UL 142

[cougarfan]

I have a question -- we have a UL 142 tank which we will need to put a vacuum releif on and wanted to know if the standard allows these tanks any vacuum rating whatsoever . If none, then how does one put a vacuum relef on such a tank.....

 

[ccaserta]

I beleive the manufacture will provide some type of rating for vacuum pressure. I think the best thing to do is call them and get their rating information or suggestions for appropriate valves.

Christopher Caserta
ccaserta@us.tuv.com
Ph:904-225-0360

 

[EGT01]

Along the same lines as the original post in this thread, I'm having to validate the vent systems (2" and 6&quot on a 1500 gallon, horizontal UL-142 tank used for diesel storage. Unfortunately, that seems to be the only information that I can find in relation to the existing installation, no manufacturer, no design pressures, no venting requirements marked on the tank.

The vent sizes seem appropriate per the tables in UL-142 except the 2" vent has a flame arrestor elevated some distance above the tank and I wanted to look closer at the inbreathing design.

Looking at the Glossary section for UL-142, they indicate certain definitions that apply for the purpose of the standard including

3.2 ATMOSPHERIC TANK – A storage tank that has been designed to operate at pressures from -0.5 psig (-3.4 kPa) through 1.0 psig (6.8 kPa) measured at the top of the tank.

From the above language, could one conclude that an atmospheric tank built to UL-142 would have at least a rating of -0.5 psig and 1.0 psig as an indication of its external and internal MAWP?