CENTRIC ORIFICE PLATE
Centric orifice plate is a thin plate with circular orifice with its centre placed in the axis of piping. In most cases, the orifice plate is placed in a flanged joint. Except for CSN standards the sealing surfaces in the orifice plates can be manufactured also in compliance with EN, DIN, GOST standards, American ASME and ANSI standards or on specification and requirements of individual customer.
Centric orifice plate can be manufactured also in so-called welded-in design. This design contains straight lengths of piping downstream the orifice plate. Welded-in centric orifice plate has the advantages, such as material savings on flanges and consequently minimized leakage in the flange joint.
Centric orifice plate is also manufactured in design with meter tube, i.e. complete set of centric orifice plate and straight lengths of piping both on the inlet (suction) and outlet (drain).
Centric orifice plates are manufactured according to type of pressure tapping:
- Orifice plates with corner pressure tapping, i.e. chamber or individual
- Orifice plates with D pressure tapping downstream and D/2 upstream the orifice plate
- Orifice plates with flange pressure tapping
Centric orifice plate is manufactured in the nominal sizes ranging from DN 15 up to DN 1,000, and depending on type of pressure differential, for nominal pressures up to PN 320.
Upon agreement with customers, outlets of differential pressures are always customized to various options of primary element’s attachment to the measuring circuit.
For the production of centric orifice plates there are mostly used carbon steel, refractory alloyed steel or stainless steel, depending on the type of pressure tapping and the type of orifice plate attachment. Upon agreement, centric orifice plate can be manufactured also from special materials based on nickel titanium alloys or on tantalum. Orifice plates are made of plastic materials, too.
Centric orifice plate is manufactured either as a working flow-meter or, as specified meter with metrological verification complying with the technical particulars and conditions of pattern approval.
The greatest advantage of centric orifice plate is its construction simplicity and its unambiguous definition by ISO 5167-2 standard, thanks to which, the plate is predetermined for the widest use in all flow measurement areas. Upon agreement, centric orifice plate can be manufactured in the range of DN and PN different than stated above.
ISO 5167-2 standard defines possibility to use centric orifice plate for diameters of pipeline ranging from 50 mm up to 1,000 mm. In relation to ISO/TR 15377 centric orifice plate can be also used for piping diameters 25 – 50 mm, provide it with drainage or vent aperture, or, use it at the end of pipe as the inlet orifice plate for measurement of flow in suction from the open space. Centric orifice plate can be incorporated both in the vertical and horizontal piping.