Fleisch Metabograph, 1960, Schematic

Metabographe_Fleisch_1960_Schematic_1

From “New methods of studying gaseous exchange and pulmonary function” by Alfred Fleisch, published by Charles C. Thomas, 1960, page 81

“Figure 22 shows a schematic representation of the air circuit.  The motor M operates the rotary blower 31 which drives the air into the chamber 42 where the CO2 is absorbed. After it has been freed of CO2 the air passes through the tube 33, the distributor 20 and the pipe 17. It reaches the mask 13 through the corrugated tube 14 and leaves it through the corrugated tube 15 and the pipe 30, returning to the blower 31. When the subject is not breathing, the air current does not flow through the double-partition spirometer 9-12 which is by passed. The bell 9 of the double spirometer is divided into two parts by the partition 10 and thus forms two chambers I and E for inspiration and expiration respectively. At inspiration the bell 9 is lowered and some of the air from chamber I passes through tubes 12 and 14 to the lungs; blower 31 draws an equal volume from the chamber E through tubes 11 and 30.  At expiration the air from the lungs fills the chamber E through the pipes 15 and 11, and the chamber I is filled with air coming from pipe 17 though the pipe 12; the bell 9 therefore rises.

“The partition 10 has a small opening in order that some air can always pass from the chamber I to the chamber E so that the latter can be free from CO2.

“The consumption of oxygen by the subject causes the bell 9 of the spirometer to fall slowly. As soon as the bell no longer closes the contact 7 at expiration, a greater quantity of oxygen is pumped into the system from a container through the junction 97 until the contact 7 is once again established.  By means of this automatic regulation the bell 9 tends to remain always at a mean position and the percentage of oxygen tends to remain constant. The quantity of oxygen which enters the system through the junction 97 is discussed in section G.

“After the mask has been fitted to the face of the subject, it often happens that the spirometer bell 9 is not a suitable height to operate the contact 7.  By pressing the button of the valve 16, atmospheric is admitted into the circuit so that the bell 9 rises. Conversely, pressure on the button of valve 16a expels so air and the bell falls.  When the bell 9 is at the right height to operate contact 7 the total volume of the circuit is 42 liters.”

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