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[ryn376]

I am trying to calculate the required venting (outbreathing) rate for an 18% Brine storage tank with a liquid temperature of 160 F (Pvapor = 4.2 psia). Please help me to understand a confusing point for me in API 2000.

 

According to Section 4.3.2.2.1 c) "For products stored above 40 °C (104 °F) or with a vapour pressure greater than 5,0 kPa (0,73 psi), increase the out-breathing by the evaporation rate." I would assume this means a vapor pressure of 0.73 psia since this is a vapor pressure value, but I would assume that it is psig  since the vapor pressure of hexane is 2.9 psia at 77 F? Which is correct?

 

Also, since the brine is stored at 160 F, can I use Equations (17) and (18) in section 5.2.1.3 to calculate the additional venting as indicated in Section © above?

 

Eqn 17: X_gas = 1 - exp[C_p*(T₂-T₁)/L]

Eqn 18: V_F = X_gas * m_pf

Edited by ryn376, 22 June 2015 - 08:33 AM.