BS EN 61518 or parts thereof to increase standardization at the discretion of the supplier and the end-user. BS EN 61518 is only valid for instrument and manifold flanges manufactured from a metallic material with yield strength equal to, or larger than, 190 N/mm2.
BS EN 61518 on mating dimensions between differential pressure is useful for:
In a process, many shut-off devices (manifolds) are flanged direct onto the differential pressure (type) measuring instrument (instrument). Very often, however, the shut-off device and the measuring device are supplied by different manufacturers. It is, therefore, essential to have the mating dimensions properly defined. In the process industry, leakages must be avoided.
Using BS EN 61518 provides manufacturers with the knowledge on how to prevent leakages caused by flammable or toxic gases, such leakages can lead to risks to the plant, its installations, the environment, and last, but not least, to the personal safety of human beings. In view of accidents reported from various locations, where the accident was caused by leakage between the instrument and the manifold, BS EN 61518 guidelines help to standardize the mating dimensions, with their tolerances, for this combination.
EN 61518:2001
IEC 61518:2001