Archived Commentary Index
Metering Research Facility:
Typical Projects Performed
Flow Measurement Section
Manager Southwest Research Institute
The GRI Metering
Research Facility (MRF) works with flow meter and valve manufacturers,
natural gas production and gathering companies, natural gas transmission
pipeline companies, and local natural gas distribution companies.
The following five projects are typical MRF projects.
Gas Measurement at Custody Transfer Points. Deregulation and
open access in the U.S. natural gas industry in the 1990s built
a competitive market, motivating more efficient company operations.
Gas companies are facing constant pressure to earn greater profits
and cut costs. With many more participants buying and selling
gas in the United States marketplace, the accurate measurement
of gas at custody transfer points is paramount (a custody transfer
point is the location where gas changes ownership, such as from
gas supplier to gas consumer). If there is a bias in the custody
transfer meter, that bias penalizes one side of the transaction,
thus, increasing operating costs and hurting competition.
MRF provides value to the industry through its ability to identify
and eliminate gas measurement bias errors. Since the inception
of the MRF in 1991, a research initiative has been underway to
identify and eliminate the measurement biases associated with
commonly used gas-metering equipment (e.g., orifice flow meters,
turbine meters, ultrasonic meters, etc.).
- Gas Meter
Calibrations. Gas companies find operational and economic
advantage in having gas flow meters calibrated before field installation.
The MRF provides accurate flow meter calibrations traceable to
the U.S. National Institute of Standards and Technology (NIST)---correcting
flow meter bias errors as small as 0.05%.
MRF is one of just a few facilities in the world that can perform
high-accuracy, gas flow meter calibrations under field-like operating
conditions. The closed-loop, re-circulating, gas flow calibration
facilities at the MRF provide maximum controllability of pressure,
temperature and flow rate, resulting in stable flow conditions
over long testing times. A key feature of the MRF is its primary
calibration system based on gyroscopically-balanced weigh tanks,
the most accurate means known for measuring gas mass flow rate.
- Gas Sampling.
In addition to focusing on volumetric flow rate measurement, the
MRF program also addresses natural gas composition determination
(i.e., heating value determination). As an example, the MRF is
evaluating commonly used gas-sampling methods to determine which
provide the most accurate characterization of natural gas mixtures
flowing through pipelines. The American Petroleum Institute (API)
and the United States Gas Processors Association (GPA) are using
the results of this research work to update their natural gas
sampling standards. It has been estimated that the economic impact
of improved gas sampling techniques for custody transfer is on
the order of $50 million annually in the United States.
Conditioners. The piping geometry upstream of a gas flow meter
can create flow field distortions that can adversely affect measurement
accuracy. If these flow distortions are allowed to propagate to
the flow meter, measurement bias errors can result.
called a flow conditioner is sometimes placed upstream
of a flow meter to help eliminate flow distortions before they
reach the meter and bias the measurement. An extensive research
program has been conducted at the MRF to characterize the flow
performance of commercially available flow conditioners.
Rate Measurement Research. In the United States, natural gas
is bought and sold based on the amount of energy delivered. This
requires that both gas volume and heating value be measured accurately.
Gas volume is usually measured with a conventional flow meter,
such as an orifice meter or a turbine meter. Heating value is
normally determined from a compositional analysis of the gas mixture.
The compositional analysis is typically acquired via gas chromatography.
The MRF, with co-funding from GRI and the United States Department
of Energy, is researching more cost-effective methods for determining
energy flow rate.
The MRF is a
one-of-a-kind facility, unique in its capability. The MRF has a
reputation in government circles and throughout the U.S. natural
gas industry as the best-equipped facility/resource for advancing
the state of the art of gas measurement technology.
To learn more about the MRF, please