Small Volume Meter Provers – Frequently Asked Questions
As the top manufacturer of Small Volume Meter Provers, we understand that you likely have many questions. This page aims to provide helpful meter prover information. Here you will find answers to some of the most common questions we are asked, including What is a Prover and how do they operate? Our goal is to make your experience as smooth as possible, we hope this page helps you find the answers you’re looking for. If you have a question that is not covered on this page, please feel free to reach out to us and we will be happy to assist you.
What is a Prover?
A Prover is a device with a “known traceable volume” designed to calibrate or prove a liquid flow meter’s accuracy and repeatability under actual operating conditions. Provers can be stationary or portable devices used to calibrate and verify the accuracy and repeatability of both volumetric and mass flow meters. Provers are commonly used in the hydrocarbon industry for custody transfer or fiscal applications, where accuracy is critical.
A Prover Establishes:
- The K-Factor (pulses per unit volume) of a meter
- The Meter Factor (factor used with a meter to correct accuracy for flow conditions)
- The Linearity over the calibrated flow range for the meter
- The repeatability for the meter system
What type of flow meters are small volume provers compatible with?
FMD small volume meter provers can be used with the following flow meter types:
- Coriolis Meters
- Positive Displacement Meters
- Liquid Ultrasonic Meters
- Turbine Meters
- Helical Turbine Meters
- Multi-Viscosity Turbine Meters
Please always verify prover sizing with Flow MD as meter type, process fluid and operating conditions must be considered to properly size a prover. Please reach out to us to discuss your specific application and the optimal FMD Prover for your application.
Visit our Application Specific Prover Page for additional information.
Flow Management Devices Small Volume Meter Provers are generally used in the petroleum and petrochemical industries to measure liquid products. FMDs provers ensure measurement quality for both custody and non-custody transfer applications and are configurable for both stationary or portable proving applications where accuracy is key.
FMDs Small Volume Provers are commonly used for the following hydrocarbon products:
- Bitumen
- Butane
- Condensate
- Crude Oil – Light (API > 31.1)
- Crude Oil – Medium (API 22.3 – 31.1)
- Crude Oil – Heavy (API < 22.3)
- Crude Oil – Extra Heavy (API < 10.0)
- Diesel
- Ethane
- Ethylene
- Fuel Oil
- Gasoline
- Isobutane
- Jet Fuel
- Kerosene
- Low Temperature Hydrocarbon Gas Liquids (HGLs)
- LPGs
- Methane
- Methanol
- NGL
- Naphtha
- Petrochemicals
- Propane
- Propylene
- Refined Products
- Other Products (contact factory)
Where can FMD Small Volume Meter Provers be used?
Upstream
- Production LACTs
- Offloading & Storage
- Upstream Production Facilities
- Floating Production Storage and Offloading (FPSO)
Midstream
- Pipelines
- Refineries
- Offloading & Storage
Downstream
- Petrochemical Plants
- Load Racks
- Terminals
- Offloading and Storage
Why is it Important to Prove a Flow Meter with a Flow MD Small Volume Prover?
Simply stated, to provide an accurate measurement.
In addition, proving is critical for financial transactions and custody transfer applications to maintain profitability and reduce financial uncertainties.
Flow meters are generally calibrated in a factory using clean and consistent factory conditions; once they reach the field, they are subject to various conditions in the field. Over time these product and process variations can lead to accuracy shifts known as drifting.
FMDs Small Volume or Unidirectional Captive Displacement Meter Provers use the known volume of the prover in comparison to the output of the flowmeter to calculate a correction factor allowing the user to adjust the flowmeter accordingly for a truly accurate representation of flow rates.
How to Obtain a Meter Factor using a FMD Small Volume Meter Prover:
A meter factor is determined by comparing the flow volume measured by your meter against the precisely known volume measured by a Small Volume Prover (SVP) during a proving run.
How the Process Works:
During proving, a calibrated displacer travels through the SVP, creating a known reference volume. At the same time, the flow computer records the volume indicated by the flow meter during the same period of time. The flow computer then compares these two measurements and calculates the meter factor using the following relationship:
Meter Factor = True Volume ÷ Meter Corrected Volume
The resulting meter factor is used to correct the meter’s readings, ensuring accurate flow measurement and custody transfer performance.
Watch the short video below to learn how Flow MD meter provers operate
Choosing the right small volume prover can be complex, as sizing depends on your meter technology, flow rates, fluid characteristics and system operating conditions. To make it easier, we offer an online sizing tool that walks you through the key parameters and helps identify the best FMD meter prover for your needs. Please always verify prover sizing information with Flow MD and your meter manufacturer for best results.
Chrome lined flow tubes offer enhanced durability and longer service life compared to standard stainless steel flow tubes. The chrome plating provides a harder, more wear-resistant surface that helps protect critical flow meter components and improve overall performance in demanding applications.
Chrome lined flow tubes are particularly beneficial in applications where:
- Abrasive particles are present in the process fluid
- Equipment is exposed to frequent wear and tear
- Long-term reliability is critical
- Reducing maintenance downtime is a priority
Key Benefits of Chrome Lined Flow Tubes
Increased Surface Hardness
Chrome plating is significantly harder than stainless steel, creating a durable protective layer that withstands abrasion and mechanical wear better than uncoated surfaces.
Longer Seal Life
The smoother, harder chrome surface reduces friction and wear on seals. This helps extend seal life, minimize maintenance requirements, and improve long-term reliability.
Protection Against Internal Damage
Chrome lining helps protect the interior of the flow tube from damage caused by foreign objects, debris, or abrasive particulates moving through the process stream. This added protection can help maintain measurement accuracy and reduce costly repairs.
Reduced Maintenance Costs
By minimizing wear on both seals and the flow tube itself, chrome-lined flow tubes can lower maintenance frequency and extend equipment lifespan, resulting in reduced operating costs over time.
See our Chrome Lined Flow Tube Specification Review for additional information.