Method 2F Compliant Three-Dimensional Flow Sensing System

The Environmental Supply Company (ESC) Three Dimensional Flow Sensing System was used in the flow study initiated by the EPA to evaluate new techniques in improving flow rate measurement under a wide range of flow and swirl conditions. The wind tunnel and field tests used in the study provided a technical basis for three new methods for velocity and volumetric flow rate determination in stacks or ducts, Methods 2F, 2G, and 2H. The final ESC system design resulted from performance evaluation during these tests, recommendations of the test teams who operated the system, and requirements specified in the new methods. The system includes a DAT or spherical style probe with calibrated reference scribe line, probe extensions with reference scribe line, three-dimensional flow sensing console, probe-mounted digital inclinometer, optional probe-mounted yaw-null magnehelic, and pressure line umbilical cable. [ Go to Method 2F System and Product Listing ]

Probes are calibrated in Environmental Supply Company's EPA-audited wind tunnel through a series of pitch angles selected to exceed expected testing conditions by 5%. The probe reference scribe line is placed at the yaw-null position of the probe. On probes with an existing scribe line, the rotational offset is calibrated relative to the yaw-null position.

During the flow study, field test teams reported that probes able to determine yaw and pitch angles of flow, such as the spherical and DAT style probes, produced results closer to those predicted by scientific theory. They also produced the best results of all probes tested, being less variable and most consistent. It was also discovered that past determinations of mass emissions at the test sites were biased high in general, and as much as 20% high in some cases. These findings promise enormous potential savings for utilities paying for mass emissions under Part 75 of EPA's Acid Rain Program regulations.