2.7 Procedures for Submitting a Flowmeter for Calibration
The Fluid Metrology Group follows the policies and procedures described in Chapters 1, 2, and 3 of
the NIST Calibration Services Users Guide [iv]. These chapters can be found on the internet at the
following addresses:
1. http://ts.nist.gov/ts/htdocs/230/233/calibrations/Policies/policy.htm
2. http://ts.nist.gov/ts/htdocs/230/233/calibrations/Policies/domestic.htm
3. http://ts.nist.gov/ts/htdocs/230/233/calibrations/Policies/foreign.htm
Chapter 2 gives instructions for ordering a calibration for domestic customers and has the subheadings:
(A) Customer Inquiries; (B) Pre-arrangements and Scheduling; (C) Purchase Orders;
(D) shipping, Insurance, and Risk of Loss; (E) Turnaround Time; and (F) Customer Checklist.
Chapter 3 gives special instructions for foreign customers.
3. OVERVIEW OF THE PROCESS USED TO ESTABLISH TRACEABILITY
This section gives an overview of the five stage procedure used to establish the traceability chain
between a flowmeter calibrated at CEESI’s Iowa facility back to NIST’s primary flow standards. A
key element of the five stage process was the critical flow venturi (CFV) bootstrap process. NIST’s
low pressure, low flow standards were used to calibrate multiple CFVs, which were used in
parallel to provide traceability at pipeline conditions for natural gas flows. A description of the
CFVs and their basic calibration parameters are described, and an overview of the uncertainty
attributed to this scale-up procedure is presented.
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3.1 Overview of the Five Stage Procedure used to Establish NIST Traceability
The traceability chain linking flowmeters calibrated at CEESI’s Iowa facility in natural gas to
NIST’s low pressure, air flow primary standard were accomplished in five stages. A diagram of
the five stage process is shown in Fig. 3.1. The first column in each row identifies the calibration
stage, followed by the flow standard, the reference flowmeter being calibrated, the fluid medium,
the expanded uncertainty (i.e., k = 2) of the reference flowmeter, and the calibrated flow (or
Reynolds number) range of the reference flowmeter. The nominal pressure conditions for all five
stages are also specified in the figure.