PlantWise Help

Equipment

Mass property attributes for equipment are: empty, fluid, and operating weights; empty, fluid, and operating centers-of-gravity; as well as empty, fluid, and operating moments-of inertia about the x, y, and z axes. To properly compute the fluid values, equipment also has commodity, density, volume, and fill level attributes.

There are three ways PlantWise can obtain equipment mass property attributes:
  1. Input (as described above) or import by the user,
  2. Equipment geometry rules (covered in Equipment Library section and Appendix C - Language Syntaxes), or
  3. Calculation from equipment attributes.

Importing Attribute Values

Equipment mass property attributes can be input via the equipment process (.rpe) file. The data is entered in the .rpe file as attribute value pairs following the comma delimited data. The same input attributes are used internally to store values entered via the PlantWise Mass Properties dialog.

Note:
  • These values are saved in internal units (inches or millimeters). See Units section for other Mass Property unit settings.
  • Center of gravity attributes are a list of x, y, z ordinate values.
  • The mp_fluid_commodity is a string and should be surrounded with quotation marks.
Empty Attributes Fluid Attributes Operating Attributes
mp_empty_weight mp_fluid_commodity mp_operating_weight
mp_empty_cg mp_fluid_density mp_operating_cg
mp_empty_mx mp_fluid_volume mp_operating_mx
mp_empty_my mp_fluid_fill_level mp_operating_mz
mp_empty_mz mp_fluid_cg mp_operating_mz
mp_fluid_mx
mp_fluid_my
mp_fluid_mz
Equipment attribute pairs are space delimited and use the following format: 
<mass property attribute> <value>
As an example, the input line for a piece of equipment that imports all of the mass property attributes could look like (note, line breaks are used for clarity only): 
tank2, storage, plain box, 15, MP_EMPTY_WEIGHT 100.0
		MP_EMPTY_CG (-2000.0 9000.0 2000.0)
		MP_EMPTY_CG (-2000.0 9000.0 2000.0)
		MP_EMPTY_MX 8.0e+7
		MP_EMPTY_MY 8.0e+7 
		MP_EMPTY_MZ 5.5e+7
		MP_FLUID_COMMODITY "SV"
		MP_FLUID_DENSITY 1.56e-7
		MP_FLUID_VOLUME 8.2e+10
		MP_FLUID_FILL_LEVEL 0.3
		MP_FLUID_CG (-3000.0 7000.0 5000.0)
		MP_FLUID_MX 2.2e+13
		MP_FLUID_MY 2.18e+13
		MP_FLUID_MZ 1.6e+13
		MP_OPERATING_WEIGHT 15000.0
		MP_OPERATING_CG (-2900.0 8550.0 4655.0)
		MP_OPERATING_MX 2.2e+11
		MP_OPERATING_MY 2.2e+12
		MP_OPERATING_MZ 8.76e+12

Order of Use

As there are multiple ways to provide PlantWise with equipment mass property attributes, the order PlantWise checks for attribute values are as follows:

Weight
  • Empty
    • user entry in dialog or in .rpe file (for more on importing mass property attributes see Importing Attribute Values).
    • mass property primitive (case = "empty")
    • equipment class weight attribute
  • Fluid
    • user entry in dialog or in .rpe file
    • mass property primitive (case = "empty")
    • calculated from density, volume, and fill level
  • Operating
    • user entry in dialog or in .rpe file
    • combined empty and fluid weights
  • Missing weight data will generate a warning on the equipment
Center of Gravity
  • Empty
    • user entry in dialog or in .rpe file
    • mass property primitive (case = "empty")
    • calculated center of volume for physical elements excluding text, service spaces, and obstacles
    • placement point of equipment
  • Fluid
    • user entry in dialog or in .rpe file
    • mass property primitive (case = "empty")
    • empty center of gravity
  • Operating
    • weighted combination of empty and fluid centers of gravity
Moment of Inertia
  • Empty or Fluid
    • user entry in dialog or in .rpe file
    • mass property primitive (case = "empty")
  • Operating
    • user entry in dialog or in .rpe file
    • combination of empty and fluid moments of inertia, using the parallel axis theorem
Note: when equipment is rotated about the vertical axis, all moment of inertia calculations for that equipment will be based on the nearest 90ยบ increment of that rotation as an approximation for the local moments about the principal axes.
Commodity
  • user entry in dialog or in .rpe file
  • mass property primitive
  • commodity of largest connected inlet pipeline
Density
  • user entry in dialog or in .rpe file
  • mass property primitive
  • lookup from commodity of largest connected intake pipeline
  • Project Setup constant for water (if water density is used instead of a known operating density, a warning will be generated)
Volume
  • user entry in dialog or in .rpe file
  • mass property primitive
Full Level
  • user entry in dialog or in .rpe file
  • mass property primitive
Parent topic: Mass Property Calculations