Abstract: A seal for a gas treatment hood assembly is disclosed. The hood assembly is placeable over a user's head for treating a user with a gas such as oxygen. The assembly may have a neck ring around a user's neck with an elastomeric, tubular neck seal with one end of the neck seal connected to the neck ring and the other end configured to fit around the user's neck. The neck seal may have a double sealing element construction and may also have variable thickness along a sidewall for enhanced structural properties and improved patient comfort. The seal and hood assembly may be used in providing oxygen to a patient in a hyperbaric chamber.

Abstract: A breathing mask is disclosed, as well as a valve and a diverter that can be used within a breathing mask. The breathing mask can include a body, a respiratory interface, a balanced exhaust valve, and an inlet valve. The body can include an inlet and an exhaust. The respiratory interface can be configured to provide fluid communication between each of the inlet and the exhaust, and a user's respiratory system. The balanced exhaust valve can be configured to selectively flow fluid between the exhaust and the respiratory interface. The inlet valve can be configured to selectively flow fluid between the inlet and the respiratory interface. The valve can be a balanced exhaust valve with a fixed balance chamber. The diverter can include a tubular diverter body, a breathing port, an exhaust port, a demand port, and a diverter wall.