Midstream Oil and Gas
Meter Prover – How Flow Meter Prover System Work
December 5, 2019 Welcome
Hydrocarbon liquid flow through pipelines needs constant monitoring to ensure it is being transported under the right conditions. Flow meters that help ensure the proper measurement of pipeline liquids may become faulty with prolonged use and give misleading results used in performance monitoring and oil and gas measurement.
Effective flow meter calibration can be achieved with the use of a meter prover. These devices will analyze the readouts from a flow meter and determine their accuracy. In this manner, any necessary adjustments can be performed and hydrocarbon liquid flow satisfactorily measured, controlled, and regulated. In this article, we will define the parameters that make a prover effective as well as consider various systems commercially available for various industrial applications.
What Is a Prover?
A meter prover is an apparatus that authenticates and calibrates the readings obtained from a liquid or gas flow meter. While these devices can either be manual or automated, the most popular and newer prover systems are automatic devices.
How Does a Flow Meter Prover System Work?
A typical flow meter prover device functions to detect changes in the amount of gas or liquid flowing through a pipeline at various times. Installed in each prover are sensors that detect changes in fluid flow and ensures flow meter readings remain as accurate as possible.
Types of Meter Provers
Depending on manufacturers’ preferences, various types of meter provers are available for industrial fluid transport processes. Outlined below are the most effective pipe proving systems currently in use.
Master Meter Provers
A master meter proving system can either function to calibrate a flow system directly or indirectly. Direct master meter proving involves the use of a line meter and a master meter connected in series. This type of proving is done at the site of the carrier pipeline.
Indirect master meter proving will require detachment of the gas meter which will be calibrated at a site remote from its primary location. This requires prover hookups on the relevant metering equipment.
Sphere/Pipe Provers
A sphere or pipe prover (which can also be referred to as ball prover) functions on the principle of constantly replicated displacement of fixed amounts of liquid between two detector devices.
When a spherical ball is passed through a calibrated part of piping, a fixed amount of liquid will be displaced. Similarly, within the prover system, an equal amount of fluid will be evacuated. The fluid moved within the ball prover can then be calculated by an attached meter. By this method, the volumes within the pipeline and the prover device can be compared and any variations corrected.
Small Volume Piston Provers
Effective meter prover calibration can be done with a small volume piston prover device. Although the mechanism of operation is like that of the ball prover, it has several advantages.
- A smaller volume of fluid is required for measurement
- Small volume piston provers are portable, saving users significant floor space
- More accurate readings obtained when compared with other bulkier prover systems
The only significant drawback to opting for an SVP is its limited ability to operate with larger volume pipe systems. In these situations, an SVP will require repeated cycles to manage the increased flow rates.
Bidirectional Meter Provers
This is a modified form of sphere prover which allows for continuous travel of the displacement ball. The typical set up involves a four-way valve which allows for the reversal of fluid flow when the sphere changes direction.
During operation, the liquid or gas entering the system pushes a spherical prover ball through the proving loop. Gas flow is channeled through a series of sensors and calibrated segments within the prover system and the number of impulses generated is calculated by a prover counter to determine the efficiency of gas flow.
Unidirectional Meter Provers
Just like the bidirectional sphere prover, unidirectional prover devices are variants of the sphere prover. When in operation, opening the main control valve of the prover will release the sphere into the flow stream displacing the gas contained within the system.
When the sphere passes set points with attached sensors, a prover counter compares the displaced fluid with pre-determined values. These devices allow the displacement ball to travel in one direction only and has a separate mechanism for returning it to the starting position.
IFS Modular Process Skids Can Support Your O&G Metering Needs
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Obtaining modular processing skids from IFS will allow you to employ the most effective metering solutions that will boost overall process efficiency and productivity.
Contact us online today to learn more about the full range of pipeline engineering solutions we offer.
