ARCO In-Airid

These are pictures of an American Radiator Company invisible air vent used on one pipe steam radiators. This air vent screwed into the top bushing on the side opposite the inlet (supply) valve. It provided a very clean look to the radiator as the only part visible was the hex nut. The same look that any radiator would have with a plug installed in the same place.

The American Radiator Co. invisible air vent.

The opposite side.

A better view.

Note the thermostatic capsule in the middle. Thats the device that actually operates.

The air is expelled via a small hole which is at the base of an arrow that tells the installer which way to have the unit end up when he was putting it in. Arrow faces up.