New Coal-Bed Methane Gas Flow Meter Offers High Accuracy in Dirty Gas Measurement

Engineers with small line size processes looking for a precision flow meter will find the versatile Wafer-Cone® Flow Meter from McCrometer offers superior accuracy and is now approved by the Bureau of Land Management for use in coal-bed methane gas applications. In order to obtain the coal-bed methane gas approval, the BLM relied on the recent certification that McCrometer’s Wafer-Cone Flow Meter conforms to the American Petroleum Institute’s API 22.2 Testing Protocol for differential pressure flow meters. The field-proven Wafer-Cone is an easy to install space-saving flow meter that requires almost no maintenance. Wafer-Cone’s low maintenance combined with its long life results in lower total installation and life-cycle costs than many other flow meters. The Wafer-Cone Flow Meter is designed for liquid or gas service in line sizes from 0.5 to 6 inches, which makes it ideal for either small process lines or many plant infrastructure tasks. Applications for the Wafer-Cone range from chemical injection or filtering in process lines to general plant needs, such as lines for natural gas, chilled water supporting burners or ovens, cooling systems, HVAC and more. McCrometer’s advanced Wafer-Cone Flow Meter relies on differential pressure sensing technology and sets the standard when it comes to performance, ease of use and economy. Its unique DP flow sensor is actually designed with built-in flow conditioning to achieve an accuracy of +0.5%, with a repeatability of +0.1%. It operates over a flow range of 10:1. With the ability to self-condition flow, the Wafer-Cone Flow Meter is a real space-saver. It eliminates the need for extensive up/down stream straight pipe runs required by other DP technologies, such as orifice plates and venturi tubes. It can be installed virtually anywhere in a piping system or be easily retrofit into an existing piping layout, resulting in significant installation flexibility and initial cost savings. Unlike traditional DP instruments such as orifice plates and venturi tubes, the Wafer-Cone Flow Meter’s design is inherently more accurate because the flow conditioning function is built-into the basic flow sensor design. The Wafer-Cone conditions fluid flow to provide a stable flow profile that increases accuracy. The flow sensor‘s design features a centrally-located cone inside a tube. The cone interacts with the fluid flow and reshapes the velocity profile to create a lower pressure region immediately downstream. The pressure difference, which is exhibited between the static line pressure and the low pressure created downstream of the cone, can be measured via two pressure sensing taps. One tap is placed slightly upstream of the cone and the other is located downstream of the cone. The pressure difference can then be incorporated into a derivation of the Bernoulli equation to determine the fluid flow rate. The cone’s central position in the line optimizes the velocity of the liquid flow at the point of measurement. It forms very short vortices as the flow passes the cone. These short vortices create a low amplitude, high frequency signal for excellent signal stability. The result is a highly stable flow profile that is repeatable for continuous accurate measurement. All of this is possible with a minimal straight pipe run of 0 to 3 diameters upstream and 0 to 1 diameters downstream from the flow meter.