H-Bars

If the property profile selected on the LY or RY graph axis has been constructed using measured data, the measurements will be represented on the graph by H-bars. An H-bar is a horizontal line spanning the boiling point range of the cut measurement.

Appearance of H-Bars

The appearance of the H-bars changes depending on the information presented:

• Distillate cuts are represented by horizontal lines, with small vertical ticks at their ends to indicate the extent of the cut. A vertical line may also be shown centred through the horizontal line the size of which indicates the uncertainty associated with the cut measurement.

• Residue and condensate cuts are represented by horizontal lines with an arrow at the right or left hand side to indicate that they are not bounded above or below in boiling point. Both residue and condensate cuts may also show a vertical line centred through the horizontal line. The size of the vertical line, if present, indicates the uncertainty associated with the cut measurement.

• Limit measurement values for cuts (for example, < 0.25 Sulphur % wt) are represented by horizontal lines, with a vertical arrow extending from the middle of the H-bar in the direction of the limit (downwards for < and upwards for >).

• Measurements which are present in the set of measurement data, and which are used to generate the profile, are shown as unbroken lines.

• Measurements which are present in the set of measurement data, but which were not used to generate the profile, are shown as broken lines.

• Whole crude values, even when used to generate the profile, are not shown on the graph.

Where applicable, you can move the H-bars on the graphs using the button on the Toolbar. You can also toggle the effect of a H-bar on the graph using the Measurement Activity button on the toolbar. See Measurement activity model.

Alongside each H-bar shading indicates the Fitting Deviation, the difference between the value Assay has calculated for that property and the value entered in the measurement grid. The dark edge of the bar shows the calculated value, so a large bar indicates that Assay has not been able to closely fit the assay measurement consistent with the other assay data. The size of the Fitting Deviation depends on the scale of the graph, so the shading may not always be visible if the fitted value is close to the measured value.

The shading of the Fitting Deviation indicates the method being used to calculate the size of uncertainty represented by the vertical H-bar axis. Two methods are available for uncertainty calculation:

• Measurement Reproducibility - Blue Shading

• 95% Confidence - Green Shading

The current method being used to calculate uncertainty can be selected using the Graphing options of the Preferences dialog: See Graphing preferences.

• Show reproducibility on h-bars - the vertical size of the h-bar represents the reproducibility of the assay measurement

• Show 95% confidence interval on h-bars - the vertical size of the h-bar represents the values within two standard deviations of the assay measurement

Measured, converted and calculated H-bars

Several different types of H-bars are shown on the graph by default. You can change the types of the H-Bars shown by pressing the button on the Profile Graph Toolbar. See Profile graph toolbar.

Types of H-bars available include:

• Show Measurements: When this option is selected, H-bars for measured values are shown on the Profile graph. For example, when this option is selected, H-bars would be shown on the graph if the Y-axis of the Profile graph is set to density at 15.6°C and measured values for density at 15.6°C exist in the assay.

• Show Converted: When this option is selected, H-bars are shown on the Profile graph if measured values for a property can be converted into the unit of measurement selected for the active Y-axis of the Profile graph. For example, converted H-bars would be shown on the graph if the Y-axis of the Profile graph were set to density at 70°C and measured values for density at 15.6°C were present in the assay.

• Show Calculated: When this option is selected, H-bars are shown on the Profile graph if values for the property on the active Y-axis of the Profile graph can be calculated from other property values present in the assay. For example, calculated H-bars would be shown if the Y-axis of the Profile graph were set to density at 15.6°C, but only measured values for API were present in the assay.

Tooltips

Hover your mouse pointer over any of the H-bar items in the graph to bring up more information about them. Where data has been calculated or converted from other measured values, additional information is provided about the original measurements.