View source for Template:PGM Class Example - calculate the Agitator Power required in a Vessel

The user wants to calculate the required agitator power in a number of vessels in a project.  This functionality will be used in a number of different projects, and hence the file with the class will be stored on the network where it can be accessed by a number of users and projects.

A formula that may be used to calculate the agitator power for turbulent flow is:

:<math>\mathbf{\mathit{P = P_o\;N^3\;D^5\;Density}}</math>
::where:
:: P - Agitation Power;
::P<sub>o</sub> - the dimensionless power number, which is a function of impeller geometry;
:: N - agitator rotational speed;
:: D - Diameter of the impeller;
:: Density - Density of the material in the vessel.

The class is saved in a file called '''AgitatorPower.pgm''' and is saved on the network at '''n:\Users\SysCAD Common Files\'''

{|border="1" cellpadding="5" cellspacing="0" style="width:85%"
|-
|<u>The Class file is as follows</u>: || <u>The main pgm file may have the following structure</u>:
|-
|Valign=top|

<syntaxhighlight lang="pgm">
Class    Class_AgitatorPower
  Textbreak
  ClassGridColumnWidth 12
  ClassGridMaxColumns 5
  TextLabel "Inputs"
  String   UnitName{Tag}*
  real     Po*<<1>>
  real     N<<0.3>>{i, comment("Rotation per second")}
  real     D<<1>>{i, ("L", "m"), comment("ImpellerDiameter")}
  TextLabel "Results"
  string   DensityTag@@{ Tag}
  real     Density@("Rho", "kg/m^3")
  real     Power@("Pwr", "kW")

  Sub Init()
	UnitName = ClassTag()
    DensityTag = Concatenate(UnitName, ".QProd.SLRho (kg/m^3)")
  EndSub

  Sub Exec()
    Density = [DensityTag]
    Power = Po * N^3 * D^5 * Density
  EndSub
EndClass
</syntaxhighlight>

*The class instance name is assumed to be the same as the SysCAD unit tag.  This is done inside the Sub Init().
|Valign=top style="width:50%"|
<syntaxhighlight lang="pgm">
PageLabel "Agitators" 
>>n:\Users\SysCAD Common Files\AgitatorPower.pgm
Textbreak
;Define class instances in grid format by adding "#"
Class_AgitatorPower # Cementation, NiCo_Precip, Ni_Diss_1

Sub InitialiseSolution()
  ForEachClass(Class_AgitatorPower, Init())
EndSub

ForEachClass(Class_AgitatorPower, Exec())
$ ; --- end of file ---

</syntaxhighlight> 
|}
And the access window of the controller will show the following fields:

[[Image:Class 1.png]]

Notes:
# The user may follow the same rules for individual functions that may be useful in a number of pgms or in separate projects.