Daniel Orifice Flow Calculator 3.0 Download !NEW!
Joie Coffield
The calculator uses the differential pressure measurement principle to calculate the flow rate. It accurately measures the difference in pressure of fluid across an orifice plate installed in the pipeline through which the fluid is flowing. The orifice plate size and shape are preselected based on the nature of the fluid, its flow rate, and other factors such as temperature and pressure.
The software interface is user-friendly and provides an easy-to-use system for selecting variables such as fluid type, pipe size, orifice plate size, temperature, pressure, and so on. It then calculates the flow rate based on these inputs and presents the results in a clear and concise format.
Daniel Orifice Flow Calculator uses the ASME MFC-3M 1989 equation to determine the rate of fluid flowing for 2" and larger pipe sizes. It will display the respective ratio, or orifice diameter to pipe diameter, for a given set of input variables. Provided for estimation purposes only, this simple, single-window program assists in sizing an orifice meter and bore size, though the calculated values for the beta ratio are approximate, typically within 2% - 5% for gases and steam, and 1% for liquids. The program's interface provides fields for inputting the operating temperature and pressure, base specific gravity, pipe size and ID, flow rate and type and differential pressure. I found that there are two calculation variables that the program does not take into account - The Reynolds Number correction and the Expansion factor. If no compressibility correction factor is entered, greater inaccuracies will occur for gas calculations with high operating pressures. Still, Daniel Orifice Flow Calculator provides useful assistance in the calculation of orifice diameters for estimation purposes.
The 'Orifice Flow Calculator' is an easy to use, one page program to assist in sizing an orifice meter and bore size. For a given set of input variables, the program will calculate the bore & beta ratio, the differential pressure, or the flow rate for 2" & larger pipe sizes. The Orifice Flow Calculator is provided for estimation purposes only.
Orifices are often used in fluid mechanics to limit mechanically the flow. The fluid going through an orifice plate will experience a pressure drop, it is therefore important to be able to size orifice plate correctly to adjust the flow as needed.
It is often required to measure the flow rate for a given experiment. A flow' meter can be included in the flow' loop for flow' rate measurements. Various flow meters can be chosen depending upon the specific application. There are differential-pressure meters such as an orifice plate, Venturi meter, and flow' nozzle; force meters such as rotameters; and momentum meters such as turbine flow meters.
Obstruction Flow' Meters: Commonly used obstruction flow meters include the orifice plate, Venturi meter, and flow nozzle. They measure the pressure drop due to an intentional reduction of flow area, as shown in Figure 2.14. They can be placed in the pipe for direct flow rate measurements. An example is included demonstrating how' to calculate the flow rate from the measured pressure drop (P, - P2) across an orifice flow' meter.
An orifice flow meter (the top and bottom drawings of Figure 2.14) is used to measure a fluid flow rate. Different sizes of the orifice bore diameter can be used to measure various ranges of the flow' rate. The mass flow' rate of the fluid is directly proportional to the pressure drop across the orifice: increasing the flow' rate increases the pressure drop. The size of the orifice plate must be selected in conjunction with the manometer or transducer used for this differential pressure measurement. If the flowrate is too large, the differential pressure could exceed the range of the transducer. If the flow'rate is too small, measurement of the small pressure difference
Because orifice meters are widely used for flow rate measurements in many industries, a number of standards are available for their construction, implementation, and usage. For example, the location of the upstream and downstream pressure taps is not arbitrary. As the fluid travels through the orifice, an area of separation is formed downstream of the plate. The pressure difference across the orifice will vary depending on where the downstream pressure measurement is taken. Also, the orifice plate should be constructed so the loss through the plate is predictable. With the calculation of the mass flow rate, multiple constants are used based on the construction of the meter, and if the plate is not constructed according to industry standards, the constants may not be applicable, and therefore, the flow rate will be measured incorrectly.
A well-known company supplying flow meters across the oil and gas industry is Emerson. While this company deals with many automation tasks, their Daniel flow meters are well-regarded for their performance and ease of operation. The Daniel orifice plates are fabricated according to industry standards with tight manufacturing tolerances. To support these meters, they have made available the Daniel Orifice Flow Calculator software. This calculator can be used w'ith a wide variety of fluids, pipe sizes, and orifice sizes. While this software package is convenient to use, researchers should be aware of w'hat is required to accurately calculate the mass flow rate from this type of meter.
