McMenon FPD320 flow nozzles

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The McMenon FPD320 flow nozzle is used for high velocity flow measurement where erosion or cavitation would wear or damage an orifice plate. It does not rely on a sharp edge (that can degrade over time) for accuracy, therefore offering excellent long-term accuracy and it is often used for flow testing on steam-raising plant. The discharge coefficient of a flow nozzle is such that a nozzle can measure approximately 55% higher flow rates than an orifice plate with a similar beta ratio and design differential pressure. In the case of steam measurement, the pressure loss may not be significant as the effect is to beneficially heat the steam slightly.

Long radius nozzle: the inlet profile is a quarter-ellipse with a cylindrical throat. The ellipse can have one of two aspect ratios (low or high), depending on the beta ratio. Tappings are typically 1 pipe diameter (D) upstream and 1/2 D downstream of the inlet, but the downstream tapping position on some low ratio versions can differ.

Throat tap nozzle: the inlet profile is a quarter-ellipse with a cylindrical throat. The upstream tapping is in the pipework, 1 D from the inlet; the downstream tapping is within the cylindrical throat and the connection to it is on the circumference of the nozzle ring. The design usually conforms to ASME PTC-6, with the nozzle mounted within a run of pipework, the upstream section of which includes a flow straightening element. McMenon flow nozzles are available in designs for clamping between flanges (within the bolt circle), as weld-in units or mounted within pipe runs.

The features and benefits include: established technology; available in sizes from DN50 to DN600 (2 to 24”); designed to maintain long-term performance; no moving parts — virtually maintenance-free; performance of device can be calculated from measurement of key dimensions alone and available in a wide range of materials to suit the process fluid and the working conditions.