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All Primary Flow Sections furnished by PFS are guaranteed to meet the requirements for fabrication and the laboratory calibration acceptance criteria set forth in ASME PTC-6, 1996. The PTC-6 Code Committee’s further explanation of those criteria as published in “Mechanical Engineering”, Feb 1999, pp81-83.

Specifically, the acceptance criteria are:

  1. The average value of Cx must be within the range, 1.0029<=Cx<-1.0079.
  2. The confidence interval of the slope of the Cx’s must include 0 (zero) or the absolute value of the slope must be less than 2.72x10-7.
  3. The confidence interval of the Cx’s must not exceed 0.0006.

In the special case when the range of Reynolds numbers achieved during the calibration matches or exceeds the range of Reynolds numbers that will be encountered during the acceptance test, the above criteria are modified as follows:

  1. The average value of Cx need not be within the range, 1.0029<=Cx<=1.0079.
  2. The confidence interval of the slope of the Cx’s need not include 0 (zero) nor must the absolute value of the slope be less than 2.72x10-7.
  3. The confidence interval of the Cx’s must not exceed 0.0006.
  4. The calibration data must be repeatable. This can be verified by a minimum of three repeat points in the calibration. The repeat points must agree to within 0.05% in order to satisfy this criterion.
  5. The calibration must be reliable. This requirement is considered to have been met if the calibration is done at a facility with an established reputation for performing this type of calibration correctly. One such laboratory is ARL, Inc. of Holden, MA.

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