An orifice flow meter in liquid flow application can achieve precise flow rate measurement. When measuring highly compressible gas-liquids or dense-phase fluids, an orifice flow meter measurement is less susceptible to errors, from variations in fluid densities due to changes in the operating conditions, compared to volume meters. The goal here is to describe how properly selected and installed special orifice plates can achieve precise and repeatable flow measurements that are acceptable for custody transfer applications.
All the early flow tests of orifice meters were conducted with water as the flowing fluid. The famous Ohio State orifice data, acquired in late 1920 and early 1930, were obtained with water as the flowing fluid. The Ohio State database was used to develop the empirical discharge coefficient equation of orifice flowmeter for the American Gas Association, AGA Report No. 3; and also the orifice flow meter standard by International Standards Organization, ISO 5167 (1991, and revised again in 2003). The database used to develop the empirical discharge coefficient (R-G) equation for orifice meters by the American Petroleum Institute (API) Manuals of Petroleum Measurement Standard (MPMS) Chapter 14.3 has more water and liquid hydrocarbon data than natural gas data.
With inventions of other metering devices, many orifice meter applications in liquid flows were replaced by Displacement and Turbine meters. These meters gained acceptance in the second half of the twentieth century. Over the last quarter of the twentieth century, flowmeters utilizing physical laws of Coriolis force, vortex shedding, and transit time of ultrasonic signals demonstrated precise flow rate measuring capabilities and are installed for liquid flow measurement. Primary measurement of Coriolis meters is in mass flow rate, but the meter can measure the density of the flowing fluid. Hence, it can output the flow rate in mass or volume unit. Two primary reasons for using Turbine, Displacement, Coriolis, Vortex, and Ultrasonic flowmeters in liquid hydrocarbon measurement instead of orifice flow meters for custody-transfer are:
Volume or mass flow rate through an orifice flow meter is a function of the square root of differential pressure and fluid density at the flowing conditions. Mass flow rate of a volume meter is obtained by multiplying the volume flow rate by the density of the fluid at the flowing condition. For applications where the density of the flowing fluid is sensitive to the operating pressure and temperature, an orifice flow meter output is less affected by the density changes than the mass flow rate output of volume meters. Unlike volume meters, the mass flow rate equation of an orifice meter is a square root function of fluid density and not a linear function. Therefore, an orifice meter is a better choice than a volume meter for highly compressible hydrocarbon fluids whose density is sensitive to changes in temperature and pressure of the flowing fluid.
Presently in North America, the most commonly used flow meter for accurate fiscal measurement of highly compressible hydrocarbon fluids (LPG mix) and dense phase fluids is by concentric, square-edged, flange tapped orifice flow meters. Although several different types of meters are used to accurately measure hydrocarbon fluids, the basic measurement verification remains the same. To verify, the mass quantity measured by the meter is compared to a known reference quantity of mass. Since mass flow rate is independent of operating conditions (pressure and temperature) and there are several reliable commercially available direct mass measuring flowmeters that can be verified in the field by provers, many new LPG mix and dense-phase fluid flow facilities often select and install direct mass flow meters (Coriolis force meter) as the flow metering device.
Measurement of any fluid by orifice flow meter applies to steady-state flow rate of fluid that can be considered clean, single-phase, homogeneous, and Newtonian. All hydrocarbon gases and most liquids and dense-phase fluids are usually Newtonian fluids. Highly compressible hydrocarbon fluids or fluid mixtures are considered homogeneous and clean.
Hydrocarbon measurement by orifice meters is primarily used for highly compressible gas, gas liquids, and dense phase fluids. Both displacement and turbine meters are lubricated by fluid medium that is being measured. Liquefied petroleum gases (LPG) and natural gas liquids (NGL) have very little lubricity and have low specific gravity at the operating conditions. At high flow rates, lack of lubricity is detrimental for meters with moving parts as the contact surfaces of the moving parts can wear rapidly over a relatively short period of use. So the meters may have to be derated; i.e., reduce the maximum flow rate limit for the meter. In addition, fluids with low specific gravity can affect the meter performance (linearity and repeatability) at low flow rates. Lack of lubricity and the low specific gravity of the fluid can adversely affect the turndown ratio of the turbine and displacement meters. On the other hand, an orifice meter does not have any moving parts. In addition, the turndown ratio of an orifice meter can easily be extended by changing the plate bore and/or by adjusting the full-scale range of the differential pressure transducer.
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