Scope
This guideline provides the criteria for meter factor acceptance.
Frequency As indicated below
METER FACTOR ACCEPTANCE CRITERIA GUIDELINES
Procedure Criteria 1: Deviation from Meter Curve
The deviation of the meter factor versus the base meter factor shall be
calculated as follows:
(Meter Factor – Initial Base Meter Factor) * 100 / (Initial Base Meter
Factor) <±0.25%
MF is calculated at normal meter flow rate
If the meter factor is outside the ±0.25% tolerance, the meter shall be
scheduled for maintenance.
Criteria 2: Deviation from Previous Meter Proof
The deviation of the meter factor from previous meter proofs
(repeatability) shall be calculated as follows:
(MF – Avg. of Previous 10 Meter Factors at Normal Meter Rate) * 100
/ (Avg. of Last 10 Meter Factors at Normal Meter Rate) < ±0.1%
MF is calculated as the latest trial meter factor in the proving run.
Only valid meter factors at the normal flow rate shall be incorporated
into the historical database. When the limits from either test are
exceeded or the repeatability criteria is not met within 10 trials, the
meter factor shall not be used for measurement, and the
corresponding meter factor at the normal meter flow rate shall not be
entered in the historical data base.
If the new meter factor is not acceptable, the computer shall ask if
another proof will be run
If the meter factor obtained after the “nth” trial (per operator’s
discretion) is still not accepted, the operator will stop further proving.
In this case, the previous official meter factor will be used for delivery
calculations.
Truck Loading/Unloading Meters
The operating flow meter is to be proved before putting it back into
service. The resultant meter factor will be used until the next proving is
conducted. The new meter factor should be compared with the
previous meter factor. If the difference within 0.15%, the preset
controller shall be updated with the new meter factor. If the difference
exceeds the 0.15%, the meter will be taken out of service for check and
repair, if required.
Aircraft Refueling, Dispensing, Defueling and Dispensing Meters
A dynamic slip test is required for aircraft refueling, defueling and
dispensing flow meters. The meter factor (MF) at 20 % of meter
maximum rated flow should not deviate than + 0.15% from MF at
normal flow rate.