During the past several years the use of ultrasonic meters (USMs) has gained world-wide acceptance for fiscal applications. The many benefits of USMs have been documented in several papers at virtually every major conference. As the cost of gas continues to rise, the benefits of accurate measurement become even more important. For this reason many users are installing flow conditioners in an attempt to create the same profile as the meter was subjected to during flow calibration. The newest release of AGA Report No. 9 has a section that discusses a recommended installation for the USM which includes a flow conditioner. However, in many applications, using a flow conditioner is not preferred due to the increased piping length, added differential pressure, and higher installed cost. This paper will discuss testing an 8-path ultrasonic meter to identify what uncertainties remain from installation effects. Data on installations with and without a flow conditioner, including corresponding accuracy results, will be presented. This data helps identify the magnitude of uncertainties that may be present in field installations, and thus may help the user make a decision as to whether or not a flow conditioner is required.
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