Scope: The following paragraphs cover the general requirements for proving a master meter by a displacement type master prover.
PROVER TROUBLESHOOTING FOR MASTER METER PROVERS
Frequency As Indicated
Procedure Each proof shall consist of five (5) consecutive runs having repeatability
within 0.05%*. This means:
®
• When using a piston-type small volume prover (such as a Calibron
SVP), five (5) consecutive single passes are required;
• When using a bi-directional pipe prover, ten (10) consecutive
passes of the displacer (five round trips of the displacer) are needed.
Notes:
(1) One prover run is equivalent to one prover pass in a piston prover
or unidirectional prover, or one round trip in a bi-directional prover.
(2) Repeatability (of the runs or passes) is defined as:
% Repeatability = (Maximum MF – Minimum MF) x 100/ Minimum MF
(3) As an alternate, each proof may consist of three (3) consecutive
runs but they shall agree within 0.02%.
Master meter used for calibrating Air Fueling Operation (AFO) meters
If the application of a master meter is only for calibrating AFO meters, the
master meter shall be calibrated at the following rates:
i. at or near its rated minimum flow rate,
ii. at or near its rated maximum flow rate,
iii. and six flow rates spread within.
iv. The flow rates selected should include at least one that is between
15-20 % of the rated (design) maximum flow rate of the working
meter (to allow for “slippage test”.)
Master meter used to calibrate Bulk Plant loading/unloading meters
If the application of a master meter is only for calibrating rack meters, the
master meter shall be calibrated at the following rates:
1. If the rack meters are equipped with mechanical preset – the
master meter should be calibrated at the normal loading rate;
2. If the rack meters are equipped with electronic preset – the master
meter should be calibrated at the low, mid, and high (normal) flow
rates used during rack meter operations. This allows the master
meter’s MFs to be applied without interpolation when the working
meter is proved at the corresponding low, mid, and high flow rate(s).
Report
The calibration report “package” should include, but not be limited the
following information:
A) Location
B) Calibration report number
C) Tag number of the master meter under test
D) Type, make/model, size and serial number of the master
meter
E) Date of calibration
F) Time start and stop calibration of each “proof” and the duration
of entire calibration
G) Flow rate
H) Type of tank prover used, material of construction, size, scale
resolution, scale correction, if any, and serial number and the
prover capacity.
I)
Calibration Certificate for the tank prover (as a separate
document attached to the master meter calibration report).
The certificate should include the certification number of the
prover and the date of calibration and the next due date of
calibration.
J) A chart plotting the meter factor at each flow rate
K) Calculation procedure for average MF of the master meter
L) Name of company performing the calibration
M) Name and signature of the person from the calibration
contractor
N) Name and signature of witnesses
O) Official stamp/seal of the company providing the certificate
P) Master meter seal number before and after calibration
Q) Due date for master meter next calibration
R) Reason for calibration(schedule, maintenance, operation
request)