Thanks. I have the same debate raging within my head right now.
I would like to point out that vne is right in pointing out that there is an error in Ankur's spreadsheet. The spreadsheet programming is incorrect.
<QUOTE>
Inbreathing
Emptying (pump-out) and ambient cooling will lead to normal inbreathing. General equation to determine inbreathing flow :
Vin,air = Vpe + CVtk0.7 Ri
where
Vin,air = Total inbreathing in Nm3/h (Air)
Vpe = Pump-out or emptying in m3/h
Vtk = Tank capacity in m3
Ri = Insulation reduction factor
C = Factor subject to vapor pressure, average temperature and latitude (see Table 1)
<UNQUOTE>
Neglecting the thermal side of it, the equation gives:
Vin,air = Vpe
where
Vin,air = Total inbreathing in Nm3/h (Air)
Vpe = Pump-out or emptying in m3/h
This is incorrect unit-wise and inconsistent with API STD 2000 (2009). Vin, air for pump out is also in m3/h and not Nm3/h
It is the same for outbreathing.
<QUOTE>
Outbreathing
Filling (pump-out) and ambient heating will lead to normal outbreathing. General equation to determine outbreathing flow :
Vout,air = Vpf + YVtk0.9 Ri
where
Vout,air = Total Outbreathing in Nm3/h (Air)
Vpf = Pump-out or filling in m3/h
Vtk = Tank capacity in m3
Ri = Insulation reduction factor
Y = Factor subject to latitude (see Table 2)
<UNQUOTE>
Neglecting the thermal outbreathing portion the equation gives:
Vout,air = Vpf
where
Vout,air = Total Outbreathing in Nm3/h (Air)
Vpf = Pump-out or filling in m3/h
This is again incorrect as they are equal unit wise. Vout,air during pump-out or filling in are equal in terms of m3/h and NOT Nm3/h.
You can double check API STD 2000 (2009) again.
Edited by tanykiat, 03 December 2014 - 05:57 AM.