NOTE: I have received many requests from all over the world about information on the Army Emergency Respirator from Harry Diamond Labs. In order to help the engineers out there I have posted schematics, additional photos, and patent info that you might find helpful. It is important to note that the inventor of this apparatus was Henrik H. Straub — an aeronautical engineer at H.D.L, the respirator is essentially a bistable fluid amplifier. Also to those who have asked for it—this piece went to a bio engineer in California who is planning to 3D scan the piece for open sourcing. Original posting info below:

The Army Emergency Respirator operates without moving parts , yet can can perform complex resucitative fuctions. A fluid amplifier is attached to a face mask a feedback line in the respirator senses the gas pressure within the face mask, and cases the respiraror to cycle between a predetermined range of positive and negative pressure. The device can breath with or for the patient. A very rare piece of medical engineering that is most likely prototype / working model from Harry Diamond Laboratories.