## Tags and keywords

This diagram shows the Block

`VaporPressureCalculation`

with a supporting ConstraintBlock `VaporPressureCalculationConstraint`

:The Constraint equation is:

`{pressure=vapor*(gasConst*((roomTemp+celciusOff)/(molecularW*volume)))}`

If you compare that with the famous `P⋅V = n⋅R⋅T`

ideal gas law, where n is the number of moles and `R = 8.314 J/(K⋅mol)`

you get:
`pressure*volume=(vapor/molecularW)*gasConst*(roomTemp+celciusOff)`

This implies `vapor/molecularW`

is just equivalent to the number of moles `n`

. But this makes no sense if "vapor" is elsewhere a rate mL/s, it only makes sense if "vapor" is a mass (in g).

Aha, maybe they've used a sneaky not-quite-accurate * trick in the spec equation:*

As it happens, 1 mL of water at most temperatures and pressures does not have a mass of exactly 1g. But even if the "vapor" were taken as g/s then the dimensional analysis suggests there is a major problem, you'd end up with the output being a pressure **rate**:

If you assume the

`volume`

is litres (L) the dimensional analysis is off by a factor of 1000.
So it seems this assumption used in this trail is correct:

And we are indeed dealing with a commercial humidifier for a large building, not a "humidified room":

## Notes

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