July 2019, Vol. 246, No. 7

Tech Notes

Flow Meter Provides Dual Measurements in Single Body

The Transus Instruments UIM-4F Duo natural gas custody transfer ultrasonic flow meter consists of two independent fiscal flow measurements in a single flow meter body, enabling enhanced condition-based diagnostics in a space saving, compact package. 

The primary measurement is accomplished by a four-path system, while an independent, concurrent three-path system provides secondary measurement for extensive diagnostic information using TIMCare software.

The primary flow measurement uses the UIM-4F four-path chordal configuration, meeting AGA Report No. 9 and OIML R137 (Class 0.5) international standards for custody transfer metering. The secondary flow measurement uses the company’s UIM-3F three-path chordal configuration, also highly accurate, and meeting AGA Report No. 9 standards.

Available in sizes of 8-inch and larger with flange ratings up to 900 pounds, this system provides continuous verification by use of the secondary measurement. 

Traditional arrangements use a secondary measurement with single or dual paths, often resulting in an overly sensitive system that can cause false indications of fouling or flow conditioner blockages. By using a three-path secondary measurement, which is less sensitive to slight profile changes.

The UIM-4F Duo provides the diagnostics needed to detect potential issues without giving false alarms. The UIM-4F Duo path layouts are oriented at different chord locations eliminating common mode errors as both meters respond differently to profile changes.

Transus Instruments’ ultrasonic transducers operate at very low transmitting voltage instead of the high voltage required by other ultrasonic flowmeters, allowing the UIM-4F Duo to be certified as Intrinsically Safe by DEKRA. Intrinsic safety certification reduces wiring and installation costs while greatly simplifying field maintenance.

The UIM-4F has been tested to meet the international standards for custody transfer metering while the UIM-3/3F is designed for flare gas, shale and coal seam gas, landfill and biogas as well as process gases. P&GJ

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