UL 142
UL 142
(OP)
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.....





RE: UL 142
Christopher Caserta
ccaserta@us.tuv.com
Ph:904-225-0360
RE: UL 142
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?