Flow Calibration in Oil and Gas Separators
As earlier stated, flow instruments that function with the separator in an oil and gas environment include the flow indicator, flow transmitter and the flow controller. Due to maintenance (which will be discussed later) or due to high usage, these flowmeters do need to be calibrated from time to time. Calibration can be defined as the process of referencing signals of known quantity that has been predetermined to suit the range of measurements required. Calibration can also be seen from a mathematical point of view in which the flowmeters are standardized by determining the deviation from the predetermined standard so as to ascertain the proper correction factors. In determining the deviation from the predetermined standard, the actual flowrate is usually first determined with the use of a master meter which is a type of flowmeter that has been calibrated with a high degree of accuracy or by weighing the flow so as to be able to obtain a gravimetric reading of the mass flow. Another type of meter used is the transfer meter. However, according to Ting et al (1989), transfer meters have been proven to be less accurate if the operating conditions are different from its original calibrated points. According to Yoder (2000), the types of flowmeters used as master meters include turbine meters, positive displacement meters, venturi meters, and Coriolis meters. In the U.S., master meters are often calibrated at a flow lab that has been certified by the National Institute of Standards and Technology, (NIST). NIST certification of a flowmeter lab means that its methods have been approved by NIST. Normally, this includes NIST traceability, meaning that the standards used in the flowmeter calibration process have been certified by NIST or are causally linked back to standards that have been approved by NIST. However there is a general belief in the industry that the second method which involves the gravimetric weighing of the amount of fluid (liquid or gas) that actually flows through the meter into or out of a container during the calibration procedure is the most ideal method for measuring the actual amount of flow. Apparently, the weighing scale used for this method also has to be traceable to the National Institute of Standards and Technology (NIST) as well. In ascertaining a proper correction factor, there is often no simple hardware adjustment to make the flowmeter start reading correctly. Instead, the deviation from the correct reading is recorded at a variety of flowrates. The data points are plotted, comparing the flowmeter output to the actual flowrate as determined by the standardized National Institute of Standards and Technology master meter or weigh scale.
Read more about this topic: Separator (oil Production)
Famous quotes containing the words flow, oil and/or gas:
“For as the interposition of a rivulet, however small, will occasion the line of the phalanx to fluctuate, so any trifling disagreement will be the cause of seditions; but they will not so soon flow from anything else as from the disagreement between virtue and vice, and next to that between poverty and riches.”
—Aristotle (384322 B.C.)
“Eat what you can get.
Wheres the salt
in this dump of a village?
And, Lucky Man,
whats the use
of a salty thing
if theres no oil in it?”
—Hla Stavhana (c. 50 A.D.)
“Shielded, what sorts of life are stirring yet:
Legs lagged like drains, slippers soft as fungus,
The gas and grate, the old cold sour grey bed.”
—Philip Larkin (19221986)