Specifications | 8695 Orifice Plate
North American's 8695 Orifice Plates are used to measure fluid flow in a pipe for electronic flow control and ratio control applications. Orifice plates are most commonly used for flow applications because of their low cost, ease of installation, reliability and extensive documentation available. SPECIFICATIONS Each 8695 orifice plate is specially sized and custom made for each application. There are many standard fluids that an 8695 orifice plate can be used with including natural gas, propane, dry air, oxygen, coke oven gas, nitrogen and butane. For other special fluids please contact North American. Standard orifice plate material is 304 SST (Oxygen service plates are constructed from monel). Plate thickness will typically be 1⁄8 " or ¼" with a bevel to accommodate the required bore thickness. Plates will not be beveled when the material thickness is within the required bore thickness specification for a square edge. Normal plate thickness for pipe sizes up to 14" will be 1⁄8 " and ¼" for pipe sizes 16" and larger. Certain applications with high differential pressures may require a thicker than normal plate to prevent plate deflection. If the plate material thickness exceeds the calculated maximum allowable plate thickness, the bore will be beveled. Plates that are not beveled are considered bidirectional. The beta ratio, β , is defined as the ratio of the orifice bore diameter to the pipe ID. For predictable performance all 8695 plates will have a " β " range of 0.1 to 0.75. For 2" through 30" sizes, orifice plates are sized and manufac- tured per “ISO 5167-1 2003 Measurement of Fluid Flow” and “ISO 5167-2 Orifice Plates” standards. For ¼" through 1½" sizes, orifice plates are sized and manufactured per the standard “ASME MFC- 14M-1995 Measurement of Fluid Flow Using Small Bore Orifice Meters”. The standards used are applicable to orifice plates used with flange pressure tappings, corner pressure tappings, or with D and D/2 pressure tappings (Note: D and D/2 pressure tappings [upstream tap = one pipe diameter from upstream face, down- stream tap = ½ diameter from upstream face] are not applicable to small bore orifices i.e. 1½" pipe size and smaller). Orifice plates with vena contracta pressure tappings are not considered or used in these standards.
PLATE IDENTIFICATION The 8695 orifice plate will have the following information stamped on the handle: order number, configuration number, nominal pipe size, plate bore diameter and “Upstream Face”.
Beveled orifice plates need to be installed with the upstream face in the correct orientation relative to the direction of flow. The sharp edge of the bore is the upstream face. The beveled edge is the downstream face.
Bulletin 8695 Page 2
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