The Relief Valve Calculation window allows you to view and edit the status of the current relief valve instrument. This window displays the process data for the selected relief valve instrument. If this is a new tag that you just created in the Calculation module, the process data section of the window will be blank. Select the required fluid state, and the process data section will become available for data entry. Some process data properties may vary depending on the selected fluid state.
Selecting Line or Equipment from the Location list also alters the window options accordingly: Line size and Line number for Line and Equipment name for Equipment.
To access this window, select and then select an instrument tag.
Fields that are mandatory for calculations appear with either cyan or yellow background highlighting, according to the following definitions:
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A cyan background indicates that you must enter a value on the process data sheet.
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A yellow background indicates that you may enter a value on the process data sheet, or you can leave it blank and enter a value for that field later on the calculation sheet.
To activate the highlighting option, select Options > Highlight Process Data.
Calculation Item Commands.
General
the selected instrument's service, line properties, and fluid properties.
Properties
the current instrument's process data values.
Additional Properties
enter or modify additional properties for the selected instrument.
Base Conditions
enter or modify base condition values for the selected instrument.
Sizing Data
enter or modify sizing data for the selected relief valve instrument.
API 2540 Standard
calculate liquid density at operating and base conditions in accordance with the API 2540 standard.
Built-Up Back Pressure
enter built up back pressure values to be included in the relief valve sizing calculation.
User-Defined Fields
enter or modify custom field values in fields defined by the Domain Administrator for the current plant.