"It was flushed into the drainage system that leads to an oil water separator that is valved off from the detention basin," Mura said.

He immediately switched from the baritone horn, a valved instrument, to trombone.

Even so, valved respirator masks are not allowed in sterile medical environments because they allow the wearer’s germs to escape.

Concern about dangerous leakage in valved masks is unfounded in both directions –– both inflow and outflow.

Mr. Sax patented his family of valved brass instruments in 1846, as militarism was sweeping Europe.