Meter Run Orifice

In small pipe sizes the accuracy of an orifice measurement depends as much on the pipe as on the plate: the bore, roundness and surface finish of the upstream and downstream sections all affect the discharge coefficient. A meter run solves this by supplying the orifice together with honed, calibrated pipe spools as one assembly, so the installation matches the conditions on which the ISO 5167 / ISA RP3.2 calculation is based.

Meter runs cover ¼" to 1½" with 10 diameters of straight pipe upstream and 5 downstream, an orifice plate held in an annular chamber, and two pairs of ½" FNPT pressure taps for the DP transmitter. End connections are raised-face or ring-type-joint flanges or butt-weld ends, in ASME Class 150 to 2500 depending on the flange selection. Materials are carbon steel, alloy steel, or 304/304L and 316/316L stainless steel; the process temperature limit follows the flange and pipe material.

The assembly arrives ready to weld or bolt into the line, with the flow calculation sheet. It is the preferred solution for fuel gas, chemical injection, sampling and utility lines where a standard orifice would be compromised by the short pipe runs available.

Meter runs are used in oil and gas, petrochemical, chemical, power generation and water plants.