Calculates the uncertainty in observed volume, mass and standard volume flowrates for a USM used for flaring. USM flowrate uncertainties are determined from an assessment of the meter calibration performance, installation and on-going performance/usage parameters. Density is derived from molecular weight and its uncertainty gained from this relationship. Pressure and temperature uncertainties are determined using the technical specification for the transmitters selected from the integrated transmitter selection tool.
The General tab is used to enter information, which is saved along with the uncertainty calculation and included in reports which are generated.
The tabs used for inputting data and calculating the uncertainty in the individual components of the uncertainty can be seen along the top of the module window.
The report tab is only visible once the calculation has been run and will not be visible if any parameters are changed until the calculation has been run once more.
The options section controls how the calculation is performed and dictates which inputs are required.
This is the line pressure of the gas stream measured upstream of the Coriolis meter.
Note: As described above, if Absolute is selected inputs are required for Absolute and Atmospheric pressure and if Gauge is selected inputs are required for Gauge and Atmospheric pressure.
The default value for Absolute Pressure is set to 1 standard atmosphere (1.01325 bar)
This is the line pressure of the gas stream measured. As described above, if Absolute is selected inputs are required for Absolute and Atmospheric pressure and if Gauge is selected inputs are required for Gauge and Atmospheric pressure.
Number of parallel meters
This input is only visible when parallel streams are selected for the station uncertainty and refers to the number of in-use metering streams the flow is divided between.
This is the measured temperature of the gas.
The velocity of gas flowing through the USM.
Note: Ultrasonic meters operate over a specified velocity range, which is independent of temperature, pressure, or composition.
The outputs section shows the calculated flow rate and uncertainty taken from the Flow Rate tab.
The following blocks are used within this uncertainty module: