Bronkhorst CoriCalc - Manual (Page 10)

page 10 9.17.056
The unit in which the pressures and the flow can be supplied can be selected at the Units frame at the bottom of the
window. For pressure, the unit types Pressure A (absolute) and Pressure G (gauge) are available. For flow, the unit
types Mass Flow, Normal Flow and Standard Flow are available. The latter two are most likely to be used for gases
only.
Note
Changing the unit will not convert any flow values from the old unit to the new unit!
4.1.3 Calculation
After selecting the desired units, the desired gas, at the Calculation frame following options can be selected for
calculation:
- Minimum pressure inlet
- Flow
- Orifice (for controllers)
- Maximum pressure outlet (for sensors only)
If all other input parameters (pressure inlet, flow, orifice, pressure outlet) are entered, the selected parameter can be
calculated by pressing the Calculate button.
The result is shown below the graphical representation of the instrument. In case no warnings or errors have
occurred, it shows OK in green. A warning is indicated in orange, whereas an error turns the indicator red. An
explanation of the warning and/or error is given in the text frame at the bottom.
4.1.3.1 Minimum pressure inlet
When this option has been selected, the minimum pressure needed for a given flow and outlet (back) pressure will be
calculated.
4.1.3.2 Flow
When this option has been selected, the maximum possible flow through the sensor at a given inlet pressure and
outlet pressure will be calculated.
4.1.3.3 Orifice (controller only)
When this option has been selected, the orifice for the valve will be calculated and advised for a given flow, inlet
pressure and outlet pressure.
The advised orifice can be taken-over by pressing the /\-button. The program will switch into minimum pressure
calculation mode. After pressing Calculate again, the advised minimum inlet pressure needed for this orifice and flow
conditions will be calculated additionally (if possible).
Note
An important check here will be the pressure across the sensor in relation to the pressure across the valve to guarantee
a proper control function.
Some important rules of thumb:
- For liquids: pressure drop across valve >= 50% of total pressure drop across instrument
- For gases: pressure drop across valve >= 75% of total pressure drop across instrument (preferably)
pressure drop across valve >= 50% of total pressure drop across instrument (advice)