Symbol Ventilator Metal Sign

About the Ventilator design

The box at the top holds a plain hollow rectangle inside its rounded shell, with a stubby nub sticking off one side like the pin on a battery. A tube leaves its left corner, loops down in a lazy S, then drops dead straight into a long crescent that sweeps the whole bottom width. That crescent ends in a thick open ring on the left, while the right tip kicks upward and gets crossed by a short diagonal, a small x hanging off the end of the curve.