March 2006 

Small Volume Prover (SVP) Proving Reports 

By G. Diane Lee 

This is the fifth and final article in the series of articles on SVPs. Previous articles 

covered all phases of small volume provers from definitions and terminology to the 

operating procedures for the use of SVPs when testing loading rack meters. However, 

knowing terminology or how to determine the mathematical meter error is not enough for 

the inspector to perform his job correctly. The professional weights and measures 

inspector must also understand the data contained in an SVP proving report. All five 

articles are located on the NIST WMD website at www.nist.gov/owm for reference and 

review. On the WMD website under “Publications,” click on “Weights and Measures 

Newsletter Quarterly Archive,” and then click on “Field Standards.” 

Data contained in SVP proving reports may affect the accuracy of the determination of 

meter error and two sample proving reports will be examined later. There are various 

software programs in use in industry, and thus SVP proving reports may vary depending 

on the software used. As noted in the fourth article of the series, in Section II of 

“Operating Procedures for the Use of SVPs when Testing Loading Rack Meter,” the 

operator is responsible for the set-up of the SVP. This includes entering the data into the 

computer. 

SVP Proving Reports 

Information such as the prover operator, business name and the location of the meter 

under test is entered into the computer and recorded on the reports. The fluid type and 

density, type and manufacturer of the SVP, and meter information are also entered into 

the computer. If this information is incorrect, it can affect the accuracy of the results. As 

such, weights and measures inspectors should be familiar with the information in an SVP 

report and verify its accuracy. The information below provides an overview of data that 

may affect the accuracy of the results if it is incorrect. At the end of this article are two 

sample reports. For guidance in interpreting the data on these reports, sections of the 

reports are numbered to correspond to the descriptive paragraphs below. 

Section 1. Fluid Data 

The operator may select the fluid type from a master list which is included in the software 

and grouped according to the API tables for petroleum fluid types. The proving report 

will show the type of fluid tested along with other temperature and density information. 

The selection of the proper fluid type is important because fluid densities may vary and 

an error in the density may affect the calculations. If products other than petroleum 

products are being dispensed through the meter under test, the inspector should be sure to 

verify that appropriate tables/density information is used. 

Section 2. Prover Data – Manufacturer Identification and SVP Specifications. 

This section of the report includes information regarding the manufacturer of the SVP, 

the prover type, the upstream and downstream volume (sometimes referred to as the Base 

Prover Volume or BPV, which is the water draw volume), the pipe inner diameter, the 
pipe wall thickness, water draw/calibration date and due date, prover material (when 

selected, the cubical expansion and elasticity of the prover material may be calculated 

automatically with some software), and switch bar material. The electrical 

switches/detectors, as described in Part 2 of this Series, are located on a switch bar. 

Detectors are used to start and stop the counters and determine the calibrated section of 

the prover. The effects of temperature on the switch bar can affect the accuracy of the 

device and must be taken into account. General prover data may be documented in the 

specifications section of the SVP operation/maintenance manual. Specific information, 

such as the base volume at the time of the last water draw, normally can be found on the 

certificate of calibration or associated worksheets and should be used to verify that the 

correct information is in the computer. 

Section 3. Proving Data 

Depending on the software used and set-up selections, the operator may be able to 

manually enter the switch bar temperature, prover pressure and temperature, and meter 

pressure and temperature, or this information may be recorded automatically from the 

pressure and temperature sensors in the system. This information, along with prover data 

from Section 2, is used to correct for the effects of temperature and pressure on the 

prover and meter volumes and, as noted above, to correct for the temperature effects on 

the switch bar. This information is located on the proving report under “Proving Data” in 

both sample reports. 

Section 4. Density 

Depending on the software, the density of the fluid is manually entered or automatically 

entered by the software using available data tables. In the examples provided, density is 

recorded under the “Fluid Data” on Sample Report 1 and under the “Proving Data” on 

Sample Report 2. 

Section 5. Meter Data 

This section includes the location, station name and number, the manufacturer, and/or the 

meter base K-factor. The meter base K-factor, as described in Part 3 of this Series, 

establishes a relationship between the pulses generated by the meter and the volume 

shown on the indicator; it is the number of pulses generated by a meter while a unit of 

volume is passing through it. The meter base K-factor is recorded on the proving report 

under “Meter Data” In both sample reports. Sample Report 2 contains a subheading for 

“Meter Data” under “Proving Data” where the meter base K-factor is recorded. Sample 

Report 1 uses the term nominal K-factor (NKF) for the meter base K-Factor. 

Section 6. Repeatability Tolerance 

NIST Handbook (HB) 44 repeatability tolerance would be applied to multiple runs by 

comparing the meter factor from each run. 

Section 7. Run Results and Temperature and Pressure Readings 

The results of the individual runs are recorded on the proving report which will typically 

include the number of pulses for each run. Temperature and pressure readings are also 

recorded on the proving report, which are used to correct the prover and meter volumes. 
Section 8. Corrected Prover Volume and Corrected Meter Volume 

The prover volume and meter volume are corrected for temperature and pressure. The 

calculations for the corrected prover volume and corrected meter volume are included in 

both sample reports. 

Section 9. Meter Factor 

The meter factor as explained in Part 3 of this Series is the corrected prover volume 

divided by the corrected meter volume. This value is included under “Proving Data” for 

both sample reports and is used to calculate the percent meter error, which is also 

explained in Part 3. The weights and measures official should compare the percent meter 

error to the NIST HB 44 percent tolerances to determine compliance. Typically this 

information would be considered “as found” data, as it is common practice for service 

technicians to program the average meter factor from the runs into the register, thereby 

adjusting the meter error to approximately zero. 

Section 10. Number of Passes Per Run 

As noted in Part 4 of this Series, some documented procedures have established a 

maximum number of passes per run based on the size of the meter to prevent the 

possibility of averaging out repeatability problems in the system. See the fourth article, 

Section II (h) for additional guidance in verifying that the maximum number of runs has 

not been exceeded. The total number of passes is recorded on the proving report. 

If you have any question concerning SVPs, you may contact G. Diane Lee of NIST 

WMD by e-mail at diane.lee@nist.gov, by fax at 301-926-0647 or by phone at 301-975-

4405. 

We extend our thanks to Dennis Beattie of Measurement Canada, Emerson Process 

Management, Marathon Ashland Petroleum, and Flow-Cal for their assistance in the 

preparation of this article.