Perform Calculations

Access the required calculation windows as described in Perform Instrument Sizing Calculations.

Control Valve Sizing window:

Flow Element Sizing window:

Relief Valve Sizing - Gases & Vapors window:

Thermowell Vibration window:

Basic details of the selected instrument are displayed at the top of the windows.

Complete the fields with the values required to perform the calculations. All values may be entered manually.

Alternatively, if an instrument has been associated with a Process Line (refer to Assign Process Equipment and Process Lines for details), and the Process Item Properties option on the Instruments tab of the Preferences window has been selected (see Instrument Engineer Options), then many of the fields may be completed with the details of that Process Line by selecting it from the Associated Item list. Complete the rest of the fields 'manually'.

Fields should be completed in the order that they are displayed on the window. For example in the Control Valve Sizing window, enter the Upstream Nominal Size first, then the Upstream Nominal Size, finishing with the Cp/Cv, leaving blank any of the values to be calculated (if values are entered in these fields they will be overwritten when a calculation is performed).

Fields with a yellow background cannot be edited. They either display general data relating to the instrument, or can only be populated when a calculation is performed.

Values entered in one calculation window automatically populate corresponding fields in other calculation windows.

If a field that must be completed is left blank, or is completed with an invalid value, an warning symbol is displayed next to that field:

Hover the mouse cursor over the symbol to display a tooltip explaining the reason for the warning:

To perform a calculation, click the appropriate button, for example, Calc. Flow, Calc. DP, PSV Size, etc.

Note that the Calc. Density button on the Control Valve Sizing window opens the Gas Compressibility Factor "Z" window (see below).

The calculated values then populate the appropriate fields in the windows.

If there are any warnings or noteworthy implications arising from a calculation, they are displayed as messages at the bottom of the window.

To save any calculations or entered values and exit a window, click Save. To exit a window without saving, click Cancel.

Gas Compressibility Factor "Z" calculations are performed by clicking Calc. Density in the Control Valve Sizing window. The Gas Compressibility Factor "Z" window then opens. As described above, enter the required values, then click Calculate to the perform the calculation.

To print the calculation results, click Print. The data is then displayed in a Print Preview window.

To exit the Gas Compressibility Factor "Z" window, click Cancel.

Note:
The calculations and entered values are not saved when the window is closed.