What is the 0.05% repeatability criterion?

API MPMS Chapter 4 requires that the range of meter factors from a set of proving runs (typically 5 consecutive runs) must not exceed 0.05% of the mean meter factor. This ensures the meter and prover are performing consistently. If repeatability exceeds 0.05%, the proving is considered invalid and must be repeated after investigating the cause.

How many proving runs are required?

API MPMS Chapter 4 typically requires a minimum of 5 consecutive proving runs that meet the repeatability criterion. Some contracts require 3 runs for pipe provers and 5 for compact/small volume provers. The meter factor is calculated as the average of all acceptable runs.

Meter Proving Repeatability Calculator

Proving Run Data

Meter Factors or K-Factors (comma-separated)

Enter 3-10 consecutive proving run values (meter factors or K-factors).

Data Type

Repeatability Limit

Proving Configuration

Prover Type

Meter Under Test

Fluid Type

Operating Conditions (Optional)

Temperature

°F

Pressure

psig

Understanding Meter Proving

Meter Factor
MF = Prover Volume / Meter Volume. Values near 1.0000 indicate good agreement. Applied as correction to meter readings.

Repeatability:
Repeatability = (Max MF - Min MF) / Mean MF × 100%. Must be ≤0.05% per API MPMS Ch. 4 for valid proving.

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Formula

Repeatability = (MF_max − MF_min) / MF_avg × 100

MF = Meter Factor (Prover Vol / Meter Vol)

Criterion = Repeatability ≤ 0.05%

Runs = Minimum 5 consecutive (API MPMS Ch. 4)

Standards & References

API MPMS Chapter 4
Proving Systems
API MPMS Chapter 12
Calculation of Petroleum Quantities
API MPMS Chapter 13
Statistical Aspects of Measuring and Sampling
AGA Report No. 7
Measurement of Gas by Turbine Meters

Engineering Notes

0.05% rule: Range of meter factors must not exceed 0.05% of the mean for valid proving
Minimum runs: API requires minimum 5 runs for compact provers, 3 for pipe provers
Outliers: Grubbs test used to detect statistical outliers at 95% confidence
Trending: Track meter factor over time to detect meter wear or calibration drift

Meter Proving Repeatability Calculator

Proving Run Data

Proving Configuration

Operating Conditions (Optional)

Understanding Meter Proving

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Results

Formula

Standards & References

Engineering Notes

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