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[bot]

Hi All,

I am involved in selecting PVVs (particulary sizes) for a refinery slop storage tank. I have already gone through the capacity calculation (both the inbreath and outbreath flow rates) in terms on SCFH of air.

All I am interested in is to find an estimated size of the relief valve(s).
If some say ' refer to API-2000 Section 4.6 Equation 4A or 4B', then my question would be, can we use it for both the cases i.e for vacuum and over pressure calcs (though it has to be just one valve offering same orifice area for both the cases).

The other part of my question would be,
If we are to use 4A or 4B, then what valves of M (Molecular Wt) & T (Temperature) do we need to use.

API-2000 define M & T as,
M = Molecular Wt of Test Medium
T = Abs temperature at Device Inlet

From this all, I collected that,
as SCFH is in terms of Air volume so therefore,
M = 28.96 (Air)
T = Ambient Temperature or Temperature of the testing media. (15 deg C , or Amb Temp)

Please help me address this as I am too much confused. I have googled this thing several time and read API-2000 a number of times to get me out of this but in vain.

Thanks.

[Art Montemayor]

Bot:

What do you mean by "PVVs" ? Please identify your acronyms. Different countries and locales have different interpretations for the same equipment.

Why don't you just download the workbooks I've prepared for just this type of exercise? All you have to do is read a few threads in this Forum and you will get the answers. I even supply the forms to do and document the calculations and identify the relief cases.