Storage tank breather vent

[handee]

Hi - this seems like it coule be an extremely useful new forum!

My application is a simple one - 5000 gal SS atmospheric storage tank for non-flammable liquid. Well be filling it at about 100 gpm and draining it at about 30 gpm. I simply need a breather vent to let the air out when filling, and let the air in when draining (its a little smelly so we'll be venting it to the roof).

My supplier has specified a $500 53-lb Crispin dual vacuum and pressure air release valve that looks awufully complicated to me for the required duty. Does someone have experience with a simpler breather vent valve?

Thanks!

Fran McConville

 

[sshep]

Hello fxm,
Although you have recieved comments in the opns forum, I would like to add these considerations:

1) The primary function of PVSVs is to reduce evaporation losses vs diffusion out an open vent. As a result of neccessarily small deadband settings, these devices have a pretty minor impact on working losses or thermal breathing. These outbreathins may be the more odorous events if the material is not very volatile, and the PVSV may not help much. If the tank is to be padded with N2 (or other) then a PVSV is needed to conserve pad gas but this doesn't seem to be your case.
2) The inbreathing basis will probably be set by a large volume draining as previously noted- the largest drain nozzle should be considered. Other cases include thermal inbreathing per API2000 (if applicable).
3) The outbreathing basis will probably be set by fire. Other cases include pump-in, blanket regulator failure, and thermal outbreathing also per API2000.
4) A simple goose neck vent may be the most economical solution if you need to keep out rain. Otherwise you don't really need anything but an open nozzle, or a standpipe to the roof.

There is such a large fraction of relief quest that I have some hope that this will be a useful forum. Your help to get this going is appreciated.

best wishes, sshep

 

[TSeener]

FXM,
I am in agreement with sshep, because it would be an "atomospheric" tank, it would typically be governed by API 2000 (you should review this and determine if your situation is covered by this code). I think the only advice that I would provide you that has not already been covered here and elsewhere, is that if you specify a gooseneck, please do not forget the screen...

Best Regards,

TSeener