Looks almost identical to the McKesson Vitalor.  Photo is from a sales brochure courtesy of James Sullivan, BA, RPFT, Supervisor, Pulmonary Laboratories, Memorial Sloan Kettering Cancer Center.

“The simplest FVC tester. The vital capacity is measured up to 6 liters by a bellows made of rubber. Immediately after the start of respiration, the recording chart starts moving, for FEVt measurement. The waveform is recorded on roll type ordinary paper. Being small and light, it can be carried simply everywhere. A special stand is available on request.”