Meter Tubes

For precise measurement it is essential to ensure stabilised fluid flow entering primary element and to meet other conditions of geometrical and mechanical accuracy given by ISO 5167 standard. Therefore it might be practical to produce tube including orifice plate as a set meeting all requirements for quality and accuracy of meter. Metrology verification is an integral part of delivery. In 1993 MATTECH company launched meter tube with centric orifice plate designed for business measurement of superheated or saturated steam, fluids or gaseous mixtures to the market.

Further demands are made on assembly organisations and users of meter tubes who are obliged to ensure especially essential direct lengths in front and behind the orifice plate in compliance with requirements of ISO 5167 standard.
We inform our customers about further requirements connected to assembly and operation of MATTECH meter tubes in exhibitions, trainings and seminars (see Services).

Meter tube is a meter with valid pattern approval with measurement error ranging from 0.55 to 0.75% according to type of the measured medium. Working position of the flow meter can be either horizontal or vertical.

It can be used with approved type of devices for differential pressure reading, pressure reading, for thermometers and evaluation units. With one pressure differential converter you can cover 15-100% of the measurement range, with two ones 2.5 –100% of the measurement range. Besides centric orifice plate the meter tubes can be fitted with ISA 1932 nozzles or classical Venturi tube.

Meter tubes with specified meters launching the market minimised discrepancies during assembly of orifice plates and their operation. Supply range of the meter producer is stated in particular pattern approval. Meter tubes are divided into individual sections so that quality and roughness of loading lengths in front of the orifice plate were met. This division at the same time enables easier control of meter tube during assembly and subsequent meter verification. Meter tube is divided into three construction sections – inlet, where flow of the medium is straightened, measuring part (orifice plate) and outlet. For the production of tubes we use 11 grade steel. Meter tubes can however be made also of 15 a 17th grade steel as well as of plastic. Since March 2003 we have been delivering it with distance bolts made of stainless steel built-in flanges clamping plate without increase of price. These distance bolts greatly simplify dismantling and following assembly of plate. The plate is made of 17 grade stainless steel. Plate is cautiously centred by simple construction placing between flange tapings.
 

Diagram of meter tube - Finish for DN 50 – DN 150

 

Section B of the meter tube in length of 2 D (D is inside diameter of the piping) in front of the orifice plate is separated from section A (see picture) and section C by a flange connection. Length of section A+B is 10D, length of C section is 5D. DN 50-DN150 is supplied with centric orifice plate with chamber taping in the flange.

Diagram of meter tube - Finish for DN200-DN1000

Section B of the meter tube in length 2D placed in front of the orifice plate is connected to section C with its length 2D by a flange connection between which centric orifice plate is placed (see picture). Section A is due to the weight reduction of the meter tube not supplied by our company and it makes a fixed part of usual piping. It can be supplied separately on request. For DN 200 – DN1000 we upply centric orifice plate with chamber taping in the flange.

Dimension table of meter tubes