TORONTO, (April 27, 2004) — The U.S. DOT’s Research Special Programs Administration (RSPA) has reversed a previous interpretation and now says that top vents and bottom drains must be kept open on specification tanks with double bulkheads or void spaces.

The Ontario Trucking Association is notifying cross-border members of RSPA’s amendment, which states: “sections 178.340-7 (c), 178.345-1(i)(2), and 178.345.3 require any MC300 or DOT400 cargo void or airspace to be vented and equipped with a drain, located on the bottom the bottom centerline, that is accessible and open at all times.”

Many carriers plug the top vent to prevent water from accumulating between bulkheads. However, RSPA believes this practice negates the role of the vent in allowing vapors to escape if there is a leak. RSPA adds that “Use of a hat device to keep out debris while maintaining an open vent and drain, thus allowing for vapors to escape, would be permissible.”